Allelism of methionine-sensitive mutants of Schizosaccharomyces pombe to loci involved in adenine biosynthesis

Methionine-sensitive mutants of Schizosaccharomyces pombe were found to map at 16 loci, min1–min16, seven of which are allelic to known ade loci involved in adenine biosynthesis. The mutant min1–106 was shown to be located within the ade6 locus by intragenic recombination analysis. Methionine sensitivity of these mutants is reversible by adenine supplementation and their pigmentation is similar to that of the corresponding ade mutants. We conclude, therefore, that these min mutants are incompletely blocked in adenine biosynthesis. These observations further indicate that adenine biosynthesis in S. pombe is inhibited by methionine or a metabolite derived from it. For some other min mutants showing reversibility of methionine sensitivity by leucine or proline, no allelism to known leu or pro loci was detected.