title: Characterization of the SAC3 gene of Saccharomyces cerevisiae.
abstract: A temperature-sensitive mutation (act1-1) in the essential actin gene of Saccharomyces cerevisiae can be suppressed by mutations in the SAC3 gene. A DNA fragment containing the SAC3 gene was sequenced. SAC3 codes for a 150 kDa hydrophillic protein which does not show any significant similarities with other proteins in the databases. Sac3 therefore is a novel yeast protein. A nuclear localization of Sac3 is suggested by the presence of a putative nuclear localization signal in the Sac3 sequence. A SAC3 disruption mutation was constructed. SAC3 disruption mutants were viable but grew more slowly and were larger than wild-type cells. In contrast to the sac3-1 mutation, the SAC3 disruption was not able to suppress the temperature sensitivity and the osmosensitivity of the act1-1 mutant. This demonstrates that act1-1 suppression by sac3-1 is not the result of a simple loss of SAC3 function. Furthermore, we examined the act1-1 and the sac3 mutants for defects in polarized cell growth by FITC-Concanavalin A (Con A)-labelling. The sac3 mutants showed a normal ConA-labelling pattern. In the act1-1 mutant, however, upon shift to non-permissive temperature, newly synthesized cell wall material, instead of being directed towards the bud, was deposited at discrete spots in the mother cell.
authors.affiliation: Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Bauer
authors.forename: R
authors.initials: R
authors.lastname: Kölling
mesh_terms: D000199:Actins / Q000032:analysis / Q000235:genetics; D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins; D001483:Base Sequence; D005800:Genes, Fungal / Q000235:genetics*; D016153:Genes, Suppressor / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D029543:Nucleocytoplasmic Transport Proteins; D010641:Phenotype; D018272:Porins; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D017422:Sequence Analysis, DNA; D013696:Temperature
chemical_list: C098619:AAC1 protein, Arabidopsis; D000199:Actins; D029681:Arabidopsis Proteins; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; D018272:Porins; C103382:SAC3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins