Identification and molecular characterization of an <i>N</i>‐acetylmuramyl‐<scp>l</scp>‐alanine amidase Sle1 involved in cell separation of <i>Staphylococcus aureus</i>

Kajimura, Junko; Fujiwara, Takanori; Yamada, Sakuo; Suzawa, Yoshika; Nishida, Tetsuya; Oyamada, Yoshihiro; Hayashi, Ikue; Yamagishi, Jun‐ichi; Komatsuzawa, Hitoshi; Sugai, Motoyuki

doi:10.1111/j.1365-2958.2005.04881.x

Cited by 157 publications

(198 citation statements)

References 32 publications

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“…It is homologous to the secretory antigen SsaA-like protein of S. aureus (80% identity), which is a surface antigen that is upregulated by sigB and is important for biofilm formation (7,10). SERP0318 is also similar to S. aureus Sle1 (46% identical), which is an autolysin with Nacetylmuramyl-L-alanine amidase activity (27). SERP2263 also appears to contain an N-acetylmuramoyl-L-alanine amidase as well as a transglycosylase domain, while IsaA is annotated as a transglycosylase, and both are known virulence factors (35,56).…”

Section: Discussionmentioning

confidence: 99%

Type I Signal Peptidase and Protein Secretion inStaphylococcus epidermidis

et al. 2011

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Bacterial protein secretion is a highly orchestrated process that is essential for infection and virulence. Despite extensive efforts to predict or experimentally detect proteins that are secreted, the characterization of the bacterial secretome has remained challenging. A central event in protein secretion is the type I signal peptidase (SPase)-mediated cleavage of the N-terminal signal peptide that targets a protein for secretion via the general secretory pathway, and the arylomycins are a class of natural products that inhibit SPase, suggesting that they may be useful chemical biology tools for characterizing the secretome. Here, using an arylomycin derivative, along with two-dimensional gel electrophoresis and liquid chromatography-tandem mass spectrometry (LC-MS/MS), we identify 11 proteins whose secretion from stationary-phase Staphylococcus epidermidis is dependent on SPase activity, 9 of which are predicted to be translated with canonical N-terminal signal peptides. In addition, we find that the presence of extracellular domains of lipoteichoic acid synthase (LtaS) and the ␤-lactam response sensor BlaR1 in the medium is dependent on SPase activity, suggesting that they are cleaved at noncanonical sites within the protein. In all, the data define the proteins whose stationaryphase secretion depends on SPase and also suggest that the arylomycins should be valuable chemical biology tools for the study of protein secretion in a wide variety of different bacteria.

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Section: Discussionmentioning

confidence: 99%

Type I Signal Peptidase and Protein Secretion inStaphylococcus epidermidis

et al. 2011

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“…In Staphylococcus aureus, the Atl protein is processed to yield two hydrolases, an amidase and glucosaminidase (49), and strains lacking Atl grow as clusters of unseparated cells (50). Mutants lacking the Sle1 N-acetylmuramyl-L-alanine amidase have multiple, misplaced, and sometimes curved septa that are positioned at odd angles so that they do not bisect daughter cells equally, effects that are magnified greatly in an atl sle1 double mutant (29). In B. subtilis, the absence of the LytE murein hydrolase produces curved or bent cells that have unnatural lengths and widths (9).…”

Section: Discussionmentioning

confidence: 99%

Role of Peptidoglycan Amidases in the Development and Morphology of the Division Septum in Escherichia coli

