scholarly journals Resistance to serine in Bacillus subtilis: Identification of the serine transporter YbeC and of a metabolic network that links serine and threonine metabolism

2020 ◽  
Author(s):  
Anika Klewing ◽  
Byoung Mo Koo ◽  
Larissa Krüger ◽  
Anja Poehlein ◽  
Daniel Reuß ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Amino Acid ◽  
Biofilm Formation ◽  
Wild Type Strain ◽  
Positive Bacterium ◽  
Genome Wide ◽  
Intimate Link ◽  
Resistant Mutants ◽  
Underlying Mechanisms ◽  
Threonine Biosynthesis

SummaryThe Gram-positive bacterium Bacillus subtilis uses serine not only as building block for proteins but also as an important precursor in many anabolic reactions. Moreover, a lack of serine results in the initiation of biofilm formation. However, in excess serine inhibits the growth of B. subtilis. To unravel the underlying mechanisms, we isolated suppressor mutants that can tolerate toxic serine concentrations by three targeted and non-targeted genome-wide screens. All screens as well as genetic complementation in Escherichia coli identified the so far uncharacterized permease YbeC as the major serine transporter of B. subtilis. In addition to YbeC, the threonine transporters BcaP and YbxG make minor contributions to serine uptake. A strain lacking these three transporters was able to tolerate 100 mM serine whereas the wild type strain was already inhibited by 1 mM of the amino acid. The screen for serine-resistant mutants also identified mutations that result in increased serine degradation and in increased expression of threonine biosynthetic enzymes suggesting that serine toxicity results from interference with threonine biosynthesis.Originality-Significance StatementSerine is an important precursor for many biosynthetic reactions, and lack of this amino acid can induce biofilm formation in Bacillus subtilis. However, serine is toxic for the growth of B. subtilis. To understand the reason(s) for this toxicity and to identify the so far unknown serine transporter(s) of this bacterium, we performed exhaustive mutant screens to isolate serine-resistant mutants. This screen identified YbeC, the major serine transporter of B. subtilis. Moreover, we observed an intimate link between serine and threonine metabolism that is responsible for serine toxicity by inhibiting threonine biosynthesis.

scholarly journals Selective Pressure for Biofilm Formation in Bacillus subtilis: Differential Effect of Mutations in the Master Regulator SinR on Bistability

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Jan Kampf ◽  
Jan Gerwig ◽  
Kerstin Kruse ◽  
Robert Cleverley ◽  
Miriam Dormeyer ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bacillus Subtilis ◽  
Biofilm Formation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Selective Pressure ◽  
Wild Type ◽  
Master Regulator ◽  
Form Complex ◽  
Content Type

ABSTRACT Biofilm formation by Bacillus subtilis requires the expression of genes encoding enzymes for extracellular polysaccharide synthesis and for an amyloid-like protein. The master regulator SinR represses all the corresponding genes, and repression of these key biofilm genes is lifted when SinR interacts with its cognate antagonist proteins. The YmdB phosphodiesterase is a recently discovered factor that is involved in the control of SinR activity: cells lacking YmdB exhibit hyperactive SinR and are unable to relieve the repression of the biofilm genes. In this study, we have examined the dynamics of gene expression patterns in wild-type and ymdB mutant cells by microfluidic analysis coupled to time-lapse microscopy. Our results confirm the bistable expression pattern for motility and biofilm genes in the wild-type strain and the loss of biofilm gene expression in the mutant. Moreover, we demonstrated dynamic behavior in subpopulations of the wild-type strain that is characterized by switches in sets of the expressed genes. In order to gain further insights into the role of YmdB, we isolated a set of spontaneous suppressor mutants derived from ymdB mutants that had regained the ability to form complex colonies and biofilms. Interestingly, all of the mutations affected SinR. In some mutants, large genomic regions encompassing sinR were deleted, whereas others had alleles encoding SinR variants. Functional and biochemical studies with these SinR variants revealed how these proteins allowed biofilm gene expression in the ymdB mutant strains. IMPORTANCE Many bacteria are able to choose between two mutually exclusive lifestyles: biofilm formation and motility. In the model bacterium Bacillus subtilis, this choice is made by each individual cell rather than at the population level. The transcriptional repressor SinR is the master regulator in this decision-making process. The regulation of SinR activity involves complex control of its own expression and of its interaction with antagonist proteins. We show that the YmdB phosphodiesterase is required to allow the expression of SinR-repressed genes in a subpopulation of cells and that such subpopulations can switch between different SinR activity states. Suppressor analyses revealed that ymdB mutants readily acquire mutations affecting SinR, thus restoring biofilm formation. These findings suggest that B. subtilis cells experience selective pressure to form the extracellular matrix that is characteristic of biofilms and that YmdB is required for the homeostasis of SinR and/or its antagonists.

scholarly journals Evidence for Cyclic Di-GMP-Mediated Signaling in Bacillus subtilis

2012 ◽  
Vol 194 (18) ◽  
pp. 5080-5090 ◽  
Author(s):  
Yun Chen ◽  
Yunrong Chai ◽  
Jian-hua Guo ◽  
Richard Losick
Keyword(s):  
Bacillus Subtilis ◽  
Biofilm Formation ◽  
Second Messenger ◽  
Negative Control ◽  
Gram Negative Bacteria ◽  
Flagellar Motor ◽  
Positive Bacterium ◽  
Content Type ◽  
Deletion Mutations ◽  
Cellular Processes

ABSTRACTCyclic di-GMP (c-di-GMP) is a second messenger that regulates diverse cellular processes in bacteria, including motility, biofilm formation, cell-cell signaling, and host colonization. Studies of c-di-GMP signaling have chiefly focused on Gram-negative bacteria. Here, we investigated c-di-GMP signaling in the Gram-positive bacteriumBacillus subtilisby constructing deletion mutations in genes predicted to be involved in the synthesis, breakdown, or response to the second messenger. We found that a putative c-di-GMP-degrading phosphodiesterase, YuxH, and a putative c-di-GMP receptor, YpfA, had strong influences on motility and that these effects depended on sequences similar to canonical EAL and RxxxR—D/NxSxxG motifs, respectively. Evidence indicates that YpfA inhibits motility by interacting with the flagellar motor protein MotA and thatyuxHis under the negative control of the master regulator Spo0A∼P. Based on these findings, we propose that YpfA inhibits motility in response to rising levels of c-di-GMP during entry into stationary phase due to the downregulation ofyuxHby Spo0A∼P. We also present evidence that YpfA has a mild influence on biofilm formation.In toto, our results demonstrate the existence of a functional c-di-GMP signaling system inB. subtilisthat directly inhibits motility and directly or indirectly influences biofilm formation.

scholarly journals σX Is Involved in Controlling Bacillus subtilis Biofilm Architecture through the AbrB Homologue Abh

2009 ◽  
Vol 191 (22) ◽  
pp. 6822-6832 ◽  
Author(s):  
Ewan J. Murray ◽  
Mark A. Strauch ◽  
Nicola R. Stanley-Wall
Keyword(s):  
Bacillus Subtilis ◽  
Characteristic Feature ◽  
Biofilm Formation ◽  
Positive Bacterium ◽  
Pellicle Formation ◽  
Environmental Signals ◽  
Biofilm Architecture ◽  
Σ Factor ◽  
Structural Homologue ◽  
Biofilm Matrix

ABSTRACT A characteristic feature of biofilm formation is the production of a protective extracellular polymeric matrix. In the gram-positive bacterium Bacillus subtilis, the biofilm matrix is synthesized by the products of the epsABCDEFGHIJKLMNO operon (hereafter called the eps operon) and yqxM-sipW-tasA loci. Transcription from these operons is repressed by two key regulators, AbrB and SinR. Relief of inhibition is necessary to allow biofilm formation to proceed. Here we present data indicating that Abh, a sequence and structural homologue of AbrB, regulates biofilm architecture by B. subtilis when colony morphology and pellicle formation are assessed. Data indicating that abh expression is dependent on the environmental signals that stimulate the activity of the extracytoplasmic function σ-factor σX are shown. We demonstrate that expression of slrR, the proposed activator of yqxM transcription, is positively controlled by Abh. Furthermore, Abh is shown to activate transcription from the promoter of the ep s operon through its control of SlrR. These findings add to the increasingly complex transcriptional network that controls biofilm formation by B. subtilis.

Liver and Statins: A Critical Appraisal of the Evidence

2019 ◽  
Vol 25 (42) ◽  
pp. 5835-5846 ◽  
Author(s):  
Anna Licata ◽  
Antonina Giammanco ◽  
Maria Giovanna Minissale ◽  
Salvatore Pagano ◽  
Salvatore Petta ◽  
...  
Keyword(s):  
Adverse Events ◽  
Association Studies ◽  
Organic Anion ◽  
Genome Wide Association Studies ◽  
Drug Induced ◽  
Drug Induced Liver Injury ◽  
Organic Anion Transporting Polypeptide ◽  
Treatment And Prevention ◽  
Genome Wide ◽  
Underlying Mechanisms

Adverse drug reactions (ADRs) represent an important cause of morbidity and mortality worldwide. Statins are a class of drugs whose main adverse effects are drug-induced liver injury (DILI) and myopathy. Some of these may be predictable, due to their pharmacokinetic and pharmacodynamic properties, while others, unfortunately, are idiosyncratic. Genetic factors may also influence patient susceptibility to DILI and myopathy in the case of statins. This review will first discuss the role of statins in cardiovascular disease treatment and prevention and the underlying mechanisms of action. Furthermore, to explore the susceptibility of statin-induced adverse events such as myopathy and hepatotoxicity, it will then focus on the recent Genome-Wide Association Studies (GWAS) concerning the transporter genes, Cytochrome P450 (CYP), organic anion-transporting polypeptide (OATP) and ABCB1 and ABCC1, which seem to play a role in the development of clinically relevant adverse events. Finally, we appraise the evidence for and against the use of statins in metabolic syndrome and in HCV-infected patients, in terms of their safety and efficacy in cardiovascular events.

scholarly journals Riboflavin synthases of Bacillus subtilis. Purification and amino acid sequence of the alpha subunit.

