scholarly journals The Transcription Factor Rim101p Governs Ion Tolerance and Cell Differentiation by Direct Repression of the Regulatory Genes NRG1 and SMP1 in Saccharomyces cerevisiae

2003 ◽  
Vol 23 (2) ◽  
pp. 677-686 ◽  
Author(s):  
Teresa M. Lamb ◽  
Aaron P. Mitchell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Transcription Factor ◽  
Transcriptional Repression ◽  
Response Regulator ◽  
Alkaline Ph ◽  
Ph Response ◽  
Induced Genes ◽  
Inducible Genes ◽  
Direct Activator

ABSTRACT Environmental pH changes have broad consequences for growth and differentiation. The best-understood eukaryotic pH response pathway acts through the zinc-finger transcription factor PacC of Aspergillus nidulans, which activates alkaline pH-induced genes directly. We show here that Saccharomyces cerevisiae Rim101p, the pH response regulator homologous to PacC, functions as a repressor in vivo. Chromatin immunoprecipitation assays show that Rim101p is associated in vivo with the promoters of seven Rim101p-repressed genes. A reporter gene containing deduced Rim101p binding sites is negatively regulated by Rim101p and is associated with Rim101p in vivo. Deletion mutations of the Rim101p repression targets NRG1 and SMP1 suppress rim101Δ mutant defects in ion tolerance, haploid invasive growth, and sporulation. Therefore, transcriptional repression is the main biological function of Rim101p. The Rim101p repression target Nrg1p is in turn required for repression of two alkaline pH-inducible genes, including the Na+ pump gene ENA1, which is required for ion tolerance. Thus, Nrg1p, a known transcriptional repressor, functions as an inhibitor of alkaline pH responses. Our findings stand in contrast to the well-characterized function of PacC as a direct activator of alkaline pH-induced genes yet explain many aspects of Rim101p and PacC function in other organisms.

scholarly journals Effect of Environmental pH on Morphological Development of Candida albicans Is Mediated via the PacC-Related Transcription Factor Encoded by PRR2

1999 ◽  
Vol 181 (24) ◽  
pp. 7524-7530 ◽  
Author(s):  
Ana M. Ramon ◽  
Amalia Porta ◽  
William A. Fonzi
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Candida Albicans ◽  
Feedback Loop ◽  
Response Regulator ◽  
Morphological Development ◽  
Alkaline Ph ◽  
Ph Response ◽  
Related Transcription Factor ◽  
Ph Dependent

ABSTRACT The ability to respond to ambient pH is critical to the growth and virulence of the fungal pathogen Candida albicans. This response entails the differential expression of several genes affecting morphogenesis. To investigate the mechanism of pH-dependent gene expression, the C. albicans homolog of pacC, designated PRR2 (for pH response regulator), was identified and cloned. pacC encodes a zinc finger-containing transcription factor that mediates pH-dependent gene expression inAspergillus nidulans. Mutants lacking PRR2 can no longer induce the expression of alkaline-expressed genes or repress acid-expressed genes at alkaline pH. Although the mutation did not affect growth of the cells at acid or alkaline pH, the mutants exhibited medium-conditional defects in filamentation. PRR2was itself expressed in a pH-conditional manner, and its induction at alkaline pH was controlled by PRR1. PRR1 is homologous to palF, a regulator of pacC. Thus,PRR2 expression is controlled by a pH-dependent feedback loop. The results demonstrate that the pH response pathway ofAspergillus is conserved and that this pathway has been adapted to control dimorphism in C. albicans.

Interspersion of an unusual GCN4 activation site with a complex transcriptional repression site in Ty2 elements of Saccharomyces cerevisiae

1993 ◽  
Vol 13 (4) ◽  
pp. 2091-2103
Author(s):  
S Türkel ◽  
P J Farabaugh
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Transcriptional Activation ◽  
Binding Sites ◽  
Transcriptional Repression ◽  
Physiological Control ◽  
Reading Frame ◽  
Negative Region ◽  
Activation Site

