Recessive and dominant genes controlling inducible sexual agglutinability in Saccharomyces cerevisiae

Summary We have characterized the two dominant genes, IND 1 and IND 2, responsible for inducible sexual agglutinability. The strains carrying these genes differ from the inducible strains carrying the recessive gene, saa 1 in the following points. The former strains produce agglutination substance at 22°, 28°, and 37° C only in response to sex pheromone of the opposite mating type, but the latter strains produce the substance constitutively without the pheromone at 22° C, only in response to the pheromone at 28° C, and do not produce the substance, even in the presence of the pheromone, at 37° C.We suggest that strains carrying one of the dominant, inducible genes are wild type and have a pheromone-controlled regulatory system of sexual agglutinability.     

Temperature-sensitive loss of sexual agglutinability in Saccharomyces cerevisiae

Temperature dependency of sexual agglutination in Saccharomyces cerevisiae was found. Of 31 strains tested, which showed normal agglutination when cultured at 25°C, 29 strains lost their sexual agglutinability when they were grown at 37°C.     

A factor in cell-free extracts inactivating sexual agglutinability of a mating type in Saccharomyces cerevisiae

Cell-free extracts of both a and a mating-type strains of Saccharomycescerevisiae contained a substance which irreversibly inactivatedsexual agglutinability of a cells, but not that of a cells. ¹ Present address: Department of Pharmacology, Osaka Collegeof Pharmacy, 2-10-65 Kawai-cho, Matsubara, Osaka 580, Japan. (Received January 9, 1976; )     

Induction of sexual cell agglutinability of A mating type cells by alpha-factor in Saccharomyces cerevisiae.

Mating hormone, α-factor, which inhibits DNA synthesis and causes characteristic changes in cell morphology in $\text{a}$ mating type cells, was also responsible for induction of sexual cell agglutinability of $\text{a}$ mating type cells.     

Mutants inducible for sexual agglutinability in Saccharomyces cerevisiae

Summary We have isolated the mutants, T55s-41(a) and T562s-161 () which have no sexual agglutinability when cultured at 28°C, but become sexually agglutinable by the action of the sex pheromone produced by respective opposite mating type. The sex-specific glycoproteins responsible for sexual agglutination were detected in the mutants treated with the opposite mating type pheromone, but not in those treated with the same mating type pheromone.The induction of sexual agglutinability by the pheromone required both nitrogen and carbon sources and was inhibited by cycloheximide. The induction by the pheromone of sexual agglutinability was much more sensitive to osmotic shock and Triton X-100 in T55s-41 than in H1-0, an inducible a strain found in our stock cultures. When cultured at 22°C both T55s-41 and T562s-161 produced respective agglutination substances without the sex pheromones.H1-0 carried more than one genes responsible for the inducibility (inducible genes). The inducible genes carried by T55s-41 and T562s-161 were recessive, possibly linked to none of the mating type locus, thr4 and his 4, and shown to be identical. The inducible gene in H22, an inducible a strain found in our stock cultures and at least one of the inducible genes in H1-0 were linked to the mating type locus. All the inducible genes observed so far were not specific to the mating type in their action.     

Genetic analysis of inducible sexual agglutination ability in the yeast Saccharomyces cerevisiae

Genetic regulation of the inducibility of sexual agglutination ability in the yeast Saccharomyces cerevisiae was studied. Detailed analysis of the degree of sexual agglutination was carried out; it showed that a greater number of genes are involved in the regulation of inducible sexual agglutination in strain H1-0 than previously assumed. Although dominancy of inducible phenotype over constitutive was confirmed, the effectiveness of one gene changing the constitutive phenotype to the inducible seemed to be somewhat low. Quantity per cell of agglutination substances responsible for sexual agglutination increased as the agglutination ability became greater.     

Mating reaction in Saccharomyces cerevisiae. X Agglutinability-inactivating factor: A factor which destroys sexual agglutinability of a mating-type cells

From cells of Saccharomyces cerevisiae a factor has been extracted that destroys the agglutinability of a mating-type cells specifically. It was found in the cell extracts of diploid and tetraploid strains as well as haploid strains of a and mating types. It is heat-labile and the molecular weight is about 50000. It is adsorbed by neither a cells nor cells. Its biological activity is dependent on the incubation temperature and the pH, and is completely inhibited by phenylmethylsulfonyl fluoride, a potent inhibitor of the serine proteases. All the results described in this paper indicate that this factor is a proteolytic enzyme.     

Repair of cisplatin-DNA adducts in mutants for genes controlling spontaneous and induced mutagenesis in Saccharomyces cerevisiae

Sensitivity to the lethal action of the anticancer substance cisplatin was studied in the yeast mutants himl, hsm2, hsm3, and hsm6, deficient for repair of spontaneous and induced mutations. The himl and hsm3 mutants were as resistant to the agent under study as the wild-type strain. The survival of the double mutant rad2 hsm3 was higher than that of the single mutant rad2. The hsm2 and hsm6 mutants were more cisplatin-sensitive than the wild type. Cisplatin was shown to have high mutagenic and recombinogenic effects on yeast cells.     

Alpha mating type-specific expression of mutations leading to constitutive agglutinability in Saccharomyces cerevisiae.

Two mutants of Saccharomyces cerevisiae have been isolated and characterized. The mutants were constitutively agglutinable at 36 degrees C, the temperature at which wild-type cells agglutinate only after induction by mating pheromone. The mutant cells had other properties specific for the normal alpha cell type, i.e., conjugation with a cells, response to a mating pheromone, and production of alpha mating pheromone. The two mutations, cag1 and cag2, were recessive and expressed only in alpha cells. cag1 is linked very closely to the MAT locus, but cag2 is unlinked to the MAT locus. These cag mutations complemented ste3-1. These results indicate that CAG genes are novel alpha-specific genes involved in the regulation of sex agglutinin synthesis.     

PET genes of Saccharomyces cerevisiae.

We describe a collection of nuclear respiratory-defective mutants (pet mutants) of Saccharomyces cerevisiae consisting of 215 complementation groups. This set of mutants probably represents a substantial fraction of the total genetic information of the nucleus required for the maintenance of functional mitochondria in S. cerevisiae. The biochemical lesions of mutants in approximately 50 complementation groups have been related to single enzymes or biosynthetic pathways, and the corresponding wild-type genes have been cloned and their structures have been determined. The genes defined by an additional 20 complementation groups were identified by allelism tests with mutants characterized in other laboratories. Mutants representative of the remaining complementation groups have been assigned to one of the following five phenotypic classes: (i) deficiency in cytochrome oxidase, (ii) deficiency in coenzyme QH2-cytochrome c reductase, (iii) deficiency in mitochondrial ATPase, (iv) absence of mitochondrial protein synthesis, and (v) normal composition of respiratory-chain complexes and of oligomycin-sensitive ATPase. In addition to the genes identified through biochemical and genetic analyses of the pet mutants, we have cataloged PET genes not matched to complementation groups in the mutant collection and other genes whose products function in the mitochondria but are not necessary for respiration. Together, this information provides an up-to-date list of the known genes coding for mitochondrial constituents and for proteins whose expression is vital for the respiratory competence of S. cerevisiae.