The isolation and characterization of an RNA helicase from nuclear extracts of HeLa cells.
An RNA helicase, isolated from nuclear extracts of HeLa cells, displaced duplex RNA in the presence of any one of the eight common nucleoside triphosphates. The unwinding reaction was supported most efficiently by ATP and GTP and poorly by dCTP and dTTP. The enzyme activity, purified 300-fold, contained two major protein bands of 80 and 55 kDa when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. All fractions that contained RNA helicase activity also possessed single-stranded RNA-dependent nucleoside triphosphatase activity. Purified RNA helicase fractions displaced a hybrid of U4/U6 RNAs with the same efficiency as it displaced other duplex RNA structures. In contrast, the RNA helicase did not displace duplex RNA/DNA and DNA/DNA structures. Evidence is presented that suggests that this RNA helicase can displace duplex RNA by translocating in both the 3' to 5' and the 5' to 3' directions. The properties of the RNA helicase described here differ from the deaminase RNA unwinding activity described in Xenopus oocytes (Bass, B.L., and Weintraub, H. (1987) Cell 48, 607-613) and from the p68 HeLa RNA helicase (Hirling, H., Scheffner, M., Restle, T., and Stahl, H. (1989) Nature 339, 562-564).
Claude
A
A
Program in Molecular Biology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
Arenas
J
J
Hurwitz
J
J
D000255:Adenosine Triphosphate / Q000378:metabolism; D001483:Base Sequence; D002467:Cell Nucleus / Q000737:chemistry*; D004247:DNA / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006160:Guanosine Triphosphate / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D006868:Hydrolysis; D008969:Molecular Sequence Data; D009692:Nucleic Acid Heteroduplexes; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D011755:Pyrophosphatases; D012313:RNA / Q000378:metabolism; D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases / Q000302:isolation & purification* / Q000378:metabolism; D013379:Substrate Specificity
D009692:Nucleic Acid Heteroduplexes; D012313:RNA; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D004247:DNA; D012316:RNA Nucleotidyltransferases; D010744:Phosphoric Monoester Hydrolases; D011755:Pyrophosphatases; C023117:thymidine-triphosphatase; D020365:RNA Helicases