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619 Publications visible to you, out of a total of 619

Abstract (Expand)

Bacillus subtilis possesses interlinked routes for the synthesis of proline. The ProJ-ProA-ProH route is responsible for the production of proline as an osmoprotectant, and the ProB-ProA-ProI route provides proline for protein synthesis. We show here that the transcription of the anabolic proBA and proI genes is controlled in response to proline limitation via a T-box-mediated termination/antitermination regulatory mechanism, a tRNA-responsive riboswitch. Primer extension analysis revealed mRNA leader transcripts of 270 and 269 nt for the proBA and proI genes, respectively, both of which are synthesized from SigA-type promoters. These leader transcripts are predicted to fold into two mutually exclusive secondary mRNA structures, forming either a terminator or an antiterminator configuration. Northern blot analysis allowed the detection of both the leader and the full-length proBA and proI transcripts. Assessment of the level of the proBA transcripts revealed that the amount of the full-length mRNA species strongly increased in proline-starved cultures. Genetic studies with a proB-treA operon fusion reporter strain demonstrated that proBA transcription is sensitively tied to proline availability and is derepressed as soon as cellular starvation for proline sets in. Both the proBA and the proI leader sequences contain a CCU proline-specific specifier codon prone to interact with the corresponding uncharged proline-specific tRNA. By replacing the CCU proline specifier codon in the proBA T-box leader with UUC, a codon recognized by a Phe-specific tRNA, we were able to synthetically re-engineer the proline-specific control of proBA transcription to a control that was responsive to starvation for phenylalanine.

Authors: Jeanette Brill, , Harald Putzer,

Date Published: 13th Jan 2011

Publication Type: Not specified

Abstract (Expand)

Glycolysis is the main pathway for ATP production in the malaria parasite Plasmodium falciparum and essential for its survival. Following a sensitivity analysis of a detailed kinetic model for glycolysis in the parasite, the glucose transport reaction was identified as the step whose activity needed to be inhibited to the least extent to result in a 50% reduction in glycolytic flux. In a subsequent inhibitor titration with cytochalasin B, we confirmed the model analysis experimentally and measured a flux control coefficient of 0.3 for the glucose transporter. In addition to the glucose transporter, the glucokinase and phosphofructokinase had high flux control coefficients, while for the ATPase a small negative flux control coefficient was predicted. In a broader comparative analysis of glycolytic models, we identified a weakness in the P. falciparum pathway design with respect to stability towards perturbations in the ATP demand.

Authors: David D. van Niekerk, Gerald P. Penkler, Francois du Toit, Jacky L. Snoep

Date Published: 1st Feb 2016

Publication Type: Not specified

Abstract (Expand)

Coronaviruses (CoVs) are a group of enveloped, single-stranded positive genomic RNA viruses and some of them are known to cause severe respiratory diseases in human, including Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS) and the ongoing coronavirus disease-19 (COVID-19). One key element in viral infection is the process of viral entry into the host cells. In the last two decades, there is increasing understanding on the importance of the endocytic pathway and the autophagy process in viral entry and replication. As a result, the endocytic pathway including endosome and lysosome has become important targets for development of therapeutic strategies in combating diseases caused by CoVs. In this mini-review, we will focus on the importance of the endocytic pathway as well as the autophagy process in viral infection of several pathogenic CoVs inclusive of SARS-CoV, MERS-CoV and the new CoV named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and discuss the development of therapeutic agents by targeting these processes. Such knowledge will provide important clues for control of the ongoing epidemic of SARS-CoV-2 infection and treatment of COVID-19.

Authors: Naidi Yang, Han-Ming Shen

Date Published: 2020

Publication Type: Journal

Abstract (Expand)

The circadian clock coordinates plant physiology and development. Mathematical clock models have provided a rigorous framework to understand how the observed rhythms emerge from disparate, molecular processes. However, models of the plant clock have largely been built and tested against RNA timeseries data in arbitrary, relative units. This limits model transferability, refinement from biochemical data and applications in synthetic biology. Here, we incorporate absolute mass units into a detailed, gene circuit model of the clock in Arabidopsis thaliana. We re-interpret the established P2011 model, highlighting a transcriptional activator that overlaps the function of REVEILLE 8/LHY-CCA1-LIKE 5, and refactor dynamic equations for the Evening Complex. The U2020 model incorporates the repressive regulation of PRR genes, a key feature of the most detailed clock model F2014, without greatly increasing model complexity. We tested the experimental error distributions of qRT-PCR data calibrated for units of RNA transcripts/cell and of circadian period estimates, in order to link the models to data more appropriately. U2019 and U2020 models were constrained using these data types, recreating previously-described circadian behaviours with RNA metabolic processes in absolute units. To test their inferred rates, we estimated a distribution of observed, transcriptome-wide transcription rates (Plant Empirical Transcription Rates, PETR) in units of transcripts/cell/hour. The PETR distribution and the equivalent degradation rates indicated that the models’ predicted rates are biologically plausible, with individual exceptions. In addition to updated, explanatory models of the plant clock, this validation process represents an advance in biochemical realism for models of plant gene regulation.

Authors: Uriel Urquiza-Garcia, Andrew J Millar

Date Published: 20th Mar 2021

Publication Type: Tech report

Abstract (Expand)

The circadian clock coordinates plant physiology and development. Mathematical clock models have provided a rigorous framework to understand how the observed rhythms emerge from disparate, molecular processes. However, models of the plant clock have largely been built and tested against RNA timeseries data in arbitrary, relative units. This limits model transferability, refinement from biochemical data and applications in synthetic biology. Here, we incorporate absolute mass units into a detailed model of the clock gene network in Arabidopsis thaliana. We re-interpret the established P2011 model, highlighting a transcriptional activator that overlaps the function of REVEILLE 8/LHY-CCA1-LIKE 5. The U2020 model incorporates the repressive regulation of PRR genes, a key feature of the most detailed clock model KF2014, without greatly increasing model complexity. We tested the experimental error distributions of qRT-PCR data calibrated for units of RNA transcripts/cell and of circadian period estimates, in order to link the models to data more appropriately. U2019 and U2020 models were constrained using these data types, recreating previously-described circadian behaviours with RNA metabolic processes in absolute units. To test their inferred rates, we estimated a distribution of observed, transcriptome-wide transcription rates (Plant Empirical Transcription Rates, PETR) in units of transcripts/cell/hour. The PETR distribution and the equivalent degradation rates indicated that the models’ predicted rates are biologically plausible, with individual exceptions. In addition to updated clock models, FAIR data resources and a software environment in Docker, this validation process represents an advance in biochemical realism for models of plant gene regulation.

Authors: Uriel Urquiza Garcia, Andrew J Millar

Date Published: 5th Aug 2021

Publication Type: Journal

Abstract (Expand)

SUMMARY: TFInfer is a novel open access, standalone tool for genome-wide inference of transcription factor activities from gene expression data. Based on an earlier MATLAB version, the software has now been extended in a number of ways. It has been significantly optimised in terms of performance, and it was given novel functionality, by allowing the user to model both time series and data from multiple independent conditions. With a full documentation and intuitive graphical user interface, together with an in-built data base of yeast and Escherichia coli transcription factors, the software does not require any mathematical or computational expertise to be used effectively. AVAILABILITY: http://homepages.inf.ed.ac.uk/gsanguin/TFInfer.html CONTACT: gsanguin@staffmail.ed.ac.uk SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Authors: H M Shahzad Asif, , , Neil D Lawrence, Magnus Rattray,

Date Published: 24th Aug 2010

Publication Type: Not specified

Abstract (Expand)

Predicting a multicellular organism’s phenotype quantitatively from its genotype is challenging, as genetic effects must propagate across scales. Circadian clocks are intracellular regulators that control temporal gene expression patterns and hence metabolism, physiology and behaviour. Here we explain and predict canonical phenotypes of circadian timing in a multicellular, model organism. We used diverse metabolic and physiological data to combine and extend mathematical models of rhythmic gene expression, photoperiod-dependent flowering, elongation growth and starch metabolism within a Framework Model for the vegetative growth of Arabidopsis thaliana, sharing the model and data files in a structured, public resource. The calibrated model predicted the effect of altered circadian timing upon each particular phenotype in clock-mutant plants under standard laboratory conditions. Altered night-time metabolism of stored starch accounted for most of the decrease in whole-plant biomass, as previously proposed. Mobilization of a secondary store of malate and fumarate was also mis-regulated, accounting for any remaining biomass defect. The three candidate mechanisms tested did not explain this organic acid accumulation. Our results link genotype through specific processes to higher-level phenotypes, formalizing our understanding of a subtle, pleiotropic syndrome at the whole-organism level, and validating the systems approach to understand complex traits starting from intracellular circuits.

Authors: Yin Hoon Chew, Daniel D Seaton, Virginie Mengin, Anna Flis, Sam T Mugford, Gavin M George, Michael Moulin, Alastair Hume, Samuel C Zeeman, Teresa B Fitzpatrick, Alison M Smith, Mark Stitt, Andrew J Millar

Date Published: 1st Jul 2022

Publication Type: Journal

Abstract (Expand)

Predicting a multicellular organism’s phenotype quantitatively from its genotype is challenging, as genetic effects must propagate across scales. Circadian clocks are intracellular regulators that control temporal gene expression patterns and hence metabolism, physiology and behaviour. Here we explain and predict canonical phenotypes of circadian timing in a multicellular, model organism. We used diverse metabolic and physiological data to combine and extend mathematical models of rhythmic gene expression, photoperiod-dependent flowering, elongation growth and starch metabolism within a Framework Model for the vegetative growth of Arabidopsis thaliana, sharing the model and data files in a structured, public resource. The calibrated model predicted the effect of altered circadian timing upon each particular phenotype in clock-mutant plants under standard laboratory conditions. Altered night-time metabolism of stored starch accounted for most of the decrease in whole-plant biomass, as previously proposed. Mobilisation of a secondary store of malate and fumarate was also mis-regulated, accounting for any remaining biomass defect. We test three candidate mechanisms for the accumulation of these organic acids. Our results link genotype through specific processes to higher-level phenotypes, formalising our understanding of a subtle, pleiotropic syndrome at the whole-organism level, and validating the systems approach to understand complex traits starting from intracellular circuits. This work updates the first biorXiv version, February 2017,with an expanded description and additional analysis of the same core data sets and the same FMv2 model, summary tables and supporting, follow-on data from three further studies with further collaborators. This biorXiv revision constitutes the second version of this report.

Authors: Yin Hoon Chew, Daniel D. Seaton, Virginie Mengin, Anna Flis, Sam T. Mugford, Gavin M. George, Michael Moulin, Alastair Hume, Samuel C. Zeeman, Teresa B. Fitzpatrick, Alison M. Smith, Mark Stitt, Andrew J. Millar

Date Published: 6th Feb 2017

Publication Type: Tech report

Abstract (Expand)

The whole-genome duplication 80 million years ago of the common ancestor of salmonids (salmonid-specific fourth vertebrate whole-genome duplication, Ss4R) provides unique opportunities to learn about the evolutionary fate of a duplicated vertebrate genome in 70 extant lineages. Here we present a high-quality genome assembly for Atlantic salmon (Salmo salar), and show that large genomic reorganizations, coinciding with bursts of transposon-mediated repeat expansions, were crucial for the post-Ss4R rediploidization process. Comparisons of duplicate gene expression patterns across a wide range of tissues with orthologous genes from a pre-Ss4R outgroup unexpectedly demonstrate far more instances of neofunctionalization than subfunctionalization. Surprisingly, we find that genes that were retained as duplicates after the teleost-specific whole-genome duplication 320 million years ago were not more likely to be retained after the Ss4R, and that the duplicate retention was not influenced to a great extent by the nature of the predicted protein interactions of the gene products. Finally, we demonstrate that the Atlantic salmon assembly can serve as a reference sequence for the study of other salmonids for a range of purposes.

Authors: S. Lien, B. F. Koop, S. R. Sandve, J. R. Miller, M. P. Kent, T. Nome, T. R. Hvidsten, J. S. Leong, D. R. Minkley, A. Zimin, F. Grammes, H. Grove, A. Gjuvsland, B. Walenz, R. A. Hermansen, K. von Schalburg, E. B. Rondeau, A. Di Genova, J. K. Samy, J. Olav Vik, M. D. Vigeland, L. Caler, U. Grimholt, S. Jentoft, D. Inge Vage, P. de Jong, T. Moen, M. Baranski, Y. Palti, D. R. Smith, J. A. Yorke, A. J. Nederbragt, A. Tooming-Klunderud, K. S. Jakobsen, X. Jiang, D. Fan, Y. Hu, D. A. Liberles, R. Vidal, P. Iturra, S. J. Jones, I. Jonassen, A. Maass, S. W. Omholt, W. S. Davidson

Date Published: 18th Apr 2016

Publication Type: Not specified

Abstract (Expand)

Sulfolobus solfataricus P2 grows on different carbohydrates as well as alcohols, peptides and amino acids. Carbohydrates such as D-glucose or D-galactose are degraded via the modified, branched Entner-Doudoroff (ED) pathway whereas growth on peptides requires the Embden-Meyerhof-Parnas (EMP) pathway for gluconeogenesis. As for most hyperthermophilic Archaea an important control point is established at the level of triosephophate conversion, however, the regulation at the level of pyruvate/phosphoenolpyruvate conversion was not tackled so far. Here we describe the cloning, expression, purification and characterization of the pyruvate kinase (PK, SSO0981) and the phosphoenolpyruvate synthetase (PEPS, SSO0883) of Sul. solfataricus. The PK showed only catabolic activity [catalytic efficiency (PEP): 627.95 mM(-1)s(-1), 70 degrees C] with phosphoenolpyruvate as substrate and ADP as phosphate acceptor and was allosterically inhibited by ATP and isocitrate (K i 0.8 mM). The PEPS was reversible, however, exhibited preferred activity in the gluconeogenic direction [catalytic efficiency (pyruvate): 1.04 mM(-1)s(-1), 70 degrees C] and showed some inhibition by AMP and alpha-ketoglutarate. The gene SSO2829 annotated as PEPS/pyruvate:phosphate dikinase (PPDK) revealed neither PEPS nor PPDK activity. Our studies suggest that the energy charge of the cell as well as the availability of building blocks in the citric acid cycle and the carbon/nitrogen balance plays a major role in the Sul. solfataricus carbon switch. The comparison of regulatory features of well-studied hyperthermophilic Archaea reveals a close link and sophisticated coordination between the respective sugar kinases and the kinetic and regulatory properties of the enzymes at the level of PEP-pyruvate conversion.

Authors: P. Haferkamp, B. Tjaden, L. Shen, C. Brasen, T. Kouril, B. Siebers

Date Published: 30th Apr 2019

Publication Type: Journal

Abstract (Expand)

How an organism copes with chemicals is largely determined by the genes and proteins that collectively function to defend against, detoxify and eliminate chemical stressors. This integrative network includes receptors and transcription factors, biotransformation enzymes, transporters, antioxidants, and metal- and heat-responsive genes, and is collectively known as the chemical defensome. Teleost fish is the largest group of vertebrate species and can provide valuable insights into the evolution and functional diversity of defensome genes. We have previously shown that the xenosensing pregnane x receptor (pxr, nr1i2) is lost in many teleost species, including Atlantic cod (Gadus morhua) and three-spined stickleback (Gasterosteus aculeatus), but it is not known if compensatory mechanisms or signaling pathways have evolved in its absence. In this study, we compared the genes comprising the chemical defensome of five fish species that span the teleosteii evolutionary branch often used as model species in toxicological studies and environmental monitoring programs: zebrafish (Danio rerio), medaka (Oryzias latipes), Atlantic killifish (Fundulus heteroclitus), Atlantic cod, and three-spined stickleback. Genome mining revealed evolved differences in the number and composition of defensome genes that can have implication for how these species sense and respond to environmental pollutants, but we did not observe any candidates of compensatory mechanisms or pathways in cod and stickleback in the absence of pxr. The results indicate that knowledge regarding the diversity and function of the defensome will be important for toxicological testing and risk assessment studies.

Authors: Marta Eide, Xiaokang Zhang, Odd André Karlsen, Jared V. Goldstone, John Stegeman, Inge Jonassen, Anders Goksøyr

Date Published: 1st Dec 2021

Publication Type: Journal

Abstract (Expand)

The plant circadian clock generates rhythms with a period close to 24 h, and it controls a wide range of physiological and developmental oscillations in habitats under natural light/dark cycles. Among clock-controlled developmental events, the best characterized is the photoperiodic control of flowering time in Arabidopsis thaliana. Recently, it was also reported that the clock regulates a daily and rhythmic elongation of hypocotyls. Here, we report that the promotion of hypocotyl elongation is in fact dependent on changes in photoperiods in such a way that an accelerated hypocotyl elongation occurs especially under short-day conditions. In this regard, we provide genetic evidence to show that the circadian clock regulates the photoperiodic (or seasonal) elongation of hypocotyls by modulating the expression profiles of the PIF4 and PIF5 genes encoding phytochrome-interacting bHLH (basic helix-loop-helix) factors, in such a manner that certain short-day conditions are necessary to enhance the expression of these genes during the night-time. In other words, long-day conditions are insufficient to open the clock-gate for triggering the expression of PIF4 and PIF5 during the night-time. Based on these and other results, the photoperiodic control of hypocotyl elongation is best explained by the accumulation of PIF4 and PIF5 during the night-time of short days, due to coincidence between the internal (circadian rhythm) and external (photoperiod) time cues. This mechanism is a mirror image of the photoperiod-dependent promotion of flowering in that plants should experience long-day conditions to initiate flowering promptly. Both of these clock-mediated coincidence mechanisms may coordinately confer ecological fitness to plants growing in natural habitats with varied photoperiods.

Authors: Y. Niwa, T. Yamashino, T. Mizuno

Date Published: 24th Feb 2009

Publication Type: Not specified

Abstract (Expand)

Circadian clocks synchronise biological processes with the day/night cycle, using molecular mechanisms that include interlocked, transcriptional feedback loops. Recent experiments identified the evening complex (EC) as a repressor that can be essential for gene expression rhythms in plants. Integrating the EC components in this role significantly alters our mechanistic, mathematical model of the clock gene circuit. Negative autoregulation of the EC genes constitutes the clock's evening loop, replacing the hypothetical component Y. The EC explains our earlier conjecture that the morning gene Pseudo-Response Regulator 9 was repressed by an evening gene, previously identified with Timing Of CAB Expression1 (TOC1). Our computational analysis suggests that TOC1 is a repressor of the morning genes Late Elongated Hypocotyl and Circadian Clock Associated1 rather than an activator as first conceived. This removes the necessity for the unknown component X (or TOC1mod) from previous clock models. As well as matching timeseries and phase-response data, the model provides a new conceptual framework for the plant clock that includes a three-component repressilator circuit in its complex structure.

Authors: A. Pokhilko, A. P. Fernandez, K. D. Edwards, M. M. Southern, K. J. Halliday, A. J. Millar

Date Published: 6th Mar 2012

Publication Type: Not specified

Abstract

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Authors: Christiane A. Opitz, Pauline Holfelder, Mirja Tamara Prentzell, Saskia Trump

Date Published: 1st Oct 2023

Publication Type: Journal

Abstract

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Author: Stuart G. Siddell

Date Published: 1995

Publication Type: InCollection

Abstract (Expand)

DEAD-box RNA helicases play important roles in remodeling RNA molecules and in facilitating a variety of RNA-protein interactions that are key to many essential cellular processes. In spite of the importance of RNA, our knowledge about RNA helicases is only limited. In this study we investigated the role of the four DEAD-box RNA helicases in Gram positive model-organism Bacillus subtilis. A strain deleted of all RNA helicases is able to grow at 37°C but not at lower temperatures. Especially the deletion of cshA, cshB or yfmL lead to cold-sensitive phenotypes. Moreover, these mutant strains exhibit unique defects in ribosome biogenesis suggesting distinct functions for the individual enzymes in this process. Based on protein accumulation, severity of the cold-sensitive phenotype and the interaction with components of the RNA degradosome, CshA is the major RNA helicase of B. subtilis. To unravel the functions of CshA in addition to ribosome biogenesis we conducted microarray analysis and identified the ysbAB and frlBONMD mRNAs as targets that are strongly affected by the deletion of the cshA gene. Our findings suggest that the different helicases make distinct contributions to the physiology of B. subtilis. Ribosome biogenesis and RNA degradation are two of their major tasks in B. subtilis.

Authors: Martin Lehnik-Habrink, Leonie Rempeters, Akos T Kovács, Christoph Wrede, Claudia Baierlein, Heike Krebber, ,

Date Published: 24th Nov 2012

Publication Type: Not specified

Abstract

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Authors: Yumiko Imai, Keiji Kuba, Josef M. Penninger

Date Published: 1st May 2008

Publication Type: Journal

Abstract (Expand)

BACKGROUND: During the lifetime of a fermenter culture, the soil bacterium S. coelicolor undergoes a major metabolic switch from exponential growth to antibiotic production. We have studied gene expression patterns during this switch, using a specifically designed Affymetrix genechip and a high-resolution time-series of fermenter-grown samples. RESULTS: Surprisingly, we find that the metabolic switch actually consists of multiple finely orchestrated switching events. Strongly coherent clusters of genes show drastic changes in gene expression already many hours before the classically defined transition phase where the switch from primary to secondary metabolism was expected. The main switch in gene expression takes only 2 hours, and changes in antibiotic biosynthesis genes are delayed relative to the metabolic rearrangements. Furthermore, global variation in morphogenesis genes indicates an involvement of cell differentiation pathways in the decision phase leading up to the commitment to antibiotic biosynthesis. CONCLUSIONS: Our study provides the first detailed insights into the complex sequence of early regulatory events during and preceding the major metabolic switch in S. coelicolor, which will form the starting point for future attempts at engineering antibiotic production in a biotechnological setting.

Authors: , Florian Battke, Alexander Herbig, , , , , , , , , Edward R Morrissey, Miguel A Juarez-Hermosillo, , Merle Nentwich, , Mudassar Iqbal, , , , , , , , Michael Bonin, , , , , , , , , ,

Date Published: 28th May 2009

Publication Type: Not specified

Abstract (Expand)

The new decade of the 21 st century (2020) started with the emergence of novel coronavirus known as SARS-CoV-2 that caused an epidemic of coronavirus disease (COVID-19) in Wuhan, China. It is the third highly pathogenic and transmissible coronavirus after severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) emerged in humans. The source of origin, transmission to humans and mechanisms associated with the pathogenicity of SARS-CoV-2 are not clear yet, however, its resemblance with SARS-CoV and several other bat coronaviruses was recently confirmed through genome sequencing related studies. The development of therapeutic strategies is necessary in order to prevent further epidemics and cure infected people. In this Review, we summarize current information about the emergence, origin, diversity, and epidemiology of three pathogenic coronaviruses with a specific focus on the current outbreak in Wuhan, China. Furthermore, we discuss the clinical features and potential therapeutic options that may be effective against SARS-CoV-2.

Authors: Suliman Khan, Rabeea Siddique, Muhammad Adnan Shereen, Ashaq Ali, Jianbo Liu, Qian Bai, Nadia Bashir, Mengzhou Xue

Date Published: 11th Mar 2020

Publication Type: Journal

Abstract

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Authors: Mark D. Wilkinson, Michel Dumontier, IJsbrand Jan Aalbersberg, Gabrielle Appleton, Myles Axton, Arie Baak, Niklas Blomberg, Jan-Willem Boiten, Luiz Bonino da Silva Santos, Philip E. Bourne, Jildau Bouwman, Anthony J. Brookes, Tim Clark, Mercè Crosas, Ingrid Dillo, Olivier Dumon, Scott Edmunds, Chris T. Evelo, Richard Finkers, Alejandra Gonzalez-Beltran, Alasdair J.G. Gray, Paul Groth, Carole Goble, Jeffrey S. Grethe, Jaap Heringa, Peter A.C ’t Hoen, Rob Hooft, Tobias Kuhn, Ruben Kok, Joost Kok, Scott J. Lusher, Maryann E. Martone, Albert Mons, Abel L. Packer, Bengt Persson, Philippe Rocca-Serra, Marco Roos, Rene van Schaik, Susanna-Assunta Sansone, Erik Schultes, Thierry Sengstag, Ted Slater, George Strawn, Morris A. Swertz, Mark Thompson, Johan van der Lei, Erik van Mulligen, Jan Velterop, Andra Waagmeester, Peter Wittenburg, Katherine Wolstencroft, Jun Zhao, Barend Mons

Date Published: 15th Mar 2016

Publication Type: Not specified

Abstract (Expand)

There is an urgent need to improve the infrastructure supporting the reuse of scholarly data. A diverse set of stakeholders-representing academia, industry, funding agencies, and scholarly publishers-have come together to design and jointly endorse a concise and measureable set of principles that we refer to as the FAIR Data Principles. The intent is that these may act as a guideline for those wishing to enhance the reusability of their data holdings. Distinct from peer initiatives that focus on the human scholar, the FAIR Principles put specific emphasis on enhancing the ability of machines to automatically find and use the data, in addition to supporting its reuse by individuals. This Comment is the first formal publication of the FAIR Principles, and includes the rationale behind them, and some exemplar implementations in the community.

Authors: M. D. Wilkinson, M. Dumontier, I. J. Aalbersberg, G. Appleton, M. Axton, A. Baak, N. Blomberg, J. W. Boiten, L. B. da Silva Santos, P. E. Bourne, J. Bouwman, A. J. Brookes, T. Clark, M. Crosas, I. Dillo, O. Dumon, S. Edmunds, C. T. Evelo, R. Finkers, A. Gonzalez-Beltran, A. J. Gray, P. Groth, C. Goble, J. S. Grethe, J. Heringa, P. A. 't Hoen, R. Hooft, T. Kuhn, R. Kok, J. Kok, S. J. Lusher, M. E. Martone, A. Mons, A. L. Packer, B. Persson, P. Rocca-Serra, M. Roos, R. van Schaik, S. A. Sansone, E. Schultes, T. Sengstag, T. Slater, G. Strawn, M. A. Swertz, M. Thompson, J. van der Lei, E. van Mulligen, J. Velterop, A. Waagmeester, P. Wittenburg, K. Wolstencroft, J. Zhao, B. Mons

Date Published: 15th Mar 2016

Publication Type: Journal

Abstract (Expand)

This paper presents a report on outcomes of the 10th Computational Modeling in Biology Network (COMBINE) meeting that was held in Heidelberg, Germany, in July of 2019. The annual event brings together researchers, biocurators and software engineers to present recent results and discuss future work in the area of standards for systems and synthetic biology. The COMBINE initiative coordinates the development of various community standards and formats for computational models in the life sciences. Over the past 10 years, COMBINE has brought together standard communities that have further developed and harmonized their standards for better interoperability of models and data. COMBINE 2019 was co-located with a stakeholder workshop of the European EU-STANDS4PM initiative that aims at harmonized data and model standardization for in silico models in the field of personalized medicine, as well as with the FAIRDOM PALs meeting to discuss findable, accessible, interoperable and reusable (FAIR) data sharing. This report briefly describes the work discussed in invited and contributed talks as well as during breakout sessions. It also highlights recent advancements in data, model, and annotation standardization efforts. Finally, this report concludes with some challenges and opportunities that this community will face during the next 10 years.

Authors: Dagmar Waltemath, Martin Golebiewski, Michael L Blinov, Padraig Gleeson, Henning Hermjakob, Michael Hucka, Esther Thea Inau, Sarah M Keating, Matthias König, Olga Krebs, Rahuman S Malik-Sheriff, David Nickerson, Ernst Oberortner, Herbert M Sauro, Falk Schreiber, Lucian Smith, Melanie I Stefan, Ulrike Wittig, Chris J Myers

Date Published: 29th Jun 2020

Publication Type: Journal

Abstract (Expand)

In this article, the four coordinators of neglected tropical disease (NTD) drug development projects funded under the European Commission (EC) Framework Programme 7 argue that the EC should reassess their funding strategy to cover the steps necessary to translate a lead compound into a drug candidate for testing in clinical trials, and suggest ways in which this might be achieved.

Authors: R. J. Pierce, J. MacDougall, R. Leurs, M. P. Costi

Date Published: 23rd May 2017

Publication Type: Journal

Abstract (Expand)

Background: The current COVID-19 pandemic has led to a surge of research activity. While this research provides important insights, the multitude of studies results in an increasing segmentation of information. To ensure comparability across projects and institutions, standard datasets are needed. Here, we introduce the "German Corona Consensus Dataset" (GECCO), a uniform dataset that uses international terminologies and health IT standards to improve interoperability of COVID-19 data. Methods: Based on previous work (e.g., the ISARIC-WHO COVID-19 case report form) and in coordination with experts from university hospitals, professional associations and research initiatives, data elements relevant for COVID-19 research were collected, prioritized and consolidated into a compact core dataset. The dataset was mapped to international terminologies, and the Fast Healthcare Interoperability Resources (FHIR) standard was used to define interoperable, machine-readable data formats. Results: A core dataset consisting of 81 data elements with 281 response options was defined, including information about, for example, demography, anamnesis, symptoms, therapy, medications or laboratory values of COVID-19 patients. Data elements and response options were mapped to SNOMED CT, LOINC, UCUM, ICD-10-GM and ATC, and FHIR profiles for interoperable data exchange were defined. Conclusion: GECCO provides a compact, interoperable dataset that can help to make COVID-19 research data more comparable across studies and institutions. The dataset will be further refined in the future by adding domain-specific extension modules for more specialized use cases.

Authors: Julian Sass, Alexander Bartschke, Moritz Lehne, Andrea Essenwanger, Eugenia Rinaldi, Stefanie Rudolph, Kai Uwe Heitmann, Joerg Janne Vehreschild, Christof von Kalle, Sylvia Thun

Date Published: 29th Jul 2020

Publication Type: Journal

Abstract (Expand)

Reconstructing and understanding the Human Physiome virtually is a complex mathematical problem, and a highly demanding computational challenge. Mathematical models spanning from the molecular level through to whole populations of individuals must be integrated, then personalized. This requires interoperability with multiple disparate and geographically separated data sources, and myriad computational software tools. Extracting and producing knowledge from such sources, even when the databases and software are readily available, is a challenging task. Despite the difficulties, researchers must frequently perform these tasks so that available knowledge can be continually integrated into the common framework required to realize the Human Physiome. Software and infrastructures that support the communities that generate these, together with their underlying standards to format, describe and interlink the corresponding data and computer models, are pivotal to the Human Physiome being realized. They provide the foundations for integrating, exchanging and re-using data and models efficiently, and correctly, while also supporting the dissemination of growing knowledge in these forms. In this paper, we explore the standards, software tooling, repositories and infrastructures that support this work, and detail what makes them vital to realizing the Human Physiome.

Authors: D. Nickerson, K. Atalag, B. de Bono, J. Geiger, C. Goble, S. Hollmann, J. Lonien, W. Muller, B. Regierer, N. J. Stanford, M. Golebiewski, P. Hunter

Date Published: 7th Apr 2016

Publication Type: Not specified

Abstract (Expand)

Abstract At the end of 2019, the SARS-CoV-2 induces an ongoing outbreak of pneumonia in China 1 , even more spread than SARS-CoV infection 2 . The entry of SARS-CoV into host cells mainly depends on the cell receptor (ACE2) recognition and spike protein cleavage-induced cell membrane fusion 3,4 . The spike protein of SARS-CoV-2 also binds to ACE2 with a similar affinity, whereas its spike protein cleavage remains unclear 5,6 . Here we show that an insertion sequence in the spike protein of SARS-CoV-2 enhances the cleavage efficiency, and besides pulmonary alveoli, intestinal and esophagus epithelium were also the target tissues of SARS-CoV-2. Compared with SARS-CoV, we found a SPRR insertion in the S1/S2 protease cleavage sites of SARS-CoV-2 spike protein increasing the cleavage efficiency by the protein sequence aligment and furin score calculation. Additionally, the insertion sequence facilitates the formation of an extended loop which was more suitable for protease recognition by the homology modeling and molicular docking. Furthermore, the single-cell transcriptomes identified that ACE2 and TMPRSSs are highly coexpressed in AT2 cells of lung, along with esophageal upper epithelial cells and absorptive enterocytes. Our results provide the bioinformatics evidence for the increased spike protein cleavage of SARS-CoV-2 and indicate its potential target cells.

Authors: Tong Meng, Hao Cao, Hao Zhang, Zijian Kang, Da Xu, Haiyi Gong, Jing Wang, Zifu Li, Xingang Cui, Huji Xu, Haifeng Wei, Xiuwu Pan, Rongrong Zhu, Jianru Xiao, Wang Zhou, Liming Cheng, Jianmin Liu

Date Published: 11th Feb 2020

Publication Type: Tech report

Abstract (Expand)

The severe acute respiratory syndrome-coronavirus (SARS-CoV) caused an outbreak of atypical pneumonia in 2003. The SARS-CoV viral genome encodes several proteins which have no homology to proteins in any other coronaviruses, and a number of these proteins have been implicated in viral cytopathies. One such protein is 3a, which is also known as X1, ORF3 and U274. 3a expression is detected in both SARS-CoV infected cultured cells and patients. Among the different functions identified, 3a is a capable of inducing apoptosis. We previously showed that caspase pathways are involved in 3a-induced apoptosis. In this study, we attempted to find out protein domains on 3a that are essential for its pro-apoptotic function. Protein sequence analysis reveals that 3a possesses three major protein signatures, the cysteine-rich, Yxx␾ and diacidic domains. We showed that 3a proteins carrying respective mutations in these protein domains exhibit reduced pro-apoptotic activities, indicating the importance of these domains on 3a’s pro-apoptotic function. It was previously reported that 3a possesses potassium ion channel activity. We further demonstrated that the blockade of 3a’s potassium channel activity abolished caspase-dependent apoptosis. This report provides the first evidence that ion channel activity of 3a is required for its proapoptotic function. As ion channel activity has been reported to regulate apoptosis in different pathologic conditions, finding ways to modulate the ion channel activity may offer a new direction toward the inhibition of apoptosis triggered by SARS-CoV.

Authors: Chak-Ming Chan, Ho Tsoi, Wing-Man Chan, Shenyu Zhai, Ching-On Wong, Xiaoqiang Yao, Wood-Yee Chan, Stephen Kwok-Wing Tsui, Ho Yin Edwin Chan

Date Published: 1st Nov 2009

Publication Type: Journal

Abstract (Expand)

The novel coronavirus SARS-CoV-2, etiological agent of recently named Coronavirus infected disease (COVID-19) by WHO, has caused more than 2, 000 deaths worldwide since its emergency in Wuhan City, Hubei province, China, in December, 2019. The symptoms of COVID-19 varied from modest, mild to acute respiratory distress syndrome (ARDS), and the latter of which is generally associated with deregulated immune cytokine production; however, we currently know little as to the interplay between the extent of clinical symptoms and the compositions of lung immune microenvironment. Here, we comprehensively characterized the lung immune microenvironment with the bronchoalveolar lavage fluid (BALF) from 3 severe and 3 mild COVID-19 patients and 8 previously reported healthy lung controls through single-cell RNA sequence (scRNA-seq) combined with TCR-seq. Our data shows that monocyte-derived FCN1+ macrophages, whereas notFABP4+ alveolar macrophages that represent a predominant macrophage subset in BALF from patients with mild diseases, overwhelm in the severely damaged lungs from patients with ARDS. These cells are highly inflammatory and enormous chemokine producers implicated in cytokine storm. Furthermore, the formation of tissue resident, highly expanded clonal CD8+ T cells in the lung microenvironment of mild symptom patients suggests a robust adaptive immune response connected to a better control of COVID-19. This study first reported the cellular atlas of lung bronchoalveolar immune microenvironment in COVID-19 patients at the single-cell resolution, and unveiled the potential immune mechanisms underlying disease progression and protection in COVID-19.

Authors: Minfeng Liao, Yang Liu, Jin Yuan, Yanling Wen, Gang Xu, Juanjuan Zhao, Lin Chen, Jinxiu Li, Xin Wang, Fuxiang Wang, Lei Liu, Shuye Zhang, Zheng Zhang

Date Published: 26th Feb 2020

Publication Type: Tech report

Abstract (Expand)

Bacillus subtilis strain 168 produces the extremely stable and broad-spectrum lantibiotic sublancin 168. Known sublancin 168-susceptible organisms include important pathogens, such as Staphylococcus aureus. Nevertheless, since its discovery, the mode of action of sublancin 168 has remained elusive. The present studies were, therefore, aimed at the identification of cellular determinants for bacterial susceptibility toward sublancin 168. Growth inhibition and competition assays on plates and in liquid cultures revealed that sublancin 168-mediated growth inhibition of susceptible B. subtilis and S. aureus cells is affected by the NaCl concentration in the growth medium. Added NaCl did not influence the production, activity, or stability of sublancin 168 but, instead, lowered the susceptibility of sensitive cells toward this lantibiotic. Importantly, the susceptibility of B. subtilis and S. aureus cells toward sublancin 168 was shown to depend on the presence of the large mechanosensitive channel of conductance MscL. In contrast, MscL was not involved in susceptibility toward the bacteriocin nisin or Pep5. Taken together, our unprecedented results demonstrate that MscL is a critical and specific determinant in bacterial sublancin 168 susceptibility that may serve either as a direct target for this lantibiotic or as a gate of entry to the cytoplasm.

Authors: Thijs R H M Kouwen, Erik N Trip, Emma L Denham, Mark J J B Sibbald, Jean-Yves F Dubois,

Date Published: 8th Sep 2009

Publication Type: Not specified

Abstract (Expand)

Catechol and 2-methylhydroquinone (2-MHQ) cause the induction of the thiol-specific stress response and four dioxygenases/glyoxalases in Bacillus subtilis. Using transcription factor arrays, the MarR-type regulator YkvE was identified as a repressor of the dioxygenase/glyoxalase-encoding mhqE gene. Transcriptional and proteome analyses of the DeltaykvE mutant revealed the upregulation of ykcA (mhqA), ydfNOP (mhqNOP), yodED (mhqED) and yvaB (azoR2) encoding multiple dioxygenases/glyoxalases, oxidoreductases and an azoreductase. Primer extension experiments identified sigma(A)-type promoter sequences upstream of mhqA, mhqNOP, mhqED and azoR2 from which transcription is elevated after thiol stress. DNase I footprinting analysis showed that YkvE protects a primary imperfect inverted repeat with the consensus sequence of tATCTcgaAtTCgAGATaaaa in the azoR2, mhqE and mhqN promoter regions. Analysis of mhqE-promoter-bgaB fusions confirmed the significance of YkvE binding to this operator in vivo. Adjacent secondary repeats were protected by YkvE in the azoR2 and mhqN promoter regions consistent with multiple DNA-protein binding complexes. DNA-binding activity of YkvE was not directly affected by thiol-reactive compounds in vitro. Mutational analyses showed that MhqA, MhqO and AzoR2 confer resistance to 2-MHQ. Moreover, the DeltaykvE mutant displayed a 2-MHQ and catechol resistant phenotype. YkvE was renamed as MhqR controlling a 2-MHQ and catechol-resistance regulon of B. subtilis.

Authors: Stefanie Töwe, Montira Leelakriangsak, Kazuo Kobayashi, Nguyen Van Duy, , Peter Zuber, Haike Antelmann

Date Published: 27th Aug 2007

Publication Type: Not specified

Abstract (Expand)

BACKGROUND: Pseudomonas putida KT2442 is a natural producer of polyhydroxyalkanoates (PHAs), which can substitute petroleum-based non-renewable plastics and form the basis for the production of tailor-made biopolymers. However, despite the substantial body of work on PHA production by P. putida strains, it is not yet clear how the bacterium re-arranges its whole metabolism when it senses the limitation of nitrogen and the excess of fatty acids as carbon source, to result in a large accumulation of PHAs within the cell. In the present study we investigated the metabolic response of KT2442 using a systems biology approach to highlight the differences between single- and multiple-nutrient-limited growth in chemostat cultures. RESULTS: We found that 26, 62, and 81% of the cell dry weight consist of PHA under conditions of carbon, dual, and nitrogen limitation, respectively. Under nitrogen limitation a specific PHA production rate of 0.43 (g.(g.h)-1) was obtained. The residual biomass was not constant for dual- and strict nitrogen-limiting growth, showing a different feature in comparison to other P. putida strains. Dual limitation resulted in patterns of gene expression, protein level, and metabolite concentrations that substantially differ from those observed under exclusive carbon or nitrogen limitation. The most pronounced differences were found in the energy metabolism, fatty acid metabolism, as well as stress proteins and enzymes belonging to the transport system. CONCLUSION: This is the first study where the interrelationship between nutrient limitations and PHA synthesis has been investigated under well-controlled conditions using a system level approach. The knowledge generated will be of great assistance for the development of bioprocesses and further metabolic engineering work in this versatile organism to both enhance and diversify the industrial production of PHAs.

Authors: , I. F. Escapa, C. Jager, J. Puchalka, , , ,

Date Published: 20th Mar 2012

Publication Type: Not specified

Abstract (Expand)

The mechanism of action of antimicrobial peptides is, to our knowledge, still poorly understood. To probe the biophysical characteristics that confer activity, we present here a molecular-dynamics and biophysical study of a cyclic antimicrobial peptide and its inactive linear analog. In the simulations, the cyclic peptide caused large perturbations in the bilayer and cooperatively opened a disordered toroidal pore, 1-2 nm in diameter. Electrophysiology measurements confirm discrete poration events of comparable size. We also show that lysine residues aligning parallel to each other in the cyclic but not linear peptide are crucial for function. By employing dual-color fluorescence burst analysis, we show that both peptides are able to fuse/aggregate liposomes but only the cyclic peptide is able to porate them. The results provide detailed insight on the molecular basis of activity of cyclic antimicrobial peptides.

Authors: Anna D Cirac, Gemma Moiset, , Armagan Koçer, Pedro Salvador, , Siewert J Marrink, Durba Sengupta

Date Published: 18th May 2011

Publication Type: Not specified

Abstract

Not specified

Author: Paul S. Masters

Date Published: 2006

Publication Type: InCollection

Abstract (Expand)

Fumarate and nitrate reduction regulatory (FNR) proteins are bacterial transcription factors that coordinate the switch between aerobic and anaerobic metabolism. In the absence of O(2), FNR binds a [4Fe-4S](2+) cluster (ligated by Cys-20, 23, 29, 122) promoting the formation of a transcriptionally active dimer. In the presence of O(2), FNR is converted into a monomeric, non-DNA-binding form containing a [2Fe-2S](2+) cluster. The reaction of the [4Fe-4S](2+) cluster with O(2) has been shown to proceed via a 2-step process, an O(2)-dependent 1-electron oxidation to yield a [3Fe-4S](+) intermediate with release of 1 Fe(2+) ion, followed by spontaneous rearrangement to the [2Fe-2S](2+) form with release of 1 Fe(3+) and 2 S(2-) ions. Here, we show that replacement of Ser-24 by Arg, His, Phe, Trp, or Tyr enhances aerobic activity of FNR in vivo. The FNR-S24F protein incorporates a [4Fe-4S](2+) cluster with spectroscopic properties similar to those of FNR. However, the substitution enhances the stability of the [4Fe-4S](2+) cluster in the presence of O(2). Kinetic analysis shows that both steps 1 and 2 are slower for FNR-S24F than for FNR. A molecular model suggests that step 1 of the FNR-S24F iron-sulfur cluster reaction with O(2) is inhibited by shielding of the iron ligand Cys-23, suggesting that Cys-23 or the cluster iron bound to it is a primary site of O(2) interaction. These data lead to a simple model of the FNR switch with physiological implications for the ability of FNR proteins to operate over different ranges of in vivo O(2) concentrations.

Authors: Adrian J Jervis, Jason C Crack, Gaye White, Peter J Artymiuk, Myles R Cheesman, Andrew J Thomson, Nick E Le Brun,

Date Published: 4th Mar 2009

Publication Type: Not specified

Abstract (Expand)

All cells and organisms exhibit stress-coping mechanisms to ensure survival. Cytoplasmic protein-RNA assemblies termed stress granules are increasingly recognized to promote cellular survival under stress. Thus, they might represent tumor vulnerabilities that are currently poorly explored. The translationinhibitory eIF2α kinases are established as main drivers of stress granule assembly. Using a systems approach, we identify the translation enhancers PI3K and MAPK/p38 as pro-stressgranule- kinases. They act through the metabolic master regulator mammalian target of rapamycin complex 1 (mTORC1) to promote stress granule assembly.When highly active, PI3K is the main driver of stress granules; however, the impact of p38 becomes apparent as PI3K activity declines. PI3K and p38 thus act in a hierarchical manner to drive mTORC1 activity and stress granule assembly. Of note, this signaling hierarchy is also present in human breast cancer tissue. Importantly, only the recognition of the PI3K-p38 hierarchy under stress enabled the discovery of p38’s role in stress granule formation. In summary, we assign a new prosurvival function to the key oncogenic kinases PI3K and p38, as they hierarchically promote stress granule formation.

Authors: Alexander Martin Heberle, Patricia Razquin Navas, Miriam Langelaar-Makkinje, Katharina Kasack, Ahmed Sadik, Erik Faessler, Udo Hahn, Philip Marx-Stoelting, Christiane A Opitz, Christine Sers, Ines Heiland, Sascha Schäuble, Kathrin Thedieck

Date Published: 28th Mar 2019

Publication Type: Not specified

Abstract (Expand)

GlnK is an important nitrogen sensor protein in Streptomyces coelicolor. Deletion of glnK results in a medium-dependent failure of aerial mycelium and spore formation and loss of antibiotic production. Thus, GlnK is not only a regulator of nitrogen metabolism but also of morphological differentiation and secondary metabolite production. Through a comparative transcriptomic approach between the S. coelicolor wild-type and a S. coelicolor glnK mutant strain, 142 genes were identified that are differentially regulated in both strains. Among these are genes of the ram and rag operon, which are involved in S. coelicolor morphogenesis, as well as genes involved in gas vesicle biosynthesis and ectoine biosynthesis. Surprisingly, no relevant nitrogen genes were found to be differentially regulated, revealing that GlnK is not an important nitrogen sensor under the tested conditions.

Authors: E. Waldvogel, A. Herbig, F. Battke, R. Amin, M. Nentwich, K. Nieselt, T. E. Ellingsen, A. Wentzel, D. A. Hodgson, W. Wohlleben, Y. Mast

Date Published: 29th Oct 2011

Publication Type: Not specified

Abstract (Expand)

We have developed a general scenario of prebiotic physicochemical evolution during the Earth's Hadean eon and reviewed the relevant literature. We suggest that prebiotic chemical evolution started in microspaces with membranous walls, where external temperature and osmotic gradients were coupled to free-energy gradients of potential chemical reactions. The key feature of this scenario is the onset of an emergent evolutionary transition within the microspaces that is described by the model of complex vectorial chemistry. This transition occurs at average macromolecular crowding of 20 to 30% of the cell volume, when the ranges of action of stabilizing colloidal forces (screened electrostatic forces, hydration, and excluded volume forces) become commensurate. Under these conditions, the macromolecules divide the interior of microspaces into dynamically crowded macromolecular regions and topologically complementary electrolyte pools. Small ions and ionic metabolites are transported vectorially between the electrolyte pools and through the (semiconducting) electrolyte pathways of the crowded macromolecular regions from their high electrochemical potential (where they are biochemically produced) to their lower electrochemical potential (where they are consumed). We suggest a sequence of tentative transitions between major evolutionary periods during the Hadean eon as follows: (i) the early water world, (ii) the appearance of land masses, (iii) the pre-RNA world, (iv) the onset of complex vectorial chemistry, and (v) the RNA world and evolution toward Darwinian thresholds. We stress the importance of high ionic strength of the Hadean ocean (short Debye's lengths) and screened electrostatic interactions that enabled the onset of the vectorial structure of the cytoplasm and the possibility of life's emergence.

Authors: Jan Spitzer,

Date Published: 3rd Jun 2009

Publication Type: Not specified

Abstract (Expand)

Bistable systems play an important role in the functioning of living cells. Depending on the strength of the necessary positive feedback one can distinguish between (irreversible) "one-way switch" or (reversible) "toggle-switch" type behavior. Besides the well- established steady-state properties, some important characteristics of bistable systems arise from an analysis of their dynamics. We demonstrate that a supercritical stimulus amplitude is not sufficient to move the system from the lower (off-state) to the higher branch (on-state) for either a step or a pulse input. A switching surface is identified for the system as a function of the initial condition, input pulse amplitude and duration (a supercritical signal). We introduce the concept of bounded autonomy for single level systems with a pulse input. Towards this end, we investigate and characterize the role of the duration of the stimulus. Furthermore we show, that a minimal signal power is also necessary to change the steady state of the bistable system. This limiting signal power is independent of the applied stimulus and is determined only by systems parameters. These results are relevant for the design of experiments, where it is often difficult to create a defined pattern for the stimulus. Furthermore, intracellular processes, like receptor internalization, do manipulate the level of stimulus such that level and duration of the stimulus is conducive to characteristic behavior.

Authors: , Sree N Sreenath, Radina P Soebiyanto, Jayant Avva, Kwang-Hyun Cho,

Date Published: 17th Jan 2007

Publication Type: Not specified

Abstract (Expand)

Stratification of head and neck squamous cell carcinomas (HNSCC) based on HPV16 DNA and RNA status, gene expression patterns, and mutated candidate genes may facilitate patient treatment decision. We characterize head and neck squamous cell carcinomas (HNSCC) with different HPV16 DNA and RNA (E6*I) status from 290 consecutively recruited patients by gene expression profiling and targeted sequencing of 50 genes. We show that tumors with transcriptionally inactive HPV16 (DNA+ RNA-) are similar to HPV-negative (DNA-) tumors regarding gene expression and frequency of TP53 mutations (47%, 8/17 and 43%, 72/167, respectively). We also find that an immune response-related gene expression cluster is associated with lymph node metastasis, independent of HPV16 status and that disruptive TP53 mutations are associated with lymph node metastasis in HPV16 DNA- tumors. We validate each of these associations in another large data set. Four gene expression clusters which we identify differ moderately but significantly in overall survival. Our findings underscore the importance of measuring the HPV16 RNA (E6*I) and TP53-mutation status for patient stratification and identify associations of an immune response-related gene expression cluster and TP53 mutations with lymph node metastasis in HNSCC.

Authors: G. Wichmann, M. Rosolowski, K. Krohn, M. Kreuz, A. Boehm, A. Reiche, U. Scharrer, D. Halama, J. Bertolini, U. Bauer, D. Holzinger, M. Pawlita, J. Hess, C. Engel, D. Hasenclever, M. Scholz, P. Ahnert, H. Kirsten, A. Hemprich, C. Wittekind, O. Herbarth, F. Horn, A. Dietz, M. Loeffler

Date Published: 15th Dec 2015

Publication Type: Journal

Abstract (Expand)

The steady-state level of each mRNA in a cell is a balance between synthesis and degradation. Here, we use high-throughput RNA sequencing (RNASeq) to determine the relationship between mRNA degradation and mRNA abundance on a transcriptome-wide scale. The model organism used was the bloodstream form of Trypanosoma brucei, a protist that lacks regulation of RNA polymerase II initiation. The mRNA half-lives varied over two orders of magnitude, with a median half-life of 13 min for total (rRNA-depleted) mRNA. Data for poly(A)+ RNA yielded shorter half-lives than for total RNA, indicating that removal of the poly(A) tail was usually the first step in degradation. Depletion of the major 5'-3' exoribonuclease, XRNA, resulted in the stabilization of most mRNAs with half-lives under 30 min. Thus, on a transcriptome-wide scale, degradation of most mRNAs is initiated by deadenylation. Trypanosome mRNA levels are strongly influenced by gene copy number and mRNA half-life: Very abundant mRNAs that are required throughout the life-cycle may be encoded by multicopy genes and have intermediate-to-long half-lives; those encoding ribosomal proteins, with one to two gene copies, are exceptionally stable. Developmentally regulated transcripts with a lower abundance in the bloodstream forms than the procyclic forms had half-lives around the median, whereas those with a higher abundance in the bloodstream forms than the procyclic forms, such as those encoding glycolytic enzymes, had longer half-lives.

Authors: Theresa Manful, ,

Date Published: 26th Sep 2011

Publication Type: Not specified

Abstract (Expand)

Mycobacterium tuberculosis can utilize various nutrients including nitrate as a source of nitrogen. Assimilation of nitrate requires the reduction of nitrate via nitrite to ammonium, which is then incorporated into metabolic pathways. This study was undertaken to define the molecular mechanism of nitrate assimilation in M. tuberculosis. Homologues to a narGHJI-encoded nitrate reductase and a nirBD-encoded nitrite reductase have been found on the chromosome of M. tuberculosis. Previous studies have implied a role for NarGHJI in nitrate respiration rather than nitrate assimilation. Here, we show that a narG mutant of M. tuberculosis failed to grow on nitrate. A nirB mutant of M. tuberculosis failed to grow on both nitrate and nitrite. Mutant strains of Mycobacterium smegmatis mc(2)155 that are unable to grow on nitrate were isolated. The mutants were rescued by screening a cosmid library from M. tuberculosis, and a gene with homology to the response regulator gene glnR of Streptomyces coelicolor was identified. A DeltaglnR mutant of M. tuberculosis was generated, which also failed to grow on nitrate, but regained its ability to utilize nitrate when nirBD was expressed from a plasmid, suggesting a role of GlnR in regulating nirBD expression. A specific binding site for GlnR within the nirB promoter was identified and confirmed by electrophoretic mobility shift assay using purified recombinant GlnR. Semiquantitative reverse transcription PCR, as well as microarray analysis, demonstrated upregulation of nirBD expression in response to GlnR under nitrogen-limiting conditions. In summary, we conclude that NarGHJI and NirBD of M. tuberculosis mediate the assimilatory reduction of nitrate and nitrite, respectively, and that GlnR acts as a transcriptional activator of nirBD.

Authors: Sven Malm, Yvonne Tiffert, Julia Micklinghoff, Sonja Schultze, Insa Joost, Isabel Weber, Sarah Horst, Birgit Ackermann, , , Stefan Ehlers, Robert Geffers, , Franz-Christoph Bange

Date Published: 1st Apr 2009

Publication Type: Not specified

Abstract (Expand)

The Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) is reported to cause apoptosis of infected cells and several of its proteins including the 3a accessory protein, are pro-apoptotic. Since the 3a protein localizes to the endoplasmic reticulum (ER)-Golgi compartment, its role in causing ER stress was investigated in transiently transfected cells. Cells expressing the 3a proteins showed ER stress based on activation of genes for the ER chaperones GRP78 and GRP94. Since ER stress can cause differential modulation of the unfolded protein response (UPR), which includes the inositol-requiring enzyme 1 (IRE-1), activating transcription factor 6 (ATF6) and PKR-like ER kinase (PERK) pathways, these were individually tested in 3a-expressing cells. Only the PERK pathway was found to be activated in 3a-expressing cells based on (1) increased phosphorylation of eukaryotic initiation factor 2 alpha (eIF2a) and inhibitory effects of a dominant-negative form of eIF2a on GRP78 promoter activity, (2) increased translation of activating transcription factor 4 (ATF4) mRNA, and (3) ATF4dependent activation of the C/EBP homologous protein (CHOP) gene promoter. Activation of PERK affects innate immunity by suppression of type 1 interferon (IFN) signaling. The 3a protein was found to induce serine phosphorylation within the IFN alpha-receptor subunit 1 (IFNAR1) degradation motif and to increase IFNAR1 ubiquitination. Confocal microscopic analysis showed increased translocation of IFNAR1 into the lysosomal compartment and flow cytometry showed reduced levels of IFNAR1 in 3a-expressing cells. These results provide further mechanistic details of the pro-apoptotic effects of the SARS-CoV 3a protein, and suggest a potential role for it in attenuating interferon responses and innate immunity.

Authors: Rinki Minakshi, Kartika Padhan, Manjusha Rani, Nabab Khan, Faizan Ahmad, Shahid Jameel

Date Published: 17th Dec 2009

Publication Type: Journal

Abstract (Expand)

The COVID-19 disease has plagued over 110 countries and has resulted in over 4,000 deaths within 10 weeks. We compare the interaction between the human ACE2 receptor and the SARS-CoV-2 spike protein with that of other pathogenic coronaviruses using molecular dynamics simulations. SARS-CoV, SARS-CoV-2, and HCoV-NL63 recognize ACE2 as the natural receptor but present a distinct binding interface to ACE2 and a different network of residue-residue contacts. SARS-CoV and SARS-CoV-2 have comparable binding affinities achieved by balancing energetics and dynamics. The SARS-CoV-2–ACE2 complex contains a higher number of contacts, a larger interface area, and decreased interface residue fluctuations relative to SARS-CoV. These findings expose an exceptional evolutionary exploration exerted by coronaviruses toward host recognition. We postulate that the versatility of cell receptor binding strategies has immediate implications on therapeutic strategies.

Authors: Esther S. Brielle, Dina Schneidman-Duhovny, Michal Linial

Date Published: 12th Mar 2020

Publication Type: Tech report

Abstract (Expand)

Systems biology research is typically performed by multidisciplinary groups of scientists, often in large consortia and in distributed locations. The data generated in these projects tend to be heterogeneous and often involves high-throughput "omics" analyses. Models are developed iteratively from data generated in the projects and from the literature. Consequently, there is a growing requirement for exchanging experimental data, mathematical models, and scientific protocols between consortium members and a necessity to record and share the outcomes of experiments and the links between data and models. The overall output of a research consortium is also a valuable commodity in its own right. The research and associated data and models should eventually be available to the whole community for reuse and future analysis. The SEEK is an open-source, Web-based platform designed for the management and exchange of systems biology data and models. The SEEK was originally developed for the SysMO (systems biology of microorganisms) consortia, but the principles and objectives are applicable to any systems biology project. The SEEK provides an index of consortium resources and acts as gateway to other tools and services commonly used in the community. For example, the model simulation tool, JWS Online, has been integrated into the SEEK, and a plug-in to PubMed allows publications to be linked to supporting data and author profiles in the SEEK. The SEEK is a pragmatic solution to data management which encourages, but does not force, researchers to share and disseminate their data to community standard formats. It provides tools to assist with management and annotation as well as incentives and added value for following these recommendations. Data exchange and reuse rely on sufficient annotation, consistent metadata descriptions, and the use of standard exchange formats for models, data, and the experiments they are derived from. In this chapter, we present the SEEK platform, its functionalities, and the methods employed for lowering the barriers to adoption of standard formats. As the production of biological data continues to grow, in systems biology and in the life sciences in general, the need to record, manage, and exploit this wealth of information in the future is increasing. We promote the SEEK as a data and model management tool that can be adapted to the specific needs of a particular systems biology project.

Editor:

Date Published: 28th Sep 2011

Publication Type: Journal

Abstract

Not specified

Authors: Y.-J. Tan, P.-Y. Tham, D. Z. L. Chan, C.-F. Chou, S. Shen, B. C. Fielding, T. H. P. Tan, S. G. Lim, W. Hong

Date Published: 13th Jul 2005

Publication Type: Journal

Abstract (Expand)

African trypanosomes have emerged as promising unicellular model organisms for the next generation of systems biology. They offer unique advantages, due to their relative simplicity, the availability of all standard genomics techniques and a long history of quantitative research. Reproducible cultivation methods exist for morphologically and physiologically distinct life-cycle stages. The genome has been sequenced, and microarrays, RNA-interference and high-accuracy metabolomics are available. Furthermore, the availability of extensive kinetic data on all glycolytic enzymes has led to the early development of a complete, experiment-based dynamic model of an important biochemical pathway. Here we describe the achievements of trypanosome systems biology so far and outline the necessary steps towards the ambitious aim of creating a 'Silicon Trypanosome', a comprehensive, experiment-based, multi-scale mathematical model of trypanosome physiology. We expect that, in the long run, the quantitative modelling enabled by the Silicon Trypanosome will play a key role in selecting the most suitable targets for developing new anti-parasite drugs.

Authors: , , , , , , Paul A M Michels, ,

Date Published: 6th May 2010

Publication Type: Not specified

Abstract (Expand)

The African trypanosome, Trypanosoma brucei, is a unicellular parasite causing African Trypanosomiasis (sleeping sickness in humans and nagana in animals). Due to some of its unique properties, it has emerged as a popular model organism in systems biology. A predictive quantitative model of glycolysis in the bloodstream form of the parasite has been constructed and updated several times. The Silicon Trypanosome is a project that brings together modellers and experimentalists to improve and extend this core model with new pathways and additional levels of regulation. These new extensions and analyses use computational methods that explicitly take different levels of uncertainty into account. During this project, numerous tools and techniques have been developed for this purpose, which can now be used for a wide range of different studies in systems biology.

Authors: , , , , , , T. Papamarkou, , , , , , , ,

Date Published: 7th May 2014

Publication Type: Not specified

Abstract (Expand)

In 2019, a new coronavirus (2019-nCoV) infecting Humans has emerged in Wuhan, China. Its genome has been sequenced and the genomic information promptly released. Despite a high similarity with the genome sequence of SARS-CoV and SARS-like CoVs, we identified a peculiar furin-like cleavage site in the Spike protein of the 2019-nCoV, lacking in the other SARS-like CoVs. In this article, we discuss the possible functional consequences of this cleavage site in the viral cycle, pathogenicity and its potential implication in the development of antivirals.

Authors: B. Coutard, C. Valle, X. de Lamballerie, B. Canard, N.G. Seidah, E. Decroly

Date Published: 1st Apr 2020

Publication Type: Journal

Abstract (Expand)

The alternative sigma factor sigma(B) of Bacillus subtilis is responsible for the induction of the large general stress regulon comprising approximately 150-200 genes. YqgZ, a member of the sigma(B) regulon, resembles the global regulator Spx of the diamide stress regulon in B. subtilis. In this work we conducted a comprehensive transcriptome and proteome analysis of the B. subtilis wild-type 168 and its isogenic DeltasigB and DeltayqgZ mutants following exposure to 4% (v/v) ethanol stress, which led to the characterization of a 'subregulon' within the general stress response that is regulated by YqgZ. Activation and induction of sigma(B) are necessary but not sufficient for a full expression of all general stress genes. Expression of 53 genes was found to be positively regulated and the expression of 18 genes was negatively affected by YqgZ. The identification of the negatively regulated group represents a so far uncharacterized regulatory phenomenon observed in the DeltasigB mutant background that can now be attributed to the function of YqgZ. Due to the strict sigma(B)-dependent expression of YqgZ it was renamed to MgsR (modulator of the general stress response).

Authors: Alexander Reder, Dirk Höper, Christin Weinberg, Ulf Gerth, Martin Fraunholz,

Date Published: 14th Jul 2008

Publication Type: Not specified

Abstract (Expand)

Streptomyces coelicolor GlnR is a global regulator that controls genes involved in nitrogen metabolism. By genomic screening 10 new GlnR targets were identified, including enzymes for ammonium assimilation (glnII, gdhA), nitrite reduction (nirB), urea cleavage (ureA) and a number of biochemically uncharacterized proteins (SCO0255, SCO0888, SCO2195, SCO2400, SCO2404, SCO7155). For the GlnR regulon, a GlnR binding site which comprises the sequence gTnAc-n(6)-GaAAc-n(6)-GtnAC-n(6)-GAAAc-n(6) has been found. Reverse transcription analysis of S. coelicolor and the S. coelicolor glnR mutant revealed that GlnR activates or represses the expression of its target genes. Furthermore, glnR expression itself was shown to be nitrogen-dependent. Physiological studies of S. coelicolor and the S. coelicolor glnR mutant with ammonium and nitrate as the sole nitrogen source revealed that GlnR is not only involved in ammonium assimilation but also in ammonium supply. blast analysis demonstrated that GlnR-homologous proteins are present in different actinomycetes containing the glnA gene with the conserved GlnR binding site. By DNA binding studies, it was furthermore demonstrated that S. coelicolor GlnR is able to interact with these glnA upstream regions. We therefore suggest that GlnR-mediated regulation is not restricted to Streptomyces but constitutes a regulon conserved in many actinomycetes.

Authors: Yvonne Tiffert, Petra Supra, Reinhild Wurm, , Rolf Wagner,

Date Published: 7th Jan 2008

Publication Type: Not specified

Abstract (Expand)

Seizure threshold 2 (SZT2) is a component of the KICSTOR complex which, under catabolic conditions, functions as a negative regulator in the amino acid-sensing branch of mTORC1. Mutations in this genee cause a severe neurodevelopmental and epileptic encephalopathy whose main symptoms include epilepsy, intellectual disability, and macrocephaly. As SZT2 remains one of the least characterized regulators of mTORC1, in this work we performed a systematic interactome analysis under catabolic and anabolic conditions. Besides numerous mTORC1 and AMPK signaling components, we identified clusters of proteins related to autophagy, ciliogenesis regulation, neurogenesis, and neurodegenerative processes. Moreover, analysis of SZT2 ablated cells revealed increased mTORC1 signaling activation that could be reversed by Rapamycin or Torin treatments. Strikingly, SZT2 KO cells also exhibited higher levels of autophagic components, independent of the physiological conditions tested. These results are consistent with our interactome data, in which we detected an enriched pool of selective autophagy receptors/regulators. Moreover, preliminary analyses indicated that SZT2 alters ciliogenesis. Overall, the data presented form the basis to comprehensively investigate the physiological functions of SZT2 that could explain major molecular events in the pathophysiology of developmental and epileptic encephalopathy in patients with SZT2 mutations.

Authors: Cecilia Cattelani, Dominik Lesiak, Gudrun Liebscher, Isabel I. Singer, Taras Stasyk, Moritz H. Wallnöfer, Alexander M. Heberle, Corrado Corti, Michael W. Hess, Kristian Pfaller, Marcel Kwiatkowski, Peter P. Pramstaller, Andrew A. Hicks, Kathrin Thedieck, Thomas Müller, Lukas A. Huber, Mariana Eca Guimaraes de Araujo

Date Published: 1st Oct 2021

Publication Type: Journal

Abstract (Expand)

Based on its effects on both tumour cell intrinsic malignant properties as well as anti-tumour immune responses, tryptophan catabolism has emerged as an important metabolic regulator of cancer progression. Three enzymes, indoleamine-2,3-dioxygenase 1 and 2 (IDO1/2) and tryptophan-2,3-dioxygenase (TDO2), catalyse the first step of the degradation of the essential amino acid tryptophan (Trp) to kynurenine (Kyn). The notion of inhibiting IDO1 using small-molecule inhibitors elicited high hopes of a positive impact in the field of immuno-oncology, by restoring anti-tumour immune responses and synergising with other immunotherapies such as immune checkpoint inhibition. However, clinical trials with IDO1 inhibitors have yielded disappointing results, hence raising many questions. This review will discuss strategies to target Trp-degrading enzymes and possible down-stream consequences of their inhibition. We aim to provide comprehensive background information on Trp catabolic enzymes as targets in immuno-oncology and their current state of development. Details of the clinical trials with IDO1 inhibitors, including patient stratification, possible effects of the inhibitors themselves, effects of pre-treatments and the therapies the inhibitors were combined with, are discussed and mechanisms proposed that might have compensated for IDO1 inhibition. Finally, alternative approaches are suggested to circumvent these problems.

Authors: C. A. Opitz, L. F. Somarribas Patterson, S. R. Mohapatra, D. L. Dewi, A. Sadik, M. Platten, S. Trump

Date Published: 11th Dec 2019

Publication Type: Journal

Abstract (Expand)

The twin arginine translocation (Tat) system transports folded proteins across the bacterial plasma membrane. In Gram-negative bacteria, membrane-bound TatABC subunits are all essential for activity, whereas Gram-positive bacteria usually contain only TatAC subunits. In Bacillus subtilis, two TatAC-type systems, TatAdCd and TatAyCy, operate in parallel with different substrate specificities. Here, we show that they recognize similar signal peptide determinants. Both systems translocate green fluorescent protein fused to three distinct Escherichia coli Tat signal peptides, namely DmsA, AmiA and MdoD, and mutagenesis of the DmsA signal peptide confirmed that both Tat pathways recognize similar targeting determinants within Tat signals. Although another E. coli Tat substrate, trimethylamine N-oxide reductase, was translocated by TatAdCd but not by TatAyCy, we conclude that these systems are not predisposed to recognize only specific Tat signal peptides, as suggested by their narrow substrate specificities in B. subtilis. We also analysed complexes involved in the second Tat pathway in B. subtilis, TatAyCy. This revealed a discrete TatAyCy complex together with a separate, homogeneous, approximately 200 kDa TatAy complex. The latter complex differs significantly from the corresponding E. coli TatA complexes, pointing to major structural differences between Tat complexes from Gram-negative and Gram-positive organisms. Like TatAd, TatAy is also detectable in the form of massive cytosolic complexes.

Authors: James P Barnett, René van der Ploeg, Robyn T Eijlander, Anja Nenninger, Sharon Mendel, Rense Rozeboom, , , Colin Robinson

Date Published: 25th Nov 2008

Publication Type: Not specified

Abstract (Expand)

As the outbreak of COVID-19 has accelerated, an urgent need for finding strategies to combat the virus is growing. Thus, gaining more knowledge on the pathogenicity mechanism of SARS-CoV2, the causing agent of COVID-19, and its interaction with the immune system is of utmost importance. Although this novel virus is not well known yet, its structural and genetic similarity with SARS-CoV as well as the comparable pattern of age-mortality relations suggest that the previous findings on SARS can be applicable for COVID-19. Therefore, a systems biology study was conducted to investigate the underlying mechanism for the differences in the age-specific mortality of SARS and the most important signaling pathways activated by the virus. The results were then validated through a literature review on COVID-19 and the other closely related viruses, SARS and MERS.

Editor:

Date Published: 12th Mar 2020

Publication Type: Tech report

Abstract (Expand)

An essential function of innate immunity is to distinguish self from non-self and receptors have evolved to specifically recognize viral components and initiate the expression of antiviral proteins to restrict viral replication. Coronaviruses are RNA viruses that replicate in the host cytoplasm and evade innate immune sensing in most cell types, either passively by hiding their viral signatures and limiting exposure to sensors or actively, by encoding viral antagonists to counteract the effects of interferons. Since many cytoplasmic viruses exploit similar mechanisms of innate immune evasion, mechanistic insight into the direct interplay between viral RNA, viral RNA-processing enzymes, cellular sensors and antiviral proteins will be highly relevant to develop novel antiviral targets and to restrict important animal and human infections.

Authors: Eveline Kindler, Volker Thiel

Date Published: 1st Aug 2014

Publication Type: Journal

Abstract (Expand)

Whole-cell (WC) modeling is a promising tool for biological research, bioengineering, and medicine. However, substantial work remains to create accurate, comprehensive models of complex cells. METHODS: We organized the 2015 Whole-Cell Modeling Summer School to teach WC modeling and evaluate the need for new WC modeling standards and software by recoding a recently published WC model in SBML. RESULTS: Our analysis revealed several challenges to representing WC models using the current standards. CONCLUSION: We, therefore, propose several new WC modeling standards, software, and databases. SIGNIFICANCE: We anticipate that these new standards and software will enable more comprehensive models.

Authors: D. Waltemath, J. Karr, F. Bergmann, V. Chelliah, M. Hucka, M. Krantz, W. Liebermeister, P. Mendes, C. Myers, P. Pir, B. Alaybeyoglu, N. Aranganathan, K. Baghalian, A. Bittig, P. Burke, M. Cantarelli, Y. Chew, R. Costa, J. Cursons, T. Czauderna, A. Goldberg, H. Gomez, J. Hahn, T. Hameri, D. Gardiol, D. Kazakiewicz, I. Kiselev, V. Knight-Schrijver, C. Knupfer, M. Konig, D. Lee, A. Lloret-Villas, N. Mandrik, J. Medley, B. Moreau, H. Naderi-Meshkin, S. Palaniappan, D. Priego-Espinosa, M. Scharm, M. Sharma, K. Smallbone, N. Stanford, J. H. Song, T. Theile, M. Tokic, N. Tomar, V. Toure, J. Uhlendorf, T. Varusai, L. Watanabe, F. Wendland, M. Wolfien, J. Yurkovich, Y. Zhu, A. Zardilis, A. Zhukova, F. Schreiber

Date Published: 16th Jun 2016

Publication Type: Not specified

Abstract (Expand)

To make full use of research data, the bioscience community needs to adopt technologies and reward mechanisms that support interoperability and promote the growth of an open 'data commoning' culture. Here we describe the prerequisites for data commoning and present an established and growing ecosystem of solutions using the shared 'Investigation-Study-Assay' framework to support that vision.

Authors: Susanna-Assunta Sansone, Philippe Rocca-Serra, Dawn Field, Eamonn Maguire, Chris Taylor, Oliver Hofmann, Hong Fang, Steffen Neumann, Weida Tong, Linda Amaral-Zettler, Kimberly Begley, Tim Booth, Lydie Bougueleret, Gully Burns, Brad Chapman, Tim Clark, Lee-Ann Coleman, Jay Copeland, Sudeshna Das, Antoine de Daruvar, Paula de Matos, Ian Dix, Scott Edmunds, Chris T Evelo, Mark J Forster, Pascale Gaudet, Jack Gilbert, , Julian L Griffin, Daniel Jacob, Jos Kleinjans, Lee Harland, Kenneth Haug, Henning Hermjakob, Shannan J Ho Sui, Alain Laederach, Shaoguang Liang, Stephen Marshall, Annette McGrath, Emily Merrill, Dorothy Reilly, Magali Roux, Caroline E Shamu, Catherine A Shang, Christoph Steinbeck, Anne Trefethen, Bryn Williams-Jones, , Ioannis Xenarios, Winston Hide

Date Published: 28th Jan 2012

Publication Type: Not specified

Abstract (Expand)

As artemisinin combination therapies (ACTs) are compromised by resistance, we are evaluating triple combination therapies (TACTs) comprising an amino-artemisinin, a redox drug, and a third drug withox drug, and a third drug with different mode of action. Thus, here we briefly review efficacy data on artemisone, artemiside, other amino-artemisinins, and 11-aza-artemisinin and conduct absorption, distribution, and metabolism and excretion (ADME) profiling in vitro and pharmacokinetic (PK) profiling in vivo via intravenous (i.v.) and oral (p.o.) administration to mice.

Authors: Daniel J. Watson, Lizahn Laing, Liezl Gibhard, Ho Ning Wong, Richard K. Haynes, Lubbe Wiesner

Date Published: 16th Jul 2021

Publication Type: Journal

Abstract (Expand)

To apply enzymes in technical processes, a detailed understanding of the molecular mechanisms is required. Kinetic and thermodynamic parameters of enzyme catalysis are crucial to plan, model, and implement biocatalytic processes more efficiently. While the kinetic parameters, Km and kcat, are often accessible by optical methods, the determination of thermodynamic parameters requires more sophisticated methods. Isothermal titration calorimetry (ITC) allows the label-free and highly sensitive analysis of kinetic and thermodynamic parameters of individual steps in the catalytic cycle of an enzyme reaction. However, since ITC is susceptible to interferences due to denaturation or agglomeration of the enzymes, the homogeneity of the enzyme sample must always be considered, and this can be accomplished by means of dynamic light scattering (DLS) analysis. We here report on the use of an ITC-dependent work flow to determine both the kinetic and the thermodynamic data for a cofactor-dependent enzyme. Using a standardized approach with the implementation of sample quality control by DLS, we obtain high-quality data suitable for the advanced modeling of the enzyme reaction mechanism. Specifically, we investigated stereoselective reactions catalyzed by the NADPH-dependent ketoreductase Gre2p under different reaction conditions. The results revealed that this enzyme operates with an ordered sequential mechanism and is affected by substrate or product inhibition depending on the reaction buffer. Data reproducibility is ensured by specifying standard operating procedures, using programmed workflows for data analysis, and storing all data in a F.A.I.R. (findable, accessible, interoperable, and reusable) repository (https://doi.org/10.15490/fairdomhub.1.investigation.464.1). Our work highlights the utility for combined binding and kinetic studies for such complex multisubstrate reactions.

Authors: Felix Ott, Kersten S. Rabe, Christof M. Niemeyer, Gudrun Gygli

Date Published: 3rd Sep 2021

Publication Type: Journal

Abstract (Expand)

Escherichia coli is a facultatively anaerobic bacterium. With glucose if no external electron acceptors are available, ATP is produced by substrate level phosphorylation. The intracellular redox balance is maintained by mixed-acid fermentation, that is, the production and excretion of several organic acids. When oxygen is available, E. coli switches to aerobic respiration to achieve redox balance and optimal energy conservation by proton translocation linked to electron transfer. The switch between fermentative and aerobic respiratory growth is driven by extensive changes in gene expression and protein synthesis, resulting in global changes in metabolic fluxes and metabolite concentrations. This oxygen response is determined by the interaction of global and local genetic regulatory mechanisms, as well as by enzymatic regulation. The response is affected by basic physical constraints such as diffusion, thermodynamics and the requirement for a balance of carbon, electrons and energy (predominantly the proton motive force and the ATP pool). A comprehensive systems level understanding of the oxygen response of E. coli requires the integrated interpretation of experimental data that are pertinent to the multiple levels of organization that mediate the response. In the pan-European venture, Systems Biology of Microorganisms (SysMO) and specifically within the project Systems Understanding of Microbial Oxygen Metabolism (SUMO), regulator activities, gene expression, metabolite levels and metabolic flux datasets were obtained using a standardized and reproducible chemostat-based experimental system. These different types and qualities of data were integrated using mathematical models. The approach described here has revealed a much more detailed picture of the aerobic-anaerobic response, especially for the environmentally critical microaerobic range that is located between unlimited oxygen availability and anaerobiosis.

Authors: , , , , , , S. Kunz, , , , , ,

Date Published: 7th May 2014

Publication Type: Not specified

Abstract (Expand)

ABSTRACT: BACKGROUND: The Gram-positive bacterium Bacillus subtilis is an important producer of high quality industrial enzymes and a few eukaryotic proteins. Most of these proteins are secreted into the growth medium, but successful examples of cytoplasmic protein production are also known. Therefore, one may anticipate that the high protein production potential of B. subtilis can be exploited for protein complexes and membrane proteins to facilitate their functional and structural analysis. The high quality of proteins produced with B. subtilis results from the action of cellular quality control systems that efficiently remove misfolded or incompletely synthesized proteins. Paradoxically, cellular quality control systems also represent bottlenecks for the production of various heterologous proteins at significant concentrations. CONCLUSION: While inactivation of quality control systems has the potential to improve protein production yields, this could be achieved at the expense of product quality. Mechanisms underlying degradation of secretory proteins are nowadays well understood and often controllable. It will therefore be a major challenge for future research to identify and modulate quality control systems of B. subtilis that limit the production of high quality protein complexes and membrane proteins, and to enhance those systems that facilitate assembly of these proteins.

Authors: Jessica C Zweers, Imrich Barák, Dörte Becher, Arnold Jm Driessen, , Vesa P Kontinen, Manfred J Saller, L'udmila Vavrová,

Date Published: 2nd Dec 2007

Publication Type: Not specified

Abstract (Expand)

Oxygen availability is the major determinant of the metabolic modes adopted by Escherichia coli. Whilst much is known about E. coli gene expression and metabolism under fully aerobic and anaerobic conditions, the intermediate oxygen tensions that are encountered in natural niches are understudied. Here for the first time the transcript profiles of E. coli K-12 across the physiologically significant range of oxygen availabilities are described. These suggested a progressive switch to aerobic respiratory metabolism and a remodeling of the cell envelope as oxygen availability increased. The transcriptional responses were consistent with changes in the abundances of cytochrome bd and bo and outer membrane protein W. The observed transcript and protein profiles result from changes in the activities of regulators that respond to oxygen itself, or to metabolic and environmental signals that are sensitive to oxygen availability (aerobiosis). A probabilistic model (TFinfer) was used to predict the activity of the indirect oxygen-sensing two-component system ArcBA across the aerobiosis range. The model implied that the activity of the regulator ArcA correlated with aerobiosis, but not with the redox state of the ubiquinone pool, challenging the idea that ArcA activity is inhibited by oxidized ubiquinone. Measurement of the amount of phosphorylated ArcA correlated with the predicted ArcA activities and with aerobiosis, suggesting that fermentation product-mediated inhibition of ArcB phosphatase activity is the dominant mechanism for regulating ArcA activity under the conditions used here.

Authors: , , , Eleanor W Trotter, H M Shahzad Asif, Guido Sanguinetti, , ,

Date Published: 22nd Jan 2011

Publication Type: Not specified

Abstract (Expand)

Abstract During fasting, mitochondrial fatty-acid β-oxidation (mFAO) is essential for the generation of glucose by the liver. Children with a loss-of-function deficiency in the mFAO enzyme medium-chain acyl-Coenzyme A dehydrogenase (MCAD) are at serious risk of life-threatening low blood glucose levels during fasting in combination with intercurrent disease. However, a subset of these children remains asymptomatic throughout life. In MCAD-deficient (MCAD-KO) mice, glucose levels are similar to those of wild-type (WT) mice, even during fasting. We investigated if metabolic adaptations in the liver may underlie the robustness of this KO mouse. WT and KO mice were given a high- or low-fat diet and subsequently fasted. We analyzed histology, mitochondrial function, targeted mitochondrial proteomics, and transcriptome in liver tissue. Loss of MCAD led to a decreased capacity to oxidize octanoyl-CoA. This was not compensated for by altered protein levels of the short- and long-chain isoenzymes SCAD and LCAD. In the transcriptome, we identified subtle adaptations in the expression of genes encoding enzymes catalyzing CoA- and NAD(P)(H)-involving reactions and of genes involved in detoxification mechanisms. We discuss how these processes may contribute to robustness in MCAD-KO mice and potentially also in asymptomatic human subjects with a complete loss of MCAD activity.

Authors: Anne-Claire M. F. Martines, Albert Gerding, Sarah Stolle, Marcel A. Vieira-Lara, Justina C. Wolters, Angelika Jurdzinski, Laura Bongiovanni, Alain de Bruin, Pieter van der Vlies, Gerben van der Vries, Vincent W. Bloks, Terry G. J. Derks, Dirk-Jan Reijngoud, Barbara M. Bakker

Date Published: 1st Dec 2019

Publication Type: Journal

Abstract (Expand)

African trypanosomes are an excellent system for quantitative modelling of post-transcriptional mRNA control. Transcription is constitutive and polycistronic; individual mRNAs are excised by trans splicing and polyadenylation. We here measure mRNA decay kinetics in two life cycle stages, bloodstream and procyclic forms, by transcription inhibition and RNASeq. Messenger RNAs with short half-lives tend to show initial fast degradation, followed by a slower phase; they are often stabilized by depletion of the 5'-3' exoribonuclease XRNA. Many longer-lived mRNAs show initial slow degradation followed by rapid destruction: we suggest that the slow phase reflects gradual deadenylation. Developmentally regulated mRNAs often show regulated decay, and switch their decay pattern. Rates of mRNA decay are good predictors of steady state levels for short mRNAs, but mRNAs longer than 3 kb show unexpectedly low abundances. Modelling shows that variations in splicing and polyadenylation rates can contribute to steady-state mRNA levels, but this is completely dependent on competition between processing and co-transcriptional mRNA precursor destruction.

Authors: , M. Ryten, D. Droll, , V. Farber, , C. Merce, , ,

Date Published: 26th Aug 2014

Publication Type: Not specified

Abstract (Expand)

A constructed lactate dehydrogenase-negative mutant of Enterococcus faecalis V583 grows at the same rate as the wild type, but ferments glucose to ethanol, formate, and acetoin. Microrray analysis showed that LDH deficiency had profound transcriptional effects, 43 genes in the mutant were found to be upregulated and 45 to be downregulated. Most of the upregulated genes encode enzymes of energy metabolism or transport. By 2D gel analysis 45 differentially expressed proteins were identified. A comparison of transcriptomic and proteomic data suggests that for several proteins the level of expression is regulated beyond the level of transcription. Pyruvate catabolic genes, including the truncated ldh, showed highly increased transcription in the mutant. These genes, along with a number of other differentially expressed genes, are preceded by sequences with homology to binding sites for the global redox-sensing repressor, Rex, of Staphylococcus aureus. The data indicate that the genes are transcriptionally regulated by the NADH/NAD ratio and that this ratio plays an important role in the regulatory network controlling energy metabolism in E. faecalis.

Authors: , , Ellen M Fergestad, Geir Mathiesen, ,

Date Published: 8th Feb 2011

Publication Type: Not specified

Abstract

Not specified

Authors: Antoine Buetti-Dinh, Olga Dethlefsen, Ran Friedman, Mark Dopson

Date Published: 26th May 2016

Publication Type: Not specified

Abstract (Expand)

Domesticated laboratory strains of Bacillus subtilis readily take up and integrate exogenous DNA. In contrast, "wild" ancestors or Bacillus strains recently isolated from the environment can only be genetically modified by phage transduction, electroporation or protoplast transformation. Such methods are laborious, have a variable yield or cannot efficiently be used to alter chromosomal DNA. A major disadvantage of using laboratory strains is that they have often lost, or do not display ecologically relevant physiologies such as the ability to form biofilms. Here we present a method that allows genetic transformation by natural competence in several environmental isolates of B. subtilis. Competence in these strains was established by expressing the B. subtilis competence transcription factor ComK from an IPTG-inducible promoter construct present on an unstable plasmid. This transiently activates expression of the genes required for DNA uptake and recombination in the host strain. After transformation, the comK encoding plasmid is lost easily because of its intrinsic instability and the transformed strain returns to its wild state. Using this method, we have successfully generated mutants and introduced foreign DNA into a number of environmental isolates and also B. subtilis strain NCIB3610, which is widely used to study biofilm formation. Application of the same method to strains of B. licheniformis was unsuccessful. The efficient and rapid approach described here may facilitate genetic studies in a wider array of environmental B. subtilis strains.

Authors: Reindert Nijland, J Grant Burgess, Jeff Errington,

Date Published: 11th Jan 2010

Publication Type: Not specified

Abstract (Expand)

Absolute measurements of protein abundance are important in the understanding of biological processes and the precise computational modeling of biological pathways. We developed targeted LC-MS/MS assays in the selected reaction monitoring (SRM) mode to quantify over 50 mitochondrial proteins in a single run. The targeted proteins cover the tricarboxylic acid cycle, fatty acid beta-oxidation, oxidative phosphorylation, and the detoxification of reactive oxygen species. Assays used isotopically labeled concatemers as internal standards designed to target murine mitochondrial proteins and their human orthologues. Most assays were also suitable to quantify the corresponding protein orthologues in rats. After exclusion of peptides that did not pass the selection criteria, we arrived at SRM assays for 55 mouse, 52 human, and 51 rat proteins. These assays were optimized in isolated mitochondrial fractions from mouse and rat liver and cultured human fibroblasts and in total liver extracts from mouse, rat, and human. The developed proteomics approach is suitable for the quantification of proteins in the mitochondrial energy metabolic pathways in mice, rats, and humans as a basis for translational research. Initial data show that the assays have great potential for elucidating the adaptive response of human patients to mutations in mitochondrial proteins in a clinical setting.

Authors: J. C. Wolters, J. Ciapaite, K. van Eunen, K. E. Niezen-Koning, A. Matton, R. J. Porte, P. Horvatovich, B. M. Bakker, R. Bischoff, H. P. Permentier

Date Published: 2nd Sep 2016

Publication Type: Journal

Abstract (Expand)

The TRAnsient Pockets in Proteins (TRAPP) webserver provides an automated workflow that allows users to explore the dynamics of a protein binding site and to detect pockets or sub-pockets that may transiently open due to protein internal motion. These transient or cryptic sub-pockets may be of interest in the design and optimization of small molecular inhibitors for a protein target of interest. The TRAPP workflow consists of the following three modules: (i) TRAPP structure- generation of an ensemble of structures using one or more of four possible molecular simulation methods; (ii) TRAPP analysis-superposition and clustering of the binding site conformations either in an ensemble of structures generated in step (i) or in PDB structures or trajectories uploaded by the user; and (iii) TRAPP pocket-detection, analysis, and visualization of the binding pocket dynamics and characteristics, such as volume, solvent-exposed area or properties of surrounding residues. A standard sequence conservation score per residue or a differential score per residue, for comparing on- and off-targets, can be calculated and displayed on the binding pocket for an uploaded multiple sequence alignment file, and known protein sequence annotations can be displayed simultaneously. The TRAPP webserver is freely available at http://trapp.h-its.org.

Authors: A. Stank, D. B. Kokh, M. Horn, E. Sizikova, R. Neil, J. Panecka, S. Richter, R. C. Wade

Date Published: 3rd Jul 2017

Publication Type: Journal

Abstract (Expand)

All regulatory processes require components that sense the environmental or metabolic conditions of the cell, and sophisticated sensory proteins have been studied in great detail. During the last few years, it turned out that enzymes can control gene expression in response to the availability of their substrates. Here, we review four different mechanisms by which these enzymes interfere with regulation in bacteria. First, some enzymes have acquired a DNA-binding domain and act as direct transcription repressors by binding DNA in the absence of their substrates. A second class is represented by aconitase, which can bind iron responsive elements in the absence of iron to control the expression of genes involved in iron homoeostasis. The third class of these enzymes is sugar permeases of the phosphotransferase system that control the activity of transcription regulators by phosphorylating them in the absence of the specific substrate. Finally, a fourth class of regulatory enzymes controls the activity of transcription factors by inhibitory protein-protein interactions. We suggest that the enzymes that are active in the control of gene expression should be designated as trigger enzymes. An analysis of the occurrence of trigger enzymes suggests that the duplication and subsequent functional specialization is a major pattern in their evolution.

Authors: Fabian M Commichau,

Date Published: 11th Dec 2007

Publication Type: Not specified

Abstract (Expand)

Abstract Background Indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan-dioxygenase (TDO) are enzymes catabolizing the essential amino acid tryptophan into kynurenine. Expression of these enzymes is frequently observed in advanced-stage cancers and is associated with poor disease prognosis and immune suppression. Mechanistically, the respective roles of tryptophan shortage and kynurenine production in suppressing immunity remain unclear. Kynurenine was proposed as an endogenous ligand for the aryl hydrocarbon receptor (AHR), which can regulate inflammation and immunity. However, controversy remains regarding the role of AHR in IDO1/TDO-mediated immune suppression, as well as the involvement of kynurenine. In this study, we aimed to clarify the link between IDO1/TDO expression, AHR pathway activation and immune suppression. Methods AHR expression and activation was analyzed by RT-qPCR and western blot analysis in cells engineered to express IDO1/TDO, or cultured in medium mimicking tryptophan catabolism by IDO1/TDO. In vitro differentiation of naïve CD4+ T cells into regulatory T cells (Tregs) was compared in T cells isolated from mice bearing different Ahr alleles or a knockout of Ahr, and cultured in medium with or without tryptophan and kynurenine. Results We confirmed that IDO1/TDO expression activated AHR in HEK-293-E cells, as measured by the induction of AHR target genes. Unexpectedly, AHR was also overexpressed on IDO1/TDO expression. AHR overexpression did not depend on kynurenine but was triggered by tryptophan deprivation. Multiple human tumor cell lines overexpressed AHR on tryptophan deprivation. AHR overexpression was not dependent on general control non-derepressible 2 (GCN2), and strongly sensitized the AHR pathway. As a result, kynurenine and other tryptophan catabolites, which are weak AHR agonists in normal conditions, strongly induced AHR target genes in tryptophan-depleted conditions. Tryptophan depletion also increased kynurenine uptake by increasing SLC7A5 (LAT1) expression in a GCN2-dependent manner. Tryptophan deprivation potentiated Treg differentiation from naïve CD4+ T cells isolated from mice bearing an AHR allele of weak affinity similar to the human AHR. Conclusions Tryptophan deprivation sensitizes the AHR pathway by inducing AHR overexpression and increasing cellular kynurenine uptake. As a result, tryptophan catabolites such as kynurenine more potently activate AHR, and Treg differentiation is promoted. Our results propose a molecular explanation for the combined roles of tryptophan deprivation and kynurenine production in mediating IDO1/TDO-induced immune suppression.

Authors: Marie Solvay, Pauline Holfelder, Simon Klaessens, Luc Pilotte, Vincent Stroobant, Juliette Lamy, Stefan Naulaerts, Quentin Spillier, Raphaël Frédérick, Etienne De Plaen, Christine Sers, Christiane A Opitz, Benoit J Van den Eynde, Jingjing Zhu

Date Published: 21st Jun 2023

Publication Type: Journal

Abstract (Expand)

L-Tryptophan (Trp) metabolism through the kynurenine pathway (KP) is involved in the regulation of immunity, neuronal function and intestinal homeostasis. Imbalances in Trp metabolism in disorders ranging from cancer to neurodegenerative disease have stimulated interest in therapeutically targeting the KP, particularly the main rate-limiting enzymes indoleamine-2,3-dioxygenase 1 (IDO1), IDO2 and tryptophan-2,3-dioxygenase (TDO) as well as kynurenine monooxygenase (KMO). However, although small-molecule IDO1 inhibitors showed promise in early-stage cancer immunotherapy clinical trials, a phase III trial was negative. This Review summarizes the physiological and pathophysiological roles of Trp metabolism, highlighting the vast opportunities and challenges for drug development in multiple diseases. Full text of this paper is available here https://inrepo01.inet.dkfz-heidelberg.de/record/143705

Authors: Michael Platten, Ellen A. A. Nollen, Ute F. Röhrig, Francesca Fallarino, Christiane A. Opitz

Date Published: 1st May 2019

Publication Type: Journal

Abstract (Expand)

Limited supply and catabolism restrict the essential amino acid tryptophan (Trp) in tumors. How tumors sustain translation under Trp stress remains unclear. Unlike other amino acids, Trp stress activatess the EGFR, which enhances macropinocytosis and RAS signaling to the MTORC1 and p38/MAPK kinases, sustaining translation. The AHR forms part of the Trp stress proteome and promotes autophagy to sustain Trp levels, and ceramide biosynthesis. Thus, Trp restriction elicits pro-translation signals enabling adaptation to nutrient stress, placing Trp into a unique position in the amino acid-mediated stress response. Our findings challenge the current perception that Trp restriction inhibits MTORC1 and the AHR and explain how both cancer drivers remain active. A glioblastoma patient subgroup with enhanced MTORC1 and AHR displays an autophagy signature, highlighting the clinical relevance of MTORC1-AHR crosstalk. Regions of high Trp or high ceramides are mutually exclusive, supporting that low Trp activates the EGFR-MTORC1-AHR axis in glioblastoma tissue.

Authors: Pauline Pfänder, Lucas Hensen, Patricia Razquin Navas, Marie Solvay, Mirja Tamara Prentzell, Ahmed Sadik, Alexander M. Heberle, Sophie Seifert, Leon Regin, Tobias Bausbacher, Anna-Sophia Egger, Madlen Hotze, Tobias Kipura, Bianca Berdel, Ivana Karabogdan, Luis F. Somarribas Patterson, Michele Reil, Deepak Sayeeram, Vera Peters, Jose Ramos Pittol, Ineke van ’t Land-Kuper, Teresa Börding, Saskia Trump, Alienke van Pijkeren, Yang Zhang, Fabricio Loayza-Puch, Alexander Kowar, Sönke Harder, Lorenz Waltl, André Gollowitzer, Tetsushi Kataura, Viktor I. Korolchuk, Shad A. Mohammed, Phillipp Sievers, Felix Sahm, Hartmut Schlüter, Andreas Koeberle, Carsten Hopf, Marcel Kwiatkowski, Christine Sers, Benoit J. Van den Eynde, Christiane A. Opitz, Kathrin Thedieck

Date Published: 17th Jan 2023

Publication Type: Journal

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