Degradation of the Saccharomyces cerevisiae Mating-Type Regulator alpha 1: Genetic Dissection of Cis-determinants and Trans-acting Pathways

作者：Nixon Christina E; Wilcox Alexander J; Laney Jeffrey D^*

来源：Genetics, 2010, 185(2): 497-U150.

DOI：10.1534/genetics.110.115907

Mating phenotype in the yeast Saccharomyces cerevisiae is a dynamic trait, and efficient transitions between alternate haploid cell types allow the organism to access the advantageous diploid form. Mating identity is determined by cell type-specific transcriptional regulators, but these factors must be rapidly removed upon mating-type switching to allow the master regulators of the alternate state to establish a new gene expression program. Targeted proteolysis by the ubiquitin-proteasome system is a commonly employed strategy to quickly disassemble regulatory networks, and yeast use this approach to evoke efficient switching from the a to the alpha phenotype by ensuring the rapid removal of the alpha 2 transcriptional repressor. Transition to the a cell phenotype, however, also requires the inactivation of the alpha alpha 1 transcriptional activator, but the mechanism by which this occurs is currently unknown. Here, we report a central role for the ubiquitin-proteasome system in alpha 1 inactivation. The alpha 1 protein is constitutively short lived and targeted for rapid turnover by multiple ubiquitin-conjugation pathways. Intriguingly, the a-domain, a conserved region of unknown function, acts as a degradation signal for a pathway defined by the SUMO-targeted ligase Slx5-Slx8, which has also been implicated in the rapid destruction of alpha 2. Our observations suggest coordinate regulation in the turnover of two master regulatory transcription factors ensures a rapid mating-type switch.

• 出版日期2010-6