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SUMMARY:Interaction of the potyvirus protein\, P3N-PIPO\, with a plasma me
 mbrane-associated host protein is crucial for virus infection - Vijayapala
 ni Paramasivan and W. Allen Miller\, Iowa State University
DTSTART:20110523T140000Z
DTEND:20110523T150000Z
UID:TALK31329@talks.cam.ac.uk
CONTACT:Dr Chung
DESCRIPTION:Since the discovery of a short\, essential potyviral ORF\, pip
 o\, in the -1 reading frame relative to the polyprotein ORF (Chung et al. 
 2008 PNAS 105\, 5897)\, we have investigated the function of the pipo-enco
 ded protein\, PIPO. pipo overlaps with the P3 coding region and is transla
 ted by ribosomal frameshifting as a fusion to the N terminus of P3\;  anti
 bodies that specifically detect either PIPO or N-terminus of P3 both recog
 nize a 25 kDa protein in Turnip mosaic virus (TuMV)-infected cells.  We ca
 ll this trans-frame fusion protein P3N-PIPO.  To determine its function\, 
 we identified host proteins with which it interacts in a yeast two-hybrid 
 screen of anArabidopsis thaliana cDNA expression library. One of the inter
 acting proteins is a plasma membrane-associated protein\, we call host fac
 tor 3 (AtHF3).  The interaction of P3N-PIPO with AtHF3 was validated in pl
 anta by co-immunoprecipitation of both proteins\, which had been co-expres
 sed by agroinfiltration\, and also by bimolecular fluorescence complementa
 tion assay. To determine the requirement\, if any\, for AtHF3 inTuMV infec
 tion\, expression of the AtHF3 ortholog in N. benthamiana (NbHF3) was knoc
 ked down by VIGS\, and plants were then challenged with TuMV engineered to
  express GFP.  Based on qRT-PCR analysis\, knockdown of HF3 expression red
 uced accumulation of viral RNA in inoculated leaves.  Also\, appearance of
  disease symptoms and green fluorescence were reduced dramatically in inoc
 ulated leaves and delayed in upper leaves.  Thus HF3 is required for effic
 ient virus infection\, and it may play a role in virus movement.  Indeed\,
  bombardment of leaves with a plasmid expressing P3N-PIPO-GFP fusion prote
 in revealed that P3N-PIPO facilitates its own cell-to-cell movement.  Thes
 e observations are consistent with others' results that suggested a moveme
 nt role for P3N-PIPO.  In summary\, HF3 is a host protein not known previo
 usly to participate in virus infection that may contribute to potyviral in
 tercellular trafficking.
LOCATION:Large Lecture Theatre\, Department of Plant Sciences
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