The alpha subunit of eucaryotic initiation factor 2 is phosphorylated in mengovirus-infected mouse L cells.
Infection of mouse L cells with mengovirus resulted in the activation of a protein kinase (PK) that selectively phosphorylated the small, 38,000-molecular-weight alpha subunit of eucaryotic initiation factor 2 (eIF-2) in vitro. The mengovirus-activated kinase was detected in vitro approximately 3 h after virus adsorption. The ratio of phosphorylated to unphosphorylated eIF-2 also increased in vivo between 3 and 7 h after adsorption. The virus-activated kinase fractionated with the ribosomal pellet and had a high affinity for DEAE-cellulose and Mono Q ion-exchange columns. Gel electrophoresis of the kinase activity eluting from the Mono Q column and silver staining of the gel revealed only one protein band with a molecular mass of 70 kilodaltons. The optimal assay conditions for the mengovirus-activated kinase paralleled those of the double-stranded RNA-activated PK (dsRNA-PK). Lysates from infected cells contained elements capable of activating partially purified dsRNA-PK. These elements were identified as double-stranded RNA by their sensitivity to double-stranded RNase. The phosphorylation of the alpha subunit of eIF-2 coincided with the synthesis of dsRNA in infected cells, suggesting that the mengovirus-activated kinase is the dsRNA-PK. The phosphorylation of the alpha subunit of eIF-2 correlated with the global inhibition of protein synthesis that occurs at late times after infection.
DeStefano
J
J
Department of Molecular and Cell Biology, University of Connecticut, Storrs 06269-3125.
Olmsted
E
E
Panniers
R
R
Lucas-Lenard
J
J
D000818:Animals; D002458:Cell Fractionation; D002472:Cell Transformation, Viral; D004789:Enzyme Activation; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D007700:Kinetics; D007739:L Cells / Q000201:enzymology / Q000378:metabolism; D046911:Macromolecular Substances; D008574:Mengovirus / Q000235:genetics*; D051379:Mice; D008970:Molecular Weight; D010766:Phosphorylation; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D012330:RNA, Double-Stranded / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism / Q000648:ultrastructure
D015852:Eukaryotic Initiation Factor-2; D046911:Macromolecular Substances; D012330:RNA, Double-Stranded; D011494:Protein Kinases