The gerC locus of Bacillus subtilis, required for menaquinone biosynthesis, is concerned only indirectly with spore germination

Leatherbarrow, A. J. H.; Yazdi, Mohammed A.; Curson, J. P.; Moir, Arthur J. G.

doi:10.1099/00221287-144-8-2125

Cited by 13 publications

(7 citation statements)

References 17 publications

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“…We observed a very strong up-regulation of the phage shock protein PspA, which is thought to counteract proton leakage upon membrane damage (25), and an even stronger up-regulation of the PspA homolog LiaH. In addition, we observed upregulation of the lia response regulator LiaR, ResD, which is involved in regulation of anaerobic respiration, and IspH, which is involved in the synthesis of the lipid carrier isopentenyl phosphate and the menaquinone precursor isoprenoid (26)(27)(28)(29).…”

Section: Resultsmentioning

confidence: 63%

Daptomycin inhibits cell envelope synthesis by interfering with fluid membrane microdomains

Müller

Wenzel

Strahl

et al. 2016

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

375

506

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Daptomycin is a highly efficient last-resort antibiotic that targets the bacterial cell membrane. Despite its clinical importance, the exact mechanism by which daptomycin kills bacteria is not fully understood. Different experiments have led to different models, including (i) blockage of cell wall synthesis, (ii) membrane pore formation, and (iii) the generation of altered membrane curvature leading to aberrant recruitment of proteins. To determine which model is correct, we carried out a comprehensive mode-of-action study using the model organism Bacillus subtilis and different assays, including proteomics, ionomics, and fluorescence light microscopy. We found that daptomycin causes a gradual decrease in membrane potential but does not form discrete membrane pores. Although we found no evidence for altered membrane curvature, we confirmed that daptomycin inhibits cell wall synthesis. Interestingly, using different fluorescent lipid probes, we showed that binding of daptomycin led to a drastic rearrangement of fluid lipid domains, affecting overall membrane fluidity. Importantly, these changes resulted in the rapid detachment of the membrane-associated lipid II synthase MurG and the phospholipid synthase PlsX. Both proteins preferentially colocalize with fluid membrane microdomains. Delocalization of these proteins presumably is a key reason why daptomycin blocks cell wall synthesis. Finally, clustering of fluid lipids by daptomycin likely causes hydrophobic mismatches between fluid and more rigid membrane areas. This mismatch can facilitate proton leakage and may explain the gradual membrane depolarization observed with daptomycin. Targeting of fluid lipid domains has not been described before for antibiotics and adds another dimension to our understanding of membrane-active antibiotics.antibiotics | daptomycin | membrane potential | cell wall biosynthesis | Bacillus subtilis

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Section: Resultsmentioning

confidence: 63%

Daptomycin inhibits cell envelope synthesis by interfering with fluid membrane microdomains

Müller

Wenzel

Strahl

et al. 2016

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

375

506

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“…A number of other loci were originally identified as involved in germination on the basis of altered germination properties of mutants: amongst these, the gerC locus [16,45,46] encodes enzymes of menaquinone biosynthesis; gerCA and gerCC encode the heptaprenyl diphosphate synthase, and gerCB the 2-heptaprenyl-1,4-naphthaquinone methyltransferase. A single gerCC point mutant was barely viable and accumulated suppressor mutations that restored viability; although the nature of these was not identified, the resulting mutants could have a variable degree of defect in placement of the vegetative septum, and of spore germination [46], therefore, the GerC proteins are not directly concerned with spore germination, although an abnormality in menaquinone biosynthesis may indirectly affect membrane-associated events in germination.…”

Section: Other Ger Genesmentioning

confidence: 99%

Spore germination

Moir¹,

Corfe²,

Behravan³

2002

Cellular and Molecular Life Sciences (CMLS)

184

205

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Despite being relatively insensitive to environmental insult, the spore is responsive to low concentrations of chemical germinants, which induce germination. The process of bacterial spore germination involves membrane permeability changes, ion fluxes and the activation of enzymes that degrade the outer layers of the spore. A number of components in the spore that are required for the germination response have been identified, including a spore-specific family of receptor proteins (the GerA family), an ion transporter and cortex lytic enzymes. The germinant traverses the outer layers of the spore and interacts with its receptor in the inner membrane to initiate the cascade of germination events, but the molecular details of this signal transduction process remain to be identified.

