MUTATOR GENES OF THE YEAST SACCHAROMYCES- CEREVISIAE INTERACTION BETWEEN MUTATIONS HIM AND HSM AND MUTATIONS BLOCKING 3 PRINCIPAL PATHWAYS OF INDUCED DNA-DAMAGE REPAIR

During recent years, genes controlling mutation in higher eukaryotes h ave been found to be involved actively in carcinoma regeneration in ce lls. In this respect, studying the genetic control of mutagenesis beco mes a key direction of research into mechanisms responsible for cancer generation. The results of studying interaction of mutations in the H IM and HSM genes, controlling spontaneous and induced mutagenesis in y easts, and mutations impairing three known pathways of DNA damage repa ir in this microorganism, are described in this work. It was shown tha t mutation rev3 completely blocks UV-induced mutagenesis in all mutant s studied. On the other hand, mutation rad2 synergistically interacts with mutations him1, hsm1, hsm3, hsm6, and hsm2, thus enhancing the fr equency of UV-induced mutagenesis in double mutants multiple times. Mu tations him2 and him3 manifested epistatic interaction with mutation r ad2. With mutation rad54, the interaction was epistatic for mutations him1 and hsm2 and was additive for mutations hsm1, him2, and him3. On the basis of the data obtained, we developed a scheme for the appearan ce of mismatch bases in the process of repair of UV-induced DNA damage .