The yeast STE12 protein binds to the DNA sequence mediating pheromone induction

Area of Science:

• Molecular Biology
• Yeast Genetics
• Signal Transduction

Background:

• The STE12 gene product in Saccharomyces cerevisiae is crucial for regulating cell-type-specific gene transcription.
• It plays a role in both a-specific and alpha-specific gene expression in yeast.

Purpose of the Study:

• To investigate the DNA-binding capabilities of the STE12 protein.
• To identify the specific DNA sequences that interact with STE12.
• To elucidate the role of STE12 in pheromone-induced signal transduction pathways.

Main Methods:

• In vitro transcription and translation to produce radiolabeled STE12 protein.
• DNA-binding assays using labeled STE12 protein and unlabeled DNA fragments from a-specific genes.
• Analysis of yeast extracts to identify STE12-dependent DNA-binding activity.
• Localization of binding sites using DNA fragments containing the pheromone induction element.

Main Results:

• Radiolabeled STE12 protein formed complexes with DNA fragments from two a-specific genes.
• Wild-type yeast extracts, but not ste12 mutant extracts, showed STE12-dependent DNA-binding activity.
• The binding site was localized to the pheromone induction element, a known regulator of gene transcription in response to pheromones.

Conclusions:

• The STE12 protein directly binds to the pheromone induction element.
• STE12 is likely an ultimate effector in the pheromone signal transduction pathway.
• This finding clarifies the molecular mechanism by which pheromones regulate gene expression in yeast.