Modification of protein synthesis initiation factors and the shut-off of host protein synthesis in adenovirus-infected cells.
A substantial body of data, largely derived from study of cell extracts, indicates that protein synthesis in adenovirus-infected cells requires VA RNAI at late times of infection to prevent the activation of a protein kinase known as DAI, and the consequent phosphorylation of the alpha-subunit of initiation factor eIF-2. To verify this conclusion, we have measured the steady-state levels of eIF-2 alpha phosphorylation in cells infected with wild-type virus (Ad2) and a mutant that produces no VA RNAI (Ad5dl331). Consistent with the proposed mechanism, the alpha-subunit was very highly phosphorylated (approximately 90%) at late times of infection with Ad5dl331. Surprisingly, eIF-2 alpha phosphorylation also increased (to approximately 30%) at late times of infection with Ad2, suggesting that VA RNA and DAI might be involved in the selective translation of viral mRNA and the shut-off of host cell protein synthesis during the late phase. In agreement with this model, host protein synthesis shut-off is defective in cells expressing low levels of DAI.
O'Malley
R P
RP
Cold Spring Harbor Laboratory, New York 11724.
Duncan
R F
RF
Hershey
J W
JW
Mathews
M B
MB
D000260:Adenoviruses, Human / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D001345:Autoradiography; D004591:Electrophoresis, Polyacrylamide Gel; D015852:Eukaryotic Initiation Factor-2; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D007525:Isoelectric Focusing; D009154:Mutation; D010448:Peptide Initiation Factors / Q000378:metabolism*; D010766:Phosphorylation; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000032:analysis; D011506:Proteins / Q000378:metabolism*; D012367:RNA, Viral / Q000502:physiology; D019892:eIF-2 Kinase
D015852:Eukaryotic Initiation Factor-2; D010448:Peptide Initiation Factors; D011506:Proteins; D012367:RNA, Viral; D011494:Protein Kinases; D019892:eIF-2 Kinase