scholarly journals Multiple and Distinct Activation and Repression Sequences Mediate the Regulated Transcription of IME1, a Transcriptional Activator of Meiosis-Specific Genes inSaccharomyces cerevisiae

1998 ◽  
Vol 18 (4) ◽  
pp. 1985-1995 ◽  
Author(s):  
Shira Sagee ◽  
Amir Sherman ◽  
Galit Shenhar ◽  
Kenneth Robzyk ◽  
Noa Ben-Doy ◽  
...  

ABSTRACT IME1 encodes a transcriptional activator required for the transcription of meiosis-specific genes and initiation of meiosis in Saccharomyces cerevisiae. The transcription ofIME1 is repressed in the presence of glucose, and a low basal level of IME1 RNA is observed in vegetative cultures with acetate as the sole carbon source. Upon nitrogen depletion a transient induction in the transcription of IME1 is observed in MATa/MATα diploids but not in MAT-insufficient strains. In this study we demonstrate that the transcription of IME1 is controlled by an extremely unusual large 5′ region, over 2,100 bp long. This area is divided into four different upstream controlling sequences (UCS). UCS2 promotes the transcription of IME1 in the presence of a nonfermentable carbon source. UCS2 is flanked by three negative regions: UCS1, which exhibits URS activity in the presence of nitrogen, and UCS3 and UCS4, which repress the activity of UCS2 in MAT-insufficient cells. UCS2 consists of alternate positive and negative elements: three distinct constitutive URS elements that prevent the function of any upstream activating sequence (UAS) under all growth conditions, a constitutive UAS element that promotes expression under all growth conditions, a UAS element that is active only in vegetative media, and two discrete elements that function as UASs in the presence of acetate. Sequence analysis of IME1 revealed the presence of two almost identical 30- to 32-bp repeats. Surprisingly, one repeat, IREd, exhibits constitutive URS activity, whereas the other repeat, IREu, serves as a carbon-source-regulated UAS element. The RAS-cyclic AMP-dependent protein kinase cAPK pathway prevents the UAS activity of IREu in the presence of glucose as the sole carbon source, while the transcriptional activators Msn2p and Msn4p promote the UAS activity of this repeat in the presence of acetate. We suggest that the use of multiple negative and positive elements is essential to restrict transcription to the appropriate conditions and that the combinatorial effect of the entire region leads to the regulated transcription ofIME1.

1992 ◽  
Vol 12 (9) ◽  
pp. 4197-4208
Author(s):  
S Silve ◽  
P R Rhode ◽  
B Coll ◽  
J Campbell ◽  
R O Poyton

Previously, we have shown that the Saccharomyces cerevisiae DNA-binding protein ABF1 exists in at least two different electrophoretic forms (K. S. Sweder, P. R. Rhode, and J. L. Campbell, J. Biol. Chem. 263: 17270-17277, 1988). In this report, we show that these forms represent different states of phosphorylation of ABF1 and that at least four different phosphorylation states can be resolved electrophoretically. The ratios of these states to one another differ according to growth conditions and carbon source. Phosphorylation of ABF1 is therefore a regulated process. In nitrogen-starved cells or in cells grown on nonfermentable carbon sources (e.g., lactate), phosphorylated forms predominate, while in cells grown on fermentable carbon sources (e.g., glucose), dephosphorylated forms are enriched. The phosphorylation pattern is affected by mutations in the SNF1-SSN6 pathway, which is involved in glucose repression-depression. Whereas a functional SNF1 gene, which encodes a protein kinase, is not required for the phosphorylation of ABF1, a functional SSN6 gene is required for itsd ephosphorylation. The phosphorylation patterns that we have observed correlate with the regulation of a specific target gene, COX6, which encodes subunit VI of cytochrome c oxidase. Transcription of COX6 is repressed by growth in medium containing a fermentable carbon source and is derepressed by growth in medium containing a nonfermentable carbon source. COX6 repression-derepression is under the control of the SNF1-SSN6 pathway. This carbon source regulation is exerted through domain 1, a region of the upstream activation sequence UAS6 that binds ABF1 (J. D. Trawick, N. Kraut, F. Simon, and R. O. Poyton, Mol. Cell Biol. 12:2302-2314, 1992). We show that the greater the phosphorylation of ABF1, the greater the transcription of COX6. Furthermore, the ABF1-containing protein-DNA complexes formed at domain 1 differ according to the phosphorylation state of ABF1 and the carbon source on which the cells were grown. From these findings, we propose that the phosphorylation of ABF1 is involved in glucose repression-derepression of COX6 transcription.


