RNA unwinding activity of SV40 large T antigen.
Large T antigen, the regulatory protein encoded by simian virus 40, has DNA helicase activity and unwinds double-stranded DNA at the expense of ATP. T antigen also functions as an RNA helicase separating duplex regions in partially double-stranded RNA substrates. Surprisingly, T antigen RNA helicase activity requires UTP, CTP, or GTP as a cofactor, whereas ATP is an inefficient energy source for the RNA unwinding reaction. Accordingly, T antigen has both an intrinsic non-ATP NTPase activity that is stimulated by single-stranded RNA and an ATPase activity stimulated by single-stranded DNA. Thus, it appears that the bound nucleotide determines whether T antigen acts as an RNA helicase or as a DNA helicase.
Scheffner
M
M
Fakultät für Biologie, Universität Konstanz, Federal Republic of Germany.
Knippers
R
R
Stahl
H
H
D000952:Antigens, Polyomavirus Transforming / Q000502:physiology*; D001665:Binding Sites; D039601:Eukaryotic Initiation Factor-4A; D066298:In Vitro Techniques; D009690:Nucleic Acid Conformation; D009711:Nucleotides / Q000502:physiology*; D010448:Peptide Initiation Factors / Q000502:physiology; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D011755:Pyrophosphatases; D012313:RNA / Q000648:ultrastructure*; D012316:RNA Nucleotidyltransferases / Q000502:physiology*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D000952:Antigens, Polyomavirus Transforming; D009711:Nucleotides; D010448:Peptide Initiation Factors; D012313:RNA; D039601:Eukaryotic Initiation Factor-4A; D012316:RNA Nucleotidyltransferases; D010744:Phosphoric Monoester Hydrolases; D011755:Pyrophosphatases; C023278:uridine triphosphatase