The Yeast GATA Factor Gat1 Occupies a Central Position in Nitrogen Catabolite Repression-Sensitive Gene Activation

Institut de Recherches Microbiologiques J.-M. Wiame, Laboratoire de Microbiologie, Université Libre de Bruxelles, Av. E. Gryson 1, B-1070 Bruxelles, Belgium.
Molecular and Cellular Biology (Impact Factor: 4.78). 05/2009; 29(13):3803-15. DOI: 10.1128/MCB.00399-09
Source: PubMed

ABSTRACT Saccharomyces cerevisiae cells are able to adapt their metabolism according to the quality of the nitrogen sources available in the environment. Nitrogen catabolite repression (NCR) restrains the yeast's capacity to use poor nitrogen sources when rich ones are available. NCR-sensitive expression is modulated by the synchronized action of four DNA-binding GATA factors. Although the first identified GATA factor, Gln3, was considered the major activator of NCR-sensitive gene expression, our work positions Gat1 as a key factor for the integrated control of NCR in yeast for the following reasons: (i) Gat1 appeared to be the limiting factor for NCR gene expression, (ii) GAT1 expression was regulated by the four GATA factors in response to nitrogen availability, (iii) the two negative GATA factors Dal80 and Gzf3 interfered with Gat1 binding to DNA, and (iv) Gln3 binding to some NCR promoters required Gat1. Our study also provides mechanistic insights into the mode of action of the two negative GATA factors. Gzf3 interfered with Gat1 by nuclear sequestration and by competition at its own promoter. Dal80-dependent repression of NCR-sensitive gene expression occurred at three possible levels: Dal80 represses GAT1 expression, it competes with Gat1 for binding, and it directly represses NCR gene transcription.

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Available from: Isabelle Georis, Sep 26, 2015
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    • "The different subcellular fractions were analyzed by Western blotting with monoclonal antibodies for c-Myc (Santa Cruz Biotechnology), Pep12 (Invitrogen) and Pgk1 (Invitrogen, Carlsbad, CA). The electrophoresis, blotting, and detection procedures have been described previously (Georis et al. 2009). "
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    ABSTRACT: Nitrogen catabolite repression (NCR) is the regulatory pathway through which Saccharomyces cerevisiae responds to the available nitrogen status and selectively utilizes rich nitrogen sources in preference to poor ones. Expression of NCR-sensitive genes is mediated by two transcription activators, Gln3 and Gat1, in response to provision of a poorly used nitrogen source or following treatment with the TORC1 inhibitor, rapamycin. During nitrogen excess, the transcription activators are sequestered in the cytoplasm in a Ure2-dependent fashion. Here, we show that Vps components are required for Gln3 localization and function in response to rapamycin treatment when cells are grown in defined yeast nitrogen base but not in complex yeast peptone dextrose medium. On the other hand, Gat1 function was altered in vps mutants in all conditions tested. A significant fraction of Gat1, like Gln3, is associated with light intracellular membranes. Further, our results are consistent with the possibility that Ure2 might function downstream of the Vps components during the control of GATA factor-mediated gene expression. These observations demonstrate distinct media-dependent requirements of vesicular trafficking components for wild-type responses of GATA factor localization and function. As a result, the current model describing participation of Vps system components in events associated with translocation of Gln3 into the nucleus following rapamycin treatment or growth in nitrogen-poor medium requires modification.
    MicrobiologyOpen 06/2014; 3(3). DOI:10.1002/mbo3.168 · 2.21 Impact Factor
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    • "With the exception of Gln3 the expression of the transcription factors is also subjected to NCR control, such that without Gln3 no derepression of NCR genes can take place (Mitchell & Magasanik, 1984). Gat1-dependent activation of NCR depends on Gln3 activating Gat1 expression, whereas Gln3-dependent activation can promote transcription in the absence of the other transcription factors (Georis, et al., 2009). "
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    ABSTRACT: The yeast Saccharomyces cerevisiae has been a favorite organism for pioneering studies on nutrient-sensing and signaling mechanisms. Many specific nutrient responses have been elucidated in great detail. This has led to important new concepts and insight into nutrient-controlled cellular regulation. Major highlights include the central role of the Snf1 protein kinase in the glucose repression pathway, galactose induction, the discovery of a G-protein coupled receptor system and role of Ras in glucose-induced cAMP signaling, the role of the protein synthesis initiation machinery in general control of nitrogen metabolism, the cyclin-controlled protein kinase Pho85 in phosphate regulation, nitrogen catabolite repression and the nitrogen-sensing TOR pathway, and the discovery of transporter-like proteins acting as nutrient sensors. In addition, a number of cellular targets, like carbohydrate stores, stress tolerance and ribosomal gene expression, are controlled by the presence of multiple nutrients. The PKA signaling pathway plays a major role in this general nutrient response. It has led to the discovery of nutrient transceptors (transporter-receptors) as nutrient sensors. Major shortcomings in our knowledge are the relationship between rapid and steady-state nutrient signaling, the role of metabolic intermediates in intracellular nutrient sensing and the identity of the nutrient sensors controlling cellular growth. This article is protected by copyright. All rights reserved.
    FEMS microbiology reviews 02/2014; 38(2). DOI:10.1111/1574-6976.12065 · 13.24 Impact Factor
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    • "There are two relatively recent publications in the literature indicating that GATA transcription factors may play a role in regulating other aspects of mineral nutrition in both plants and yeast. Georis et al. (2009) have shown that four other yeast GATA family members, GAT1, GLN3, DAL80 and GZF3, may play a role in nitrogen sensing and regulation of yeast growth (Georis et al. 2009). In that study there was no indication that any of the four GATA proteins enhanced expression of N transporters. "
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    ABSTRACT: To gain a better understanding of the regulation of Zn homeostasis in plants and the degree of conservation of Zn homeostasis between plants and yeast, a cDNA library from the Zn/Cd hyperaccumulating plant species, Noccaea caerulescens, was screened for its ability to restore growth under Zn limiting conditions in the yeast mutant zap1▵. ZAP1 is a transcription factor that activates the Zn dependent transcription of genes involved in Zn uptake, including ZRT1, the yeast high affinity Zn transporter. From this screen two members of the E2F family of transcription factors were found to activate ZRT1 expression in a Zn independent manner. The activation of ZRT1 by the plant E2F proteins involves E2F-mediated activation of a yeast GATA transcription factor which in turn activates ZRT1 expression. A ZRT1 promoter region necessary for activation by E2F and GATA proteins is upstream of two zinc responsive elements previously shown to bind ZAP1 in ZRT1. This activation may not involve direct binding of E2F to the ZRT1 promoter. The expression of E2F genes in yeast does not replace function of ZAP1; instead it appears to activate a novel GATA regulatory pathway involved in Zn uptake and homeostasis that is not Zn responsive.
    Journal of Integrative Plant Biology 01/2014; 56(3). DOI:10.1111/jipb.12169 · 3.34 Impact Factor
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