2014 ◽  
Vol 80 (17) ◽  
pp. 5349-5358 ◽  
Author(s):  
Muhammad Afzal ◽  
Sulman Shafeeq ◽  
Oscar P. Kuipers

ABSTRACTComparison of the transcriptome ofStreptococcus pneumoniaestrain D39 grown in the presence of either lactose or galactose with that of the strain grown in the presence of glucose revealed the elevated expression of various genes and operons, including thelacgene cluster, which is organized into two operons, i.e.,lacoperon I (lacABCD) andlacoperon II (lacTFEG). Deletion of the DeoR family transcriptional regulatorlacRthat is present downstream of thelacgene cluster revealed elevated expression oflacoperon I even in the absence of lactose. This suggests a function of LacR as a transcriptional repressor oflacoperon I, which encodes enzymes involved in the phosphorylated tagatose pathway in the absence of lactose or galactose. Deletion oflacRdid not affect the expression oflacoperon II, which encodes a lactose-specific phosphotransferase. This finding was further confirmed by β-galactosidase assays with PlacA-lacZand PlacT-lacZin the presence of either lactose or glucose as the sole carbon source in the medium. This suggests the involvement of another transcriptional regulator in the regulation oflacoperon II, which is the BglG-family transcriptional antiterminator LacT. We demonstrate the role of LacT as a transcriptional activator oflacoperon II in the presence of lactose and CcpA-independent regulation of thelacgene cluster inS. pneumoniae.


2019 ◽  
Vol 116 (32) ◽  
pp. 15914-15923 ◽  
Author(s):  
Artem Melnykov ◽  
Shun-Jia Chen ◽  
Alexander Varshavsky

In eukaryotes, N-degron pathways (formerly “N-end rule pathways”) comprise a set of proteolytic systems whose unifying feature is their ability to recognize proteins containing N-terminal degradation signals called N-degrons, thereby causing degradation of these proteins by the 26S proteasome or autophagy. Gid4, a subunit of the GID ubiquitin ligase in the yeast Saccharomyces cerevisiae, is the recognition component (N-recognin) of the GID-mediated Pro/N-degron pathway. Gid4 targets proteins by recognizing their N-terminal Pro residues or a Pro at position 2, in the presence of distinct adjoining sequence motifs. Under conditions of low or absent glucose, cells make it through gluconeogenesis. When S. cerevisiae grows on a nonfermentable carbon source, its gluconeogenic enzymes Fbp1, Icl1, Mdh2, and Pck1 are expressed and long-lived. Transition to a medium containing glucose inhibits the synthesis of these enzymes and induces their degradation by the Gid4-dependent Pro/N-degron pathway. While studying yeast Gid4, we identified a similar but uncharacterized yeast protein (YGR066C), which we named Gid10. A screen for N-terminal peptide sequences that can bind to Gid10 showed that substrate specificities of Gid10 and Gid4 overlap but are not identical. Gid10 is not expressed under usual (unstressful) growth conditions, but is induced upon starvation or osmotic stresses. Using protein binding analyses and degradation assays with substrates of GID, we show that Gid10 can function as a specific N-recognin of the Pro/N-degron pathway.


2008 ◽  
Vol 55 (2) ◽  
pp. 215-225 ◽  
Author(s):  
Małgorzata Cieśla ◽  
Magdalena Boguta

Maf1 was the first protein discovered to regulate polymerase III RNA in yeast and because it is evolutionarily conserved, a Maf1 ortholog also serves to restrain transcription in mouse and human cells. Understanding the mechanism of the regulation has been made possible by recent studies showing that Maf1 is a nuclear/cytoplasmic protein whose subcellular distribution and hence negative regulation of Pol III transcription is mediated by the nutrient-sensing signaling pathways, TOR and RAS. Under stress conditions and during growth in a nonfermentable carbon source Maf1 is dephosphorylated and imported to the nucleus. In its non-phosphorylated form, Maf1 interacts with the polymerase III transcription machinery. Phosphorylation serves to locate Maf1 to the cytoplasm under favorable growth conditions, thereby preventing it from non-negatively regulating polymerase III when high levels of tRNA transcription are required. Relocation of Maf1 to the cytoplasm is dependent on Msn5, a carrier responsible for export of several other phosphoproteins out of the nucleus. The absence of Maf1-mediated control of tRNA synthesis impairs yeast viability in nonfermentable carbon sources. Moreover, in cells grown in a nonfermentable carbon source, Maf1 regulates the levels of different tRNAs to various extents. This differential regulation may contribute to the physiological role of Maf1.


