A small protein (Ags1p) and the Pho80p-Pho85p kinase complex contribute to aminoglycoside antibiotic resistance of the yeast Saccharomyces cerevisiae.
We identified the AGS1 and AGS3 genes by their ability to partially complement an ags mutant (RC1707) which is supersensitive to various aminoglycoside antibiotics (J. F. Ernst and R. K. Chan, J. Bacteriol. 163:8-14, 1985). AGS1 is located in proximity to the centromere of chromosome III and encodes a small protein of 88 amino acids. The size of the AGS1 transcript, which in wild-type cells is 1 kb, is reduced to 0.75 kb in mutant RC1707. Disruption of AGS1 rendered strains supersensitive to hygromycin B and increased their resistance to vanadate. In addition, ags1delta strains underglycosylated invertase but had normal carboxypeptidase Y glycosylation, suggesting that Ags1p is required for the elaboration of outer N-glycosyl chains. AGS3 was found to be identical to PHO80 (TUP7), which encodes a cyclin activating the Pho85p protein kinase. Deletion of either PHO80 or PHO85 led to aminoglycoside supersensitivity; pho80delta ags1delta strains showed an enhanced-sensitivity phenotype compared to single mutants. pho80 and pho85 mutants were rendered resistant by deletion of PHO4, indicating that activation of the Pho4p transcription factor is required for increased aminoglycoside sensitivity. Thus, both the Pho80p-Pho85p kinase complex (by Pho4p phosphorylation) and a novel component of the N glycosylation pathway contribute to basal levels of aminoglycoside resistance in Saccharomyces cerevisiae.
Wickert
S
S
Institut für Mikrobiologie, Heinrich-Heine-Universität, Düsseldorf, Germany.
Finck
M
M
Herz
B
B
Ernst
J F
JF
D000595:Amino Acid Sequence; D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003001:Cloning, Molecular; D018844:Cyclin-Dependent Kinases / Q000502:physiology*; D016213:Cyclins / Q000502:physiology*; D004352:Drug Resistance, Microbial; D005656:Fungal Proteins / Q000502:physiology*; D005816:Genetic Complementation Test; D006031:Glycosylation; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D012333:RNA, Messenger / Q000032:analysis; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D016213:Cyclins; D005656:Fungal Proteins; C066824:PHO80 protein, S cerevisiae; D012333:RNA, Messenger; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D018844:Cyclin-Dependent Kinases; C058605:PHO85 protein, S cerevisiae