Tobacco mosaic virus infection stimulates the phosphorylation of a plant protein associated with double-stranded RNA-dependent protein kinase activity.
The influence of tobacco mosaic virus (TMV) infection on nucleotide binding and phosphorylation of an Mr 68,000 host-encoded protein (p68) was examined. The phosphorylation of p68 in homogenates from TMV-infected tissues was 4-fold greater than in homogenates from mock inoculated tissues. Phosphorylation of p68 in extracts from mock inoculated tissues was enhanced by the addition of double-stranded (ds) RNA. Nucleotide photoaffinity labeling experiments indicate that p68 contains an ATP binding site with characteristics consistent with protein kinase activity. Antiserum raised against a dsRNA-dependent protein kinase activity. Antiserum raised against a dsRNA-dependent protein kinase from interferon-treated human cells immunoprecipitated p68 from extracts of TMV-infected tissue, and p68-containing immunocomplexes catalyzed the phosphorylation of endogenous p68. These data suggest that p68 may be an autophosphorylating, dsRNA-dependent protein kinase involved in viral pathogenesis. Based upon analogous functions demonstrated for dsRNA-dependent protein kinases in mammalian systems, p68 may have a role in the regulation of protein synthesis and viral replication in infected cells.
Department of Plant, Soil, and Insect Sciences, University of Wyoming, Laramie 82071.
C J
CJ
Crum
J
J
Hu
H J
HJ
Hiddinga
D A
DA
Roth
D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D010766:Phosphorylation; D010935:Plant Diseases; D010940:Plant Proteins / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D012330:RNA, Double-Stranded / Q000378:metabolism*; D014027:Tobacco Mosaic Virus / Q000378:metabolism*
D010940:Plant Proteins; D012330:RNA, Double-Stranded; D011494:Protein Kinases