Transcription of the Ty2-917 retrotransposon of Saccharomyces cerevisiae is modulated by a complex set of positive and negative elements, including a negative region located within the first open reading frame, TYA2. The negative region includes three downstream repression sites (DRSI, DRSII, and DRSIII). In addition, the negative region includes at least two downstream activation sites (DASs). This paper concerns the characterization of DASI. A 36-bp DASI oligonucleotide acts as an autonomous transcriptional activation site and includes two sequence elements which are both required for activation. We show that these sites bind in vitro the transcriptional activation protein GCN4 and that their activity in vivo responds to the level of GCN4 in the cell. We have termed the two sites GCN4 binding sites (GBS1 and GBS2). GBS1 is a high-affinity GCN4 binding site (dissociation constant, approximately 25 nM at 30 degrees C), binding GCN4 with about the affinity of a consensus UASGCN4, this though GBS1 includes two differences from the right half of the palindromic consensus site. GBS2 is more diverged from the consensus and binds GCN4 with about 20-fold-lower affinity. Nucleotides 13 to 36 of DASI overlap DRSII. Since DRSII is a transcriptional repression site, we tested whether DASI includes repression elements. We identify two sites flanking GBS2, both of which repress transcription activated by the consensus GCN4-specific upstream activation site (UASGCN4). One of these is repeated in the 12 bp immediately adjacent to DASI. Thus, in a 48-bp region of Ty2-917 are interspersed two positive and three negative transcriptional regulators. The net effect of the region must depend on the interaction of the proteins bound at these sites, which may include their competing for binding sites, and on the physiological control of the activity of these proteins.

scholarly journals Chromatin remodeler Ino80C acts independently of H2A.Z to evict promoter nucleosomes and stimulate transcription of highly expressed genes in yeast

2020 ◽  
Vol 48 (15) ◽  
pp. 8408-8430 ◽  
Author(s):  
Hongfang Qiu ◽  
Emily Biernat ◽  
Chhabi K Govind ◽  
Yashpal Rawal ◽  
Răzvan V Chereji ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Transcriptional Activation ◽  
Histone Variant ◽  
Yeast Genome ◽  
Chromatin Remodeler ◽  
Chromatin Remodelers ◽  
Highly Expressed Genes ◽  
Induced Genes ◽  
Yeast Genes

Abstract The chromatin remodelers SWI/SNF and RSC function in evicting promoter nucleosomes at highly expressed yeast genes, particularly those activated by transcription factor Gcn4. Ino80 remodeling complex (Ino80C) can establish nucleosome-depleted regions (NDRs) in reconstituted chromatin, and was implicated in removing histone variant H2A.Z from the −1 and +1 nucleosomes flanking NDRs; however, Ino80C’s function in transcriptional activation in vivo is not well understood. Analyzing the cohort of Gcn4-induced genes in ino80Δ mutants has uncovered a role for Ino80C on par with SWI/SNF in evicting promoter nucleosomes and transcriptional activation. Compared to SWI/SNF, Ino80C generally functions over a wider region, spanning the −1 and +1 nucleosomes, NDR and proximal genic nucleosomes, at genes highly dependent on its function. Defects in nucleosome eviction in ino80Δ cells are frequently accompanied by reduced promoter occupancies of TBP, and diminished transcription; and Ino80 is enriched at genes requiring its remodeler activity. Importantly, nuclear depletion of Ino80 impairs promoter nucleosome eviction even in a mutant lacking H2A.Z. Thus, Ino80C acts widely in the yeast genome together with RSC and SWI/SNF in evicting promoter nucleosomes and enhancing transcription, all in a manner at least partly independent of H2A.Z editing.

scholarly journals Rgt1, a glucose sensing transcription factor, is required for transcriptional repression of the HXK2 gene in Saccharomyces cerevisiae

2005 ◽  
Vol 388 (2) ◽  
pp. 697-703 ◽  
Author(s):  
Aaron PALOMINO ◽  
Pilar HERRERO ◽  
Fernando MORENO
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Transcription Factor ◽  
Transcriptional Repression ◽  
Glucose Repression ◽  
Fold Increase ◽  
Glucose Sensing ◽  
Start Codon ◽  
Dependent Manner ◽  
Gene Encoding ◽  
Regulatory Functions

Expression of HXK2, a gene encoding a Saccharomyces cerevisiae bifunctional protein with catalytic and regulatory functions, is controlled by glucose availability, being activated in the presence of glucose and inhibited when the levels of the sugar are low. In the present study, we identified Rgt1 as a transcription factor that, together with the Med8 protein, is essential for repression of the HXK2 gene in the absence of glucose. Rgt1 represses HXK2 expression by binding specifically to the motif (CGGAAAA) located at −395 bp relative to the ATG translation start codon in the HXK2 promoter. Disruption of the RGT1 gene causes an 18-fold increase in the level of HXK2 transcript in the absence of glucose. Rgt1 binds to the RGT1 element of HXK2 promoter in a glucose-dependent manner, and the repression of target gene depends on binding of Rgt1 to DNA. The physiological significance of the connection between two glucose-signalling pathways, the Snf3/Rgt2 that causes glucose induction and the Mig1/Hxk2 that causes glucose repression, was also analysed.

