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Koo BM, Todor H, Sun J, van Gestel J, Hawkins JS, Hearne CC, Banta AB, Huang KC, Peters JM, Gross CA. Comprehensive double-mutant analysis of the Bacillus subtilis envelope using double-CRISPRi. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.14.608006. [PMID: 39185233 PMCID: PMC11343205 DOI: 10.1101/2024.08.14.608006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
Understanding bacterial gene function remains a major biological challenge. Double-mutant genetic interaction (GI) analysis addresses this challenge by uncovering the functional partners of targeted genes, allowing us to associate genes of unknown function with novel pathways and unravel connections between well-studied pathways, but is difficult to implement at the genome-scale. Here, we develop and use double-CRISPRi to systematically quantify genetic interactions at scale in the Bacillus subtilis envelope, including essential genes. We discover > 1000 known and novel genetic interactions. Our analysis pipeline and experimental follow-ups reveal the distinct roles of paralogous genes such as the mreB and mbl actin homologs, and identify new genes involved in the well-studied process of cell division. Overall, our study provides valuable insights into gene function and demonstrates the utility of double-CRISPRi for high-throughput dissection of bacterial gene networks, providing a blueprint for future studies in diverse bacterial species.
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Affiliation(s)
- Byoung-Mo Koo
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - Horia Todor
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - Jiawei Sun
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Jordi van Gestel
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - John S. Hawkins
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - Cameron C. Hearne
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - Amy B. Banta
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Jason M. Peters
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Carol A. Gross
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, California, USA
- California Institute of Quantitative Biology, University of California, San Francisco, San Francisco, CA, USA
- Lead Contact
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2
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Cheng X, Ning J, Xu X, Zhou X. The role of bacterial cyclic di-adenosine monophosphate in the host immune response. Front Microbiol 2022; 13:958133. [PMID: 36106081 PMCID: PMC9465037 DOI: 10.3389/fmicb.2022.958133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 08/04/2022] [Indexed: 11/13/2022] Open
Abstract
Cyclic di-adenosine monophosphate (c-di-AMP) is a second messenger which is widely used in signal transduction in bacteria and archaea. c-di-AMP plays an important role in the regulation of bacterial physiological activities, such as the cell cycle, cell wall stability, environmental stress response, and biofilm formation. Moreover, c-di-AMP produced by pathogens can be recognized by host cells for the activation of innate immune responses. It can induce type I interferon (IFN) response in a stimulator of interferon genes (STING)-dependent manner, activate the nuclear factor kappa B (NF-κB) pathway, inflammasome, and host autophagy, and promote the production and secretion of cytokines. In addition, c-di-AMP is capable of triggering a host mucosal immune response as a mucosal adjuvant. Therefore, c-di-AMP is now considered to be a new pathogen-associated molecular pattern in host immunity and has become a promising target in bacterial/viral vaccine and drug research. In this review, we discussed the crosstalk between bacteria and host immunity mediated by c-di-AMP and addressed the role of c-di-AMP as a mucosal adjuvant in boosting evoked immune responses of subunit vaccines. The potential application of c-di-AMP in immunomodulation and immunotherapy was also discussed in this review.
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Affiliation(s)
- Xingqun Cheng
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jia Ning
- The School and Hospital of Stomatology, Tianjin Medical University, Tianjin, China
| | - Xin Xu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- *Correspondence: Xuedong Zhou,
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3
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Shinjyo Y, Midorikawa N, Matsumoto T, Sugaya Y, Ozawa Y, Oana A, Horie C, Yoshikawa H, Takahashi Y, Hasegawa T, Asai K. Analysis of cell death in Bacillus subtilis caused by sesquiterpenes from Chrysopogon zizanioides (L.) Roberty. J GEN APPL MICROBIOL 2022; 68:62-70. [PMID: 35418537 DOI: 10.2323/jgam.2021.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Recently, the antibacterial effects of essential oils have been investigated in addition to their therapeutic purposes. Owing to their hydrophobic nature, they are thought to perturb the integrity of the bacterial cell membrane, leading to cell death. Against such antibiotic challenges, bacteria develop mechanisms for cell envelope stress responses (CESR). In Bacillus subtilis, a gram-positive sporulating soil bacterium, the extracytoplasmic function (ECF) sigma factor-mediated response system plays a pivotal role in CESR. Among them, σM is strongly involved in response to cell envelope stress, including a shortage of available bactoprenol. Vetiver essential oil, a product of Chrysopogon zizanioides (L.) Roberty root, is also known to possess bactericidal activity. σM was exclusively and strongly induced when the cells were exposed to Vetiver extract, and depletion of multi-ECF sigma factors (ΔsigM, ΔsigW, ΔsigX, and ΔsigV) enhanced sensitivity to it. From this quadruple mutant strain, the suppressor strains, which restored resistance to the bactericidal activity of Vetiver extract, emerged, although attempts to obtain resistant strains from the wild type did not succeed. Whole-genome resequencing of the suppressor strains and genetic analysis revealed inactivation of xseB or pnpA, which code for exodeoxyribonuclease or polynucleotide phosphorylase, respectively. This allowed the quadruple mutant strain to escape from cell death caused by Vetiver extract. Composition analysis suggested that the sesquiterpene, khusimol, might contribute to the bactericidal activity of the Vetiver extract.
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Affiliation(s)
- Yu Shinjyo
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Naoya Midorikawa
- Department of Chemistry, Graduate School of Science and Engineering, Saitama University
| | - Takashi Matsumoto
- Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture
| | - Yuki Sugaya
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Yoshiki Ozawa
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Ayumi Oana
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Chiaki Horie
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Hirofumi Yoshikawa
- Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture.,Department of Bioscience, Tokyo University of Agriculture
| | - Yasuhiro Takahashi
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Toshio Hasegawa
- Department of Chemistry, Graduate School of Science and Engineering, Saitama University
| | - Kei Asai
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University.,Department of Bioscience, Tokyo University of Agriculture
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4
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Wex KW, Saur JS, Handel F, Ortlieb N, Mokeev V, Kulik A, Niedermeyer THJ, Mast Y, Grond S, Berscheid A, Brötz-Oesterhelt H. Bioreporters for direct mode of action-informed screening of antibiotic producer strains. Cell Chem Biol 2021; 28:1242-1252.e4. [PMID: 33761329 DOI: 10.1016/j.chembiol.2021.02.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 01/27/2021] [Accepted: 02/23/2021] [Indexed: 01/17/2023]
Abstract
A big challenge in natural product research of today is rapid dereplication of already known substances, to free capacities for the exploration of new agents. Prompt information on bioactivities and mode of action (MOA) speeds up the lead discovery process and is required for rational compound optimization. Here, we present a bioreporter approach as a versatile strategy for combined bioactivity- and MOA-informed primary screening for antimicrobials. The approach is suitable for directly probing producer strains grown on agar, without need for initial compound enrichment or purification, and works along the entire purification pipeline with culture supernatants, extracts, fractions, and pure substances. The technology allows for MOA-informed purification to selectively prioritize activities of interest. In combination with high-resolution mass spectrometry, the biosensor panel is an efficient and sensitive tool for compound deconvolution. Concomitant information on the affected metabolic pathway enables the selection of appropriate follow-up assays to elucidate the molecular target.
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Affiliation(s)
- Katharina W Wex
- Department of Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany; German Center for Infection Research (DZIF), Partner Site Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany
| | - Julian S Saur
- Biomolecular Chemistry, Institute of Organic Chemistry, University of Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany
| | - Franziska Handel
- Department of Microbiology and Biotechnology, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany; German Center for Infection Research (DZIF), Partner Site Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany
| | - Nico Ortlieb
- Department of Microbiology and Biotechnology, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany; German Center for Infection Research (DZIF), Partner Site Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany
| | - Vladislav Mokeev
- Department of Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany; Cluster of Excellence EXC 2124 - Controlling Microbes to Fight Infections, Tuebingen, Baden-Württemberg 72076, Germany
| | - Andreas Kulik
- Department of Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany; Department of Microbiology and Biotechnology, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany; Cluster of Excellence EXC 2124 - Controlling Microbes to Fight Infections, Tuebingen, Baden-Württemberg 72076, Germany
| | - Timo H J Niedermeyer
- Department of Microbiology and Biotechnology, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany; Department of Pharmaceutical Biology/Pharmacognosy Institute of Pharmacy, Martin-Luther-University Halle-Wittenberg, Halle, Sachsen-Anhalt 06120, Germany; German Center for Infection Research (DZIF), Partner Site Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany
| | - Yvonne Mast
- Department of Microbiology and Biotechnology, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany; Department Bioresources for Bioeconomy and Health Research, Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Niedersachsen 38124, Germany; German Center for Infection Research (DZIF), Partner Site Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany
| | - Stephanie Grond
- Biomolecular Chemistry, Institute of Organic Chemistry, University of Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany; Cluster of Excellence EXC 2124 - Controlling Microbes to Fight Infections, Tuebingen, Baden-Württemberg 72076, Germany
| | - Anne Berscheid
- Department of Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany; German Center for Infection Research (DZIF), Partner Site Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany
| | - Heike Brötz-Oesterhelt
- Department of Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany; German Center for Infection Research (DZIF), Partner Site Tuebingen, Tuebingen, Baden-Württemberg 72076, Germany; Cluster of Excellence EXC 2124 - Controlling Microbes to Fight Infections, Tuebingen, Baden-Württemberg 72076, Germany.
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5
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Cell morphology maintenance in Bacillus subtilis through balanced peptidoglycan synthesis and hydrolysis. Sci Rep 2020; 10:17910. [PMID: 33087775 PMCID: PMC7578834 DOI: 10.1038/s41598-020-74609-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/28/2020] [Indexed: 01/12/2023] Open
Abstract
The peptidoglycan layer is responsible for maintaining bacterial cell shape and permitting cell division. Cell wall growth is facilitated by peptidoglycan synthases and hydrolases and is potentially modulated by components of the central carbon metabolism. In Bacillus subtilis, UgtP synthesises the glucolipid precursor for lipoteichoic acid and has been suggested to function as a metabolic sensor governing cell size. Here we show that ugtP mutant cells have increased levels of cell wall precursors and changes in their peptidoglycan that suggest elevated DL-endopeptidase activity. The additional deletion of lytE, encoding a DL-endopeptidase important for cell elongation, in the ugtP mutant background produced cells with severe shape defects. Interestingly, the ugtP lytE mutant recovered normal rod-shape by acquiring mutations that decreased the expression of the peptidoglycan synthase PBP1. Together our results suggest that cells lacking ugtP must re-adjust the balance between peptidoglycan synthesis and hydrolysis to maintain proper cell morphology.
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6
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Šiková M, Wiedermannová J, Převorovský M, Barvík I, Sudzinová P, Kofroňová O, Benada O, Šanderová H, Condon C, Krásný L. The torpedo effect in Bacillus subtilis: RNase J1 resolves stalled transcription complexes. EMBO J 2020; 39:e102500. [PMID: 31840842 PMCID: PMC6996504 DOI: 10.15252/embj.2019102500] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 11/26/2019] [Accepted: 11/27/2019] [Indexed: 12/17/2022] Open
Abstract
RNase J1 is the major 5'-to-3' bacterial exoribonuclease. We demonstrate that in its absence, RNA polymerases (RNAPs) are redistributed on DNA, with increased RNAP occupancy on some genes without a parallel increase in transcriptional output. This suggests that some of these RNAPs represent stalled, non-transcribing complexes. We show that RNase J1 is able to resolve these stalled RNAP complexes by a "torpedo" mechanism, whereby RNase J1 degrades the nascent RNA and causes the transcription complex to disassemble upon collision with RNAP. A heterologous enzyme, yeast Xrn1 (5'-to-3' exonuclease), is less efficient than RNase J1 in resolving stalled Bacillus subtilis RNAP, suggesting that the effect is RNase-specific. Our results thus reveal a novel general principle, whereby an RNase can participate in genome-wide surveillance of stalled RNAP complexes, preventing potentially deleterious transcription-replication collisions.
