title: An3 protein encoded by a localized maternal mRNA in Xenopus laevis is an ATPase with substrate-specific RNA helicase activity.
abstract: ATP-dependent RNA helicases from the DEAD box family of proteins are involved in a number of RNA processing and utilization events. An3 protein from Xenopus laevis is an RNA helicase of the DEAD box family of proteins. An3 is synthesized by a mRNA that is localized to one end of Xenopus laevis oocytes. An3 protein is found in the nucleus of ooctes, and more specifically, during the middle stages of oocyte development, with extra nucleoli that contain amplified copies of rRNA genes in the nucleolus. By expressing glutathione-S-transferase:An3 fusion proteins in E. coli, sufficient amounts of An3 protein were isolated to examine its enzymatic activities. ATPase activity, NTP substrate range and RNA helicase activity were tested. An3 protein ATPase activity was evident but not stimulated by any of a variety of RNA tested. An3 protein was able to resolve the duplex formed by an in vitro substrate, in the presence of ATP or dATP. An3 required both 3' and 5' single-stranded regions of RNA flanking the RNA duplex it resolves.
authors.affiliation: Department of Biochemistry, University of Iowa, Iowa City 52242, USA.
authors.forename: R
authors.initials: R
authors.lastname: Gururajan
authors.forename: D L
authors.initials: DL
authors.lastname: Weeks
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D017931:DNA Primers / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009865:Oocytes / Q000378:metabolism; D012313:RNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity; D014981:Xenopus
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012313:RNA; D012316:RNA Nucleotidyltransferases; D000251:Adenosine Triphosphatases; D020365:RNA Helicases