A mutation that permits the expression of normally silent copies of mating-type information in Saccharomyces cerevisiae.

摘要: Studies of heterothallic and homothallic strains Saccharomyces cerevisiae have led to the suggestion that mating-type information is located at three distinct sites on chromosome 3, although only (MAT) locus expressed (Hicks, Strathern Herskowitz, 1977). We found recessive mutation cmt permits expression normally silent copies HMa HMα loci. In haploid carrying HMα, allows simultaneous both a α information, leading nonmating ("MATa/MATα") phenotype. The effects can be masked by changing or HMα. For example, cell genotype MATa hma has an mating type, while MATα strain nonmating. Expression HM loci correct sporulation defects mata* matα10 alleles. Meiotic segregants recovered from cmt/cmt diploids mat mutations demonstrate these mutants are not "healed" normal MAT alleles, as case in parallel studies using homothallism gene HO.—All results consistent with notion hmα alleles code for information. demonstrates functionally equivalent MAT. does cause interconversions MAT, it genetically linked HMa, HO. heterozygotes, becomes homozygous frequency greater than 1% when mata*/MATα matα10/MATa.