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Affiliation(s)
- Michaela Šiková
- Institute of Microbiology of the Czech Academy of SciencesPrague 4Czech Republic
| | - Jana Wiedermannová
- Institute of Microbiology of the Czech Academy of SciencesPrague 4Czech Republic
| | - Martin Převorovský
- Department of Cell BiologyFaculty of ScienceCharles UniversityPragueCzech Republic
| | - Ivan Barvík
- Division of Biomolecular PhysicsInstitute of PhysicsCharles UniversityPrague 2Czech Republic
| | - Petra Sudzinová
- Institute of Microbiology of the Czech Academy of SciencesPrague 4Czech Republic
| | - Olga Kofroňová
- Institute of Microbiology of the Czech Academy of SciencesPrague 4Czech Republic
| | - Oldřich Benada
- Institute of Microbiology of the Czech Academy of SciencesPrague 4Czech Republic
| | - Hana Šanderová
- Institute of Microbiology of the Czech Academy of SciencesPrague 4Czech Republic
| | - Ciarán Condon
- UMR8261CNRSUniversité de ParisInstitut de Biologie Physico‐ChimiqueParisFrance
| | - Libor Krásný
- Institute of Microbiology of the Czech Academy of SciencesPrague 4Czech Republic
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7
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Activation of the Extracytoplasmic Function σ Factor σ P by β-Lactams in Bacillus thuringiensis Requires the Site-2 Protease RasP. mSphere 2019; 4:4/4/e00511-19. [PMID: 31391284 PMCID: PMC6686233 DOI: 10.1128/msphere.00511-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The discovery of antibiotics to treat bacterial infections has had a dramatic and positive impact on human health. However, shortly after the introduction of a new antibiotic, bacteria often develop resistance. The bacterial cell envelope is essential for cell viability and is the target of many of the most commonly used antibiotics, including β-lactam antibiotics. Resistance to β-lactams is often dependent upon β-lactamases. In B. cereus, B. thuringiensis, and some B. anthracis strains, the expression of some β-lactamases is inducible. This inducible β-lactamase expression is controlled by activation of an alternative σ factor called σP. Here, we show that β-lactam antibiotics induce σP activation by degradation of the anti-σ factor RsiP. Bacteria can utilize alternative σ factors to regulate sets of genes in response to changes in the environment. The largest and most diverse group of alternative σ factors are the extracytoplasmic function (ECF) σ factors. σP is an ECF σ factor found in Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis. Previous work showed that σP is induced by ampicillin, a β-lactam antibiotic, and required for resistance to ampicillin. However, it was not known how activation of σP is controlled or what other antibiotics may activate σP. Here, we report that activation of σP is specific to a subset of β-lactams and that σP is required for resistance to these β-lactams. We demonstrate that activation of σP is controlled by the proteolytic destruction of the anti-σ factor RsiP and that degradation of RsiP requires multiple proteases. Upon exposure to β-lactams, the extracellular domain of RsiP is cleaved by an unknown protease, which we predict cleaves at site-1. Following cleavage by the unknown protease, the N terminus of RsiP is further degraded by the site-2 intramembrane protease RasP. Our data indicate that RasP cleavage of RsiP is not the rate-limiting step in σP activation. This proteolytic cascade leads to activation of σP, which induces resistance to β-lactams likely via increased expression of β-lactamases. IMPORTANCE The discovery of antibiotics to treat bacterial infections has had a dramatic and positive impact on human health. However, shortly after the introduction of a new antibiotic, bacteria often develop resistance. The bacterial cell envelope is essential for cell viability and is the target of many of the most commonly used antibiotics, including β-lactam antibiotics. Resistance to β-lactams is often dependent upon β-lactamases. In B. cereus, B. thuringiensis, and some B. anthracis strains, the expression of some β-lactamases is inducible. This inducible β-lactamase expression is controlled by activation of an alternative σ factor called σP. Here, we show that β-lactam antibiotics induce σP activation by degradation of the anti-σ factor RsiP.
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8
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Zhao H, Roistacher DM, Helmann JD. Deciphering the essentiality and function of the anti-σ M factors in Bacillus subtilis. Mol Microbiol 2019; 112:482-497. [PMID: 30715747 PMCID: PMC6679829 DOI: 10.1111/mmi.14216] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2019] [Indexed: 12/27/2022]
Abstract
Bacteria use alternative sigma factors to adapt to different growth and stress conditions. The Bacillus subtilis extracytoplasmic function sigma factor SigM regulates genes for cell wall synthesis and is crucial for maintaining cell wall homeostasis under stress conditions. The activity of SigM is regulated by its anti-sigma factor, YhdL, and the accessory protein YhdK. Here, we show that dysregulation of SigM caused by the absence of either component of the anti-sigma factor complex leads to toxic levels of SigM and severe growth defects. High SigM activity results from a dysregulated positive feedback loop, and can be suppressed by overexpression of the housekeeping sigma, SigA. Using a sigM merodiploid strain, we selected for suppressor mutations that allow survival of yhdL depletion strain. The recovered suppressor mutations map to the beta and beta-prime subunits of RNA polymerase core enzyme and selectively reduce SigM activity, and in some cases increase the activity of other alternative sigma factors. This work highlights the ability of mutations in RNA polymerase that remodel the sigma-core interface to differentially affect sigma factor activity, and thereby alter the transcriptional landscape of the cell.
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Affiliation(s)
- Heng Zhao
- Cornell University, Department of Microbiology, Ithaca, NY, USA
| | | | - John D. Helmann
- Cornell University, Department of Microbiology, Ithaca, NY, USA
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Rojas-Tapias DF, Helmann JD. Roles and regulation of Spx family transcription factors in Bacillus subtilis and related species. Adv Microb Physiol 2019; 75:279-323. [PMID: 31655740 DOI: 10.1016/bs.ampbs.2019.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Bacillus subtilis Spx is the prototype for a large family of redox-responsive transcription factors found in many bacteria, most notably those from the phylum Firmicutes. Unusually for a transcription factor, B. subtilis Spx protein modulates gene expression by binding as a monomer to the αCTD domain of RNA polymerase (RNAP), and only interacts with DNA during subsequent promoter engagement. B. subtilis Spx drives the expression of a large regulon in response to proteotoxic conditions, such as heat and disulfide stress, as well as cell wall stress. Here, we review the detailed mechanisms that control the expression, stability, and activity of Spx in response to a variety of stress conditions. We also summarize current knowledge regarding Spx homologs in other Firmicutes, the environmental conditions in which those homologs are activated, and their biological role.
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Affiliation(s)
| | - John D Helmann
- Department of Microbiology, Cornell University, Ithaca, NY, United States
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10
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Identification of Novel Spx Regulatory Pathways in Bacillus subtilis Uncovers a Close Relationship between the CtsR and Spx Regulons. J Bacteriol 2019; 201:JB.00151-19. [PMID: 30962353 DOI: 10.1128/jb.00151-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 04/04/2019] [Indexed: 12/15/2022] Open
Abstract
In Bacillus subtilis, the Spx transcription factor controls a large regulon in response to disulfide, heat, and cell wall stresses. The regulatory mechanisms that activate the Spx regulon are remarkably complex and involve changes in transcription, proteolysis, and posttranslational modifications. To identify genes involved in Spx regulation, we performed a transposon screen for mutations affecting expression of trxB, an Spx-dependent gene. Inactivation of ctsR, encoding the regulator of the Clp proteases, reduced trxB expression and lowered Spx levels. This effect required ClpP, but involved ClpC rather than the ClpX unfoldase. Moreover, cells lacking McsB, a dual function arginine kinase and ClpCP adaptor, largely reverted the ctsR phenotype and increased trxB expression. The role of McsB appears to involve its kinase activity, since loss of the YwlE phosphoarginine phosphatase also led to reduced trxB expression. Finally, we show that Spx is itself a regulator of the ctsR operon. Altogether, this work provides evidence for a role of CtsR regulon members ClpC, ClpP, and McsB in Spx regulation and identifies a new feedback pathway associated with Spx activity in B. subtilis IMPORTANCE In Bacillus subtilis, the Spx transcription factor is proteolytically unstable, and protein stabilization figures prominently in the induction of the Spx regulon in response to oxidative and cell envelope stresses. ClpXP is largely, but not entirely, responsible for Spx instability. Here, we identify ClpCP as the protease that degrades Spx under conditions that antagonize the ClpXP pathway. Spx itself contributes to activation of the ctsR operon, which encodes ClpC as well as the McsB arginine kinase and protease adaptor, thereby providing a negative feedback mechanism. Genetic studies reveal that dysregulation of the CtsR regulon or inactivation of the YwlE phosphoarginine phosphatase decreases Spx activity through mechanisms involving both protein degradation and posttranslational modification.
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11
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Schäfer H, Heinz A, Sudzinová P, Voß M, Hantke I, Krásný L, Turgay K. Spx, the central regulator of the heat and oxidative stress response in B. subtilis, can repress transcription of translation-related genes. Mol Microbiol 2018; 111:514-533. [PMID: 30480837 DOI: 10.1111/mmi.14171] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2018] [Indexed: 12/19/2022]
Abstract
Spx is a Bacillus subtilis transcription factor that interacts with the alpha subunits of RNA polymerase. It can activate the thiol stress response regulon and interfere with the activation of many developmental processes. Here, we show that Spx is a central player orchestrating the heat shock response by up-regulating relevant stress response genes as revealed by comparative transcriptomic experiments. Moreover, these experiments revealed the potential of Spx to inhibit transcription of translation-related genes. By in vivo and in vitro experiments, we confirmed that Spx can inhibit transcription from rRNA. This inhibition depended mostly on UP elements and the alpha subunits of RNA polymerase. However, the concurrent up-regulation activity of stress genes by Spx, but not the inhibition of translation related genes, was essential for mediating stress response and antibiotic tolerance under the applied stress conditions. The observed inhibitory activity might be compensated in vivo by additional stress response processes interfering with translation. Nevertheless, the impact of Spx on limiting translation becomes apparent under conditions with high cellular Spx levels. Interestingly, we observed a subpopulation of stationary phase cells that contains raised Spx levels, which may contribute to growth inhibition and a persister-like behaviour of this subpopulation during outgrowth.
