REGULATION OF SNM1, AN INDUCIBLE SACCHAROMYCES-CEREVISIAE GENE REQUIRED FOR REPAIR OF DNA CROSS-LINKS

The interstrand cross-link repair gene SNM1 of Saccharomyces cerevisia e was examined for regulation in response to DNA-damaging agents. Indu ction of SNM1-lacZ fusions was detected in response to nitrogen mustar d, cis-platinum (II) diamine dichloride, UV light, and 8-methoxypsoral en + UVA, but not after heat-shock treatment or incubation with 2-dime thylaminoethylchloride, methylmethane sulfonate or 4-nitroquinoline-N- oxide. The promoter of SNM1 contains a 15 bp motif, which shows homolo gy to the DRE2 box of the RAD2 promoter. Similar motifs have been foun d in promoter regions of other damage-inducible DNA repair genes. Dele tion of this motif results in loss of inducibility of SNM1. Also, a pu tative negative upstream regulation sequence was found to be responsib le for repression of constitutive transcription of SNM1. Surprisingly, no inducibility of SNM1 was found after treatment with DNA-damaging a gents in strains without an intact DUN1 gene, while regulation seems u nchanged in sad1 mutants.