|Family type peptidase||S65.001 - picornain-like cysteine peptidase (Breda-1 torovirus) (Breda virus), MEROPS Accession MER0044929 (peptidase unit: 3131-3395)|
|Content of family||Peptidase family S65 contains endopeptidases.|
Identifier created: MEROPS 9.7 (1 August 2012)|
Toroviruses are single stranded RNA viruses related to coronaviruses which infect vertebrates. The genome encodes a very large non-structural polyprotein which is processed by a serine peptidase that is a component of the polyprotein (non-structural protein 4).
|Active site residues||H3184 E3222 S3291 |
|Active site||A catalytic triad (His, Glu, Ser) has been predicted by comparison with other members of clan PA. In the peptidase from the Breda virus, Ser3184 has been identified by site-directed mutagenesis. However, substitution of the catalytic Ser for Cys retained partial activity (Smits et al., 2006). Other components of a catalytic triad are predicted to be His3184 and Glu3222, but mutagenesis of Glu3222 did not affect activity (Smits et al., 2006).|
|Activities and specificities||Processing of the polyprotein occurs at Phe-Xaa-Xaa-Gln consensus sequences (Smits et al., 2006).|
|Molecular structure||No tertiary structure for any member of the family has been solved. Family S65 is included in clan PA because the putative active site residues are in the same order in the linear sequence as in other members of the clan, and it is included in subclan PA(S) because the putative nucleophile is the hydroxyl of a serine.|