Peptidoglycan binding-like <p>This entry represents peptidoglycan binding domain (PGBD), as well as related domains that share the same structure. PGBD may have a general peptidoglycan binding function, has a core structure consisting of a closed, three-helical bundle with a left-handed twist. It is found at the N or C terminus of a variety of enzymes involved in bacterial cell wall degradation [<cite idref="PUB00006403"/>, <cite idref="PUB00003979"/>, <cite idref="PUB00003115"/>]. Examples are:</p><p> <ul><li>Muramoyl-pentapeptide carboxypeptidase (<db_xref db="EC" dbkey="3.4.17.8"/>)</li> <li>N-acetylmuramoyl-L-alanine amidase cwlA precursor (cell wall hydrolase, autolysin, <db_xref db="EC" dbkey="3.5.1.28"/>)</li><li>Autolytic lysozyme (1,4-beta-N-acetylmuramidase, autolysin, <db_xref db="EC" dbkey="3.2.1.17"/>)</li><li>Membrane-bound lytic murein transglycosylase B</li><li>Zinc-containing D-alanyl-D-alanine-cleaving carboxypeptidase, VanX [<cite idref="PUB00013218"/>].</li></ul> </p><p>Many of the proteins having this domain are as yet uncharacterised. However, some are known to belong to MEROPS peptidase family M15 (clan MD), subfamily M15A metallopeptidases. A number of the proteins belonging to subfamily M15A are non-peptidase homologues as they either have been found experimentally to be without peptidase activity, or lack amino acid residues that are believed to be essential for the catalytic activity.</p><p>Eukaryotic enzymes can contain structurally similar PGBD-like domains. Matrix metalloproteinases (MMP), which catalyse extracellular matrix degradation, have N-terminal domains that resemble PGBD. Examples are gelatinase A (MMP-2), which degrades type IV collagen [<cite idref="PUB00013219"/>], stromelysin-1 (MMP-3), which plays a role in arthritis and tumour invasion [<cite idref="PUB00013220"/>, <cite idref="PUB00013221"/>], and gelatinase B (MMP-9) secreted by neutrophils as part of the innate immune defence mechanism [<cite idref="PUB00013222"/>]. Several MMPs are implicated in cancer progression, since degradation of the extracellular matrix is an essential step in the cascade of metastasis [<cite idref="PUB00013223"/>].</p>