Family C51


Summary Holotypes Alignment Tree Genomes Structure Literature

Summary for family C51

Family type peptidaseC51.001 - D-alanyl-glycyl peptidase (staphylococcal phage phi11-type) (Staphylococcus aureus), MEROPS Accession MER0011132 (peptidase unit: 1-127)
Content of familyFamily C51 contains endopeptidases that hydrolyse bacterial cell-wall crosslinking peptides.
History Identifier created: MEROPS 5.00 (20 April 2000)
There are a wide variety of peptidases that are capable of lysing bacterial cell walls, including the lytic enzymes of bacteriophages. Bacteriophages escape from the bacterial cell by use of lytic enzymes that are either amidases that disrupt the acetylmuramyl bonds or are peptidases that cleave the crosslinking peptide that links the murein chains. The lytic enzyme from bacteriophage phi11 is a bifunctional enzyme that possesses both amidase and peptidase activities. The peptidase domain is also known as the CHAP domain (Bateman & Rawlings, 2003).
Catalytic typeCysteine
Active site residuesC32 H95 
Active siteWe predict an active site dyad consisting of Cys32 and His95. Asp25 (or Gln31) and Asn113 may complete a papain-like active site tetrad (see the Alignment).
Activities and specificitiesD-Ala-Gly peptidase (C51.001) from bacteriophage phi11 has been shown to cleave the crosslinking peptide of the host Staphylococcus aureus at the D-AlaGly bond. Cleavage of similar bonds also releases surface proteins that are bound to the crosslinking peptides (Navarre et al., 1999). As an amidase, it acts as an N-acetylmuramyl-L-alanyl amidase.
Molecular structureD-Ala-Gly peptidase has a two-domain structure, and mutational analysis has confirmed that the peptidase unit is in the N-terminal domain (Navarre et al., 1999). The C-terminal domain is an amidase, and is also present in lysostaphin (M23.004) from peptidase family M23 . No tertiary structures have been determined for any member of family C51, but the family is included in clan CA on the basis of our prediction of the active site residues.
Basis of clan assignmentProtein fold of the peptidase unit for members of this family and resembles that of papain, the type example for clan CA.
Distribution of family Bacteria details  
Archaea details  
Protozoa details  
Fungi -  
Plants -  
Animals details  
Viruses details  
Biological functionsHomologues from bacteriophages are lytic enzymes required for the release of phage particles from the host.
Pharmaceutical and biotech relevanceThe phi11 peptidase has been used as a tool to solubilize surface proteins from the bacterial cell wall (Navarre et al., 1998).
Statistics for family C51Sequences:214
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
D-alanyl-glycyl peptidase (staphylococcal phage phi11-type)C51.001-
bacteriophage B30 lysinC51.002-
fused glutathionylspermidine amidase/glutathionylspermidine synthetase (Escherichia coli)C51.A01Yes
family C51 non-peptidase homologuesnon-peptidase homologue-
family C51 unassigned peptidasesunassigned-