title: Suppressors of yeast actin mutations.
abstract: Suppressors of a temperature-sensitive mutation (act1-1) in the single actin gene of Saccharomyces cerevisiae were selected that had simultaneously acquired a cold-sensitive growth phenotype. Five genes, called SAC (suppressor of actin) were defined by complementation tests; both suppression and cold-sensitive phenotypes were recessive. Three of the genes (SAC1, SAC2 and SAC3) were subjected to extensive genetic and phenotypic analysis, including molecular cloning. Suppression was found to be allele-specific with respect to actin alleles. The sac mutants, even in ACT1+ genetic backgrounds, displayed phenotypes similar to those of actin mutants, notably aberrant organization of intracellular actin and deposition of chitin at the cell surface. These results are interpreted as being consistent with the idea that the SAC genes encode proteins that interact with actin, presumably as components or controllers of the assembly or stability of the yeast actin cytoskeleton. Two unexpected properties of the SAC1 gene were noted. Disruptions of the gene indicated that its function is essential only at temperatures below about 17 degrees and all sac1 alleles are inviable when combined with act1-2. These properties are interpreted in the context of the evolution of the actin cytoskeleton of yeast.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
authors.forename: P
authors.initials: P
authors.lastname: Novick
authors.forename: B C
authors.initials: BC
authors.lastname: Osmond
authors.forename: D
authors.initials: D
authors.lastname: Botstein
mesh_terms: D000199:Actins / Q000235:genetics*; D002686:Chitin / Q000032:analysis; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003080:Cold Temperature; D003470:Culture Media; D003599:Cytoskeleton; D005455:Fluorescent Antibody Technique; D005799:Genes, Dominant; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D006026:Glycoside Hydrolases / Q000378:metabolism; D008854:Microscopy, Electron; D009154:Mutation; D010641:Phenotype; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D013489:Suppression, Genetic; D043324:beta-Fructofuranosidase
chemical_list: D000199:Actins; D003470:Culture Media; D002686:Chitin; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase