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Function and regulation of yeast copperthionein
D J Thiele1, C F Wright, M J Walling
1Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health.
Experientia. Supplementum
|January 1, 1987
Summary
The CUP1 gene in yeast protects against copper toxicity and is self-regulated. Monkey metallothioneins can replace its functions, demonstrating conserved mechanisms for copper homeostasis.
Area of Science:
- Molecular Biology
- Yeast Genetics
- Biochemistry
Background:
- The CUP1 gene in Saccharomyces cerevisiae confers resistance to copper toxicity.
- This gene is essential for preventing cell damage from excess copper but not for basic growth.
- CUP1 expression is regulated by copper levels, indicating a role in cellular homeostasis.
Purpose of the Study:
- To investigate the functions of the yeast CUP1 gene in copper resistance and transcriptional autoregulation.
- To determine if metallothioneins from other species can functionally complement CUP1.
- To identify the regulatory elements responsible for copper-inducible transcription of CUP1.
Main Methods:
- Gene expression analysis in Saccharomyces cerevisiae.
- Functional complementation assays using monkey metallothionein cDNAs.
- Reporter gene assays with synthetic CUP1 promoter sequences.
Main Results:
- The CUP1 gene is crucial for copper detoxification and exhibits negative autoregulation.
- Monkey metallothionein isoforms successfully complemented both copper protection and autoregulation functions in yeast.
- Tandemly repeated upstream sequences of CUP1 were identified as cis-dominant elements mediating copper inducibility.
Conclusions:
- The CUP1 gene plays a vital role in yeast copper homeostasis through protection and autoregulation.
- Heterologous metallothioneins share functional similarities with yeast CUP1, suggesting conserved mechanisms.
- Specific upstream regulatory sequences are key to copper-mediated transcriptional induction of CUP1.