title: COT1, a gene involved in cobalt accumulation in Saccharomyces cerevisiae.
abstract: The COT1 gene of Saccharomyces cerevisiae has been isolated as a dosage-dependent suppressor of cobalt toxicity. Overexpression of the COT1 gene confers increased tolerance to cobalt and rhodium ions but not other divalent cations. Strains containing null alleles of COT1 are viable yet more sensitive to cobalt than are wild-type strains. Transcription of COT1 responds minimally to the extracellular cobalt concentration. Addition of cobalt ions to growth media results in a twofold increase in COT1 mRNA abundance. The gene encodes a 48-kDa protein which is found in mitochondrial membrane fractions of cells. The protein contains six possible membrane-spanning domains and several potential metal-binding amino acid residues. The COT1 protein shares 60% identity with the ZRC1 gene product, which confers resistance to zinc and cadmium ions. Cobalt transport studies indicate that the COT1 product is involved in the uptake of cobalt ions yet is not solely responsible for it. The increased tolerance of strains containing multiple copies of the COT1 gene is probably due to increased compartmentalization or sequestration of the ion within mitochondria.
authors.affiliation: Laboratory of Molecular Biology, University of Wisconsin, Madison 53706.
authors.forename: D S
authors.initials: DS
authors.lastname: Conklin
authors.forename: J A
authors.initials: JA
authors.lastname: McMaster
authors.forename: M R
authors.initials: MR
authors.lastname: Culbertson
authors.forename: C
authors.initials: C
authors.lastname: Kung
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001692:Biological Transport; D027682:Cation Transport Proteins; D003001:Cloning, Molecular; D003035:Cobalt / Q000378:metabolism*; D004271:DNA, Fungal; D004352:Drug Resistance, Microbial / Q000235:genetics; D005656:Fungal Proteins / Q000032:analysis / Q000235:genetics*; D005800:Genes, Fungal; D015151:Immunoblotting; D007425:Intracellular Membranes / Q000737:chemistry; D026901:Membrane Transport Proteins; D008928:Mitochondria / Q000737:chemistry; D008969:Molecular Sequence Data; D010641:Phenotype; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D012689:Sequence Homology, Nucleic Acid
chemical_list: C076223:COT1 protein, S cerevisiae; D027682:Cation Transport Proteins; D004271:DNA, Fungal; D005656:Fungal Proteins; D026901:Membrane Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; D003035:Cobalt