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The mechanism of action of inhibitory domain 1 of GAL4

University of British Columbia

The mechanisms involved in the regulation of gene expression are of major interest in molecular biological research. Simpler models of lower eukaryotes such as yeast have been classically employed in such studies as a basis for the further characterization of more complex organisms. The galactose catabolism pathway of Saccharomyces cerevisiae provides an ideal model for research on gene regulation. The carbon source available to the yeast dictates the expression of the GAL genes involved in the utilization of galactose in budding yeast. The key regulator in this pathway is the transcriptional activator GAL4. GAL4 is active in the presence of galactose and absence of glucose, the preferred carbon source. When glucose is present, though, GAL4 is rendered inactive by several glucose repression mechanisms. One of these mechanisms acts through the central region of the GAL4 protein itself, which is composed of a glucose-responsive domain and at least three inhibitory domains, one being inhibitory domain 1. The activity of the inhibitory domains has been suggested to be governed by the glucose-responsive domain. With biochemical evidence, I suggest that the mechanism of transcriptional inactivation by inhibitory domain 1 occurs through multimerization of the GAL4 protein. Multimerization disrupts the formation of GAL4 dimers, preventing the transcriptional activator from binding to D N A and rendering the protein inactive.

Thesis/Dissertation

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2009-01-31

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http://hdl.handle.net/2429/4053

Biochemistry and Molecular Biology

University of British Columbia

UBCV

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