title: Regulation of RAD54- and RAD52-lacZ gene fusions in Saccharomyces cerevisiae in response to DNA damage.
abstract: The RAD52 and RAD54 genes in the yeast Saccharomyces cerevisiae are involved in both DNA repair and DNA recombination. RAD54 has recently been shown to be inducible by X-rays, while RAD52 is not. To further investigate the regulation of these genes, we constructed gene fusions using 5' regions upstream of the RAD52 and RAD54 genes and a 3'-terminal fragment of the Escherichia coli beta-galactosidase gene. Yeast transformants with either an integrated or an autonomously replicating plasmid containing these fusions expressed beta-galactosidase activity constitutively. In addition, the RAD54 gene fusion was inducible in both haploid and diploid cells in response to the DNA-damaging agents X-rays, UV light, and methyl methanesulfonate, but not in response to heat shock. The RAD52-lacZ gene fusion showed little or no induction in response to X-ray or UV radiation nor methyl methanesulfonate. Typical induction levels for RAD54 in cells exposed to such agents were from 3- to 12-fold, in good agreement with previous mRNA analyses. When MATa cells were arrested in G1 with alpha-factor, RAD54 was still inducible after DNA damage, indicating that the observed induction is independent of the cell cycle. Using a yeast vector containing the EcoRI structural gene fused to the GAL1 promoter, we showed that double-strand breaks alone are sufficient in vivo for induction of RAD54.
mesh_terms: D002453:Cell Cycle; D004249:DNA Damage; D004260:DNA Repair; D005786:Gene Expression Regulation; D005800:Genes, Fungal / Q000187:drug effects / Q000528:radiation effects; D006358:Hot Temperature; D008741:Methyl Methanesulfonate; D010957:Plasmids; D013014:SOS Response, Genetics; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D014170:Transformation, Genetic; D014466:Ultraviolet Rays
chemical_list: D008741:Methyl Methanesulfonate