title: The Sge1 protein of Saccharomyces cerevisiae is a membrane-associated multidrug transporter.
abstract: In this study, we report the further characterization of the Saccharomyces cerevisiae crystal violet-resistance protein Sge1. Sge1 is a highly hydrophobic 59 kDa protein with 14 predicted membrane-spanning domains. It shares homologies with several drug-resistance proteins and sugar transporters of the major facilitator superfamily. Here, we have demonstrated that Sge1 is not only a crystal violet-resistance protein, but that it also confers resistance to ethidium bromide and methylmethane sulfonate. Disruption of SGE1 leads to increased sensitivity towards all three compounds, thus designating Sge1 as a multiple drug-resistance protein. Subcellular fractionation as well as immunolocalization on whole yeast cells demonstrated that Sge1 was tightly associated with the yeast plasma membrane. Furthermore, Sge1 was highly enriched in preparations of yeast plasma membranes. In analogy to other multidrug-resistance proteins, we suggest that Sge1 functions as a drug export permease.
authors.affiliation: Institute of Toxicology, Swiss Federal Institute of Technology, Switzerland.
authors.forename: A E
authors.initials: AE
authors.lastname: Ehrenhofer-Murray
authors.forename: M U
authors.initials: MU
authors.lastname: Seitz
authors.forename: C
authors.initials: C
authors.lastname: Sengstag
mesh_terms: D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000494:pharmacology; D002462:Cell Membrane / Q000737:chemistry; D002499:Centrifugation, Density Gradient; D004352:Drug Resistance, Microbial; D018432:Drug Resistance, Multiple; D004996:Ethidium / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D005656:Fungal Proteins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D005840:Gentian Violet / Q000494:pharmacology; D008565:Membrane Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D026901:Membrane Transport Proteins; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000187:drug effects* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013379:Substrate Specificity; D014157:Transcription Factors
chemical_list: D000935:Antifungal Agents; D005656:Fungal Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C082639:SGE1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D008741:Methyl Methanesulfonate; D004996:Ethidium; D005840:Gentian Violet