A highly coordinated cell wall degradation machine governs spore morphogenesis in <i>Bacillus subtilis</i>

Morlot, Cécile; Uehara, Tsuyoshi; Marquis, Kathleen A.; Bernhardt, Thomas G.; Rudner, David Z.

doi:10.1101/gad.1878110

Cited by 96 publications

(163 citation statements)

References 35 publications

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“…We identified one mutation (E88A) that eliminates and three others (R106A, K203A, and D210A) that reduce peptidoglycan degradation activity and show that SpoIID activity is required for the earliest stage of engulfment (septal thinning), as well as throughout membrane migration. Our results confirm and extend those of Morlot et al (27) and also demonstrate that SpoIID activity is required throughout engulfment. Furthermore, our data indicate that the enzymatically inactive mutant protein (E88A) shows increased septal localization compared to the wild-type protein, suggesting that peptidoglycan degradation contributes to the release of SpoIID from the septum.…”

supporting

confidence: 82%

“…The SpoIID extracytoplasmic domain is conserved throughout the endospore forming bacteria, with more distant relatives found in many other bacterial phyla (14). Our results indicated that this domain was responsible for the peptidoglycan degradation activity of purified SpoIID in zymography gels (see below), but until recently (27), none of the proteins that are homologous to SpoIID have had characterized activities.…”

Section: Resultsmentioning

confidence: 85%

“…This requirement has been demonstrated for SpoIIP (8) and, while this work was under review, for SpoIID. SpoIID shows no sequence similarity to any characterized enzyme that degrades peptidoglycan and thus constitutes the founding member of a new class of enzymes that remodel peptidoglycan (1,27). However, SpoIID does show some similarity to B. subtilis LytB (24), a protein that enhances the activity of the amidase LytC (5,20,34), while SpoIIP is related to LytC (14).…”

mentioning

confidence: 99%

“…However, SpoIID does show some similarity to B. subtilis LytB (24), a protein that enhances the activity of the amidase LytC (5,20,34), while SpoIIP is related to LytC (14). A recent study demonstrated that SpoIIP is both an amidase and endopeptidase and that SpoIID both activates SpoIIP and functions as a lytic transglycosylase, cleaving peptidoglycan between NAG and NAM (27). Together, these two enzymes degrade peptidoglycan into its smallest repeating subunits.…”

mentioning

confidence: 99%

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SpoIID-Mediated Peptidoglycan Degradation Is Required throughout Engulfment during Bacillus subtilis Sporulation

2010

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SpoIID is a membrane-anchored enzyme that degrades peptidoglycan and is essential for engulfment and sporulation in Bacillus subtilis. SpoIID is targeted to the sporulation septum, where it interacts with two other proteins required for engulfment: SpoIIP and SpoIIM. We changed conserved amino acids in SpoIID to alanine to determine whether there was a correlation between the effect of each substitution on the in vivo and in vitro activities of SpoIID. We identified one amino acid substitution, E88A, that eliminated peptidoglycan degradation activity and one, D210A, that reduced it, as well as two substitutions that destabilized the protein in B. subtilis (R106A and K203A). Using these mutants, we show that the peptidoglycan degradation activity of SpoIID is required for the first step of engulfment (septal thinning), as well as throughout membrane migration, and we show that SpoIID levels are substantially above the minimum required for engulfment. The inactive mutant E88A shows increased septal localization compared to the wild type, suggesting that the degradation cycle of the SpoIID/SpoIIP complex is accompanied by the activity-dependent release of SpoIID from the complex and subsequent rebinding. This mutant is also capable of moving SpoIIP across the sporulation septum, suggesting that SpoIID binding, but not peptidoglycan degradation activity, is needed for relocalization of SpoIIP. Finally, the mutant with reduced activity (D210A) causes uneven engulfment and time-lapse microscopy indicates that the fastest-moving membrane arm has greater concentrations of SpoIIP than the slower-moving arm, demonstrating a correlation between SpoIIP protein levels and the rate of membrane migration.Endospore formation is an evolutionarily conserved process that allows Bacillus subtilis and related Gram-positive bacteria to adapt to changes in the environment, such as nutrient depletion. Many dramatic morphological changes occur during sporulation, each requiring a multitude of specialized proteins (reviewed in references 13 and 17). First, a sporulation septum is formed near one of the cell poles, forming two separate compartments of unequal sizes and with differing fates (Fig. 1A). The smaller of the two, the forespore, will eventually become the spore, while the larger, the mother cell, will ultimately lyse. Next, the mother cell membranes move up and around the forespore in the poorly understood process of engulfment. Although this process is superficially similar to eukaryotic engulfment, it is complicated by the thick cell wall that surrounds and separates the two compartments. After engulfment, the migrating membranes pinch off from the mother cell membrane, thereby releasing the forespore into the cytoplasm of the mother cell, where it can be enveloped with protective coat proteins and eventually released into the environment as a mature spore. Sporulation provides an ideal, nonessential system for understanding how bacterial cells are capable of undergoing dramatic morphological changes.Engulfment involves dynam...

