Summary for clan SH
| Clan type peptidase | S21.002 - cytomegalovirus assemblin (human herpesvirus 5), MEROPS Accession MER0000613 (peptidase unit: 1-256); PDB accession 1LAY |
| History | PEPTIDAS.TXT (SwissProt document) |
| Description | Serine nucleophile; catalytic residues in the order His, Ser, His in sequence |
| Contents of clan | Clan SH contains only family S21 . |
| Evidence | All known members of the clan are endopeptidases from DNA viruses and are involved in the assembly of the viral prohead (Rawlings & Barrett, 2004). |
| Catalytic mechanism | The order of the catalytic triad is His, Ser, His. |
| Peptidase activity | Family S21 contains assemblin. Assemblin is involved in the late stages of virion assembly, and breaks down the scaffold protein upon which the viral prohead is assembled (Rawlings & Barrett, 2004). |
| Protein fold | Tertiary structures have been determined for several members of the clan. The first structure determined was for assemblin from human cytomegalovirus (S21.002; Chen et al., 1996). Peptidases in clan SH are alpha/beta proteins containing a beta barrel surrounded by helices. The active site residues are within the barrel. |
| Homologous non-peptidase families | The fold is unique to clan SH. |
| Activation mechanism | (See family S21.) |
|
Other databases
| SCOP | 50789 |
Families
| S21 |
cytomegalovirus assemblin (human herpesvirus 5) |
Yes |
| S73 |
gpO peptidase (Enterobacteria phage P2) (Enterobacteria phage P2) |
- |
| S77 |
prohead peptidase gp21 (bacteriophage T4) (Enterobacteria phage T4) |
- |
| S78 |
prohead peptidase (bacteriophage HK97) (Enterobacteria phage HK97) |
- |
| S80 |
prohead peptidase gp175 (Pseudomonas aeruginosa phage phiKZ) (Pseudomonas phage phiKZ) |
- |
Distribution of clan SH among Kingdoms of Organisms
