P1 peptidase--a mysterious protein of family Potyviridae.

The Potyviridae family, named after its type member, Potato virus Y (PVY), is the largest of the 65 plant virus groups and families currently recognized. The coding region for P1 peptidase is located at the very beginning of the viral genome of the family Potyviridae. Until recently P1 was thought of as serine peptidase with RNA-binding activity and with possible influence in cell-to-cell viral spreading. This N-terminal protein, among all of the potyviruses, is the most divergent protein: varying in length and in its amino acid sequence. Nevertheless, P1 peptidase in many ways is still a mysterious viral protein. In this review, we would like to offer a comprehensive overview, discussing the proteomic, biochemical and phylogenetic views of the P1 protein.