title: RNA helicase A interacts with dsDNA and topoisomerase IIalpha.
abstract: RNA helicase A (RHA) is a multifunctional protein involved in various nuclear processes such as transcription and RNA export. It is believed that the interacting factors play important roles in determining the functional specificity of RHA. Here we show that RHA directly interacts with double-stranded (ds) nucleic acids (NAs) and assembles complexes with topoisomerase IIalpha. First, electrophoresis mobility shift assays demonstrate that RHA interacts with dsDNAs of different lengths ranging from 15 to 104 bp. Secondly, the binding of RHA to closed circular dsDNA stimulates the relaxation reaction catalyzed by either calf thymus topoisomerase I or HeLa topoisomerase IIalpha. Thirdly, immunoprecipitation, coupled with western blot analysis using anti-RHA and anti-topoisomerase IIalpha antibodies, shows that RHA and topoisomerase IIalpha assemble a complex in the presence of as yet unknown RNA molecules and additional protein factors such as Ubc9. Our observation suggests physical and functional interaction between RHA and topoisomerase IIalpha, which, perhaps, play important roles in regulating chromatin structure. The putative role of RHA-topoisomerase IIalpha complex in RNA polymerase II-mediated transcription is discussed.
authors.affiliation: Department of Biochemistry and Molecular Biology, Graduate School of Biomedical Sciences, University of Medicine and Dentistry of New Jersey, 185 South Orange Avenue, Newark, NJ 07013, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhou
authors.forename: Kyoo-Tae
authors.initials: KT
authors.lastname: Choe
authors.forename: Zaheer
authors.initials: Z
authors.lastname: Zaidi
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Michael B
authors.initials: MB
authors.lastname: Mathews
authors.forename: Chee-Gun
authors.initials: CG
authors.lastname: Lee
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D000951:Antigens, Neoplasm; D001324:Autoantigens / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D053487:DEAD-box RNA Helicases; D004247:DNA / Q000378:metabolism*; D004250:DNA Topoisomerases, Type II / Q000235:genetics / Q000378:metabolism*; D004270:DNA, Circular / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism; D004278:DNA, Superhelical / Q000378:metabolism; D004268:DNA-Binding Proteins; D006367:HeLa Cells; D006801:Humans; D008025:Ligases / Q000235:genetics / Q000378:metabolism; D009363:Neoplasm Proteins; D011485:Protein Binding; D020365:RNA Helicases / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D014162:Transfection; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: D000951:Antigens, Neoplasm; D001324:Autoantigens; D004270:DNA, Circular; D004277:DNA, Single-Stranded; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D004247:DNA; D044763:Ubiquitin-Conjugating Enzymes; D000251:Adenosine Triphosphatases; C098487:DHX9 protein, human; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases; D004250:DNA Topoisomerases, Type II; D008025:Ligases; D000098843:Ubiquitin-Conjugating Enzyme UBC9