2007

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Escherichia coli contains multiple peptidoglycan-specific hydrolases, but their physiological purposes are poorly understood. Several mutants lacking combinations of hydrolases grow as chains of unseparated cells, indicating that these enzymes help cleave the septum to separate daughter cells after cell division. Here, we confirm previous observations that in the absence of two or more amidases, thickened and dark bands, which we term septal peptidoglycan (SP) rings, appear at division sites in isolated sacculi. The formation of SP rings depends on active cell division, and they apparently represent a cell division structure that accumulates because septal synthesis and hydrolysis are uncoupled. Even though septal constriction was incomplete, SP rings exhibited two properties of mature cell poles: they behaved as though composed of inert peptidoglycan, and they attracted the IcsA protein. Despite not being separated by a completed peptidoglycan wall, adjacent cells in these chains were often compartmentalized by the inner membrane, indicating that cytokinesis could occur in the absence of invagination of the entire cell envelope. Finally, deletion of penicillin-binding protein 5 from amidase mutants exacerbated the formation of twisted chains, producing numerous cells having septa with abnormal placements and geometries. The results suggest that the amidases are necessary for continued peptidoglycan synthesis during cell division, that their activities help create a septum having the appropriate geometry, and that they may contribute to the development of inert peptidoglycan.Most eubacteria produce multiple hydrolases that cleave different bonds within the peptidoglycan (PG or murein) cell wall: amidases remove peptide side chains from the carbohydrate polymer, endopeptidases cleave cross-linked peptides that connect the glycan chains, and lytic transglycosylases hydrolyze the glycan backbone (24, 47). These PG-specific hydrolases were once thought to be essential for inserting new material into the wall during bacterial growth (24, 25), a view based on the reasonable hypothesis that cross-links between the glycan chains had to be broken so that new PG strands could be incorporated into the existing wall (31). However, bacterial growth continues perfectly well in the absence of these dedicated hydrolases, including almost all of the amidases, endopeptidases, and lytic transglycosylases (14,22,23), meaning that any bond-breaking during normal cell wall elongation must be performed by other enzymes. So why, then, does Escherichia coli carry so many murein-specific hydrolases?In the gram-positive bacteria, PG hydrolases split the septum that separates daughter cells at the end of cell division. For example, in Streptococcus pneumoniae, LytA (an amidase) and LytB (a glucosaminidase) localize to the equatorial and polar regions, respectively, and mutants lacking either hydrolase grow in long chains, with double mutants being especially deficient in cell separation (13,46). In Bacillus subtilis, the DL-endopeptidases ...

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“…There are multiple examples of mutations in murein hydrolase genes in both gram-positive and gram-negative bacteria that result in the inability of the cells to separate (25,38,51,65,70,71,108,118,244,249). Based on the frequency with which murein hydrolase mutations are associated with this phenotype, the primary functions of these enzymes in daughter cell separation are unambiguous.…”

Section: Murein Hydrolasesmentioning

confidence: 99%

Molecular Control of Bacterial Death and Lysis

Rice

Bayles

2008

Microbiol Mol Biol Rev

318

312

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SUMMARY Although the phenomenon of bacterial cell death and lysis has been studied for over 100 years, the contribution of these important processes to bacterial physiology and development has only recently been recognized. Contemporary study of cell death and lysis in a number of different bacteria has revealed that these processes, once thought of as being passive and unregulated, are actually governed by highly complex regulatory systems. An emerging paradigm in this field suggests that, analogous to programmed cell death in eukaryotes, regulated cell death and lysis in bacteria play an important role in both developmental processes, such as competence and biofilm development, and the elimination of damaged cells, such as those irreversibly injured by environmental or antibiotic stress. Further study in this exciting field of bacterial research may provide new insight into the potential evolutionary link between control of cell death in bacteria and programmed cell death (apoptosis) in eukaryotes.

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Identification and molecular characterization of an N‐acetylmuramyl‐l‐alanine amidase Sle1 involved in cell separation of Staphylococcus aureus

Cited by 157 publications

References 32 publications

Type I Signal Peptidase and Protein Secretion inStaphylococcus epidermidis

Type I Signal Peptidase and Protein Secretion inStaphylococcus epidermidis

Role of Peptidoglycan Amidases in the Development and Morphology of the Division Septum in Escherichia coli

Molecular Control of Bacterial Death and Lysis

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