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Affiliation(s)
- Heinrich Schäfer
- Institute of Microbiology, Leibniz Universität Hannover, Herrenhäuser Str. 2, D-30419, Hannover, Germany
| | - Anja Heinz
- Institute of Biology-Microbiology, Freie Universität Berlin, Königin-Luise-Str. 12-16, D-14195, Berlin, Germany
| | - Petra Sudzinová
- Institute of Microbiology, Czech Academy of Sciences, Vídeňská 1083, 142 20, Prague, Czech Republic
| | - Michelle Voß
- Institute of Microbiology, Leibniz Universität Hannover, Herrenhäuser Str. 2, D-30419, Hannover, Germany
| | - Ingo Hantke
- Institute of Microbiology, Leibniz Universität Hannover, Herrenhäuser Str. 2, D-30419, Hannover, Germany
| | - Libor Krásný
- Institute of Microbiology, Czech Academy of Sciences, Vídeňská 1083, 142 20, Prague, Czech Republic
| | - Kürşad Turgay
- Institute of Microbiology, Leibniz Universität Hannover, Herrenhäuser Str. 2, D-30419, Hannover, Germany
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Vinayavekhin N, Vangnai AS. The effects of disruption in membrane lipid biosynthetic genes on 1-butanol tolerance of Bacillus subtilis. Appl Microbiol Biotechnol 2018; 102:9279-9289. [DOI: 10.1007/s00253-018-9298-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 07/23/2018] [Accepted: 08/02/2018] [Indexed: 01/24/2023]
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13
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Signal Peptidase Is Necessary and Sufficient for Site 1 Cleavage of RsiV in Bacillus subtilis in Response to Lysozyme. J Bacteriol 2018; 200:JB.00663-17. [PMID: 29358498 DOI: 10.1128/jb.00663-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 01/18/2018] [Indexed: 01/09/2023] Open
Abstract
Extracytoplasmic function (ECF) σ factors are a diverse family of alternative σ factors that allow bacteria to sense and respond to changes in the environment. σV is an ECF σ factor found primarily in low-GC Gram-positive bacteria and is required for lysozyme resistance in several opportunistic pathogens. In the absence of lysozyme, σV is inhibited by the anti-σ factor RsiV. In response to lysozyme, RsiV is degraded via the process of regulated intramembrane proteolysis (RIP). RIP is initiated by cleavage of RsiV at site 1, which allows the intramembrane protease RasP to cleave RsiV within the transmembrane domain at site 2 and leads to activation of σV Previous work suggested that RsiV is cleaved by signal peptidase at site 1. Here we demonstrate in vitro that signal peptidase is sufficient for cleavage of RsiV only in the presence of lysozyme and provide evidence that multiple Bacillus subtilis signal peptidases can cleave RsiV in vitro This cleavage is dependent upon the concentration of lysozyme, consistent with previous work that showed that binding to RsiV was required for σV activation. We also show that signal peptidase activity is required for site 1 cleavage of RsiV in vivo Thus, we demonstrate that signal peptidase is the site 1 protease for RsiV.IMPORTANCE Extracytoplasmic function (ECF) σ factors are a diverse family of alternative σ factors that respond to extracellular signals. The ECF σ factor σV is present in many low-GC Gram-positive bacteria and induces resistance to lysozyme, a component of the innate immune system. The anti-σ factor RsiV inhibits σV activity in the absence of lysozyme. Lysozyme binds RsiV, which initiates a proteolytic cascade leading to destruction of RsiV and activation of σV This proteolytic cascade is initiated by signal peptidase, a component of the general secretory system. We show that signal peptidase is necessary and sufficient for cleavage of RsiV at site 1 in the presence of lysozyme. This report describes a role for signal peptidase in controlling gene expression.
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14
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Rojas-Tapias DF, Helmann JD. Induction of the Spx regulon by cell wall stress reveals novel regulatory mechanisms in Bacillus subtilis. Mol Microbiol 2018; 107:659-674. [PMID: 29271514 DOI: 10.1111/mmi.13906] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 12/18/2017] [Accepted: 12/20/2017] [Indexed: 12/18/2022]
Abstract
The transcription factor Spx is the master regulator of the disulfide stress response in Bacillus subtilis. Intriguingly, the activation of Spx by diamide relies entirely on posttranslational regulatory events in spite of the complex transcriptional control of the spx gene. Here, we show that cell wall stress, but not membrane stress, also results in induction of the Spx regulon. Remarkably, two major differences were found regarding the mechanism of induction of Spx under cell wall stress in comparison to disulfide stress. First, transcriptional induction of the spx gene from a σM -dependent promoter is required for accumulation of Spx in response to cell wall stress. Second, activation of the Spx regulon during cell wall stress is not accompanied by oxidation of the Spx disulfide switch. Finally, we demonstrate that cells lacking Spx have increased sensitivity toward antibiotics inhibiting both early and late steps in peptidoglycan synthesis, suggesting that the Spx regulon plays an important adaptive role in the cell wall stress response. This study expands the functional role of the Spx regulon and reveals novel regulatory mechanisms that result in induction of Spx in B. subtilis.
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Affiliation(s)
| | - John D Helmann
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
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15
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Woods EC, McBride SM. Regulation of antimicrobial resistance by extracytoplasmic function (ECF) sigma factors. Microbes Infect 2017; 19:238-248. [PMID: 28153747 DOI: 10.1016/j.micinf.2017.01.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 01/20/2017] [Accepted: 01/21/2017] [Indexed: 11/27/2022]
Abstract
Extracytoplasmic function (ECF) sigma factors are a subfamily of σ70 sigma factors that activate genes involved in stress-response functions. In many bacteria, ECF sigma factors regulate resistance to antimicrobial compounds. This review will summarize the ECF sigma factors that regulate antimicrobial resistance in model organisms and clinically relevant pathogens.
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Affiliation(s)
- Emily C Woods
- Department of Microbiology and Immunology, Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Shonna M McBride
- Department of Microbiology and Immunology, Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, USA.
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16
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Ogura M, Asai K. Glucose Induces ECF Sigma Factor Genes, sigX and sigM, Independent of Cognate Anti-sigma Factors through Acetylation of CshA in Bacillus subtilis. Front Microbiol 2016; 7:1918. [PMID: 27965645 PMCID: PMC5126115 DOI: 10.3389/fmicb.2016.01918] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 11/15/2016] [Indexed: 12/23/2022] Open
Abstract
Extracytoplasmic function (ECF) σ factors have roles related to cell envelope and/or cell membrane functions, in addition to other cellular functions. Without cell-surface stresses, ECF σ factors are sequestered by the cognate anti-σ factor, leading to inactivation and the resultant repression of regulons due to the inhibition of transcription of their own genes. Bacillus subtilis has seven ECF σ factors including σX and σM that transcribe their own structural genes. Here, we report that glucose addition to the medium induced sigX and sigM transcription independent of their anti-σ factors. This induction was dependent on an intracellular acetyl-CoA pool. Transposon mutagenesis searching for the mutants showing no induction of sigX and sigM revealed that the cshA gene encoding DEAD-box RNA helicase is required for gene induction. Global analysis of the acetylome in B. subtilis showed CshA has two acetylated lysine residues. We found that in a cshA mutant with acetylation-abolishing K to R exchange mutations, glucose induction of sigX and sigM was abolished and that glucose addition stimulated acetylation of CshA in the wild type strain. Thus, we present a model wherein glucose addition results in a larger acetyl-CoA pool, probably leading to increased levels of acetylated CshA. CshA is known to associate with RNA polymerase (RNAP), and thus RNAP with acetylated CshA could stimulate the autoregulation of sigX and sigM. This is a unique model showing a functional link between nutritional signals and the basal transcription machinery.
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Affiliation(s)
- Mitsuo Ogura
- Institute of Oceanic Research and Development, Tokai University Shizuoka, Japan
| | - Kei Asai
- Department of Bioscience, Saitama University Saitama, Japan
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17
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Evidence that Oxidative Stress Induces spxA2 Transcription in Bacillus anthracis Sterne through a Mechanism Requiring SpxA1 and Positive Autoregulation. J Bacteriol 2016; 198:2902-2913. [PMID: 27501985 PMCID: PMC5055595 DOI: 10.1128/jb.00512-16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 08/02/2016] [Indexed: 12/22/2022] Open
Abstract
Bacillus anthracis possesses two paralogs of the transcriptional regulator, Spx. SpxA1 and SpxA2 interact with RNA polymerase (RNAP) to activate the transcription of genes implicated in the prevention and alleviation of oxidative protein damage. The spxA2 gene is highly upregulated in infected macrophages, but how this is achieved is unknown. Previous studies have shown that the spxA2 gene was under negative control by the Rrf2 family repressor protein, SaiR, whose activity is sensitive to oxidative stress. These studies also suggested that spxA2 was under positive autoregulation. In the present study, we show by in vivo and in vitro analyses that spxA2 is under direct autoregulation but is also dependent on the SpxA1 paralogous protein. The deletion of either spxA1 or spxA2 reduced the diamide-inducible expression of an spxA2-lacZ construct. In vitro transcription reactions using purified B. anthracis RNAP showed that SpxA1 and SpxA2 protein stimulates transcription from a DNA fragment containing the spxA2 promoter. Ectopically positioned spxA2-lacZ fusion requires both SpxA1 and SpxA2 for expression, but the requirement for SpxA1 is partially overcome when saiR is deleted. Electrophoretic mobility shift assays showed that SpxA1 and SpxA2 enhance the affinity of RNAP for spxA2 promoter DNA and that this activity is sensitive to reductant. We hypothesize that the previously observed upregulation of spxA2 in the oxidative environment of the macrophage is at least partly due to SpxA1-mediated SaiR repressor inactivation and the positive autoregulation of spxA2 transcription. IMPORTANCE Regulators of transcription initiation are known to govern the expression of genes required for virulence in pathogenic bacterial species. Members of the Spx family of transcription factors function in control of genes required for virulence and viability in low-GC Gram-positive bacteria. In Bacillus anthracis, the spxA2 gene is highly induced in infected macrophages, which suggests an important role in the control of virulence gene expression during the anthrax disease state. We provide evidence that elevated concentrations of oxidized, active SpxA2 result from an autoregulatory positive-feedback loop driving spxA2 transcription.
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18
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Xiao Y, Liu H, Nie H, Xie S, Luo X, Chen W, Huang Q. Expression of the phosphodiesterase BifA facilitating swimming motility is partly controlled by FliA in Pseudomonas putida KT2440. Microbiologyopen 2016; 6. [PMID: 27663176 PMCID: PMC5300878 DOI: 10.1002/mbo3.402] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/12/2016] [Accepted: 08/19/2016] [Indexed: 12/30/2022] Open
Abstract
Flagella‐mediated motility is an important capability of many bacteria to survive in nutrient‐depleted and harsh environments. Decreasing the intracellular cyclic di‐GMP (c‐di‐GMP) level by overexpression of phosphodiesterase BifA promotes flagellar‐mediated motility and induces planktonic lifestyle in Pseudomonas. The mechanism that regulates expression of bifA gene was poorly studied. Here we showed that expression of BifA was partly controlled by flagellar sigma factor FliA (σ28) in Pseudomonas putidaKT2440. FliA deletion led to an approximately twofold decrease in transcription of bifA. 5′ race assay revealed two transcription start points in bifA promoter region, with the putative σ70 and σ28 promoter sequences upstream, respectively. Point mutation in σ28 promoter region reduced transcriptional activity of the promoter in wild‐type KT2440, but showed no influence on that in fliA deletion mutant. FliA overexpression decreased the intracellular c‐di‐GMP level in a BifA‐dependent way, suggesting that FliA was able to modulate the intracellular c‐di‐GMP level and BifA function was required for the modulation. Besides, FliA overexpression enhanced swimming ability of wild‐type strain, while made no difference to the bifA mutant. Our results suggest that FliA acts as a negative regulator to modulate the c‐di‐GMP level via controlling transcription of bifA to facilitate swimming motility.
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Affiliation(s)
- Yujie Xiao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
| | - Huizhong Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
| | - Hailing Nie
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
| | - Shan Xie
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
| | - Xuesong Luo
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, China
| | - Wenli Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, China
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19
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Song Y, Nikoloff JM, Fu G, Chen J, Li Q, Xie N, Zheng P, Sun J, Zhang D. Promoter Screening from Bacillus subtilis in Various Conditions Hunting for Synthetic Biology and Industrial Applications. PLoS One 2016; 11:e0158447. [PMID: 27380260 PMCID: PMC4933340 DOI: 10.1371/journal.pone.0158447] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 06/16/2016] [Indexed: 11/24/2022] Open
Abstract
The use of Bacillus subtilis in synthetic biology and metabolic engineering is highly desirable to take advantage of the unique metabolic pathways present in this organism. To do this, an evaluation of B. subtilis’ intrinsic biological parts is required to determine the best strategies to accurately regulate metabolic circuits and expression of target proteins. The strengths of promoter candidates were evaluated by measuring relative fluorescence units of a green fluorescent protein reporter, integrated into B. subtilis’ chromosome. A total of 84 predicted promoter sequences located upstream of different classes of proteins including heat shock proteins, cell-envelope proteins, and proteins resistant against toxic metals (based on similarity) and other kinds of genes were tested. The expression levels measured ranged from 0.0023 to 4.53-fold of the activity of the well-characterized strong promoter P43. No significant shifts were observed when strains, carrying different promoter candidates, were cultured at high temperature or in media with ethanol, but some strains showed increased activity when cultured under high osmotic pressure. Randomly selected promoter candidates were tested and found to activate transcription of thermostable β-galactosidase (bgaB) at a similar level, implying the ability of these sequences to function as promoter elements in multiple genetic contexts. In addition, selected promoters elevated the final production of both cytoplasmic bgaB and secreted protein α-amylase to about fourfold and twofold, respectively. The generated data allows a deeper understanding of B. subtilis’ metabolism and will facilitate future work to develop this organism for synthetic biology.
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Affiliation(s)
- Yafeng Song
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
| | - Jonas M Nikoloff
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
| | - Gang Fu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
| | - Jingqi Chen
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
| | - Qinggang Li
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
| | - Nengzhong Xie
- National Engineering Research Center for Non-food Biorefinery, State Key Laboratory of Non-food Biomass Energy and Enzyme Technology, Nanning 5300074, P. R. China
- Guangxi Biomass Industrialization Engineering Institute, Guangxi Academy of Sciences, Nanning 530007, P. R. China
| | - Ping Zheng
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
| | - Jibin Sun
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
| | - Dawei Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
- Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
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20
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Helmann JD. Bacillus subtilis extracytoplasmic function (ECF) sigma factors and defense of the cell envelope. Curr Opin Microbiol 2016; 30:122-132. [PMID: 26901131 DOI: 10.1016/j.mib.2016.02.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 01/29/2016] [Accepted: 02/02/2016] [Indexed: 01/20/2023]
Abstract
Bacillus subtilis provides a model for investigation of the bacterial cell envelope, the first line of defense against environmental threats. Extracytoplasmic function (ECF) sigma factors activate genes that confer resistance to agents that threaten the integrity of the envelope. Although their individual regulons overlap, σ(W) is most closely associated with membrane-active agents, σ(X) with cationic antimicrobial peptide resistance, and σ(V) with resistance to lysozyme. Here, I highlight the role of the σ(M) regulon, which is strongly induced by conditions that impair peptidoglycan synthesis and includes the core pathways of envelope synthesis and cell division, as well as stress-inducible alternative enzymes. Studies of these cell envelope stress responses provide insights into how bacteria acclimate to the presence of antibiotics.
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Affiliation(s)
- John D Helmann
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA.
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21
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Ruiz N. Lipid Flippases for Bacterial Peptidoglycan Biosynthesis. Lipid Insights 2016; 8:21-31. [PMID: 26792999 PMCID: PMC4714577 DOI: 10.4137/lpi.s31783] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 11/10/2015] [Accepted: 11/30/2015] [Indexed: 12/26/2022] Open
Abstract
The biosynthesis of cellular polysaccharides and glycoconjugates often involves lipid-linked intermediates that need to be translocated across membranes. Essential pathways such as N-glycosylation in eukaryotes and biogenesis of the peptidoglycan (PG) cell wall in bacteria share a common strategy where nucleotide-sugars are used to build a membrane-bound oligosaccharide precursor that is linked to a phosphorylated isoprenoid lipid. Once made, these lipid-linked intermediates must be translocated across a membrane so that they can serve as substrates in a different cellular compartment. How translocation occurs is poorly understood, although it clearly requires a transporter or flippase. Identification of these transporters is notoriously difficult, and, in particular, the identity of the flippase of lipid II, an intermediate required for PG biogenesis, has been the subject of much debate. Here, I will review the body of work that has recently fueled this controversy, centered on proposed flippase candidates FtsW, MurJ, and AmJ.
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Affiliation(s)
- Natividad Ruiz
- Associate Professor, Department of Microbiology, The Ohio State University, Columbus, OH, USA
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22
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Vinayavekhin N, Mahipant G, Vangnai AS, Sangvanich P. Untargeted metabolomics analysis revealed changes in the composition of glycerolipids and phospholipids in Bacillus subtilis under 1-butanol stress. Appl Microbiol Biotechnol 2015; 99:5971-83. [PMID: 26025016 DOI: 10.1007/s00253-015-6692-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 04/18/2015] [Accepted: 05/15/2015] [Indexed: 01/21/2023]
Abstract
1-Butanol has been utilized widely in industry and can be produced or transformed by microbes. However, current knowledge about the mechanisms of 1-butanol tolerance in bacteria remains quite limited. Here, we applied untargeted metabolomics to study Bacillus subtilis cells under 1-butanol stress and identified 55 and 37 ions with significantly increased and decreased levels, respectively. Using accurate mass determination, tandem mass spectra, and synthetic standards, 86 % of these ions were characterized. The levels of phosphatidylethanolamine, diglucosyldiacylglycerol, and phosphatidylserine were found to be upregulated upon 1-butanol treatment, whereas those of diacylglycerol and lysyl phosphatidylglycerol were downregulated. Most lipids contained 15:0/15:0, 16:0/15:0, and 17:0/15:0 acyl chains, and all were mapped to membrane lipid biosynthetic pathways. Subsequent two-stage quantitative real-time reverse transcriptase PCR analyses of genes in the two principal membrane lipid biosynthesis pathways revealed elevated levels of ywiE transcripts in the presence of 1-butanol and reduced expression levels of cdsA, pgsA, mprF, clsA, and yfnI transcripts. Thus, the gene transcript levels showed agreement with the metabolomics data. Lastly, the cell morphology was investigated by scanning electron microscopy, which indicated that cells became almost twofold longer after 1.4 % (v/v) 1-butanol stress for 12 h. Overall, the studies uncovered changes in the composition of glycerolipids and phospholipids in B. subtilis under 1-butanol stress, emphasizing the power of untargeted metabolomics in the discovery of new biological insights.
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Affiliation(s)
- Nawaporn Vinayavekhin
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand,
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23
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MurJ and a novel lipid II flippase are required for cell wall biogenesis in Bacillus subtilis. Proc Natl Acad Sci U S A 2015; 112:6437-42. [PMID: 25918422 DOI: 10.1073/pnas.1504967112] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Bacterial surface polysaccharides are synthesized from lipid-linked precursors at the inner surface of the cytoplasmic membrane before being translocated across the bilayer for envelope assembly. Transport of the cell wall precursor lipid II in Escherichia coli requires the broadly conserved and essential multidrug/oligosaccharidyl-lipid/polysaccharide (MOP) exporter superfamily member MurJ. Here, we show that Bacillus subtilis cells lacking all 10 MOP superfamily members are viable with only minor morphological defects, arguing for the existence of an alternate lipid II flippase. To identify this factor, we screened for synthetic lethal partners of MOP family members using transposon sequencing. We discovered that an uncharacterized gene amj (alternate to MurJ; ydaH) and B. subtilis MurJ (murJBs; formerly ytgP) are a synthetic lethal pair. Cells defective for both Amj and MurJBs exhibit cell shape defects and lyse. Furthermore, expression of Amj or MurJBs in E. coli supports lipid II flipping and viability in the absence of E. coli MurJ. Amj is present in a subset of gram-negative and gram-positive bacteria and is the founding member of a novel family of flippases. Finally, we show that Amj is expressed under the control of the cell envelope stress-response transcription factor σ(M) and cells lacking MurJBs increase amj transcription. These findings raise the possibility that antagonists of the canonical MurJ flippase trigger expression of an alternate translocase that can resist inhibition.
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Abstract
Gram-positive organisms, including the pathogens Staphylococcus aureus, Streptococcus pneumoniae, and Enterococcus faecalis, have dynamic cell envelopes that mediate interactions with the environment and serve as the first line of defense against toxic molecules. Major components of the cell envelope include peptidoglycan (PG), which is a well-established target for antibiotics, teichoic acids (TAs), capsular polysaccharides (CPS), surface proteins, and phospholipids. These components can undergo modification to promote pathogenesis, decrease susceptibility to antibiotics and host immune defenses, and enhance survival in hostile environments. This chapter will cover the structure, biosynthesis, and important functions of major cell envelope components in gram-positive bacteria. Possible targets for new antimicrobials will be noted.
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25
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Kiriyama Y, Yazawa K, Tanaka T, Yoshikawa R, Yamane H, Hashimoto M, Sekiguchi J, Yamamoto H. Localization and expression of the Bacillus subtilis
dl-endopeptidase LytF are influenced by mutations in LTA synthases and glycolipid anchor synthetic enzymes. Microbiology (Reading) 2014; 160:2639-2649. [DOI: 10.1099/mic.0.080366-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Bacillus subtilis LytF plays a principal role in cell separation through its localization at the septa and poles on the vegetative cell surface. In this study, we found that a mutation in a major lipoteichoic acid (LTA) synthase gene – ltaS – results in a considerable reduction in the σD-dependent transcription of lytF. The lytF transcription was also reduced in mutants that affected glycolipid anchor biosynthesis. Immunofluorescence microscopy revealed that both the numbers of cells expressing LytF and the LytF foci in these mutants were decreased. In addition, the transcriptional activity of lytF was almost abolished in the double (ltaS yfnI), triple (ltaS yfnI yqgS), and quadruple (ltaS yfnI yqgS yvgJ) mutants during vegetative growth. Cell separation defects in these mutants were partially restored with artificial expression of LytF. Interestingly, when lytF transcription was induced in the ltaS single or multiple mutants, LytF was localized not only at the septum, but also along the sidewall. The amounts of LytF bound to cell wall in the single (ltaS) and double (ltaS yfnI) mutants gradually increased as compared with that in the WT strain, and those in the triple (ltaS yfnI yqgS) and quadruple mutants were almost similar to that in the double mutant. Moreover, reduction of the lytF transcription and chained cell morphology in the ltaS mutant were completely restored with artificial induction of the yqgS gene. These results strongly suggest that LTA influences the temporal, σD-dependent transcription of lytF and is an additional inhibitory component to the vegetative cell separation enzyme LytF.
