title: Biochemical characterization of the ATPase and helicase activity of UAP56, an essential pre-mRNA splicing and mRNA export factor.
abstract: DEXD/H-box protein UAP56 is an essential pre-mRNA splicing factor required for the first ATP-dependent spliceosome assembly step. UAP56 is also essential for the export of the majority of mRNAs from the nucleus to the cytoplasm. We performed biochemical characterization of UAP56's ATPase and helicase activity, which is important for further understanding the role of these activities in UAP56's function. We showed that UAP56 is an RNA-stimulated ATPase that can only hydrolyze ATP. We demonstrated that UAP56 is an ATP-dependent RNA helicase that can unwind substrates with 5' or 3' overhangs or blunt ends in vitro. We showed that U2AF(65) and Aly, two proteins known to interact with UAP56, do not influence UAP56's ATPase or helicase activity. We also demonstrated that several mutants in the conserved helicase motifs I, II, and III abolish UAP56's ATPase and/or helicase activity, providing tools for future investigation of the role of UAP56's ATPase and helicase activity in spliceosome assembly and mRNA export.
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado 80045, USA.
authors.forename: Jingping
authors.initials: J
authors.lastname: Shen
authors.forename: Lingdi
authors.initials: L
authors.lastname: Zhang
authors.forename: Rui
authors.initials: R
authors.lastname: Zhao
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D017398:Alternative Splicing; D020816:Amino Acid Motifs; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D053487:DEAD-box RNA Helicases / Q000737:chemistry*; D004265:DNA Helicases / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D012333:RNA, Messenger / Q000378:metabolism; D017381:Spliceosomes / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C487886:DDX39B protein, human; D004265:DNA Helicases; D053487:DEAD-box RNA Helicases