Family S73


Summary Holotypes Alignment Tree Genomes Literature

Summary for family S73

Family type peptidaseS73.001 - gpO peptidase (Enterobacteria phage P2) (Enterobacteria phage P2), MEROPS Accession MER0150756 (peptidase unit: 1-284)
Content of familyFamily S29 contains serine endopeptidases.
History Identifier created: MEROPS 8.5 (24 August 2009)
In common with most bacteriophages, the procapsid of bacteriophage P2 is assembled around a scaffolding protein, gpO (S73.001), which is subsequently degraded so that DNA can be inserted (Chang et al., 2009). The capsid protein is synthesized as a precursor requiring proteolytic activation, and cleavage was first observed by Lengyel et al., 1973. Chang et al., 2009 have shown that gpO autoactivates.
Catalytic typeSerine
Active site residuesD19 H48 S107 
Active siteAn active site consisting of Asp19, His48 and Ser107 has been identified in the gpO protein from bacteriophage P2 by site-directed mutagenesis (Chang et al., 2009).
Molecular structureThe gpO protein contains multiple domains with the serine peptidase restricted to the N-terminus. Only the C-terminal 90 residues are required for procapsid assembly . During capsid maturation, protein gpO undergoes autoproteolytic degradation to release an N-terminal 15.5 kDa fragment known as O*; this fragment contains the peptidase domain and remains in the capsid (Chang et al., 2008). On the assumption that Asp replaces one of the histidines, the catalytic triad residues occur in the order characteristic of clan SH, and family S73 is placed in this clan.
Distribution of family Bacteria details  
Archaea -  
Protozoa -  
Fungi -  
Plants details  
Animals details  
Viruses details  
Biological functionsThe active peptidase O* is presumed to process the capsid protein gpN (Chang et al., 2009).
Statistics for family S73Sequences:338
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
gpO peptidase (Enterobacteria phage P2)S73.001-
non-peptidase homologue-
family S73 unassigned peptidasesunassigned-