Diversity of Firmicutes peptidoglycan hydrolases and specificities of those involved in daughter cell separation

Layec, Séverine; Decaris, Bernard; Leblond‐Bourget, Nathalie

doi:10.1016/j.resmic.2008.06.008

Cited by 58 publications

(83 citation statements)

References 76 publications

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“…In Firmicutes, hydrolases often are composed of two or more PG-binding or catalytic domains, a feature thought to be important for ensuring regulatory control of the complex events surrounding metabolism of the thick cell wall (47,48). The T4SS-associated hydrolases in G ϩ bacteria also possess multidomain architectures, in this case probably for coordinating ear-stage reactions associated with morphogenesis of the translocation channel (5).…”

Section: Discussionmentioning

confidence: 99%

PrgK, a Multidomain Peptidoglycan Hydrolase, Is Essential for Conjugative Transfer of the Pheromone-Responsive Plasmid pCF10

2014

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Peptidoglycan (PG) hydrolases associated with bacterial type IV secretion systems (T4SSs) are thought to generate localized lesions in the PG layer to facilitate assembly of the translocation channel. The pheromone-responsive plasmid pCF10 of Enterococcus faecalis encodes a putative cell wall hydrolase, PrgK, and here we report that a prgK deletion abolished functionality of the pCF10-encoded T4SS as monitored by pCF10 conjugative transfer. Expression in trans of wild-type prgK fully complemented this mutation. PrgK has three potential hydrolase motifs resembling staphylococcal LytM, soluble lytic transglycosylase (SLT), and cysteine-, histidine-dependent amidohydrolase/peptidase (CHAP) domains. Complementation analyses with mutant alleles established that PrgK bearing two hydrolase domains in any combination supported near-wild-type plasmid transfer, and PrgK bearing a single hydrolase domain supported at least a low level of transfer in filter matings. When exported to the Escherichia coli periplasm, each domain disrupted cell growth, and combinations of domains additionally induced cell rounding and blebbing and conferred enhanced sensitivity to osmotic shock. Each domain bound PG in vitro, but only the SLT domain exhibited detectable hydrolase activity, as shown by zymographic analyses and release of fluorescent PG fragments. Genes encoding three T4SS-associated, putative hydrolases, Lactococcus lactis CsiA, Tn925 Orf14, and pIP501 TraG, partially complemented the ⌬prgK mutation. Our findings establish that PrgK is an essential component of the pCF10-encoded Prg/Pcf T4SS and that its hydrolase domains coordinate their activities for full PrgK function. PrgK is indispensable for plasmid transfer in liquid matings, suggestive of a role in formation or stabilization of mating junctions.

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Section: Discussionmentioning

confidence: 99%

PrgK, a Multidomain Peptidoglycan Hydrolase, Is Essential for Conjugative Transfer of the Pheromone-Responsive Plasmid pCF10

2014

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“…Indeed, Smith et al (55) pointed to a set of amidases (XlyA, XlyB, BlyA, CwlA, and CwlH) that are encoded by prophages or prophage-related DNA elements present in the B. subtilis genome. All these proteins are predicted to carry an amidase_2 domain (PF01510) (49), a domain which is frequently found in zinc-containing enzymes possessing N-acetylmuramoyl-L-alanine activity (36).…”

Section: Discussionmentioning

confidence: 99%

Activity of the Osmotically Regulated yqiHIK Promoter from Bacillus subtilis Is Controlled at a Distance

Fischer

Bremer

2012

J Bacteriol

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The yqiHIK gene cluster from Bacillus subtilis is predicted to encode an extracellular lipoprotein (YqiH), a secreted N-acetylmuramoyl-L-alanine amidase (YqiI), and a cytoplasmic glycerophosphodiester phosphodiesterase (YqiK). Reverse transcriptase PCR (RT-PCR) analysis showed that the yqiHIK genes are transcribed as an operon. Consistent with the in silico prediction, we found that the purified YqiI protein exhibited hydrolytic activity toward peptidoglycan sacculi. Transcription studies with yqiHtreA reporter fusion strains revealed that the expression of yqiHIK is subjected to finely tuned osmotic control, but enhanced expression occurs only in severely osmotically stressed cells. Primer extension analysis pinpointed the osmotically responsive yqiHIK promoter, and site-directed mutagenesis was employed to assess functionally important sequences required for promoter activity and osmotic control. Promoter variants with constitutive activity were isolated. A deletion analysis of the yqiHIK regulatory region showed that a 53-bp AT-rich DNA segment positioned 180 bp upstream of the ؊35 sequence is critical for the activity and osmotic regulation of the yqiHIK promoter. Hence, the expression of yqiHIK is subjected to genetic control at a distance. Upon the onset of growth of cells of the B. subtilis wild-type strain in high-salinity medium (1.2 M NaCl), we observed gross morphological deformations of cells that were then reversed to a rod-shaped morphology again when the cells had adjusted to the high-salinity environment. The products of the yqiHIK gene cluster were not critical for reestablishing rod-shaped morphology, but the deletion of this operon yielded a B. subtilis mutant impaired in growth in a defined minimal medium and at high salinity.

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“…Pneumococcal CbpD consists of one catalytic domain and two types of cell wall binding domains. The N-terminal CHAP (cysteine histidinedependent aminohydrolase/peptidase) domain most likely functions either as an amidase that disrupts the N-acetylmuramyl-LAla bond or as an endopeptidase that cleaves within the peptide part of peptidoglycan (1,30,44). At the C-terminal end of CbpD, there are four choline-binding repeats.…”

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confidence: 99%

LytF, a Novel Competence-Regulated Murein Hydrolase in the Genus Streptococcus

2012

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Streptococcus pneumoniae and probably most other members of the genus Streptococcus are competent for natural genetic transformation. During the competent state, S. pneumoniae produces a murein hydrolase, CbpD, that kills and lyses noncompetent pneumococci and closely related species. Previous studies have shown that CbpD is essential for efficient transfer of genomic DNA from noncompetent to competent cells in vitro. Consequently, it has been proposed that CbpD together with the cognate immunity protein ComM constitutes a DNA acquisition mechanism that enables competent pneumococci to capture homologous DNA from closely related streptococci sharing the same habitat. Although genes encoding CbpD homologs or CbpD-related proteins are present in many different streptococcal species, the genomes of a number of streptococci do not encode CbpD-type proteins. In the present study we show that the genomes of nearly all species lacking CbpD encode an unrelated competence-regulated murein hydrolase termed LytF. Using Streptococcus gordonii as a model system, we obtained evidence indicating that LytF is a functional analogue of CbpD. In sum, our results show that a murein hydrolase gene is part of the competence regulon of most or all streptococcal species, demonstrating that these muralytic enzymes constitute an essential part of the streptococcal natural transformation system.

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Diversity of Firmicutes peptidoglycan hydrolases and specificities of those involved in daughter cell separation

Cited by 58 publications

References 76 publications

PrgK, a Multidomain Peptidoglycan Hydrolase, Is Essential for Conjugative Transfer of the Pheromone-Responsive Plasmid pCF10

PrgK, a Multidomain Peptidoglycan Hydrolase, Is Essential for Conjugative Transfer of the Pheromone-Responsive Plasmid pCF10

Activity of the Osmotically Regulated yqiHIK Promoter from Bacillus subtilis Is Controlled at a Distance

LytF, a Novel Competence-Regulated Murein Hydrolase in the Genus Streptococcus

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