title: Ty3 reverse transcriptase complexed with an RNA-DNA hybrid shows structural and functional asymmetry.
abstract: Retrotransposons are a class of mobile genetic elements that replicate by converting their single-stranded RNA intermediate to double-stranded DNA through the combined DNA polymerase and ribonuclease H (RNase H) activities of the element-encoded reverse transcriptase (RT). Although a wealth of structural information is available for lentiviral and gammaretroviral RTs, equivalent studies on counterpart enzymes of long terminal repeat (LTR)-containing retrotransposons, from which they are evolutionarily derived, is lacking. In this study, we report the first crystal structure of a complex of RT from the Saccharomyces cerevisiae LTR retrotransposon Ty3 in the presence of its polypurine tract-containing RNA-DNA hybrid. In contrast to its retroviral counterparts, Ty3 RT adopts an asymmetric homodimeric architecture whose assembly is substrate dependent. Moreover, our structure and biochemical data suggest that the RNase H and DNA polymerase activities are contributed by individual subunits of the homodimer.
authors.affiliation: Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland.
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Nowak
authors.affiliation: Reverse Transcriptase Biochemistry Section, HIV Drug Resistance Program, Frederick National Laboratory, Frederick, Maryland, USA.
authors.forename: Jennifer T
authors.initials: JT
authors.lastname: Miller
authors.affiliation: Reverse Transcriptase Biochemistry Section, HIV Drug Resistance Program, Frederick National Laboratory, Frederick, Maryland, USA.
authors.forename: Marion K
authors.initials: MK
authors.lastname: Bona
authors.affiliation: Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland.
authors.forename: Justyna
authors.initials: J
authors.lastname: Studnicka
authors.affiliation: Biophysics Core Facility, International Institute of Molecular and Cell Biology, Warsaw, Poland.
authors.forename: Roman H
authors.initials: RH
authors.lastname: Szczepanowski
authors.affiliation: Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland.
authors.forename: Jakub
authors.initials: J
authors.lastname: Jurkowski
authors.affiliation: Reverse Transcriptase Biochemistry Section, HIV Drug Resistance Program, Frederick National Laboratory, Frederick, Maryland, USA.
authors.forename: Stuart F J
authors.initials: SF
authors.lastname: Le Grice
authors.affiliation: Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Nowotny
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D019281:Dimerization; D008958:Models, Molecular; D017434:Protein Structure, Tertiary; D012194:RNA-Directed DNA Polymerase / Q000737:chemistry* / Q000502:physiology; D018626:Retroelements; D016914:Ribonuclease H / Q000737:chemistry* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000502:physiology
chemical_list: D018626:Retroelements; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; D012194:RNA-Directed DNA Polymerase; C496084:reverse transcriptase Ty3, S cerevisiae; D016914:Ribonuclease H