Biochemical control of recombination in Saccharomyces cerevisiae. II. L-histidine inhibition of intragenic mitotic recombination at two unlinked loci

Summary A yeast strain heteroallelic at, two unlinked loci, ad ₃ and ur ₂ is used to study mitotic intragenic recombination. The recombination at these two loci is inhibited by L-histidine. The ad ₃ mutation is necessary to have histidine inhibition, his function is not yet, clear. This mutation gives rise to the double requirement in adenine and histidine, and starvation for this amino acid might be the primary cause of a high level of genetic recombination. On the other hand, the biochemical defect of ad ₃ mutants is related to folic coenzymes, and it might well be that these coenzymes play an unsuspected role in genetic recombination.