RH70, a bidirectional RNA helicase, co-purifies with U1snRNP.
In this report, I describe the co-purification of a novel 70-kDa RNA helicase (RH70) and U1snRNP through six column steps. Peptide sequence analysis by mass spectrometry and Edman degradation revealed that RH70 is the previously reported DDX17. Biochemical characterization of RH70, obtained by partial separation from U1snRNP, yielded the following results. (a) RH70 mediates the unwinding of duplex RNA but not DNA in an ATP-dependent manner. (b) Both the RNA-dependent ATPase and RNA helicase activities of RH70 are highly specific for ATP, exhibiting an apparent K(m) of 0.5 mm. (c) RH70 catalyzes the unwinding of duplex RNA containing single-stranded regions at either the 5'- or 3'-end. Its association with U1snRNP and ATP specificity suggest a role for RH70 in pre-mRNA splicing, in particular, at the early stages of the splicing reaction involving U1snRNP.
Department of Biochemistry and Molecular Biology, Graduate School of Biomedical Sciences, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103, USA. leecg@umdnj.edu
Chee-Gun
CG
Lee
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D053487:DEAD-box RNA Helicases; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D011233:Precipitin Tests; D011485:Protein Binding; D012313:RNA / Q000378:metabolism; D020365:RNA Helicases / Q000737:chemistry* / Q000378:metabolism*; D012330:RNA, Double-Stranded / Q000378:metabolism; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000737:chemistry* / Q000378:metabolism
D012330:RNA, Double-Stranded; D017412:Ribonucleoprotein, U1 Small Nuclear; D012313:RNA; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C102004:DDX17 protein, human; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases