Family M44


Summary Holotypes Alignment Tree Genomes Literature

Summary for family M44

Family type peptidaseM44.001 - pox virus metallopeptidase (Vaccinia virus), MEROPS Accession MER0002122 (peptidase unit: 1-591)
Content of familyPeptidase family M44 contains a metalloendopeptidase from the pox viruses.
History Identifier created: Proteolysis in Cell Function, pp13-21, IOS Press, Amsterdam (1997)
Catalytic typeMetallo
Active site residuesH41 E44 H45 E112 
Active siteFamily M44 members contain three zinc-binding ligands and a catalytic glutamate. The first two zinc ligands are histidine residues, found together with the catalytic glutamate in a HXXEH motif, an inverse of the classical metallopeptidase motif, HEXXH. The third zinc ligand is a glutamate C-terminal to the HXXEH motif within a motif ELENEY (see the Alignment).
Activities and specificitiesThe vaccinia virus metalloendopeptidase (M44.001) processes the viral polyprotein into multiple fragments at Ala-GlyXaa motifs where Xaa is Ala, Ser, Thr or Lys (Byrd et al., 2004). The enzyme is inactivated by mutations in the HXXEH motif.
Molecular structureIt is predicted that vaccinia virus metalloendopeptidase is structurally similar to mitochondrial processing peptidase (M16.003). Therefore, the family M44 is included in clan ME (Hedengren-Olcott et al., 2004).
Basis of clan assignmentActive site residues for members of this family and family M16 occur in the motif HXXEH
Distribution of family Bacteria details  
Archaea -  
Protozoa -  
Fungi -  
Plants -  
Animals -  
Viruses details  
Biological functionsThe work of Hedengren-Olcott et al. (2004) demonstrates that the vaccinia virus metalloendopeptidase is essential for viral maturation; without this peptidase there is almost no product of infectious progeny.
Statistics for family M44Sequences:41
Identifiers with PDB entries:0
Downloadable files Sequence library (FastA format)
Sequence alignment (FastA format)
Phylogenetic tree (Newick format)
Peptidases and Homologues MEROPS ID Structure
pox virus metallopeptidaseM44.001-
family M44 non-peptidase homologuesnon-peptidase homologue-
family M44 unassigned peptidasesunassigned-