1990 ◽  
Vol 265 (8) ◽  
pp. 4204-4209
Author(s):  
K Schott ◽  
J Kellermann ◽  
F Lottspeich ◽  
A Bacher
Keyword(s):  
Bacillus Subtilis ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Alpha Subunit

scholarly journals Release factor-dependent ribosome rescue by BrfA in the Gram-positive bacterium Bacillus subtilis

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Naomi Shimokawa-Chiba ◽  
Claudia Müller ◽  
Keigo Fujiwara ◽  
Bertrand Beckert ◽  
Koreaki Ito ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Stop Codon ◽  
Release Factor ◽  
Positive Bacterium ◽  
Gram Positive ◽  
E Coli ◽  
Cryo Electron Microscopy ◽  
Dead End ◽  
Bacterium Bacillus Subtilis ◽  
Bacterium Bacillus

AbstractRescue of the ribosomes from dead-end translation complexes, such as those on truncated (non-stop) mRNA, is essential for the cell. Whereas bacteria use trans-translation for ribosome rescue, some Gram-negative species possess alternative and release factor (RF)-dependent rescue factors, which enable an RF to catalyze stop-codon-independent polypeptide release. We now discover that the Gram-positive Bacillus subtilis has an evolutionarily distinct ribosome rescue factor named BrfA. Genetic analysis shows that B. subtilis requires the function of either trans-translation or BrfA for growth, even in the absence of proteotoxic stresses. Biochemical and cryo-electron microscopy (cryo-EM) characterization demonstrates that BrfA binds to non-stop stalled ribosomes, recruits homologous RF2, but not RF1, and induces its transition into an open active conformation. Although BrfA is distinct from E. coli ArfA, they use convergent strategies in terms of mode of action and expression regulation, indicating that many bacteria may have evolved as yet unidentified ribosome rescue systems.

scholarly journals Modified Monosaccharides Content of Xanthan Gum Impairs Citrus Canker Disease by Affecting the Epiphytic Lifestyle of Xanthomonas citri subsp. citri

2021 ◽  
Vol 9 (6) ◽  
pp. 1176
Author(s):  
Simone Cristina Picchi ◽  
Laís Moreira Granato ◽  
Maria Júlia Festa Franzini ◽  
Maxuel Oliveira Andrade ◽  
Marco Aurélio Takita ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Xanthan Gum ◽  
Wild Type Strain ◽  
Natural Infection ◽  
Citrus Canker ◽  
Wild Type ◽  
Xanthomonas Citri ◽  
Canker Disease ◽  
Key Enzyme ◽  
Citrus Canker Disease

Xanthomonas citri subsp. citri (X. citri) is a plant pathogenic bacterium causing citrus canker disease. The xanA gene encodes a phosphoglucomutase/phosphomannomutase protein that is a key enzyme required for the synthesis of lipopolysaccharides and exopolysaccharides in Xanthomonads. In this work, firstly we isolated a xanA transposon mutant (xanA::Tn5) and analyzed its phenotypes as biofilm formation, xanthan gum production, and pathogenesis on the sweet orange host. Moreover, to confirm the xanA role in the impaired phenotypes we further produced a non-polar deletion mutant (ΔxanA) and performed the complementation of both xanA mutants. In addition, we analyzed the percentages of the xanthan gum monosaccharides produced by X. citri wild-type and xanA mutant. The mutant strain had higher ratios of mannose, galactose, and xylose and lower ratios of rhamnose, glucuronic acid, and glucose than the wild-type strain. Such changes in the saccharide composition led to the reduction of xanthan yield in the xanA deficient strain, affecting also other important features in X. citri, such as biofilm formation and sliding motility. Moreover, we showed that xanA::Tn5 caused no symptoms on host leaves after spraying, a method that mimetics the natural infection condition. These results suggest that xanA plays an important role in the epiphytical stage on the leaves that is essential for the successful interaction with the host, including adaptive advantage for bacterial X. citri survival and host invasion, which culminates in pathogenicity.

scholarly journals Deletion of Rap‐Phr systems in Bacillus subtilis influences in vitro biofilm formation and plant root colonization

2021 ◽  
Vol 10 (3) ◽  
Author(s):  
Mathilde Nordgaard ◽  
Rasmus Møller Rosenbek Mortensen ◽  
Nikolaj Kaae Kirk ◽  
Ramses Gallegos‐Monterrosa ◽  
Ákos T. Kovács
Keyword(s):  
Bacillus Subtilis ◽  
Biofilm Formation ◽  
Root Colonization ◽  
Plant Root
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