This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Blank, T. E. Articles by Hopper, J. E. Search for Related Content PubMed PubMed Citation Articles by Blank, T. E. Articles by Hopper, J. E.

 Previous Article  |  Next Article 

Mol. Cell. Biol., May 1997, 2566-2575, Vol 17, No. 5
Copyright © 1997, American Society for Microbiology

Novel Gal3 proteins showing altered Gal80p binding cause constitutive transcription of Gal4p-activated genes in Saccharomyces cerevisiae

TE Blank, MP Woods, CM Lebo, P Xin and JE Hopper
Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey 17033, USA.

Gal4p-mediated activation of galactose gene expression in Saccharomyces cerevisiae normally requires both galactose and the activity of Gal3p. Recent evidence suggests that in cells exposed to galactose, Gal3p binds to and inhibits Ga180p, an inhibitor of the transcriptional activator Gal4p. Here, we report on the isolation and characterization of novel mutant forms of Gal3p that can induce Gal4p activity independently of galactose. Five mutant GAL3(c) alleles were isolated by using a selection demanding constitutive expression of a GAL1 promoter-driven HIS3 gene. This constitutive effect is not due to overproduction of Gal3p. The level of constitutive GAL gene expression in cells bearing different GAL3(c) alleles varies over more than a fourfold range and increases in response to galactose. Utilizing glutathione S-transferase-Gal3p fusions, we determined that the mutant Gal3p proteins show altered Gal80p-binding characteristics. The Gal3p mutant proteins differ in their requirements for galactose and ATP for their Gal80p-binding ability. The behavior of the novel Gal3p proteins provides strong support for a model wherein galactose causes an alteration in Gal3p that increases either its ability to bind to Gal80p or its access to Gal80p. With the Gal3p-Gal80p interaction being a critical step in the induction process, the Gal3p proteins constitute an important new reagent for studying the induction mechanism through both in vivo and in vitro methods.

This article has been cited by other articles:

• Diep, C. Q., Tao, X., Pilauri, V., Losiewicz, M., Blank, T. E., Hopper, J. E. (2008). Genetic Evidence for Sites of Interaction Between the Gal3 and Gal80 Proteins of the Saccharomyces cerevisiae GAL Gene Switch. Genetics 178: 725-736 [Abstract] [Full Text]  
• Anders, A., Lilie, H., Franke, K., Kapp, L., Stelling, J., Gilles, E. D., Breunig, K. D. (2006). The Galactose Switch in Kluyveromyces lactis Depends on Nuclear Competition between Gal4 and Gal1 for Gal80 Binding. J. Biol. Chem. 281: 29337-29348 [Abstract] [Full Text]  
• Diep, C. Q., Peng, G., Bewley, M., Pilauri, V., Ropson, I., Hopper, J. E. (2006). Intragenic Suppression of Gal3C Interaction With Gal80 in the Saccharomyces cerevisiae GAL Gene Switch. Genetics 172: 77-87 [Abstract] [Full Text]  
• Thoden, J. B., Sellick, C. A., Timson, D. J., Reece, R. J., Holden, H. M. (2005). Molecular Structure of Saccharomyces cerevisiae Gal1p, a Bifunctional Galactokinase and Transcriptional Inducer. J. Biol. Chem. 280: 36905-36911 [Abstract] [Full Text]  
• Pilauri, V., Bewley, M., Diep, C., Hopper, J. (2005). Gal80 Dimerization and the Yeast GAL Gene Switch. Genetics 169: 1903-1914 [Abstract] [Full Text]  
• Hasper, A. A., Trindade, L. M., van der Veen, D., van Ooyen, A. J. J., de Graaff, L. H. (2004). Functional analysis of the transcriptional activator XlnR from Aspergillus niger. Microbiology 150: 1367-1375 [Abstract] [Full Text]  
• Verma, M., Bhat, P. J., Venkatesh, K. V. (2003). Quantitative Analysis of GAL Genetic Switch of Saccharomyces cerevisiae Reveals That Nucleocytoplasmic Shuttling of Gal80p Results in a Highly Sensitive Response to Galactose. J. Biol. Chem. 278: 48764-48769 [Abstract] [Full Text]  
• Peng, G., Hopper, J. E. (2002). Gene activation by interaction of an inhibitor with a cytoplasmic signaling protein. Proc. Natl. Acad. Sci. USA 99: 8548-8553 [Abstract] [Full Text]  
• Peng, G., Hopper, J. E. (2000). Evidence for Gal3p's Cytoplasmic Location and Gal80p's Dual Cytoplasmic-Nuclear Location Implicates New Mechanisms for Controlling Gal4p Activity in Saccharomyces cerevisiae. Mol. Cell. Biol. 20: 5140-5148 [Abstract] [Full Text]  
• D'Alessio, M., Brandriss, M. C. (2000). Cross-Pathway Regulation in Saccharomyces cerevisiae: Activation of the Proline Utilization Pathway by Gal4p In Vivo. J. Bacteriol. 182: 3748-3753 [Abstract] [Full Text]  
• Platt, A., Ross, H. C., Hankin, S., Reece, R. J. (2000). The insertion of two amino acids into a transcriptional inducer converts it into a galactokinase. Proc. Natl. Acad. Sci. USA 97: 3154-3159 [Abstract] [Full Text]  
• Hu, Z., Yue, Y., Jiang, H., Zhang, B., Sherwood, P. W., Michels, C. A. (2000). Analysis of the Mechanism by Which Glucose Inhibits Maltose Induction of MAL Gene Expression in Saccharomyces. Genetics 154: 121-132 [Abstract] [Full Text]  
• Dudley, A. M., Rougeulle, C., Winston, F. (1999). The Spt components of SAGA facilitate TBP binding to a promoter at a post-activator-binding step in vivo. Genes Dev. 13: 2940-2945 [Abstract] [Full Text]  
• Sil, A. K., Alam, S., Xin, P., Ma, L., Morgan, M., Lebo, C. M., Woods, M. P., Hopper, J. E. (1999). The Gal3p-Gal80p-Gal4p Transcription Switch of Yeast: Gal3p Destabilizes the Gal80p-Gal4p Complex in Response to Galactose and ATP. Mol. Cell. Biol. 19: 7828-7840 [Abstract] [Full Text]  
• Ozcan, S., Johnston, M. (1999). Function and Regulation of Yeast Hexose Transporters. Microbiol. Mol. Biol. Rev. 63: 554-569 [Abstract] [Full Text]  
• Baumgartner, U., Hamilton, B., Piskacek, M., Ruis, H., Rottensteiner, H. (1999). Functional Analysis of the Zn2Cys6 Transcription Factors Oaf1p and Pip2p. DIFFERENT ROLES IN FATTY ACID INDUCTION OF beta -OXIDATION IN SACCHAROMYCES CEREVISIAE. J. Biol. Chem. 274: 22208-22216 [Abstract] [Full Text]  
• Hach, A., Hon, T., Zhang, L. (1999). A New Class of Repression Modules Is Critical for Heme Regulation of the Yeast Transcriptional Activator Hap1. Mol. Cell. Biol. 19: 4324-4333 [Abstract] [Full Text]