The Nuclear Pore Complex Mediates Binding of the Mig1 Repressor to Target Promoters

Nayan J. Sarma, University of Southern Mississippi
Thomas D. Buford, University of Southern Mississippi
Terry Haley, University of Southern Mississippi
Kellie Barbara-Haley, University of Southern Mississippi

Abstract

All eukaryotic cells alter their transcriptional program in response to the sugar glucose. In Saccharomyces cerevisiae, the best-studied downstream effector of this response is the glucose-regulated repressor Mig1. We show here that nuclear pore complexes also contribute to glucose-regulated gene expression. NPCs participate in glucose-responsive repression by physically interacting with Mig1 and mediating its function independently of nucleocytoplasmic transport. Surprisingly, despite its abundant presence in the nucleus of glucose-grown nup120 Delta or nup133 Delta cells, Mig1 has lost its ability to interact with target promoters. The glucose repression defect in the absence of these nuclear pore components therefore appears to result from the failure of Mig1 to access its consensus recognition sites in genomic DNA. We propose that the NPC contributes to both repression and activation at the level of transcription.