scholarly journals Transcriptional Repression by the Pho4 Transcription Factor Controls the Timing of SNZ1 Expression

2008 ◽  
Vol 7 (6) ◽  
pp. 949-957 ◽  
Author(s):  
Masafumi Nishizawa ◽  
Tae Komai ◽  
Nobuyuki Morohashi ◽  
Mitsuhiro Shimizu ◽  
Akio Toh-e
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Transcriptional Repression ◽  
Structural Changes ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Nutrient Sensing ◽  
Yeast Cells ◽  
Diauxic Shift

ABSTRACT Nutrient-sensing kinases play important roles for the yeast Saccharomyces cerevisiae to adapt to new nutrient conditions when the nutrient status changes. Our previous global gene expression analysis revealed that the Pho85 kinase, one of the yeast nutrient-sensing kinases, is involved in the changes in gene expression profiles when yeast cells undergo a diauxic shift. We also found that the stationary phase-specific genes SNZ1 and SNO1, whch share a common promoter, are not properly induced when Pho85 is absent. To examine the role of the kinase in SNZ1/SNO1 regulation, we analyzed their expression during the growth of various yeast mutants, including those affecting Pho85 function or lacking the Pho4 transcription factor, an in vivo substrate of Pho85, and tested Pho4 binding by chromatin immunoprecipitation. Pho4 exhibits temporal binding to the SNZ1/SNO1 promoter to down-regulate the promoter activity, and a Δpho4 mutation advances the timing of SNZ1/SNO1 expression. SNZ2, another member of the SNZ/SNO family, is expressed at an earlier growth stage than SNZ1, and Pho4 does not affect this timing, although Pho85 is required for SNZ2 expression. Thus, Pho4 appears to regulate the different timing of the expression of the SNZ/SNO family members. Pho4 binding to the SNZ1/SNO1 promoter is accompanied by alterations in chromatin structure, and Rpd3 histone deacetylase is required for the proper timing of SNZ1/SNO1 expression, while Asf1 histone chaperone is indispensable for their expression. These results imply that Pho4 plays positive and negative roles in transcriptional regulation, with both cases involving structural changes in its target chromatin.

scholarly journals Activity of the Yap1 Transcription Factor in Saccharomyces cerevisiae Is Modulated by Methylglyoxal, a Metabolite Derived from Glycolysis

2004 ◽  
Vol 24 (19) ◽  
pp. 8753-8764 ◽  
Author(s):  
Kazuhiro Maeta ◽  
Shingo Izawa ◽  
Shoko Okazaki ◽  
Shusuke Kuge ◽  
Yoshiharu Inoue
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Transcription Factor ◽  
Disulfide Bond ◽  
Target Genes ◽  
Cysteine Residue ◽  
Cysteine Residues ◽  
Glyoxalase I ◽  
Toxic Metabolite ◽  
Basic Leucine Zipper

ABSTRACT Methylglyoxal (MG) is synthesized during glycolysis, although it inhibits cell growth in all types of organisms. Hence, it has long been asked why such a toxic metabolite is synthesized in vivo. Glyoxalase I is a major enzyme detoxifying MG. Here we show that the Yap1 transcription factor, which is critical for the oxidative-stress response in Saccharomyces cerevisiae, is constitutively concentrated in the nucleus and activates the expression of its target genes in a glyoxalase I-deficient mutant. Yap1 contains six cysteine residues in two cysteine-rich domains (CRDs), i.e., three cysteine residues clustering near the N terminus (n-CRD) and the remaining three cysteine residues near the C terminus (c-CRD). We reveal that any of the three cysteine residues in the c-CRD is sufficient for MG to allow Yap1 to translocate into the nucleus and to activate the expression of its target gene. A Yap1 mutant possessing only one cysteine residue in the c-CRD but no cysteine in the n-CRD and deletion of the basic leucine zipper domain can concentrate in the nucleus with MG treatment. However, substitution of all the cysteine residues in Yap1 abolishes the ability of this transcription factor to concentrate in the nucleus following MG treatment. The redox status of Yap1 is substantially unchanged, and protein(s) interaction with Yap1 through disulfide bond is hardly detected in cells treated with MG. Collectively, neither intermolecular nor intramolecular disulfide bond formation seems to be involved in Yap1 activation by MG. Moreover, we show that nucleocytoplasmic localization of Yap1 closely correlates with growth phase and intracellular MG level. We propose a novel regulatory pathway underlying Yap1 activation by a natural metabolite in the cell.

