Detection of Potato Virus Y P1 Protein in Infected Cells and Analysis of Its Cleavage Site

Abstract

  The P1 protein is liberated from the N-terminal region of the potyviral polyprotein by cleavage depending on its own autoproteolytic activity. Existence of the 32-kDa P1 protein in tobacco plants infected with potato virus Y ordinary strain (PVY-O) was detected by an antiserum against a recombinant PVY-O P1 protein. In vivo analysis using tobacco protoplasts confirmed that the Phe²⁸⁴-Ser²⁸⁵ was the cleavage site separating the P1 protein from the PVY-O polyprotein. Phe²⁸⁴ was indispensable for proteolysis and Ser²⁸⁵ was needed for optimal cleavage susceptibility.