Family S73
Summary for family S73
| Family type peptidase | S73.001 - gpO peptidase (Enterobacteria phage P2) (Enterobacteria phage P2), MEROPS Accession MER0150756 (peptidase unit: 1-284) |
| Content of family | Family 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 type | Serine |
| Active site residues | D19 H48 S107 |
| Active site | An 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 structure | The 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. |
| Clan | SH |
