Structural highlights
Function[GAL3_YEAST] The GAL3 regulatory function is required for rapid induction of the galactose system. At normal induction, galactose in the presence of the GAL3 protein may lead to the induction of the GAL genes, including GAL1. Then the galactokinase protein (GAL1) in the presence of galactose may reinforce the induction leading to a higher expression level. Upon depletion of galactose, the inducing activity of the galactokinase protein may decrease, after which transcription of the GAL genes, including GAL1, may decrease. Publication Abstract from PubMedA wealth of genetic information and some biochemical analysis have made the GAL regulon of the yeast Saccharomyces cerevisiae a classic model system for studying transcriptional activation in eukaryotes. Galactose induces this transcriptional switch, which is regulated by three proteins: the transcriptional activator Gal4p, bound to DNA; the repressor Gal80p; and the transducer Gal3p. We showed previously that NADP appears to act as a trigger to kick the repressor off the activator. Sustained activation involves a complex of the transducer Gal3p and Gal80p mediated by galactose and ATP. We solved the crystal structure of the complex of Gal3p-Gal80p with alpha-D-galactose and ATP to 2.1 A resolution. The interaction between the proteins occurs only when Gal3p is in a "closed" state induced by ligand binding. The structure of the complex provides a rationale for the phenotypes of several well-known Gal80p and Gal3p mutants as well as the lack of galactokinase activity of Gal3p. The Gal3p transducer of the GAL regulon interacts with the Gal80p repressor in its ligand-induced closed conformation.,Lavy T, Kumar PR, He H, Joshua-Tor L Genes Dev. 2012 Feb 1;26(3):294-303. doi: 10.1101/gad.182691.111. PMID:22302941[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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