Family A3
Summary for family A3
| Family type peptidase | A03.001 - cauliflower mosaic virus-type peptidase (cauliflower mosaic virus), MEROPS Accession MER0000987 (peptidase unit: 40-130) |
| Content of family | Peptidase family A3 contains endopeptidases. |
| History |
Identifier created: Methods Enzymol. 248:105-120 (1995)
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| Catalytic type | Aspartic |
| Active site | The active site residue of family A3 was identified by site-directed mutagenesis as an Asp (Torruella et al., 1989), which is located within a D-T/S-G motif. The CaMV endopeptidase (A03.001) is assumed to be a dimer in analogy to the related retropepsins (A2) and to contain a similar structure with an active site consisting of the loop with the active aspartate and the flaps (Le Grice et al., 1988, Wlodawer et al., 1989). |
| Activities and specificities | The only substrates known for the CaMV endopeptidase are derived from ORFs IV (gag) and V (pol). The peptidase activates itself by cleaving the ORF V polypeptide into a peptidase at the N-terminus and a reverse transcriptase. Several cleavage sites are thought to exist within ORF IV are used by CaMV endopeptidase (A03.001), thus explaining the variety of OFR IV products found in virus particles (Al Anil, 1979); however only the site creating the N-terminus of ORF IV derivative p44 has been identified (Torruella et al., 1989). This is a Leu Ala cleavage site found within a highly hydrophobic region. Six cleavage sites in the polyprotein for the rice tungro bacilliform virus peptidase (A03.002) have also been determined (Marmey et al., 2005). |
| Inhibitors | The CaMV endopeptidase (A03.001) is weakly inhibited by pepstatin (Torruella et al., 1989). |
| Molecular structure | The is currently no tertiary structure available for any of the members of family A3 |
| Clan | AA |
| Basis of clan assignment | Active site residues for members of this family and family A1 occur in the motif D-T/S-G. |
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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 |
details |
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| Peptidases and Homologues |
MEROPS ID |
Structure |
| cauliflower mosaic virus-type peptidase | A03.001 | - |
| banana streak virus peptidase | A03.003 | - |
| Commelina yellow mottle virus peptidase | A03.004 | - |
| cassava vein mosaic virus-type peptidase | A03.005 | - |
| retrotransposon peptidase (Nicotiana-type) | A03.006 | - |
| Subfamily A3A unassigned peptidases | unassigned | - |
| Peptidases and Homologues |
MEROPS ID |
Structure |
| bacilliform virus peptidase | A03.002 | - |
| Subfamily A3B unassigned peptidases | unassigned | - |
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Peptidases not assigned to subfamily
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