Induction of Ty1 at high temperature by deletion of RFX1, a repressor of damage-inducible genes.
Mary Heaton, Jill Keeney
Biology, Juniata College, 1700 Moore St., Huntingdon, PA, 16652, USA
The viral-like Ty1 element in Saccharomyces cerevisiae produces an RNA molecule responsible for encoding the translation of Gag and Gag-Pol proteins. The similarities between Ty1 element and mammalian retroviruses allow for identification of host genes responsible for transposition of Ty1 that could provide insight into the processes of retroviral replication. A unique feature of the Ty1 transposition process is its temperature sensitivity. We hope to identify host genes controlling transposition by screening a pooled haploid collection of mutants from the Saccharomyces Genome Deletion Project for increased transposition at high temperature. The deletion library pool was transformed with a plasmid containing a galactose-inducible Ty1 element with a marker gene, and screened for transposition at 34oC. The deleted locus in selected mutants is identified by unique sequence tags cataloged by the Deletion Project. We screened at least five library equivalents and identified seven putative clones that show increased transposition at high temperature. Two of these clones have been identified as RFX (CRT1), a DNA-binding protein that recruits the Ssn6 and Tup1 repressors to the promoters of damage-inducible genes. RFX1 has previously been shown to marginally regulate Ty1. (Research support from Pfizer and NIH grant GM65848.).
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