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Affiliation(s)
- Yuuka Kiriyama
- Department of Applied Biology, Graduate School of Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda-shi, Nagano 386-8567, Japan
| | - Kazuya Yazawa
- Department of Applied Biology, Graduate School of Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda-shi, Nagano 386-8567, Japan
| | - Tatsuhito Tanaka
- Department of Applied Biology, Graduate School of Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda-shi, Nagano 386-8567, Japan
| | - Ritsuko Yoshikawa
- Department of Applied Biology, Graduate School of Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda-shi, Nagano 386-8567, Japan
| | - Hisaya Yamane
- Department of Applied Biology, Graduate School of Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda-shi, Nagano 386-8567, Japan
| | - Masayuki Hashimoto
- Center of Infectious Disease and Signal Transduction, National Cheng Kung University Medical College, Tainan City 704-56, Taiwan
- Institute of Molecular Medicine, Tainan City 704-56, Taiwan
| | - Junichi Sekiguchi
- Department of Applied Biology, Graduate School of Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda-shi, Nagano 386-8567, Japan
| | - Hiroki Yamamoto
- Department of Applied Biology, Graduate School of Science and Technology, Shinshu University, 3-15-1 Tokida, Ueda-shi, Nagano 386-8567, Japan
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26
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Mehne FMP, Schröder-Tittmann K, Eijlander RT, Herzberg C, Hewitt L, Kaever V, Lewis RJ, Kuipers OP, Tittmann K, Stülke J. Control of the diadenylate cyclase CdaS in Bacillus subtilis: an autoinhibitory domain limits cyclic di-AMP production. J Biol Chem 2014; 289:21098-107. [PMID: 24939848 PMCID: PMC4110313 DOI: 10.1074/jbc.m114.562066] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 06/07/2014] [Indexed: 01/07/2023] Open
Abstract
The Gram-positive bacterium Bacillus subtilis encodes three diadenylate cyclases that synthesize the essential signaling nucleotide cyclic di-AMP. The activities of the vegetative enzymes DisA and CdaA are controlled by protein-protein interactions with their conserved partner proteins. Here, we have analyzed the regulation of the unique sporulation-specific diadenylate cyclase CdaS. Very low expression of CdaS as the single diadenylate cyclase resulted in the appearance of spontaneous suppressor mutations. Several of these mutations in the cdaS gene affected the N-terminal domain of CdaS. The corresponding CdaS mutant proteins exhibited a significantly increased enzymatic activity. The N-terminal domain of CdaS consists of two α-helices and is attached to the C-terminal catalytically active diadenylate cyclase (DAC) domain. Deletion of the first or both helices resulted also in strongly increased activity indicating that the N-terminal domain serves to limit the enzyme activity of the DAC domain. The structure of YojJ, a protein highly similar to CdaS, indicates that the protein forms hexamers that are incompatible with enzymatic activity of the DAC domains. In contrast, the mutations and the deletions of the N-terminal domain result in conformational changes that lead to highly increased enzymatic activity. Although the full-length CdaS protein was found to form hexamers, a truncated version with a deletion of the first N-terminal helix formed dimers with high enzyme activity. To assess the role of CdaS in sporulation, we assayed the germination of wild type and cdaS mutant spores. The results indicate that cyclic di-AMP formed by CdaS is required for efficient germination.
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Affiliation(s)
- Felix M P Mehne
- From the Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August University, D-37077 Göttingen, Germany
| | - Kathrin Schröder-Tittmann
- Department of Bioanalytics, Albrecht-von-Haller Institute for Plant Sciences, Göttingen Center for Molecular Biosciences, Georg-August University Göttingen, 9747 AG Groningen, Germany
| | - Robyn T Eijlander
- Department for Molecular Genetics, University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, 9747 AG Groningen, The Netherlands, Top Institute Food and Nutrition (TIFN), Nieuwe Kanaal 9A, 6709 PA Wageningen, The Netherlands
| | - Christina Herzberg
- From the Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August University, D-37077 Göttingen, Germany
| | - Lorraine Hewitt
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom, and
| | - Volkhard Kaever
- Research Core Unit for Mass Spectrometry, Metabolomics and Institute of Pharmacology, Hannover Medical School, D-30625 Hannover, Germany, and
| | - Richard J Lewis
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom, and
| | - Oscar P Kuipers
- Department for Molecular Genetics, University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, 9747 AG Groningen, The Netherlands, Top Institute Food and Nutrition (TIFN), Nieuwe Kanaal 9A, 6709 PA Wageningen, The Netherlands
| | - Kai Tittmann
- Department of Bioanalytics, Albrecht-von-Haller Institute for Plant Sciences, Göttingen Center for Molecular Biosciences, Georg-August University Göttingen, 9747 AG Groningen, Germany
| | - Jörg Stülke
- From the Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August University, D-37077 Göttingen, Germany,
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27
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Souza BM, Castro TLDP, Carvalho RDDO, Seyffert N, Silva A, Miyoshi A, Azevedo V. σ(ECF) factors of gram-positive bacteria: a focus on Bacillus subtilis and the CMNR group. Virulence 2014; 5:587-600. [PMID: 24921931 PMCID: PMC4105308 DOI: 10.4161/viru.29514] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The survival of bacteria to different environmental conditions depends on the activation of adaptive mechanisms, which are intricately driven through gene regulation. Because transcriptional initiation is considered to be the major step in the control of bacterial genes, we discuss the characteristics and roles of the sigma factors, addressing (1) their structural, functional and phylogenetic classification; (2) how their activity is regulated; and (3) the promoters recognized by these factors. Finally, we focus on a specific group of alternative sigma factors, the so-called σ(ECF) factors, in Bacillus subtilis and some of the main species that comprise the CMNR group, providing information on the roles they play in the microorganisms' physiology and indicating some of the genes whose transcription they regulate.
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Affiliation(s)
- Bianca Mendes Souza
- Laboratório de Genética Celular e Molecular; Instituto de Ciências Biológicas; Departamento de Biologia Geral; Universidade Federal de Minas Gerais; Belo Horizonte, MG Brazil
| | - Thiago Luiz de Paula Castro
- Laboratório de Genética Celular e Molecular; Instituto de Ciências Biológicas; Departamento de Biologia Geral; Universidade Federal de Minas Gerais; Belo Horizonte, MG Brazil
| | - Rodrigo Dias de Oliveira Carvalho
- Laboratório de Genética Celular e Molecular; Instituto de Ciências Biológicas; Departamento de Biologia Geral; Universidade Federal de Minas Gerais; Belo Horizonte, MG Brazil
| | - Nubia Seyffert
- Laboratório de Genética Celular e Molecular; Instituto de Ciências Biológicas; Departamento de Biologia Geral; Universidade Federal de Minas Gerais; Belo Horizonte, MG Brazil
| | - Artur Silva
- Laboratório de Polimorfismo de DNA; Instituto de Ciências Biológicas; Departamento de Genética; Universidade Federal do Pará; Belém, PA Brazil
| | - Anderson Miyoshi
- Laboratório de Genética Celular e Molecular; Instituto de Ciências Biológicas; Departamento de Biologia Geral; Universidade Federal de Minas Gerais; Belo Horizonte, MG Brazil
| | - Vasco Azevedo
- Laboratório de Genética Celular e Molecular; Instituto de Ciências Biológicas; Departamento de Biologia Geral; Universidade Federal de Minas Gerais; Belo Horizonte, MG Brazil
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Barendt S, Lee H, Birch C, Nakano MM, Jones M, Zuber P. Transcriptomic and phenotypic analysis of paralogous spx gene function in Bacillus anthracis Sterne. Microbiologyopen 2013; 2:695-714. [PMID: 23873705 PMCID: PMC3831629 DOI: 10.1002/mbo3.109] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 06/05/2013] [Accepted: 06/17/2013] [Indexed: 11/15/2022] Open
Abstract
Spx of Bacillus subtilis is a redox-sensitive protein, which, under disulfide stress, interacts with RNA polymerase to activate genes required for maintaining thiol homeostasis. Spx orthologs are highly conserved among low %GC Gram-positive bacteria, and often exist in multiple paralogous forms. In this study, we used B. anthracis Sterne, which harbors two paralogous spx genes, spxA1 and spxA2, to examine the phenotypes of spx null mutations and to identify the genes regulated by each Spx paralog. Cells devoid of spxA1 were sensitive to diamide and hydrogen peroxide, while the spxA1 spoxA2 double mutant was hypersensitive to the thiol-specific oxidant, diamide. Bacillus anthracis Sterne strains expressing spxA1DD or spxA2DD alleles encoding protease-resistant products were used in microarray and quantitative real-time polymerase chain reaction (RT-qPCR) analyses in order to uncover genes under SpxA1, SpxA2, or SpxA1/SpxA2 control. Comparison of transcriptomes identified many genes that were upregulated when either SpxA1DD or SpxA2DD was produced, but several genes were uncovered whose transcript levels increased in only one of the two SpxADD-expression strains, suggesting that each Spx paralog governs a unique regulon. Among genes that were upregulated were those encoding orthologs of proteins that are specifically involved in maintaining intracellular thiol homeostasis or alleviating oxidative stress. Some of these genes have important roles in B. anthracis pathogenesis, and a large number of upregulated hypothetical genes have no homology outside of the B. cereus/thuringiensis group. Microarray and RT-qPCR analyses also unveiled a regulatory link that exists between the two spx paralogous genes. The data indicate that spxA1 and spxA2 are transcriptional regulators involved in relieving disulfide stress but also control a set of genes whose products function in other cellular processes. Bacillus anthracis harbors two paralogs of the global transcriptional regulator of stress response, SpxA. SpxA1 and SpxA2 contribute to disulfide stress tolerance, but only SpxA1 functions in resistance to peroxide. Transcriptome analysis uncovered potential SpxA1 and SpxA2 regulon members, which include genes activated by both paralogs. However, paralog-specific gene activation was also observed. Genes encoding glutamate racemase, CoA disulfide reductase, and products functioning in bacillithiol biosynthesis, are among the genes activated by the SpxA paralogs.
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Affiliation(s)
- Skye Barendt
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health and Science University, Beaverton, Oregon
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Corrigan RM, Gründling A. Cyclic di-AMP: another second messenger enters the fray. Nat Rev Microbiol 2013; 11:513-24. [PMID: 23812326 DOI: 10.1038/nrmicro3069] [Citation(s) in RCA: 272] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Nucleotide signalling molecules contribute to the regulation of cellular pathways in all forms of life. In recent years, the discovery of new signalling molecules in bacteria and archaea, as well as the elucidation of the pathways they regulate, has brought insights into signalling mechanisms not only in bacterial and archaeal cells but also in eukaryotic host cells. Here, we provide an overview of the synthesis and regulation of cyclic di-AMP (c-di-AMP), one of the latest cyclic nucleotide second messengers to be discovered in bacteria. We also discuss the currently known receptor proteins and pathways that are directly or indirectly controlled by c-di-AMP, the domain structure of the enzymes involved in its production and degradation, and the recognition of c-di-AMP by the eukaryotic host.
