title: RNA branching and debranching in the yeast retrovirus-like element Ty1.
abstract: Ty elements of Saccharomyces cerevisiae are long terminal repeat (LTR) retroelements related to retroviruses. Normal levels of Ty1 transposition require Dbr1p, a cellular enzyme that cleaves 2'-5' RNA bonds. We show that Ty1 RNAs lacking identifiable 5' ends accumulate in virus-like particles (VLPs) in dbr1 mutants. Debranching this RNA in vitro with Dbr1p creates an uncapped version of the normal Ty1 RNA 5' end. We show that the 5' nucleotide (nt) of Ty1 RNA forms a 2'-5' bond with a nt near the 3' end of the same RNA, creating a lariat. The properties of the lariat suggest it forms by a novel mechanism and that branching and debranching may play roles in Ty1 reverse transcription at the minus-strand transfer step.
authors.affiliation: School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Cheng
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Menees
mesh_terms: D020029:Base Pairing; D001483:Base Sequence; D015152:Blotting, Northern; D018076:DNA, Complementary / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D012315:RNA Caps; D012316:RNA Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism; D012331:RNA, Fungal / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism; D018626:Retroelements / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016914:Ribonuclease H / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D020079:Terminal Repeat Sequences; D014158:Transcription, Genetic
chemical_list: D018076:DNA, Complementary; D012315:RNA Caps; D012331:RNA, Fungal; D012333:RNA, Messenger; D018626:Retroelements; D012316:RNA Nucleotidyltransferases; C048135:lariat debranching enzyme; D012194:RNA-Directed DNA Polymerase; D016914:Ribonuclease H