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Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Inactivation of the centromere-binding factor 1 (CBF1) gene results in yeast strains that require methionine for growth. This auxotrophy is due to the inability of such strains to concentrate and assimilate sulfate from the medium. Northern (RNA) blot experiments reveal that the CBF1 protein is required for full induction of MET25 and MET16 gene transcription. However, we show that induction of the sulfate assimilation pathway is not achieved solely by CBF1. This induction also requires the integrity of a positive trans-acting factor, encoded by the MET4 gene. The MET4 gene was cloned, and its sequence reveals that it encodes a protein related to the family of the bZIP transcriptional activators. Evidence that MET4 is a transcriptional activator was provided by demonstrating that DNA-bound LexA-MET4 fusion proteins stimulate expression of a nearby promoter. The use of LexA-MET4 fusion proteins also reveals that the leucine zipper of MET4 is required for the recognition of the MET25 promoter. Moreover, an 18-bp fragment of the MET25 5' upstream region was found to confer S-adenosylmethionine-dependent regulation of a fusion gene. This regulation was shown to depend on both MET4 and CBF1. The obtained results suggest that the binding of CBF1 to its cognate sequences increases the ability of MET4 to stimulate transcription of the MET genes.
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PMID:MET4, a leucine zipper protein, and centromere-binding factor 1 are both required for transcriptional activation of sulfur metabolism in Saccharomyces cerevisiae. 154 23

GAL4I, GAL4II, and GAL4III are three forms of the yeast transcriptional activator protein that are readily distinguished on the basis of electrophoretic mobility during sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Phosphorylation accounts for the reduced mobility of the slowest-migrating form, GAL4III, which is found to be closely associated with high-level GAL/MEL gene expression (L. Mylin, P. Bhat, and J. Hopper, Genes Dev. 3:1157-1165, 1989). Here we show that GAL4II, like GAL4III, can be converted to GAL4I by phosphatase treatment, suggesting that in vivo GAL4II is derived from GAL4I by phosphorylation. We found that cells which overproduced GAL4 under conditions in which it drove moderate to low levels of GAL/MEL gene expression showed only forms GAL4I and GAL4II. To distinguish which forms of GAL4 (GAL4I, GAL4II, or both) might be responsible for transcription activation in the absence of GAL4III, we performed immunoblot analysis on UASgal-binding-competent GAL4 proteins from four gal4 missense mutants selected for their inability to activate transcription (M. Johnston and J. Dover, Proc. Natl. Acad. Sci. USA 84:2401-2405, 1987; Genetics 120;63-74, 1988). The three mutants with no detectable GAL1 expression did not appear to form GAL4II or GAL4III, but revertants in which GAL4-dependent transcription was restored did display GAL4II- or GAL4III-like electrophoretic species. Detection of GAL4II in a UASgal-binding mutant suggests that neither UASgal binding nor GAL/MEL gene activation is required for the formation of GAL4II. Overall, our results imply that GAL4I may be inactive in transcriptional activation, whereas GAL4II appears to be active. In light of this work, we hypothesize that phosphorylation of GAL4I makes it competent to activate transcription.
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PMID:Phosphorylated forms of GAL4 are correlated with ability to activate transcription. 220 97

The human progesterone receptor (PR) is a member of the steroid/thyroid hormone superfamily of nuclear receptors. The receptor is expressed as two forms, PR-B and the shorter PR-A, which lacks the NH2-terminal 164 amino acids of PR-B; whereas PR-B seems to be predominantly a transcriptional activator, PR-A also functions as a repressor. Our previous studies of PR expressed in T47D breast cancer cells have shown that PR is a phosphoprotein whose phosphorylation is enhanced in response to hormone. There is an initial rapid (minutes) increase in phosphorylation followed by a slower, less substantial increase, which results in decreased mobility of the receptor on sodium dodecyl sulfate gels. We now report the identification of three phosphorylation sites, which are predominantly phosphorylated during the later phase of the response to hormone. These sites, Ser102, Ser294, and Ser345, are all found in Ser-Pro consensus sequences. Whereas Ser294 and Ser345 are common to PR-A and PR-B, Ser102 is unique to PR-B. Finally, we demonstrate that phosphorylation of Ser345 is associated with the altered mobility on sodium dodecyl sulfate gels.
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PMID:Identification of a group of Ser-Pro motif hormone-inducible phosphorylation sites in the human progesterone receptor. 747 77

