Centre for Research in Biomolecular Interactions presents Dr. Allen Miller, director of Center for Plant Responses to Environmental Stresses, Iowa State University.

Talk Title: Expression and function of the Potyvirus frameshift protein, Pipo

Abstract:
The Potyviridae family is the largest and most economically important family of plant viruses.  Its genome consists of a positive sense RNA that contains a large open reading frame (ORF) encoding the polyprotein from which the functional viral proteins are proteolytically cleaved.  Recently, we discovered a short ORF, pipo, that overlaps with the polyprotein ORF. pipo overlaps with the P3 coding region and is translated by ribosomal frameshifting as a fusion to the N terminus of P3.  We call this trans-frame fusion protein P3N-PIPO.  To determine its function, we identified host proteins with which P3N-PIPO interacts. One of the interacting proteins is a plasma membrane-associated protein, PCaP1. To determine the requirement, if any, for PCaP1 in potyvirus infection, we observed the effect of knocking out PCaP1 expression on infection by Turnip mosaic potyvirus, which had been engineered to express green fluorescent protein. We found that viral RNA levels, green fluorescence, and disease symptoms all were reduced dramatically in PCaP1 knockout plants vs wild type plants.  Thus PCaP1 is required for efficient virus infection, and it may play a role in virus movement.  Indeed, bombardment of leaves with a plasmid expressing P3N-PIPO-GFP fusion protein revealed that P3N-PIPO facilitates its own cell-to-cell movement.  These observations are consistent with others' results that suggested a movement role for P3N-PIPO.  Ability to disrupt efficent cell-to-cell movement may lead to new strategies for breeding virus resistant crops.

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