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Affiliation(s)
- Rebecca M Corrigan
- Section of Microbiology and Medical Research Council Centre for Molecular Bacteriology and Infection, Imperial College London, UK
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30
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Mehne FMP, Gunka K, Eilers H, Herzberg C, Kaever V, Stülke J. Cyclic di-AMP homeostasis in bacillus subtilis: both lack and high level accumulation of the nucleotide are detrimental for cell growth. J Biol Chem 2012. [PMID: 23192352 DOI: 10.1074/jbc.m112.395491] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The genome of the Gram-positive soil bacterium Bacillus subtilis encodes three potential diadenylate cyclases that may synthesize the signaling nucleotide cyclic di-AMP (c-di-AMP). These enzymes are expressed under different conditions in different cell compartments, and they localize to distinct positions in the cell. Here we demonstrate the diadenylate cyclase activity of the so far uncharacterized enzymes CdaA (previously known as YbbP) and CdaS (YojJ). Our work confirms that c-di-AMP is essential for the growth of B. subtilis and shows that an excess of the molecule is also harmful for the bacteria. Several lines of evidence suggest that the diadenylate cyclase CdaA is part of the conserved essential cda-glm module involved in cell wall metabolism. In contrast, the CdaS enzyme seems to provide c-di-AMP for spores. Accumulation of large amounts of c-di-AMP impairs the growth of B. subtilis and results in the formation of aberrant curly cells. This phenotype can be partially suppressed by elevated concentrations of magnesium. These observations suggest that c-di-AMP interferes with the peptidoglycan synthesis machinery. The activity of the diadenylate cyclases is controlled by distinct molecular mechanisms. CdaA is stimulated by a regulatory interaction with the CdaR (YbbR) protein. In contrast, the activity of CdaS seems to be intrinsically restricted, and a single amino acid substitution is sufficient to drastically increase the activity of the enzyme. Taken together, our results support the idea of an important role for c-di-AMP in B. subtilis and suggest that the levels of the nucleotide have to be tightly controlled.
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Affiliation(s)
- Felix M P Mehne
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August University Göttingen, D-37077 Göttingen, Germany
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31
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Zweers JC, Nicolas P, Wiegert T, van Dijl JM, Denham EL. Definition of the σ(W) regulon of Bacillus subtilis in the absence of stress. PLoS One 2012; 7:e48471. [PMID: 23155385 PMCID: PMC3498285 DOI: 10.1371/journal.pone.0048471] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 09/26/2012] [Indexed: 01/05/2023] Open
Abstract
Bacteria employ extracytoplasmic function (ECF) sigma factors for their responses to environmental stresses. Despite intensive research, the molecular dissection of ECF sigma factor regulons has remained a major challenge due to overlaps in the ECF sigma factor-regulated genes and the stimuli that activate the different ECF sigma factors. Here we have employed tiling arrays to single out the ECF σW regulon of the Gram-positive bacterium Bacillus subtilis from the overlapping ECF σX, σY, and σM regulons. For this purpose, we profiled the transcriptome of a B. subtilis sigW mutant under non-stress conditions to select candidate genes that are strictly σW-regulated. Under these conditions, σW exhibits a basal level of activity. Subsequently, we verified the σW-dependency of candidate genes by comparing their transcript profiles to transcriptome data obtained with the parental B. subtilis strain 168 grown under 104 different conditions, including relevant stress conditions, such as salt shock. In addition, we investigated the transcriptomes of rasP or prsW mutant strains that lack the proteases involved in the degradation of the σW anti-sigma factor RsiW and subsequent activation of the σW-regulon. Taken together, our studies identify 89 genes as being strictly σW-regulated, including several genes for non-coding RNAs. The effects of rasP or prsW mutations on the expression of σW-dependent genes were relatively mild, which implies that σW-dependent transcription under non-stress conditions is not strictly related to RasP and PrsW. Lastly, we show that the pleiotropic phenotype of rasP mutant cells, which have defects in competence development, protein secretion and membrane protein production, is not mirrored in the transcript profile of these cells. This implies that RasP is not only important for transcriptional regulation via σW, but that this membrane protease also exerts other important post-transcriptional regulatory functions.
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Affiliation(s)
- Jessica C. Zweers
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Pierre Nicolas
- INRA, UR1077, Mathématique Informatique et Génome, Jouy-en-Josas, France
| | - Thomas Wiegert
- Hochschule Zittau/Görlitz, FN/Biotechnologie, Zittau, Germany
| | - Jan Maarten van Dijl
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- * E-mail:
| | - Emma L. Denham
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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Hashimoto M, Seki T, Matsuoka S, Hara H, Asai K, Sadaie Y, Matsumoto K. Induction of extracytoplasmic function sigma factors in Bacillus subtilis cells with defects in lipoteichoic acid synthesis. MICROBIOLOGY-SGM 2012; 159:23-35. [PMID: 23103977 DOI: 10.1099/mic.0.063420-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Lipoteichoic acid (LTA) is an important cell envelope component of Gram-positive bacteria. Bacillus subtilis has four homologous genes for LTA synthesis: ltaS (yflE), yfnI, yqgS and yvgJ. The products LtaS (YflE), YfnI and YqgS are bona fide LTA synthetases, whereas YvgJ functions only as an LTA primase. To clarify whether defects in LTA on the cell envelope trigger extracytoplasmic function (ECF) sigma factors, mRNA levels of the autoregulated ECF sigma factors in cells with singly and multiply deleted alleles of the ltaS homologues were examined by real-time RT-PCR. This revealed that sigM and sigX were induced in cells with a null allele of ΔltaS and ΔyfnI, respectively, and that no ECF sigma factor was induced in cells with a single null allele of ΔyqgS or ΔyvgJ. In cells with double null alleles (ΔltaS and ΔyfnI), sigW and ylaC were induced in addition to sigM and sigX. Cells with triple null alleles (ΔltaS ΔyfnI and ΔyqgS) showed a pattern of induction similar to that of the double null. In cells with quadruple null alleles, sigV and sigY were newly induced. Cells with ΔltaS had approximately 1/4 the diglucosyldiacylglycerol and over 10 times the CDP-diacylglycerol of wild-type cells. Compensatory elevation of the mRNA level of other homologues was observed (in ΔltaS cells the level of yfnI was elevated; in ΔyfnI cells that of yqgS and yvgJ was elevated; both were even higher in ΔltaS ΔyfnI cells). In ΔltaS cells, the mRNA level of yfnI was corroborated to be regulated by σ(M), which is activated in the null mutant cells. In ΔyfnI cells, the mRNA levels of yqgS and yvgJ reverted to less than those of wild-type when a defective sigX allele was introduced. Since sigX was activated in cells with ΔyfnI, this suggests that the induction of yqgS and yvgJ is dependent on σ(X). The LTAs produced by the four ltaS homologues seem to play distinct physiological roles to maintain the full function of LTA on the B. subtilis cell envelope.
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Affiliation(s)
- Michihiro Hashimoto
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-ohkubo, Sakura-ku, Saitama-shi, Saitama-ken 338-8570, Japan
| | - Takahiro Seki
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-ohkubo, Sakura-ku, Saitama-shi, Saitama-ken 338-8570, Japan
| | - Satoshi Matsuoka
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-ohkubo, Sakura-ku, Saitama-shi, Saitama-ken 338-8570, Japan
| | - Hiroshi Hara
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-ohkubo, Sakura-ku, Saitama-shi, Saitama-ken 338-8570, Japan
| | - Kei Asai
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-ohkubo, Sakura-ku, Saitama-shi, Saitama-ken 338-8570, Japan
| | - Yoshito Sadaie
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-ohkubo, Sakura-ku, Saitama-shi, Saitama-ken 338-8570, Japan
| | - Kouji Matsumoto
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-ohkubo, Sakura-ku, Saitama-shi, Saitama-ken 338-8570, Japan
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Marciniak BC, Trip H, van-der Veek PJ, Kuipers OP. Comparative transcriptional analysis of Bacillus subtilis cells overproducing either secreted proteins, lipoproteins or membrane proteins. Microb Cell Fact 2012; 11:66. [PMID: 22624725 PMCID: PMC3514339 DOI: 10.1186/1475-2859-11-66] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 05/05/2012] [Indexed: 11/14/2022] Open
Abstract
Background Bacillus subtilis is a favorable host for the production of industrially relevant proteins because of its capacity of secreting proteins into the medium to high levels, its GRAS (Generally Recognized As Safe) status, its genetic accessibility and its capacity to grow in large fermentations. However, production of heterologous proteins still faces limitations. Results This study aimed at the identification of bottlenecks in secretory protein production by analyzing the response of B. subtilis at the transcriptome level to overproduction of eight secretory proteins of endogenous and heterologous origin and with different subcellular or extracellular destination: secreted proteins (NprE and XynA of B. subtilis, Usp45 of Lactococcus lactis, TEM-1 β-lactamase of Escherichia coli), membrane proteins (LmrA of L. lactis and XylP of Lactobacillus pentosus) and lipoproteins (MntA and YcdH of B. subtilis). Responses specific for proteins with a common localization as well as more general stress responses were observed. The latter include upregulation of genes encoding intracellular stress proteins (groES/EL, CtsR regulated genes). Specific responses include upregulation of the liaIHGFSR operon under Usp45 and TEM-1 β-lactamase overproduction; cssRS, htrA and htrB under all secreted proteins overproduction; sigW and SigW-regulated genes mainly under membrane proteins overproduction; and ykrL (encoding an HtpX homologue) specifically under membrane proteins overproduction. Conclusions The results give better insights into B. subtilis responses to protein overproduction stress and provide potential targets for genetic engineering in order to further improve B. subtilis as a protein production host.
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Affiliation(s)
- Bogumiła C Marciniak
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
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Luo Y, Helmann JD. Analysis of the role of Bacillus subtilis σ(M) in β-lactam resistance reveals an essential role for c-di-AMP in peptidoglycan homeostasis. Mol Microbiol 2012; 83:623-39. [PMID: 22211522 DOI: 10.1111/j.1365-2958.2011.07953.x] [Citation(s) in RCA: 186] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The Bacillus subtilis extracytoplasmic function (ECF) σ factor σ(M) is inducible by, and confers resistance to, several cell envelope-acting antibiotics. Here, we demonstrate that σ(M) is responsible for intrinsic β-lactam resistance, with σ(X) playing a secondary role. Activation of σ(M) upregulates several cell wall biosynthetic enzymes including one, PBP1, shown here to be a target for the beta-lactam cefuroxime. However, σ(M) still plays a major role in cefuroxime resistance even in cells lacking PBP1. To better define the role of σ(M) in β-lactam resistance, we characterized suppressor mutations that restore cefuroxime resistance to a sigM null mutant. The most frequent suppressors inactivated gdpP (yybT) which encodes a cyclic-di-AMP phosphodiesterase (PDE). Intriguingly, σ(M) is a known activator of disA encoding one of three paralogous diadenylate cyclases (DAC). Overproduction of the GdpP PDE greatly sensitized cells to β-lactam antibiotics. Conversely, genetic studies indicate that at least one DAC is required for growth with depletion leading to cell lysis. These findings support a model in which c-di-AMP is an essential signal molecule required for cell wall homeostasis. Other suppressors highlight the roles of ECF σ factors in counteracting the deleterious effects of autolysins and reactive oxygen species in β-lactam-treated cells.
