title: Structure of Ty1 Internally Initiated RNA Influences Restriction Factor Expression.
abstract: The long-terminal repeat retrotransposon Ty1 is the most abundant mobile genetic element in manySaccharomyces cerevisiaeisolates. Ty1 retrotransposons contribute to the genetic diversity of host cells, but they can also act as an insertional mutagen and cause genetic instability. Interestingly, retrotransposition occurs at a low level despite a high level of Ty1 RNA, even thoughS. cerevisiaelacks the intrinsic defense mechanisms that other eukaryotes use to prevent transposon movement. p22 is a recently discovered Ty1 protein that inhibits retrotransposition in a dose-dependent manner. p22 is a truncated form of Gag encoded by internally initiated Ty1i RNA that contains two closely-spaced AUG codons. Mutations of either AUG codon compromise p22 translation. We found that both AUG codons were utilized and that translation efficiency depended on the Ty1i RNA structure. Structural features that stimulated p22 translation were context dependent and present only in Ty1i RNA. Destabilization of the 5' untranslated region (5' UTR) of Ty1i RNA decreased the p22 level, both in vitro and in vivo. Our data suggest that protein factors such as Gag could contribute to the stability and translational activity of Ty1i RNA through specific interactions with structural motifs in the RNA.
authors.affiliation: Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan 61-704, Poland. blaszcz@ibch.poznan.pl.
authors.forename: Leszek
authors.initials: L
authors.lastname: Błaszczyk
authors.affiliation: Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan 61-704, Poland. biesiada@ibch.poznan.pl.
authors.forename: Marcin
authors.initials: M
authors.lastname: Biesiada
authors.affiliation: Department of Biochemistry & Molecular Biology, University of Georgia, Athens, GA 30602, USA. agniva.saha@gmail.com.
authors.forename: Agniva
authors.initials: A
authors.lastname: Saha
authors.affiliation: Department of Biochemistry & Molecular Biology, University of Georgia, Athens, GA 30602, USA. djgarf@uga.edu.
authors.forename: David J
authors.initials: DJ
authors.lastname: Garfinkel
authors.affiliation: Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan 61-704, Poland. purzycka@ibch.poznan.pl.
authors.forename: Katarzyna J
authors.initials: KJ
authors.lastname: Purzycka
mesh_terms: D015683:Gene Products, gag / Q000378:metabolism*; D014176:Protein Biosynthesis; D012331:RNA, Fungal / Q000378:metabolism*; D011995:Recombination, Genetic; D018626:Retroelements; D012441:Saccharomyces cerevisiae / Q000235:genetics*
chemical_list: D015683:Gene Products, gag; D012331:RNA, Fungal; D018626:Retroelements
keywords: Gag; RNA structure; Ty1 retrotransposon; translation regulation