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HAP1 positive control mutants specific for one of two binding sites
1Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Genes & Development
|October 1, 1992
Summary
Researchers studied the HAP1 activator in yeast gene expression. Mutants revealed that HAP1
Area of Science:
- Molecular Biology
- Yeast Genetics
- Transcription Regulation
Background:
- The HAP1 activator controls yeast CYC1 and CYC7 gene expression.
- HAP1 features a GAL4-like zinc finger for DNA binding and an acidic domain for transcriptional activation.
Purpose of the Study:
- To investigate the mechanism of HAP1 binding to UAS1 and CYC7 DNA sites.
- To identify key regions within HAP1's DNA-binding domain responsible for differential gene activation.
Main Methods:
- Saturation mutagenesis of the HAP1 DNA-binding domain.
- Analysis of mutant HAP1 activity at CYC1 (UAS1) and CYC7 promoters.
- Assessment of DNA binding affinity for wild-type and mutant HAP1 proteins.
Main Results:
- Mutants were classified based on altered activity at UAS1 and CYC7.
- Several mutants showed wild-type DNA binding but defective transcriptional activation (positive control mutants).
- These positive control mutants map to residues flanking the zinc finger.
Conclusions:
- HAP1's activation function involves cofactor proteins interacting with UAS1 and CYC7.
- The existence of CYC7-specific activation mutants suggests differential cofactor usage for HAP1 at different target sites.