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“…Spore sections were prepared as described previously (16). Sections were placed on Formvar-coated copper grids and examined under a CM100 transmission electron microscope operating at an acceleration voltage of 100 kV.…”

Section: Methodsmentioning

confidence: 99%

ExsY and CotY Are Required for the Correct Assembly of the Exosporium and Spore Coat of Bacillus cereus

et al. 2006

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The exosporium-defective phenotype of a transposon insertion mutant of Bacillus cereus implicated ExsY, a homologue of B. subtilis cysteine-rich spore coat proteins CotY and CotZ, in assembly of an intact exosporium. Single and double mutants of B. cereus lacking ExsY and its paralogue, CotY, were constructed. The exsY mutant spores are not surrounded by an intact exosporium, though they often carry attached exosporium fragments. In contrast, the cotY mutant spores have an intact exosporium, although its overall shape is altered. The single mutants show altered, but different, spore coat properties. The exsY mutant spore coat is permeable to lysozyme, whereas the cotY mutant spores are less resistant to several organic solvents than is the case for the wild type. The exsY cotY double-mutant spores lack exosporium and have very thin coats that are permeable to lysozyme and are sensitive to chloroform, toluene, and phenol. These spore coat as well as exosporium defects suggest that ExsY and CotY are important to correct formation of both the exosporium and the spore coat in B. cereus. Both ExsY and CotY proteins were detected in Western blots of purified wild-type exosporium, in complexes of high molecular weight, and as monomers. Both exsY and cotY genes are expressed at late stages of sporulation. Endospores of the Bacillus cereus family, which includesBacillus anthracis and Bacillus thuringiensis, are enveloped by a large, balloon-like layer known as the exosporium (11,19). B. subtilis, the paradigm sporeformer, does not have this distinct layer, although the B. subtilis spore coat may have a tight-fitting outermost layer that can be visualized after extraction of coat material with urea or mercaptoethanol (23). Scanning electron microscopy has revealed that the exosporium is composed of two layers-a paracrystalline basal layer with hexagonal periodicity and a "hairy nap" outer layer (11). The exosporium is chemically complex and is composed of 53% protein, 20% amino and neutral polysaccharides, 18% lipids, and ϳ4% ash (17).Multiple proteins from the exosporium of both B. cereus and B. anthracis have been identified (22,24,31); the majority do not have homologues in B. subtilis. For example, the surface layers of B. cereus, B. anthracis, and B. thuringiensis spores all contain glycoproteins with characteristic collagen-like repeat regions (5,10,27). Of these, the B. anthracis glycoprotein BclA is an essential component of the hairy nap layer of the exosporium (27, 29).Analysis of genome sequence information from B. cereus ATCC 14579 and B. anthracis Ames identified a cluster of genes near bclA implicated in exosporium production, including the region whose genes were designated yjbX-exsYyjcA-yjcB-exsFA-cotY (31). The ExsY and CotY proteins are homologues (ca. 35% amino acid identity) of the B. subtilis coat proteins CotY and CotZ (37). ExsY and CotY proteins have both been detected in purified exosporium from B. anthracis endospores by N-terminal sequencing of separated peptides (22). ExsY and CotY are very sim...

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The gerC locus of Bacillus subtilis, required for menaquinone biosynthesis, is concerned only indirectly with spore germination

Cited by 13 publications

References 17 publications

Daptomycin inhibits cell envelope synthesis by interfering with fluid membrane microdomains

Daptomycin inhibits cell envelope synthesis by interfering with fluid membrane microdomains

Spore germination

ExsY and CotY Are Required for the Correct Assembly of the Exosporium and Spore Coat of Bacillus cereus

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