Relationship between chromosomal alpha-specific suppressors of sir4-11 and polymorphism of the HMRa-bearing fragment.
In the course of studying sir4-11 which is responsible for the non-mating phenotype of asd-homothallism of Saccharomyces cerevisiae, we detected chromosomal alpha-specific suppressors of it. By examining the mating-type cassette constitution of two strains and the spore-clones derived from a diploid culture formed by a mass mating between these strains, we obtained the following results; (1) the HMRa-bearing HindIII-Bg/II restriction fragment was dimorphic, as judged by size, within each tetrad, (2) while one form was common to all tetrads, the other varied among tetrads, (3) spore-clones with the alpha-specific suppressor of sir4-11 had the variant forms while those without had the common form, and (4) while the two parents had the common form, each independent diploid clone had the common form plus a variant form. From these results, we conclude that the mating of cells in certain combinations induces a change of DNA structure at or near HMRa in a mating-pair specific manner and that the change makes HMRa non-derepressible or non-functional when derepressed.
Ono
B
B
Laboratory of Environmental Hygiene Chemistry, Faculty of Pharmaceutical Sciences, Okayama University, Japan.
Takasugi
K
K
Ishino-Arao
Y
Y
Yamate
K
K
Nakagami
S
S
Yamane
A
A
Shinoda
S
S
D002453:Cell Cycle / Q000235:genetics; D004171:Diploidy; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D012150:Polymorphism, Restriction Fragment Length; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics*; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D013489:Suppression, Genetic
D005656:Fungal Proteins; C061573:SIR4 protein, S cerevisiae; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae