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Controlling integration specificity of a yeast retrotransposon
- Department of Zoology and Genetics, 2208 Molecular Biology Building, Iowa State University, Ames, IA 50014
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Edited by Mary-Lou Pardue, Massachusetts Institute of Technology, Cambridge, MA, and approved February 20, 2003 (received for review November 4, 2002)
Abstract
Retrotransposons and retroviruses integrate nonrandomly into eukaryotic genomes. For the yeast retrotransposon Ty5, integration preferentially occurs within domains of heterochromatin. Targeting to these locations is determined by interactions between an amino acid sequence motif at the C terminus of Ty5 integrase (IN) called the targeting domain, and the heterochromatin protein Sir4p. Here we show that new Ty5 integration hot spots are created when Sir4p is tethered to ectopic DNA sites. Targeting to sites of tethered Sir4p is abrogated by single amino acid substitutions in either IN or Sir4p that prevent their interaction. Ty5 target specificity can be altered by replacing the IN-targeting domain with other peptide motifs that interact with known protein partners. Integration occurs at high efficiency and in close proximity to DNA sites where the protein partners are tethered. These findings define a mechanism by which retrotransposons shape their host genomes and suggest ways in which retroviral integration can be controlled.
Footnotes
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↵ * To whom correspondence should be addressed. E-mail: voytas{at}iastate.edu.
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This paper was submitted directly (Track II) to the PNAS office.
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See commentary on page 5586.
- Abbreviations:
- IN,
- integrase;
- INC,
- IN C terminus;
- TD,
- targeting domain;
- SIR4C,
- Sir4p C terminus;
- GAD,
- Gal4p transcriptional activation domain;
- Pol III,
- RNA polymerase III;
- SC-T-L-U,
- synthetic complete media lacking, tryptophan, leucine, and uracil
- Copyright © 2003, The National Academy of Sciences
