Family

Peptidase M7, snapalysin (IPR000013)

Short name: Peptidase_M7

Family relationships

None.

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 [PMID: 7674922]. 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 [PMID: 7674922].

This group of metallopeptidases belong to the MEROPS peptidase family M7 (snapalysin family, clan MA(M)). The protein fold of the peptidase domain for members of this family resembles that of thermolysin, the type example for clan MA.

With a molecular weight of around 16kDa, Streptomyces extracellular neutral protease is one of the smallest known proteases [PMID: 7674922]; it is capable of hydrolysing milk proteins [PMID: 7674922]. The enzyme is synthesised as a proenzyme with a signal peptide, a propeptide and an active domain that contains the conserved HEXXH motif characteristic of metalloproteases. Although family M7 shows active site sequence similarity to other members, it differs in one major respect: the third zinc ligand appears to be an aspartate residue rather than the usual histidine.

GO terms

Biological Process

GO:0006508 proteolysis

Molecular Function

GO:0004222 metalloendopeptidase activity
GO:0008270 zinc ion binding

Cellular Component

GO:0005576 extracellular region

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PIRSF
Pfam
ProDom
PRINTS