SigM, an Extracytoplasmic Function Sigma Factor of<i>Bacillus subtilis</i>, Is Activated in Response to Cell Wall Antibiotics, Ethanol, Heat, Acid, and Superoxide Stress

Thackray, Penny D.; Moir, Anne

doi:10.1128/jb.185.12.3491-3498.2003

Cited by 112 publications

(125 citation statements)

References 28 publications

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“…Thus, both sigM and ydaH appear to be conditionally essential in the absence of the four putative MurJ paralogs. SigM (σ M ) is an extracytoplasmic function sigma factor that activates the expression of many genes involved in cell wall synthesis in response to cell envelope stress (17)(18)(19). Intriguingly, the ydaH gene is among the most strongly induced genes expressed under σ M control (18,19), and it is predicted to encode a polytopic membrane protein with six transmembrane segments.…”

Section: Significancementioning

confidence: 99%

MurJ and a novel lipid II flippase are required for cell wall biogenesis inBacillus subtilis

Meeske

Sham

Kimsey

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

176

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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 (murJ Bs ; formerly ytgP) are a synthetic lethal pair. Cells defective for both Amj and MurJ Bs exhibit cell shape defects and lyse. Furthermore, expression of Amj or MurJ Bs 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 MurJ Bs 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.T he bacterial cell wall or peptidoglycan (PG) is composed of glycan strands cross-linked together by short peptides. This 3D meshwork protects the cell from osmotic lysis and determines shape, and its assembly is the target of some of our most successful antibiotics. Cell wall synthesis begins in the cytoplasm, where a set of highly conserved enzymes catalyze the formation of the lipid-linked precursor lipid II, which is composed of undecaprenyl-pyrophosphate (UndPP) linked to N-acetylglucosamine-N-acetylmuramic acid pentapeptide. Lipid II is synthesized on the inner face of the cytoplasmic membrane (1). The molecule is then translocated to the outer face of the membrane, where the disaccharide-peptide monomer is incorporated into the existing PG by cell wall synthetic machineries composed of penicillin-binding proteins and additional factors (2). The enzymes that transport lipid II across the membrane have been the subject of extensive research and speculation (3-6). Recent work in Escherichia coli has provided strong evidence that the polytopic membrane protein MurJ is required for lipid II transport across the membrane, and is likely to be a lipid II flippase (6). MurJ is a member of the multidrug/oligosaccharidyl-lipid/polysaccharide (MOP) exporter superfamily (7). It is broadly conserved among Eubacteria and essential for viability in many organisms. Intriguingly, work in the model gram-positive bacterium Bacillus subtilis indicates that cells lacking four MOP superfamily members similar to MurJ are viable and have...

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Section: Significancementioning

confidence: 99%

MurJ and a novel lipid II flippase are required for cell wall biogenesis inBacillus subtilis

Meeske

Sham

Kimsey

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

176

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“…The functions of SigV, SigZ and YlaC remain to be elucidated, while four sigmas, SigM, SigW, SigX, and SigY, have been studied well. They are required for stresses caused by salt, heat, ethanol, acid, cell wall antibiotics, superoxide, alkali, and nitrogen-starvation (Horsburg and Moir, 1999;Thackray and Moir, 2003;Cao et al, 2002B;Cao and Helmann, 2002;Cao et al, 2003;Tojo et al, Edited by Fujio Kawamura * Corresponding author. E-mail: ysadaie@molbiol.saitama-u.ac.jp Wiegert et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Transcriptional analysis of the ylaABCD operon of Bacillus subtilis encoding a sigma factor of extracytoplasmic function family

