Mutational analysis of the double-stranded RNA (dsRNA) binding domain of the dsRNA-activated protein kinase, PKR.
The interferon-induced, double-stranded RNA (dsRNA)-dependent protein kinase, PKR, is an inhibitor of translation and has antiviral, antiproliferative, and antitumor properties. Previously, the dsRNA binding domain had been located within the N-terminal region of PKR and subsequently shown to include two nearly identical domains comprising residues 55-75 and 145-166. We have undertaken both random and site-directed, alanine-scanning mutagenesis in order to investigate the contribution of individual amino acids within these domains to dsRNA binding. Here we identify 2 residues that were absolutely required for dsRNA binding, glycine 57 and lysine 60. Mutation of 2 other residues within the domain (lysine 64 and leucine 75) resulted in less than 10% binding (compared to wild type). We have also identified a number of other residues that influence dsRNA binding to varying degrees. Mutants that were unable to bind dsRNA were not active in vitro and possessed no antiproliferative activity in vivo. However, dsRNA binding mutants were partially transdominant over wild type PKR in mammalian cells, suggesting that binding of dsRNA activator is not the mechanism responsible for the phenotype of PKR mutants.
McMillan
N A
NA
Department of Cancer Biology, Cleveland Clinic Foundation, Ohio 44195.
Carpick
B W
BW
Hollis
B
B
Toone
W M
WM
Zamanian-Daryoush
M
M
Williams
B R
BR
D016475:3T3 Cells; D000409:Alanine / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012330:RNA, Double-Stranded / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D019892:eIF-2 Kinase
D012330:RNA, Double-Stranded; D017346:Protein Serine-Threonine Kinases; D019892:eIF-2 Kinase; D000409:Alanine