scholarly journals Transcriptional repression in Saccharomyces cerevisiae by a SIN3-LexA fusion protein

1993 ◽  
Vol 13 (3) ◽  
pp. 1805-1814
Author(s):  
H Wang ◽  
D J Stillman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Binding ◽  
Fusion Protein ◽  
Protein Interactions ◽  
Transcriptional Repression ◽  
Binding Proteins ◽  
Dna Binding Proteins ◽  
Predicted Amino Acid Sequence

The yeast SIN3 gene (also known as SDI1, UME4, RPD1, and GAM2) has been identified as a transcriptional regulator. Previous work has led to the suggestion that SIN3 regulates transcription via interactions with DNA-binding proteins. Although the SIN3 protein is located in the nucleus, it does not bind directly to DNA in vitro. We have expressed a LexA-SIN3 fusion protein in Saccharomyces cerevisiae and show that this fusion protein represses transcription from heterologous promoters that contain lexA operators. The predicted amino acid sequence of the SIN3 protein contains four copies of a paired amphipathic helix (PAH) motif, similar to motifs found in HLH (helix-loop-helix) and TPR (tetratricopeptide repeat) proteins, and these motifs are proposed to be involved in protein-protein interactions. We have conducted a deletion analysis of the SIN3 gene and show that the PAH motifs are required for SIN3 activity. Additionally, the C-terminal region of the SIN3 protein is sufficient for repression activity in a LexA-SIN3 fusion, and deletion of a PAH motif in this region inactivates this repression activity. A model is presented in which SIN3 recognizes specific DNA-binding proteins in vivo in order to repress transcription.

Identification of Schizosaccharomyces pombe transcription factor PGA4, which binds cooperatively to Saccharomyces cerevisiae GAL4-binding sites

1990 ◽  
Vol 10 (4) ◽  
pp. 1432-1438
Author(s):  
D M Ruden
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Transcription Factor ◽  
Schizosaccharomyces Pombe ◽  
Binding Sites ◽  
Transcription Activator ◽  
Integral Number ◽  
Dna Binding Site ◽  
Adh1 Gene

When the DNA-binding site for the Saccharomyces cerevisiae transcription activator GAL4 is placed upstream of the Schizosaccharomyces pombe ADH1 TATA box, transcription of the ADH1 gene is activated in S. pombe in vivo by an endogenous transcription factor. In vitro studies show that this S. pombe protein, PGA4, binds specifically to DNA containing a GAL4 site and that when two GAL4 sites are present, this protein binds cooperatively. Cooperating binding of PGA4 to DNA is favored if the GAL4 sites are separated by an integral number of turns of the DNA helix.

scholarly journals Nicotinamide Clearance by Pnc1 Directly Regulates Sir2-Mediated Silencing and Longevity

2004 ◽  
Vol 24 (3) ◽  
pp. 1301-1312 ◽  
Author(s):  
Christopher M. Gallo ◽  
Daniel L. Smith ◽  
Jeffrey S. Smith
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nicotinic Acid ◽  
Life Span ◽  
Histone Deacetylase ◽  
Transcriptional Repression ◽  
Transcriptional Silencing ◽  
Inhibitory Effect ◽  
Salvage Pathway

ABSTRACT The Saccharomyces cerevisiae Sir2 protein is an NAD+-dependent histone deacetylase (HDAC) that functions in transcriptional silencing and longevity. The NAD+ salvage pathway protein, Npt1, regulates Sir2-mediated processes by maintaining a sufficiently high intracellular NAD+ concentration. However, another NAD+ salvage pathway component, Pnc1, modulates silencing independently of the NAD+ concentration. Nicotinamide (NAM) is a by-product of the Sir2 deacetylase reaction and is a natural Sir2 inhibitor. Pnc1 is a nicotinamidase that converts NAM to nicotinic acid. Here we show that recombinant Pnc1 stimulates Sir2 HDAC activity in vitro by preventing the accumulation of NAM produced by Sir2. In vivo, telomeric, rDNA, and HM silencing are differentially sensitive to inhibition by NAM. Furthermore, PNC1 overexpression suppresses the inhibitory effect of exogenously added NAM on silencing, life span, and Hst1-mediated transcriptional repression. Finally, we show that stress suppresses the inhibitory effect of NAM through the induction of PNC1 expression. Pnc1, therefore, positively regulates Sir2-mediated silencing and longevity by preventing the accumulation of intracellular NAM during times of stress.

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