et al. 2005

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The ylaABCD operon of Bacillus subtilis contains four predicted ORFs in the order ylaA, ylaB, ylaC and ylaD , where ylaC is assumed to code for a sigma factor of the extracytoplasmic function (ECF) family. Predicted YlaD may function as the anti-YlaC factor as it has an oxidative stress sensing domain similar to that of the RsrA, which is the anti-sigma factor of SigR, an ECF sigma of Streptomyces coelicolor . Northern blot analysis of the ylaABCD operon revealed two transcriptional products resulting from a distal promoter upstream of ylaA and from an internal promoter located at the first codon of ylaC . Both transcription start sites were determine by primer extension and 5'-RACE PCR. The transcription from the distal promoter was initiated by over-expression of YlaC on a multi-copy plasmid and depended on YlaC. DNA sequences of the -35 and -10 regions were similar to those recognized by other ECF sigmas of B. subtilis . On the other hand the transcription from the internal promoter was induced by oxidative stress and depended on Spx, which is an oxidative stress responding factor interacting with the alpha subunit of RNA polymerase core enzyme. The latter transcription depended possibly on SigA. We could not detect translation of YlaC from this transcript. Experiments with ylaD -disruption or co-overexpression of ylaD with ylaC suggested that YlaD functions as the anti-YlaC factor. Although YlaD has an oxidative stress sensing domain, oxidative stress did not induce the whole ylaABCD operon.

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“…In particular, Horsburgh & Moir (1999) showed that in B. subtilis, the sigM gene product is required for normal cell growth under salt stress. Moreover, the SigM protein is involved in maintaining the membrane and cell wall integrity in response to different stresses in exponential growth phase and is activated by these stresses (Thackray & Moir, 2003).…”

Section: Introductionmentioning

confidence: 99%

Role of anionic phospholipids in the adaptation of Bacillus subtilis to high salinity

et al. 2006

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The importance of the content of anionic phospholipids [cardiolipin (CL) and phosphatidylglycerol (PG)] in the osmotic adaptation and in the membrane structure of Bacillus subtilis cultures was investigated. Insertion mutations in the three putative cardiolipin synthase genes (ywiE, ywnE and ywjE) were obtained. Only the ywnE mutation resulted in a complete deficiency in cardiolipin and thus corresponds to a true clsA gene. The osmotolerance of a clsA mutant was impaired: although at NaCl concentrations lower than 1?2 M the growth curves were similar to those of its wild-type control, at 1?5 M NaCl (LBN medium) the lag period increased and the maximal optical density reached was lower. The membrane of the clsA mutant strain showed an increased PG content, at both exponential and stationary phase, but no trace of CL in either LB or LBN medium. As well as the deficiency in CL synthesis, the clsA mutant showed other differences in lipid and fatty acids content compared to the wild-type, suggesting a cross-regulation in membrane lipid pathways, crucial for the maintenance of membrane functionality and integrity. The biophysical characteristics of membranes and large unilamellar vesicles from the wild-type and clsA mutant strains were studied by Laurdan's steady-state fluorescence spectroscopy. At physiological temperature, the clsA mutant showed a decreased lateral lipid packing in the protein-free vesicles and isolated membranes compared with the wild-type strain. Interestingly, the lateral lipid packing of the membranes of both the wild-type and clsA mutant strains increased when they were grown in LBN. In a conditional IPTG-controlled pgsA mutant, unable to synthesize PG and CL in the absence of IPTG, the osmoresistance of the cultures correlated with their content of anionic phospholipids. The transcriptional activity of the clsA and pgsA genes was similar and increased twofold upon entry to stationary phase or under osmotic upshift. Overall, these results support the involvement of the anionic phospholipids in the growth of B. subtilis in media containing elevated NaCl concentrations.

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SigM, an Extracytoplasmic Function Sigma Factor ofBacillus subtilis, Is Activated in Response to Cell Wall Antibiotics, Ethanol, Heat, Acid, and Superoxide Stress

Cited by 112 publications

References 28 publications

MurJ and a novel lipid II flippase are required for cell wall biogenesis inBacillus subtilis

MurJ and a novel lipid II flippase are required for cell wall biogenesis inBacillus subtilis

Transcriptional analysis of the ylaABCD operon of Bacillus subtilis encoding a sigma factor of extracytoplasmic function family

Role of anionic phospholipids in the adaptation of Bacillus subtilis to high salinity

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