Structure-Function Model for Kissing Loop Interactions That Initiate Dimerization of Ty1 RNAReportar como inadecuado


Structure-Function Model for Kissing Loop Interactions That Initiate Dimerization of Ty1 RNA


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1

Laboratory of Molecular Genetics, Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA

2

Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA

3

Department of Biochemistry and Biophysics and Center for RNA Biology, University of Rochester Medical Center, Rochester, NY 14642, USA

4

Department of Biomedical Sciences, University at Albany-SUNY, Albany, NY 12201, USA





*

Author to whom correspondence should be addressed.



Academic Editors: David J. Garfinkel and Katarzyna J. Purzycka

Abstract The genomic RNA of the retrotransposon Ty1 is packaged as a dimer into virus-like particles. The 5′ terminus of Ty1 RNA harbors cis-acting sequences required for translation initiation, packaging and initiation of reverse transcription TIPIRT. To identify RNA motifs involved in dimerization and packaging, a structural model of the TIPIRT domain in vitro was developed from single-nucleotide resolution RNA structural data. In general agreement with previous models, the first 326 nucleotides of Ty1 RNA form a pseudoknot with a 7-bp stem S1, a 1-nucleotide interhelical loop and an 8-bp stem S2 that delineate two long, structured loops. Nucleotide substitutions that disrupt either pseudoknot stem greatly reduced helper-Ty1-mediated retrotransposition of a mini-Ty1, but only mutations in S2 destabilized mini-Ty1 RNA in cis and helper-Ty1 RNA in trans. Nested in different loops of the pseudoknot are two hairpins with complementary 7-nucleotide motifs at their apices. Nucleotide substitutions in either motif also reduced retrotransposition and destabilized mini- and helper-Ty1 RNA. Compensatory mutations that restore base-pairing in the S2 stem or between the hairpins rescued retrotransposition and RNA stability in cis and trans. These data inform a model whereby a Ty1 RNA kissing complex with two intermolecular kissing-loop interactions initiates dimerization and packaging. View Full-Text

Keywords: long terminal repeat-retrotransposon; Ty1; Saccharomyces cerevisiae; RNA secondary structure; RNA packaging; RNA kissing complex; pseudoknot; kissing loop; SHAPE analysis long terminal repeat-retrotransposon; Ty1; Saccharomyces cerevisiae; RNA secondary structure; RNA packaging; RNA kissing complex; pseudoknot; kissing loop; SHAPE analysis





Autor: Eric R. Gamache 1, Jung H. Doh 1, Justin Ritz 2, Alain Laederach 2, Stanislav Bellaousov 3, David H. Mathews 3 and M. Joan Curcio 1,4,*

Fuente: http://mdpi.com/



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