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Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Murein hydrolase activities were analyzed in synchronized cultures of Escherichia coli B/r. Cell wall-bound murein hydrolase activities, including the penicillin-sensitive endopeptidase, increased discontinuously during the cell cycle and showed maximum activity at a cell age of 30 to 35 min (generation time, 43 min). Maximum activity was observed at the same time that the rate of cell wall synthesis reached its maximum. These oscillations depended on the termination of replication: no increase in hydrolase activity was found if deoxyribonucleic acid synthesis was inhibited at an early time in the life cycle. In contrast, the activity of another murein hydrolase that was not tightly bound to the membrane (transglycosylase) increased exponentially with time, even when deoxyribonucleic acid synthesis was inhibited.
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PMID:Activity of murein hydrolases in synchronized cultures of Escherichia coli. 32 19

Envelopes from regions of the cell which in vivo show very little, if any, murein synthesis were isolated using the minicell-producing strain P678-54. Envelopes from minicells, representing in fact cell ends, were able to synthesize murein and to carry out transpeptidation in vitro; also all four murein hydrolase activities tested, carboxypeptidase, endopeptidase, amidase and transglycosylase, were found to be present. The specific activities of the murein synthesizing and degrading enzymes in envelopes derived from cell poles and from actively growing cells were similar. The topological distribution of murein-synthesizing enzymes and of murein hydrolases over the cell envelope is discussed.
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PMID:Enzymes synthesizing and hydrolyzing murein in Escherichia coli. Topographical distribution over the cell envelope. 33 1

D-alanyl-meso-2, 6-diaminopimelic acid (D-Alanyl-meso-A2pm) endopeptidase was isolated and purified from a crude Streptomyces L-3 enzyme preparation by ion exchange chromatography and isoelectric focusing in a density gradient. During its purification, its hydrolytic activity was assayed on cell walls of Lactobacillus plantarum ATCC 8014 and soluble glycopeptides and peptides, of known chemical structures, prepared enzymatically from these cell walls. A fraction with an isoelectric point of pH 7.9 cleaved the bond between the carboxyl group of the D-alanine residue at the C-terminal in one peptide subunit and one of the two amino groups of the A2pm residue in the neighboring peptide subunit. Unlike the crude enzyme, the endopeptidase in this fraction showed no N-acetylmuramyl-L-alanine amidase, A2pm carboxyamide amidase or proteinase(s) activity and it was immunologically homogeneous.
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PMID:Isolation and purification of D-alanyl-meso-2, 6-diaminopimelic acid endopeptidase of Streptomyces L-3 enzyme using soluble substrates of known chemical structure from Lactobacillus plantarum cell wall digests. 101 17

The mechanism of lysis of Eubacterium alactolyticum cell walls by Streptomyces albus G enzyme was studied. The analysis of the peptide terminal groups and peptide subunits isolated from the cell wall digest, released during solubilization of the cell walls, revealed that lytic action of S. albus G enzyme was mainly due to D-alanyl-A2pm endopeptidase, N-acetylmuramyl-L-alanine amidase, N-acetylmuramidase and N-acetylglucosaminidase. E. alactolyticum cell wall peptidoglycan is composed mainly of glucosamine, muramic acid, D-glutamic acid, L- and D-alanine, meso-diaminopimelic acid and glycine. The peptide subunit consists of L-alanyl-D-glutamyl-meso-A2pm-D-alanine. D-Alanine is connected directly with the amino group of the meso-A2pm residue of another peptide subunit. All of the L-amino groups of meso-diaminopimelic acid are involved in cross-linking. The possible structure of the peptide moiety of E. alactolyticum cell wall peptidoglycan is presented.
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PMID:Chemical composition of Eubacterium alactolyticum cell wall peptidoglycan. 274 50

Spermidine and cadaverine were found to be constituents of the cell wall peptidoglycan of Anaerovibrio lipolytica, a strictly anaerobic bacterium. The peptidoglycan was degraded with the N-acetylmuramyl-L-alanine amidase and endopeptidase into two peptide fragments, peptide I and peptide II, at a molar ratio of 4:1. Peptides I and II were identified as L-alanine-D-glutamic acid(alphacadaverine)gammameso-diaminopimelic acid (DAP)-D-alanine and L-alanine-D-glutamic acid(alphaspermidine)gammameso-DAP-D-alanine, respectively. The N(1)-amino group of spermidine was linked to the alpha-carboxyl group of the D-glutamic acid residue of peptide II.
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PMID:Covalent linkage of polyamines to peptidoglycan in Anaerovibrio lipolytica. 1064 44

Sequencing of the Moraxella sp. CK-1 autolysin (cell wall hydrolases) gene showed the presence of an open reading frame which encodes a polypeptide of 273 amino acids with a molecular mass of 33,316 Da. A presumed ribosomal binding site, a possible -10 and -35 region, and rho-dependent terminators were found. The C-terminal region of the mature protein showed considerable homology with the Thermus sp. serine proteinase. Enzyme assay suggests that the recombinant autolysin has amidase or endopeptidase activity. Analysis of the peptidoglycan fragments, following the treatment with the autolysin, indicates that this protein is an N-acetylmuramyl-L-alanine amidase. Insertional inactivation of the autolysin of Moraxella sp. CK-1 chromosome led to a decrease in cell wall hydrolytic activity, clumping of the cells, and color change. No lytic band present in inactivated magA mutant by renaturing SDS-PAGE.
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PMID:Sequence analysis and insertional inactivation of a gene encoding Moraxella sp. CK-1 cell wall hydrolase. 1152 2

