Two major mediators of glucose repression in Saccharomyces cerevisiae are the proteins Mig1 and Hxk2. The mechanism of Hxk2-dependent glucose repression pathway is not well understood, but the Mig1-dependent part of the pathway has been elucidated in great detail. Here we report that Hxk2 has a glucose-regulated nuclear localization and that Mig1, a transcriptional repressor responsible for glucose repression of many genes, is required to sequester Hxk2 into the nucleus. Mig1 and Hxk2 interacted in vivo in a yeast two-hybrid assay and in vitro in immunoprecipitation and glutathione S-transferase pull-down experiments. We found that the Lys(6)-Met(15) decapeptide of Hxk2, which is necessary for nuclear localization of the protein, is also essential for interaction with the Mig1 protein. Our results also show that the Hxk2-Mig1 interaction is of physiological significance because both proteins have been found interacting together in a cluster with DNA fragments containing the MIG1 site of SUC2 promoter. We conclude that Hxk2 operates by interacting with Mig1 to generate a repressor complex located in the nucleus of S. cerevisiae during growth in glucose medium.

• PMID: 14715653
• DOI full text
• PubMed

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Journal Article | Research Support, Non-U.S. Gov't

Authors

Ahuatzi D, Herrero P, de la Cera T, Moreno F

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