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Affiliation(s)
- Yun Luo
- Department of Microbiology, Cornell University, Ithaca, NY 14853-8101, USA
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35
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Nannapaneni P, Hertwig F, Depke M, Hecker M, Mäder U, Völker U, Steil L, van Hijum SAFT. Defining the structure of the general stress regulon of Bacillus subtilis using targeted microarray analysis and random forest classification. MICROBIOLOGY-SGM 2011; 158:696-707. [PMID: 22174379 DOI: 10.1099/mic.0.055434-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The structure of the SigB-dependent general stress regulon of Bacillus subtilis has previously been characterized by proteomics approaches as well as DNA array-based expression studies. However, comparing the SigB targets published in three previous major transcriptional profiling studies it is obvious that although each of them identified well above 100 target genes, only 67 were identified in all three studies. These substantial differences can likely be attributed to the different strains, growth conditions, microarray platforms and experimental setups used in the studies. In order to gain a better understanding of the structure of this important regulon, a targeted DNA microarray analysis covering most of the known SigB-inducing conditions was performed, and the changes in expression kinetics of 252 potential members of the SigB regulon and appropriate control genes were recorded. Transcriptional data for the B. subtilis wild-type strain 168 and its isogenic sigB mutant BSM29 were analysed using random forest, a machine learning algorithm, by incorporating the knowledge from previous studies. This analysis revealed a strictly SigB-dependent expression pattern for 166 genes following ethanol, butanol, osmotic and oxidative stress, low-temperature growth and heat shock, as well as limitation of oxygen or glucose. Kinetic analysis of the data for the wild-type strain identified 30 additional members of the SigB regulon, which were also subject to control by additional transcriptional regulators, thus displaying atypical SigB-independent induction patterns in the mutant strain under some of the conditions tested. For 19 of these 30 SigB regulon members, published reports support control by secondary regulators along with SigB. Thus, this microarray-based study assigns a total of 196 genes to the SigB-dependent general stress regulon of B. subtilis.
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Affiliation(s)
- Priyanka Nannapaneni
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Falk Hertwig
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Maren Depke
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Michael Hecker
- Institut für Mikrobiologie, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Ulrike Mäder
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Uwe Völker
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Leif Steil
- Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
| | - Sacha A F T van Hijum
- NIZO Food Research, PO Box 20, 6710 BA Ede, The Netherlands.,Radboud University Nijmegen Medical Centre, Center for Molecular and Biomolecular Informatics, Nijmegen Center for Molecular Life Sciences, PO Box 9101, 6500 HB Nijmegen, The Netherlands.,Interfakultäres Institut für Genetik und Funktionelle Genomforschung, Ernst-Moritz-Arndt-Universität Greifswald, Germany
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Bacillus subtilis σ(V) confers lysozyme resistance by activation of two cell wall modification pathways, peptidoglycan O-acetylation and D-alanylation of teichoic acids. J Bacteriol 2011; 193:6223-32. [PMID: 21926231 DOI: 10.1128/jb.06023-11] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The seven extracytoplasmic function (ECF) sigma (σ) factors of Bacillus subtilis are broadly implicated in resistance to antibiotics and other cell envelope stressors mediated, in part, by regulation of cell envelope synthesis and modification enzymes. We here define the regulon of σ(V) as including at least 20 operons, many of which are also regulated by σ(M), σ(X), or σ(W). The σ(V) regulon is strongly and specifically induced by lysozyme, and this induction is key to the intrinsic resistance of B. subtilis to lysozyme. Strains with null mutations in either sigV or all seven ECF σ factor genes (Δ7ECF) have essentially equal increases in sensitivity to lysozyme. Induction of σ(V) in the Δ7ECF background restores lysozyme resistance, whereas induction of σ(M), σ(X), or σ(W) does not. Lysozyme resistance results from the ability of σ(V) to activate the transcription of two operons: the autoregulated sigV-rsiV-oatA-yrhK operon and dltABCDE. Genetic analyses reveal that oatA and dlt are largely redundant with respect to lysozyme sensitivity: single mutants are not affected in lysozyme sensitivity, whereas an oatA dltA double mutant is as sensitive as a sigV null strain. Moreover, the sigV oatA dltA triple mutant is no more sensitive than the oatA dltA double mutant, indicating that there are no other σ(V)-dependent genes necessary for lysozyme resistance. Thus, we suggest that σ(V) confers lysozyme resistance by the activation of two cell wall modification pathways: O-acetylation of peptidoglycan catalyzed by OatA and D-alanylation of teichoic acids by DltABCDE.
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Reichmann NT, Gründling A. Location, synthesis and function of glycolipids and polyglycerolphosphate lipoteichoic acid in Gram-positive bacteria of the phylum Firmicutes. FEMS Microbiol Lett 2011; 319:97-105. [PMID: 21388439 PMCID: PMC3089915 DOI: 10.1111/j.1574-6968.2011.02260.x] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Lipoteichoic acid (LTA) is a zwitterionic polymer found in the cell wall of many Gram-positive bacteria. A widespread and one of the best-studied forms of LTA consists of a polyglycerolphosphate (PGP) chain that is tethered to the membrane via a glycolipid anchor. In this review, we will summarize our current understanding of the enzymes involved in glycolipid and PGP backbone synthesis in a variety of different Gram-positive bacteria. The recent identification of key LTA synthesis proteins allowed the construction and analysis of mutant strains with defined defects in glycolipid or backbone synthesis. Using these strains, new information on the functions of LTA for bacterial growth, physiology and during developmental processes was gained and will be discussed. Furthermore, we will reintroduce the idea that LTA remains in close proximity to the bacterial membrane for its function during bacterial growth rather than as a surface-exposed structure.
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Affiliation(s)
- Nathalie T Reichmann
- Section of Microbiology, Imperial College London, South Kensington Campus, London, UK
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Matsuoka S, Chiba M, Tanimura Y, Hashimoto M, Hara H, Matsumoto K. Abnormal morphology of Bacillus subtilis ugtP mutant cells lacking glucolipids. Genes Genet Syst 2011; 86:295-304. [DOI: 10.1266/ggs.86.295] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Satoshi Matsuoka
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Minako Chiba
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Yu Tanimura
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Michihiro Hashimoto
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Hiroshi Hara
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Kouji Matsumoto
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
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Wörmann ME, Corrigan RM, Simpson PJ, Matthews SJ, Gründling A. Enzymatic activities and functional interdependencies of Bacillus subtilis lipoteichoic acid synthesis enzymes. Mol Microbiol 2010; 79:566-83. [PMID: 21255105 PMCID: PMC3089822 DOI: 10.1111/j.1365-2958.2010.07472.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Lipoteichoic acid (LTA) is an important cell wall polymer in Gram-positive bacteria. The enzyme responsible for polyglycerolphosphate LTA synthesis is LtaS, first described in Staphylococcus aureus. Four LtaS orthologues, LtaSBS, YfnI, YqgS and YvgJ, are present in Bacillus subtilis. Using an in vitro enzyme assay, we determined that all four proteins are Mn2+-dependent metal enzymes that use phosphatidylglycerol as a substrate. We show that LtaSBS, YfnI and YqgS can produce polymers, suggesting that these three proteins are bona-fide LTA synthases while YvgJ functions as an LTA primase, as indicated by the accumulation of a GroP-Glc2-DAG glycolipid. Western blot analysis of LTA produced by ltaSBS, yfnI, yqgS and yvgJ single, triple and the quadruple mutant, showed that LTA production was only abolished in the quadruple and the YvgJ-only expressing mutant. B. subtilis strains expressing YfnI in the absence of LtaSBS produced LTA of retarded mobility, presumably caused by an increase in chain length as suggested by a structural analysis of purified LTA. Taken together, the presented results indicate that the mere presence or absence of LTA cannot account for cell division and sporulation defects observed in the absence of individual enzymes and revealed an unexpected enzymatic interdependency of LtaS-type proteins in B. subtilis.
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Affiliation(s)
- Mirka E Wörmann
- Section of Microbiology Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
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Sutcliffe IC. Priming and elongation: dissection of the lipoteichoic acid biosynthetic pathway in Gram-positive bacteria. Mol Microbiol 2010; 79:553-6. [PMID: 21255102 DOI: 10.1111/j.1365-2958.2010.07480.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The biosynthesis of lipoteichoic acids is a potential target for the development of novel antimicrobials against significant Firmicute pathogens. Excellent progress has been made in recent years towards understanding the biochemistry and genetics of polyglycerophosphate lipoteichoic acid biosynthesis but it has remained unclear whether this pathway requires an initial 'priming' reaction to initiate synthesis on the glycolipid anchor. Recent work from the laboratory of Angelika Gründling, including a new study by Wörmann et al. in this issue of Molecular Microbiology, provides confirmation of the priming step and further insights into the functional redundancy of lipoteichoic acid biosynthesis enzymes in Bacillus subtilis.
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Affiliation(s)
- Iain C Sutcliffe
- Biomolecular and Biomedical Research Centre, School of Life Sciences, Northumbria University, Newcastle upon Tyne NE1 8ST, UK.
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Transcriptomic and phenotypic characterization of a Bacillus subtilis strain without extracytoplasmic function σ factors. J Bacteriol 2010; 192:5736-45. [PMID: 20817771 DOI: 10.1128/jb.00826-10] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Bacillus subtilis encodes seven extracytoplasmic function (ECF) σ factors. Three (σ(M), σ(W), and σ(X)) mediate responses to cell envelope-active antibiotics. The functions of σ(V), σ(Y), σ(Z), and σ(YlaC) remain largely unknown, and strong inducers of these σ factors and their regulons have yet to be defined. Here, we define transcriptomic and phenotypic differences under nonstress conditions between a strain carrying deletions in all seven ECF σ factor genes (the Δ7ECF mutant), a ΔMWX triple mutant, and the parental 168 strain. Our results identify >80 genes as at least partially dependent on ECF σ factors, and as expected, most of these are dependent on σ(M), σ(W), or σ(X), which are active at a significant basal level during growth. Several genes, including the eps operon encoding enzymes for exopolysaccharide (EPS) production, were decreased in expression in the Δ7ECF mutant but affected less in the ΔMWX mutant. Consistent with this observation, the Δ7ECF mutant (but not the ΔMWX mutant) showed reduced biofilm formation. Extending previous observations, we also note that the ΔMWX mutant is sensitive to a variety of antibiotics and the Δ7ECF mutant is either as sensitive as, or slightly more sensitive than, the ΔMWX strain to these stressors. These findings emphasize the overlapping nature of the seven ECF σ factor regulons in B. subtilis, confirm that three of these (σ(M), σ(W), and σ(X)) play the dominant role in conferring intrinsic resistance to antibiotics, and provide initial insights into the roles of the remaining ECF σ factors.
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A comprehensive proteomics and transcriptomics analysis of Bacillus subtilis salt stress adaptation. J Bacteriol 2009; 192:870-82. [PMID: 19948795 DOI: 10.1128/jb.01106-09] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
In its natural habitats, Bacillus subtilis is exposed to changing osmolarity, necessitating adaptive stress responses. Transcriptomic and proteomic approaches can provide a picture of the dynamic changes occurring in salt-stressed B. subtilis cultures because these studies provide an unbiased view of cells coping with high salinity. We applied whole-genome microarray technology and metabolic labeling, combined with state-of-the-art proteomic techniques, to provide a global and time-resolved picture of the physiological response of B. subtilis cells exposed to a severe and sudden osmotic upshift. This combined experimental approach provided quantitative data for 3,961 mRNA transcription profiles, 590 expression profiles of proteins detected in the cytosol, and 383 expression profiles of proteins detected in the membrane fraction. Our study uncovered a well-coordinated induction of gene expression subsequent to an osmotic upshift that involves large parts of the SigB, SigW, SigM, and SigX regulons. Additionally osmotic upregulation of a large number of genes that do not belong to these regulons was observed. In total, osmotic upregulation of about 500 B. subtilis genes was detected. Our data provide an unprecedented rich basis for further in-depth investigation of the physiological and genetic responses of B. subtilis to hyperosmotic stress.