A polysaccharide deacetylase homologue, PdaA, was determined to act as an N-acetylmuramic acid deacetylase in vitro. Histidine-tagged truncated PdaA (with the putative signal sequence removed) was overexpressed in Escherichia coli cells and purified. Measurement of deacetylase activity showed that PdaA could deacetylate peptidoglycan treated with N-acetylmuramoyl-L-alanine amidase CwlH but could not deacetylate peptidoglycan treated with or without DL-endopeptidase LytF (CwlE). Reverse-phase high-performance liquid chromatography and mass spectrometry (MS) and MS-MS analyses indicated that PdaA could deacetylate the N-acetylmuramic acid residues of purified glycan strands derived from Bacillus subtilis peptidoglycan.
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PMID:A polysaccharide deacetylase homologue, PdaA, in Bacillus subtilis acts as an N-acetylmuramic acid deacetylase in vitro. 1568 92

The substrate specificity of autolytic enzymes of the bacterium Lysobacter sp. XL 1 has been established. The periplasmic enzyme A8, the cytosolic enzyme A1, and the enzyme A10 solubilized from the cell walls and membranes with Triton X-100 exhibit glucosaminidase activity; the cytosolic enzyme A4 and the enzyme A9 solubilized from the cell walls and membranes with LiCl exhibit the muramidase activity. The cytosolic enzymes A3 and A6 have N-acetylmuramoyl-L-alanine amidase activity, and the enzyme A5 exhibits the diaminopimelinoyl-alanine endopeptidase activity. Some physicochemical properties of the most active autolytic cytosolic enzymes of Lysobacter sp. XL 1 (endopeptidases A5 and A7 and N-acetylmuramoyl-L-alanine amidase A6) were studied. The enzymes exhibit maximal activity over a wide range of buffer concentrations in weakly alkaline medium and moderate temperatures. The investigated enzymes are comparatively thermolabile proteins.
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PMID:Substrate specificity and some physicochemical properties of autolytic enzymes of the bacterium Lysobacter sp. XL 1. 1768 Jul 68

Cell division is a dynamic process ending by separation of the daughter cells. This final step requires the cleavage of the murein septum synthetized during cell division. In Streptococcus thermophilus, cse plays an important role in cell separation. Cse protein contains, at its N-terminal end, a signal peptide and a putative LysM motif suggesting that it is secreted and able to bind to the cell wall. Furthermore, the C-terminus of Cse carries a putative cysteine, histidine-dependent amidohydrolases/peptidases (CHAP) domain conferring to the protein a potential catalytic activity. To gain insight into the role of Cse in the cell division process, in silico analysis of the Firmicutes proteins displaying CHAP-related domain was undertaken. This work allowed us to distinguish and characterize within the Firmicutes the 2 families of proteins (CHAP and NlpC/p60) belonging to the CHAP superfamily. These 2 families regroup mainly peptidoglycan hydrolases. Data from the literature indicate that NlpC/p60 and CHAP proteins cleave distinct peptidoglycan bonds. Among the enzymes characterized within the Firmicutes, NlpC/p60 proteins are gamma-D-glutamate-meso-diaminopimelate muropeptidase. Instead, CHAP enzymes involved in cell separation are N-acetylmuramoyl-L-alanine amidase and CHAP lysins have endopeptidase activity.
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PMID:Characterization of proteins belonging to the CHAP-related superfamily within the Firmicutes. 1795 8

Similar to many other bacterial cell-wall-hydrolyzing enzymes, the Listeria bacteriophage A500 endopeptidase Ply500 has a modular architecture consisting of an enzymatically active domain (EAD) linked to a cell-wall-binding domain (CBD) in a single polypeptide chain. The crystal structure of the EAD of Ply500 has been solved at 1.8 A resolution. The shape of the enzyme resembles a sofa chair: one alpha-helix and three antiparallel beta-strands form the seat, which is supported by two more alpha-helices, while another alpha-helix together with the following loop give rise to the backrest. A sulfate anion bound to the active site, which harbours a catalytic Zn2+ ion, indicates mechanistic details of the peptidase reaction, which involves a tetrahedral transition state. Despite very low sequence similarity, a clear structural relationship was detected to the peptidases VanX, DDC, MSH and MepA, which belong to the so-called 'LAS' family. Their gross functional similarity is supported by a common bound Zn2+ ion and a highly conserved set of coordinating residues (His80, Asp87 and His133) as well as other side chains (Arg50, Gln55, Ser78 and Asp130) in the active site. Considering the high sequence similarity to the EAD of the Listeria phage endopeptidase Ply118, both enzymes can thus be assigned to the LAS family. The same is the case for the L,D-endopeptidase CwlK from Bacillus subtilis, which shows both functional and amino-acid sequence similarity. The fact that the CBD of Ply500 is closely homologous to the CBD of the Listeria phage N-acetylmuramoyl-L-alanine amidase PlyPSA, which exhibits a totally different EAD, illustrates the modular composition and functional variability of this class of enzymes and opens interesting possibilities for protein engineering.
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PMID:Structural analysis of the L-alanoyl-D-glutamate endopeptidase domain of Listeria bacteriophage endolysin Ply500 reveals a new member of the LAS peptidase family. 1856 Jan 52


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