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supporting

confidence: 82%

Section: Resultsmentioning

confidence: 85%

mentioning

confidence: 99%

mentioning

confidence: 99%

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SpoIID-Mediated Peptidoglycan Degradation Is Required throughout Engulfment during Bacillus subtilis Sporulation

2010

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“…This implies that an additional mechanism promotes fission during sporulation. Possible candidates include peptidoglycan synthesis as proposed by Dworkin and colleagues (Meyer et al 2010) or peptidoglycan hydrolysis carried out by the membrane-anchored peptidoglycan hydrolase complex composed of SpoIID, SpoIIP, and SpoIIM (Abanes-De Mello et al 2002;Aung et al 2007;Morlot et al 2010). Either of these machines could bring the engulfing membranes into close proximity and promote fission (Judd et al 2005), although at a slower rate than FisB.…”

Section: Discussionmentioning

confidence: 99%

FisB mediates membrane fission during sporulation in Bacillus subtilis

et al. 2013

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How bacteria catalyze membrane fission during growth and differentiation is an outstanding question in prokaryotic cell biology. Here, we describe a protein (FisB, for fission protein B) that mediates membrane fission during the morphological process of spore formation in Bacillus subtilis. Sporulating cells divide asymmetrically, generating a large mother cell and smaller forespore. After division, the mother cell membranes migrate around the forespore in a phagocytic-like process called engulfment. Membrane fission releases the forespore into the mother cell cytoplasm. Cells lacking FisB are severely and specifically impaired in the fission reaction. Moreover, GFP-FisB forms dynamic foci that become immobilized at the site of fission. Purified FisB catalyzes lipid mixing in vitro and is only required in one of the fusing membranes, suggesting that FisB-lipid interactions drive membrane remodeling. Consistent with this idea, the extracytoplasmic domain of FisB binds with remarkable specificity to cardiolipin, a lipid enriched in the engulfing membranes and regions of negative curvature. We propose that membrane topology at the final stage of engulfment and FisB-cardiolipin interactions ensure that the mother cell membranes are severed at the right time and place. The unique properties of FisB set it apart from the known fission machineries in eukaryotes, suggesting that it represents a new class of fission proteins.

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Bacterial Cell Wall Recycling

Mayer

2012

Encyclopedia of Life Sciences

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Cell wall recycling is a process whereby bacteria degrade their own wall during growth, recover released constituents by active transport and reutilise them either to rebuild the wall or to gain energy. Most knowledge about cell wall recycling comes from studies with the Gram‐negative bacterium Escherichia coli . Within one generation, this organism breaks down and efficiently recycles approximately 60% of the mature peptidoglycan of its side‐wall during cell elongation and approximately 30% of newly deposited septal peptidoglycan during cell division. The reason for the massive turnover of the peptidoglycan is still unclear, although many other bacteria, including Gram‐positives, have been reported to turnover their cell wall and release similar quantities of peptidoglycan fragments during growth and differentiation. Whether these fragments are also recycled is basically unknown. The presence of recycling genes on most bacterial genomes, however, suggests that cell wall recycling is a very common pathway of bacteria. Key Concepts: The peptidoglycan of the bacterial cell wall represents a single, giant, reticular macromolecule (i.e. the murein sacculus) that encases the entire bacterial cell. The peptidoglycan cell wall has to be cleaved continuously during growth to allow cell expansion by insertion of new wall material. Bacteria possess a huge and partially redundant set of cell wall lytic enzymes that potentially target every covalent bond connecting the amino acid and amino sugar building blocks within the peptidoglycan network (cell wall lytic complement). Many bacteria release a great amount of cell wall material during bacterial growth (cell elongation and division). The reason for the massive turnover of approximately 50% of the existing peptidoglycan in one generation is still unclear. Bacteria eventually recover cell wall turnover fragments. The pathways for the continuous recycling of peptidoglycan have been explored in great detail in Escherichia coli . Cell wall recycling in Gram‐positive bacteria has been appreciated just recently and apparently differs from the E. coli paradigm as well as between Gram‐positive species. Cell wall‐derived peptidoglycan fragments function as potent biological effectors. They are involved in sensing the cell wall and growth state, inducing expression of antibiotic resistance genes, and triggering cell differentiation and resuscitation of dormant cells.

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A highly coordinated cell wall degradation machine governs spore morphogenesis in Bacillus subtilis

Cited by 96 publications

References 35 publications

SpoIID-Mediated Peptidoglycan Degradation Is Required throughout Engulfment during Bacillus subtilis Sporulation

SpoIID-Mediated Peptidoglycan Degradation Is Required throughout Engulfment during Bacillus subtilis Sporulation

FisB mediates membrane fission during sporulation in Bacillus subtilis

Bacterial Cell Wall Recycling

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