Identification and analysis of a Saccharomyces cerevisiae copper homeostasis gene encoding a homeodomain protein.
Yeast metallothionein, encoded by the CUP1 gene, and its copper-dependent transcriptional activator ACE1 play a key role in mediating copper resistance in Saccharomyces cerevisiae. Using an ethyl methanesulfonate mutant of a yeast strain in which CUP1 and ACE1 were deleted, we isolated a gene, designated CUP9, which permits yeast cells to grow at high concentrations of environmental copper, most notably when lactate is the sole carbon source. Disruption of CUP9, which is located on chromosome XVI, caused a loss of copper resistance in strains which possessed CUP1 and ACE1, as well as in the cup1 ace1 deletion strain. Measurement of intracellular copper levels of the wild-type and cup9-1 mutant demonstrated that total intracellular copper concentrations were unaffected by CUP9. CUP9 mRNA levels were, however, down regulated by copper when yeast cells were grown with glucose but not with lactate or glycerol-ethanol as the sole carbon source. This down regulation was independent of the copper metalloregulatory transcription factor ACE1. The DNA sequence of CUP9 predicts an open reading frame of 306 amino acids in which a 55-amino-acid sequence showed 47% identity with the homeobox domain of the human proto-oncogene PBX1, suggesting that CUP9 is a DNA-binding protein which regulates the expression of important copper homeostatic genes.
Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor 48109-0606.
S A
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Knight
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Tamai
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Kosman
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Thiele
D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins; D003001:Cloning, Molecular; D003300:Copper / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000502:physiology; D015966:Gene Expression Regulation, Fungal; D005801:Genes, Homeobox; D005814:Genes, Viral; D005816:Genetic Complementation Test; D018398:Homeodomain Proteins / Q000235:genetics*; D006706:Homeostasis; D008668:Metallothionein / Q000502:physiology; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D000090063:Proto-Oncogene Mas; D012331:RNA, Fungal / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology; D015678:Viral Structural Proteins / Q000235:genetics
C500769:CUP1-1 protein, S cerevisiae; C060256:CUP2 protein, S cerevisiae; C090457:CUP9 protein, S cerevisiae; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D012331:RNA, Fungal; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D015678:Viral Structural Proteins; C007121:copper thionein; D003300:Copper; D008668:Metallothionein