Family C16
Summary for family C16
| Family type peptidase | C16.001 - murine hepatitis coronavirus papain-like peptidase 1 (murine hepatitis virus), MEROPS Accession MER0000859 (peptidase unit: 1083-1332) |
| Content of family | Peptidase family C16 contains polyprotein processing endopeptidases from coronaviruses. |
| History |
Identifier created: Methods Enzymol. 244:461-486 (1994)
The murine hepatitis coronavirus genome contains one large polyprotein. The polyprotein gene is ORF1 and because of a ribosomal frameshift it can be translated as an ORF1a or ORF1b polyprotein. The polyprotein is processed to fifteen proteins, including an RNA-directed RNA polymerase, a helicase and three endopeptidases. Papain-like proteinase 1 (PLP1; C16.001) and papain-like proteinase 2 (PLP2, C16.006) are both members of family C16, whereas the 3C-like proteinase is a member of family C30. |
| Catalytic type | Cysteine |
| Active site | A catalytic triad, Cys, His, Asp has been demonstrated in the SARS coronavirus papain-like peptidase (C16.009) both by site-directed mutagenesis (Barretto et al., 2005) and X-ray crystallography (Ratia et al., 2006), and this is present throughout the family (see the Alignment). |
| Activities and specificities | Both PLP1 and PLP2 have restricted specificities, cleaving only two and one bond(s) in the polyprotein, respectively. The restricted activity may be due to extended specificity sites: a requirement for Arg or Lys in P5 has been shown for PLP1 (Dong & Baker, 1994), and a requirement for Phe in P6 in PLP2 (Kanjanahaluethai & Baker, 2003). |
| Inhibitors | No potent inhibitors of the peptidases in family C16 have been described, but there are indications of weak inhibition by leupeptin, E-64d or loxistatin and Zn2+ (reviewed by Kanjanahaluethai & Baker, 2004). There may also be inhibition by ubiquitin aldehyde (Ratia et al., 2006). |
| Molecular structure | The structure of the SARS coronavirus papain-like peptidase (C16.009) confirms the place of family C16 in clan CA, and shows the closest similarity to deubiquitinating peptidases in family C19 (Ratia et al., 2006). Binding sites for ubiquitin and zinc are present. |
| Clan | CA |
| Basis of clan assignment | Active site residues for members of this family and family C1 occur in the same order in the sequence: C, H. |
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Distribution of family
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Bacteria |
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Archaea |
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Protozoa |
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Fungi |
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Plants |
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Animals |
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Viruses |
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| Peptidases and Homologues |
MEROPS ID |
Structure |
| murine hepatitis coronavirus papain-like peptidase 1 | C16.001 | - |
| Subfamily C16A non-peptidase homologues | non-peptidase homologue | - |
| Subfamily C16A unassigned peptidases | unassigned | - |
| Peptidases and Homologues |
MEROPS ID |
Structure |
| human coronavirus 229E papain-like peptidase 1 | C16.002 | - |
| porcine epidemic diarrhea virus papain-like peptidase 1 | C16.003 | - |
| porcine transmissible gastroenteritis coronavirus papain-like peptidase 1 | C16.004 | - |
| avian infectious bronchitis coronavirus papain-like peptidase | C16.005 | Yes |
| mouse hepatitis coronavirus papain-like peptidase 2 | C16.006 | - |
| porcine transmissible gastroenteritis coronavirus papain-like peptidase 2 | C16.008 | - |
| severe acute respiratory syndrome coronavirus papain-like peptidase | C16.009 | Yes |
| human coronavirus 229E papain-like peptidase 2 | C16.010 | - |
| Middle East respiratory syndrome coronavirus papain-like peptidase | C16.011 | Yes |
| coronavirus COVID-19 papain-like peptidase | C16.012 | - |
| Subfamily C16B non-peptidase homologues | non-peptidase homologue | - |
| Subfamily C16B unassigned peptidases | unassigned | - |