1992 ◽  
Vol 12 (9) ◽  
pp. 4197-4208 ◽  
Author(s):  
S Silve ◽  
P R Rhode ◽  
B Coll ◽  
J Campbell ◽  
R O Poyton

Previously, we have shown that the Saccharomyces cerevisiae DNA-binding protein ABF1 exists in at least two different electrophoretic forms (K. S. Sweder, P. R. Rhode, and J. L. Campbell, J. Biol. Chem. 263: 17270-17277, 1988). In this report, we show that these forms represent different states of phosphorylation of ABF1 and that at least four different phosphorylation states can be resolved electrophoretically. The ratios of these states to one another differ according to growth conditions and carbon source. Phosphorylation of ABF1 is therefore a regulated process. In nitrogen-starved cells or in cells grown on nonfermentable carbon sources (e.g., lactate), phosphorylated forms predominate, while in cells grown on fermentable carbon sources (e.g., glucose), dephosphorylated forms are enriched. The phosphorylation pattern is affected by mutations in the SNF1-SSN6 pathway, which is involved in glucose repression-depression. Whereas a functional SNF1 gene, which encodes a protein kinase, is not required for the phosphorylation of ABF1, a functional SSN6 gene is required for itsd ephosphorylation. The phosphorylation patterns that we have observed correlate with the regulation of a specific target gene, COX6, which encodes subunit VI of cytochrome c oxidase. Transcription of COX6 is repressed by growth in medium containing a fermentable carbon source and is derepressed by growth in medium containing a nonfermentable carbon source. COX6 repression-derepression is under the control of the SNF1-SSN6 pathway. This carbon source regulation is exerted through domain 1, a region of the upstream activation sequence UAS6 that binds ABF1 (J. D. Trawick, N. Kraut, F. Simon, and R. O. Poyton, Mol. Cell Biol. 12:2302-2314, 1992). We show that the greater the phosphorylation of ABF1, the greater the transcription of COX6. Furthermore, the ABF1-containing protein-DNA complexes formed at domain 1 differ according to the phosphorylation state of ABF1 and the carbon source on which the cells were grown. From these findings, we propose that the phosphorylation of ABF1 is involved in glucose repression-derepression of COX6 transcription.


2005 ◽  
Vol 4 (5) ◽  
pp. 861-866 ◽  
Author(s):  
Myoung-Dong Kim ◽  
Seung-Pyo Hong ◽  
Marian Carlson

ABSTRACT In Saccharomyces cerevisiae, Snf1 protein kinase of the Snf1/AMP-activated protein kinase family is required for growth on nonfermentable carbon sources and nonpreferred sugars. Three kinases, Pak1, Elm1, and Tos3, activate Snf1 by phosphorylation of its activation-loop threonine, and the absence of all three causes the Snf− phenotype. No phenotype has previously been reported for the tos3Δ single mutation. We show here that, when cells are grown on glycerol-ethanol, tos3Δ reduces growth rate, Snf1 catalytic activity, and activation of the Snf1-dependent carbon source-responsive element (CSRE) in the promoters of gluconeogenic genes. In contrast, tos3Δ did not significantly affect Snf1 catalytic activity or CSRE function during abrupt glucose depletion, indicating that Tos3 has a more substantial role in activating Snf1 protein kinase during growth on a nonfermentable carbon source than during acute carbon stress. We also report that Tos3 is localized in the cytosol during growth in either glucose or glycerol-ethanol. These findings lend support to the idea that the Snf1 protein kinase kinases make different contributions to cellular regulation under different growth conditions.


Author(s):  
Vivek Kumar Ranjan ◽  
Shriparna Mukherjee ◽  
Subarna Thakur ◽  
Krutika Gupta ◽  
Ranadhir Chakraborty

2008 ◽  
Vol 5 (4) ◽  
pp. 367-374 ◽  
Author(s):  
Jing Wang ◽  
Guiwen Yan ◽  
Mingquan An ◽  
Jieli Liu ◽  
Houming Zhang ◽  
...  

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