Protein Domain : Peptidase M9A/M9B, collagenase, bacterial IPR002169

Type	Family
Description	Over 70 metallopeptidase families have been identified to date. In these enzymes a divalent cation which is usually zinc, but may be cobalt, manganese or copper, activates the water molecule. The metal ion is held in place by amino acid ligands, usually three in number. In some families of co-catalytic metallopeptidases, two metal ions are observed in crystal structures ligated by five amino acids, with one amino acid ligating both metal ions. The known metal ligands are His, Glu, Asp or Lys. At least one other residue is required for catalysis, which may play an electrophillic role. Many metalloproteases contain an HEXXH motif, which has been shown in crystallographic studies to form part of the metal-binding site []. The HEXXH motif is relatively common, but can be more stringently defined for metalloproteases as 'abXHEbbHbc', where 'a' is most often valine or threonine and forms part of the S1' subsite in thermolysin and neprilysin, 'b' is an uncharged residue, and 'c' a hydrophobic residue. Proline is never found in this site, possibly because it would break the helical structure adopted by this motif in metalloproteases [].This entry represents sequences belonging to peptidase family M9, subfamilies M9A and M9B (microbial collagenase, clan MA(E)). The protein fold of the peptidase domain for members of this family resembles that of thermolysin, the type example for clan MA and the metal ligands and active site residues for members of this family and thermolysin occur in the motif HEXXH [ ].Microbial collagenases have been identified from bacteria of both the Vibrio and Clostridium genera. Collagenase is used during bacterial attack to degrade the collagen barrier of the host during invasion. Vibrio bacteria are non-pathogenic, and are sometimes used in hospitals to remove dead tissue from burns and ulcers. Clostridium histolyticum is a pathogen that causes gas gangrene; nevertheless, the isolated collagenase has been used to treat bed sores. Collagen cleavage occurs within the Gly-Xaa-Yaa repeats at Xaa+Gly in Vibrio and at Yaa+Gly bonds in Clostridium collagenase.Analysis of the primary structure of the gene product from Clostridium perfringens has revealed that the enzyme is produced with a stretch of 86 residues that contain a putative signal sequence [ ]. Within this stretch is found PLGP, an amino acid sequence typical of collagenase substrates. This sequence may thus be implicated in self-processing of the collagenase [].
Short Name	Peptidase_M9A/M9B