Role of alpha2 protein in donor locus selection during mating type interconversion

Area of Science:

• Molecular Biology
• Yeast Genetics
• Transcriptional Regulation

Background:

• The homeodomain protein alpha2p is involved in cell type determination and mating partner selection in yeast.
• Alpha2p functions as a transcriptional repressor, interacting with other proteins like Mcm1p, Tup1p, and Ssn6p.
• Understanding the precise mechanism of alpha2p's role in donor selection is key to deciphering yeast mating behavior.

Purpose of the Study:

• To investigate the mechanism by which alpha2p directs donor selection during yeast mating.
• To determine the specific protein interactions of alpha2p essential for donor preference.
• To elucidate the relationship between alpha2p-mediated transcriptional repression and donor selection.

Main Methods:

• Analysis of mutant alleles of MATalpha2 affecting specific protein interactions.
• Assessing the impact of these mutations on donor preference.
• Evaluating the roles of Tup1p and Ssn6p in alpha2p-mediated repression and donor selection.

Main Results:

• Mutations disrupting alpha2p interaction with Mcm1p or Tup1p abolish donor preference.
• Mutations affecting alpha2p interaction with a1p do not impair donor preference.
• TUP1 is essential for both alpha2p-mediated repression and donor selection, while SSN6 has a minor role.

Conclusions:

• The alpha2p-Mcm1p-Tup1p complex is critical for establishing yeast mating type and likely influences donor preference.
• Donor selection may be regulated indirectly through transcriptional control of a-specific genes by the alpha2p complex.
• The alpha2p complex might also directly impact donor preference through DNA binding and chromatin organization.