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Schirner K, Marles-Wright J, Lewis RJ, Errington J. Distinct and essential morphogenic functions for wall- and lipo-teichoic acids in Bacillus subtilis. EMBO J 2009; 28:830-42. [PMID: 19229300 PMCID: PMC2670855 DOI: 10.1038/emboj.2009.25] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Accepted: 01/16/2009] [Indexed: 11/09/2022] Open
Abstract
Teichoic acids (TAs) are anionic polymers that constitute a major component of the cell wall in most Gram-positive bacteria. Despite decades of study, their function has remained unclear. TAs are covalently linked either to the cell wall peptidoglycan (wall TA (WTA)) or to the membrane (lipo-TA (LTA)). We have characterized the key enzyme of LTA synthesis in Bacillus subtilis, LTA synthase (LtaS). We show that LTA is needed for divalent cation homoeostasis and that its absence has severe effects on cell morphogenesis and cell division. Inactivation of both LTA and WTA is lethal and comparison of the individual mutants suggests that they have differentiated roles in elongation (WTA) and division (LTA). B. subtilis has four ltaS paralogues and we show how their roles are partially differentiated. Two paralogues have a redundant role in LTA synthesis during sporulation and their absence gives a novel absolute block in sporulation. The crystal structure of the extracytoplasmic part of LtaS, solved at 2.4-A resolution, reveals a phosphorylated threonine residue, which provides clues about the catalytic mechanism and identifies the active site of the enzyme.
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Affiliation(s)
- Kathrin Schirner
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Jon Marles-Wright
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Richard J Lewis
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Jeff Errington
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Newcastle upon Tyne, UK
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Genetic analysis of factors affecting susceptibility of Bacillus subtilis to daptomycin. Antimicrob Agents Chemother 2009; 53:1598-609. [PMID: 19164152 DOI: 10.1128/aac.01329-08] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Daptomycin is the first of a new class of cyclic lipopeptide antibiotics used against multidrug-resistant, gram-positive pathogens. The proposed mechanism of action involves disruption of the functional integrity of the bacterial membrane in a Ca(2+)-dependent manner. We have used transcriptional profiling to demonstrate that treatment of Bacillus subtilis with daptomycin strongly induces the lia operon including the autoregulatory LiaRS two-component system (homologous to Staphylococcus aureus VraSR). The lia operon protects against daptomycin, and deletion of liaH, encoding a phage-shock protein A (PspA)-like protein, leads to threefold increased susceptibility. Since daptomycin interacts with the membrane, we tested mutants with altered membrane composition for effects on susceptibility. Deletion mutations of mprF (lacking lysyl-phosphatidylglycerol) or des (lipid desaturase) increased daptomycin susceptibility, whereas overexpression of MprF decreased susceptibility. Conversely, depletion of the cell for the anionic lipid phosphatidylglycerol led to increased resistance. Fluorescently labeled daptomycin localized to the septa and in a helical pattern around the cell envelope and was delocalized upon the depletion of phosphatidylglycerol. Together, these results indicate that the daptomycin-Ca(2+) complex interacts preferentially with regions enriched in anionic phospholipids and leads to membrane stresses that can be ameliorated by PspA family proteins.
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Hashimoto M, Takahashi H, Hara Y, Hara H, Asai K, Sadaie Y, Matsumoto K. Induction of extracytoplasmic function sigma factors in Bacillus subtilis cells with membranes of reduced phosphatidylglycerol content. Genes Genet Syst 2009; 84:191-8. [DOI: 10.1266/ggs.84.191] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Michihiro Hashimoto
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Hiroaki Takahashi
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Yoshinori Hara
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Hiroshi Hara
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Kei Asai
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Yoshito Sadaie
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Kouji Matsumoto
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
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46
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Nguyen TTH, Eiamphungporn W, Mäder U, Liebeke M, Lalk M, Hecker M, Helmann JD, Antelmann H. Genome-wide responses to carbonyl electrophiles in Bacillus subtilis: control of the thiol-dependent formaldehyde dehydrogenase AdhA and cysteine proteinase YraA by the MerR-family regulator YraB (AdhR). Mol Microbiol 2008; 71:876-94. [PMID: 19170879 DOI: 10.1111/j.1365-2958.2008.06568.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Quinones and alpha,beta-unsaturated carbonyls are naturally occurring electrophiles that target cysteine residues via thiol-(S)-alkylation. We analysed the global expression profile of Bacillus subtilis to the toxic carbonyls methylglyoxal (MG) and formaldehyde (FA). Both carbonyl compounds cause a stress response characteristic for thiol-reactive electrophiles as revealed by the induction of the Spx, CtsR, CymR, PerR, ArsR, CzrA, CsoR and SigmaD regulons. MG and FA triggered also a SOS response which indicates DNA damage. Protection against FA is mediated by both the hxlAB operon, encoding the ribulose monophosphate pathway for FA fixation, and a thiol-dependent formaldehyde dehydrogenase (AdhA) and DJ-1/PfpI-family cysteine proteinase (YraA). The adhA-yraA operon and the yraC gene, encoding a gamma-carboxymuconolactone decarboxylase, are positively regulated by the MerR-family regulator, YraB(AdhR). AdhR binds specifically to its target promoters which contain a 7-4-7 inverted repeat (CTTAAAG-N4-CTTTAAG) between the -35 and -10 elements. Activation of adhA-yraA transcription by AdhR requires the conserved Cys52 residue in vivo. We speculate that AdhR is redox-regulated via thiol-(S)-alkylation by aldehydes and that AdhA and YraA are specifically involved in reduction of aldehydes and degradation or repair of damaged thiol-containing proteins respectively.
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Affiliation(s)
- Thi Thu Huyen Nguyen
- Institute for Microbiology, Ernst-Moritz-Arndt-University of Greifswald, D-17487 Greifswald, Germany
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ROMA: an in vitro approach to defining target genes for transcription regulators. Methods 2008; 47:73-7. [PMID: 18948201 DOI: 10.1016/j.ymeth.2008.10.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 10/14/2008] [Accepted: 10/14/2008] [Indexed: 01/05/2023] Open
Abstract
We describe an in vitro transcription-based method called ROMA (run-off transcription-microarray analysis) for the genome-wide analysis of transcription regulated by sigma factors and other transcriptional regulators. ROMA uses purified RNA polymerase with and without a regulatory protein to monitor products of transcription from a genomic DNA template. Transcribed RNA is converted to cDNA and hybridized to gene arrays allowing for the identification of genes that are specifically activated by the regulator. We discuss the use of ROMA to define sigma factor regulons in Bacillus subtilis and its broad application to defining regulons for other transcriptional regulators in various species.
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Blom EJ, Breitling R, Hofstede KJ, Roerdink JBTM, van Hijum SAFT, Kuipers OP. Prosecutor: parameter-free inference of gene function for prokaryotes using DNA microarray data, genomic context and multiple gene annotation sources. BMC Genomics 2008; 9:495. [PMID: 18939968 PMCID: PMC2585105 DOI: 10.1186/1471-2164-9-495] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Accepted: 10/21/2008] [Indexed: 01/23/2023] Open
Abstract
Background Despite a plethora of functional genomic efforts, the function of many genes in sequenced genomes remains unknown. The increasing amount of microarray data for many species allows employing the guilt-by-association principle to predict function on a large scale: genes exhibiting similar expression patterns are more likely to participate in shared biological processes. Results We developed Prosecutor, an application that enables researchers to rapidly infer gene function based on available gene expression data and functional annotations. Our parameter-free functional prediction method uses a sensitive algorithm to achieve a high association rate of linking genes with unknown function to annotated genes. Furthermore, Prosecutor utilizes additional biological information such as genomic context and known regulatory mechanisms that are specific for prokaryotes. We analyzed publicly available transcriptome data sets and used literature sources to validate putative functions suggested by Prosecutor. We supply the complete results of our analysis for 11 prokaryotic organisms on a dedicated website. Conclusion The Prosecutor software and supplementary datasets available at allow researchers working on any of the analyzed organisms to quickly identify the putative functions of their genes of interest. A de novo analysis allows new organisms to be studied.
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Affiliation(s)
- Evert Jan Blom
- Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, the Netherlands.
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Römling U. Great times for small molecules: c-di-AMP, a second messenger candidate in Bacteria and Archaea. Sci Signal 2008; 1:pe39. [PMID: 18714086 DOI: 10.1126/scisignal.133pe39] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Successful cell division in pro- and eukaryotes is ensured by checkpoints that regulate cell cycle progression. Structural and biochemical analyses of the DNA integrity scanning protein (DisA) have recently shown that its domain of unknown function, DUF147 [renamed DAC (for diadenylate cyclase)], has diadenylate cyclase activity. This diadenylate cyclase activity is abolished when DisA binds to branched DNA substrates, which arise during DNA double-strand breaks that can spontaneously occur during DNA replication. This finding identifies cyclic di(3'-->5')-adenylic acid (c-di-AMP) as a second messenger candidate that signals DNA integrity in Bacillus subtilis during sporulation, a specialized cell division process that leads to formation of a dormant cell called a spore. The DAC domain is widespread in Bacteria and Archaea; moreover, it is found in proteins containing diverse domains, suggesting that c-di-AMP acts as a second messenger molecule in response to various signals besides branched DNA. To elucidate the biological importance and molecular mechanisms of action for c-di-AMP and the recently recognized second messenger c-di-GMP will require a multidisciplinary approach.
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Affiliation(s)
- Ute Römling
- Karolinska Institutet, Department of Microbiology, Tumor and Cell Biology, FE280, SE-171 77 Stockholm, Sweden.
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MacLellan SR, Wecke T, Helmann JD. A previously unidentified sigma factor and two accessory proteins regulate oxalate decarboxylase expression in Bacillus subtilis. Mol Microbiol 2008; 69:954-67. [PMID: 18573182 DOI: 10.1111/j.1365-2958.2008.06331.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We have investigated the function of a cell envelope stress-inducible gene, yvrI, which encodes a 22.5 kDa protein that includes a predicted sigma(70) region 4 domain, but lacks an apparent region 2 domain. YvrI interacts with RNA polymerase and overexpression of YvrI results in induction of OxdC, an oxalate decarboxylase maximally expressed under low-pH conditions. We have used microarray-based analyses to define the YvrI regulon. YvrI is required for the transcription of three operons (oxdC-yvrL, yvrJ and yvrI-yvrHa) each of which is preceded by a highly similar promoter sequence. Activation of these promoters requires both YvrI and the product of the second gene in the yvrI-yvrHa operon, YvrHa. YvrI and YvrHa together allow recognition of the oxdC promoter, stimulate DNA melting and activate transcription by core RNA polymerase. Together, these results suggest that YvrI is a previously unrecognized sigma factor in Bacillus subtilis and that the 9.5 kDa YvrHa protein acts as a required co-activator of transcription. A yvrL deletion results in the upregulation of YvrI activity suggesting that YvrL is a negative regulator of YvrI-dependent transcription, possibly functioning as an anti-sigma factor.
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Affiliation(s)
- Shawn R MacLellan
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
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