Family M7


Summary Holotypes Alignment Tree Genomes Structure Literature

Summary for family M7

NamePeptidase family M7 (snapalysin family)
Family type peptidaseM07.001 - snapalysin (Streptomyces lividans), MEROPS Accession MER0001060 (peptidase unit: 43-227)
Content of familyPeptidase family M7 contains a metalloendopeptidase, snapalysin.
History Identifier created: Biochem.J. 290:205-218 (1993)
Catalytic typeMetallo
Active site residuesH163 E164 H167 D173 
Active siteZinc is bound by two histidines and an aspartate in an HEXXHXXGXXD sequence motif; the glutamate is a catalytic residue. This motif is also found in family M6.
Activities and specificitiesSnapalysin is active at neutral pH. The only known activity is cleavage of proteins of skimmed milk to form clear plaques around the growing bacterial colonies.
InhibitorsLike many metalloenzymes, snapalysin is inhibited by 10 mM 1,10-phenanthroline (Butler, 2004).
Molecular structureSnapalysin is one of the smallest peptidases known, with only 185 residues in its processed form. Most peptidases have a two domain structure with the active site between the domains, but the tertiary structure of snapalysin shows that its C-terminal domain is reduced to a single helix. The structure is similar to the N-terminal domain of thermolysin (M04.001), hence family M7 is included in clan MA. Because the zinc ligands are similarly spaced to those of astacin (M12.001), the family is included in subclan MA(M). In common with other members of subclan MA(M), there is a conserved methionine (in the "Met-turn") C-terminal to the active site motif. Snapalysin is unusual amongst peptidases of subclan MA(M) in not having a tyrosine residue conserved on the "Met-turn", nor a cysteine in the propeptide.
Basis of clan assignmentProtein fold of the peptidase unit for members of this family resembles that of thermolysin, the type example for clan MA.
Distribution of family Bacteria details  
Archaea -  
Protozoa -  
Fungi -  
Plants -  
Animals -  
Viruses -  
Biological functionsSnapalysin is a secreted enzyme apparently without a signal peptide or a propeptide, even though N-terminal processing occurs. The endopeptidase is active with or without this processing (Butler, 2004).
Statistics for family M7Sequences:109
Identifiers with PDB entries:1
Downloadable files Sequence library (FastA format)
Sequence alignment (FastA format)
Phylogenetic tree (Newick format)
Peptidases and Homologues MEROPS ID Structure
family M7 unassigned peptidasesunassigned-