Activation of interferon-inducible 2'-5' oligoadenylate synthetase by adenoviral VAI RNA.
2'-5' oligoadenylate (2-5(A)) synthetase and protein kinase, RNA activated (PKR) are the only two known enzymes that bind double-stranded RNA (dsRNA) and get activated by it. We have previously identified their dsRNA binding domains, which do not have any sequence homology. Here, we report a profound difference between the two enzymes with respect to the structural features of the dsRNA that are required for their activation. The adenoviral virus-associated type I (VAI) RNA cannot activate PKR, although it binds to the protein and thereby prevents its activation by authentic dsRNA. In contrast, we observed that VAI RNA can both bind and activate 2-5(A) synthetase. Mutations in VAI RNA, which removed occasional mismatches present in its double-stranded stems, markedly enhanced its 2-5(A) synthetase-activating capacity. These mutants, however, are incapable of activating PKR. Other mutations, which disrupted the structure of the central stem-loop region of the VAI RNA, reduced its ability to activate 2-5(A) synthetase. These debilitated mutants could bind to the synthetase protein, although they fail to bind to PKR.
Desai
S Y
SY
Department of Molecular Biology, Cleveland Clinic Foundation, Ohio 44195.
Patel
R C
RC
Sen
G C
GC
Malhotra
P
P
Ghadge
G D
GD
Thimmapaya
B
B
D015088:2',5'-Oligoadenylate Synthetase / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D000260:Adenoviruses, Human / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D004789:Enzyme Activation; D004790:Enzyme Induction; D004926:Escherichia coli; D007372:Interferons / Q000494:pharmacology; D007700:Kinetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009690:Nucleic Acid Conformation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012330:RNA, Double-Stranded / Q000737:chemistry / Q000378:metabolism*; D012367:RNA, Viral / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D014158:Transcription, Genetic; D019892:eIF-2 Kinase
D012330:RNA, Double-Stranded; D012367:RNA, Viral; D011994:Recombinant Proteins; C052835:adenovirus associated RNA; D007372:Interferons; D017346:Protein Serine-Threonine Kinases; D019892:eIF-2 Kinase; D015088:2',5'-Oligoadenylate Synthetase