Expression of the soluble (SH) and membrane-bound (MBH) hydrogenases in the facultatively lithoautotrophic bacterium Alcaligenes eutrophus is dependent on the transcriptional activator HoxA and the alternative sigma factor sigma 54. Deletion analysis revealed that a region 170 bp upstream of the transcriptional start of the SH operon is necessary for high-level promoter activity. Mobility shift assays with DNA fragments containing the SH upstream region and purified beta-galactosidase-HoxA fusion protein isolated from Escherichia coli or authentic HoxA isolated by immunoaffinity chromatography from A. eutrophus failed to detect specific binding. In contrast, A. eutrophus extracts enriched for HoxA by heparin-Sepharose chromatography and ammonium sulfate fractionation produced a weak but discrete shift in the mobility of the target DNA. This effect was not observed with comparable extracts prepared from hoxA mutants. A similar experiment using antibodies against HoxA confirmed that HoxA was responsible for the observed mobility shift. Extracts prepared from a temperature-tolerant mutant of A. eutrophus gave a stronger retardation than did those from the wild type. Unlike the wild type, the hox(Tr) mutant is able to grow with hydrogen at temperatures above 33 degrees C because of a mutation in the regulatory gene hoxA. In this paper, we show that a single amino acid substitution (Gly-468-->Val) in the C-terminal part of HoxA is responsible for temperature tolerance. The SH upstream region also contains sequence motifs resembling the E. coli integration host factor (IHF) binding site, and purified E. coli IHF protein shifted the corresponding indicator fragment.
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PMID:Temperature tolerance of hydrogenase expression in Alcaligenes eutrophus is conferred by a single amino acid exchange in the transcriptional activator HoxA. 773 Feb 67

Controlled protease cleavage experiments and N-terminal sequence analyses were used to show that the transcriptional activator MotA from bacteriophage T4 has a two-domain structure. The N and C-terminal domains have M(r) values of 10,300 and 11,800, respectively, and were separately cloned and overexpressed in Escherichia coli. One and two-dimensional NMR spectroscopy indicate that both domains have stably folded structures and contain extensive secondary structure. The N-terminal domain is substantially alpha-helical, whereas the C-terminal domain has a high content of beta-strand. The N-terminal domain has been crystallized under three different conditions, all with the space group P3(1(2))21 and similar unit cell dimensions. The best crystals are grown from ammonium sulfate, have cell dimensions a = b = 46.7 A, c = 139.6 A, and diffract to beyond 2.4 A. The high quality of the NMR and diffraction data will allow a complete structural analysis of MotA by a combination of these techniques.
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PMID:The MotA protein from bacteriophage T4 contains two domains. Preliminary structural analysis by X-ray diffraction and nuclear magnetic resonance. 833 66

The Klebsiella aerogenes nac gene, whose product is necessary for nitrogen regulation of a number of operons, was identified and its DNA sequence determined. The nac sequence predicted a protein a 305 amino acids with a strong similarity to members of the LysR family of regulatory proteins, especially OxyR from Escherichia coli. Analysis of proteins expressed in minicells showed that nac is a single-gene operon whose product has an apparent molecular weight of about 32 kDa as measured in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immediately downstream from nac is a two-gene operon, the first gene of which encodes another member of the LysR family. Upstream from nac is a tRNAAsn gene transcribed divergently from nac. About 60 bp upstream from the nac open reading frame lies a sequence nearly identical to the consensus for sigma 54-dependent promoters, with the conserved GG and GC nucleotides at -26 and -14 relative to the start of transcription. About 130 bp farther upstream (at -153 relative to the start of transcription) is a sequence nearly identical to the transcriptional activator NTRC-responsive enhancer consensus. Another weaker NTRC-binding site is located adjacent to this site (at -133 relative to the start of transcription). Thus, we propose that nac is transcribed by RNA polymerase carrying sigma 54 in response to the nitrogen regulatory (NTR) system. A transposon located between the promoter and the nac ORF prevented NTR-mediated expression of nac, supporting this identification of the promoter sequence. The insertion of over 5 kb of transposon DNA between the enhancer and its target promoter had only a weak effect on enhancer-mediated regulation, suggesting that enhancers may be able to act at a considerable distance on the bacterial chromosome.
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PMID:The nac (nitrogen assimilation control) gene from Klebsiella aerogenes. 845 53

A specific repression mechanism regulates the biosynthesis of sulfur amino acids in Saccharomyces cerevisiae. When the intracellular S-adenosylmethionine (AdoMet) concentration increases, transcription of the sulfur genes is repressed. Using a specific reporter system, we have isolated mutations impairing the AdoMet-mediated transcriptional regulation of the sulfur network. These mutations identified a new gene, MET30, and were shown to also affect the regulation of the methyl cycle. The MET30 gene was isolated and sequenced. Sequence analysis reveals that Met30p contains five copies of the WD40 motif within its carboxy-terminal part, like the yeast transcriptional repressors Hir1p and Tup1p. We identified one target of Met30p as Met4p, a transcriptional activator regulating the sulfate assimilation pathway. By the two-hybrid method, we showed that Met30p interacts with Met4p and identified a region of Met4p involved in this interaction. Further analysis reveals that expression of Met30p is essential for cell viability.
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PMID:Met30p, a yeast transcriptional inhibitor that responds to S-adenosylmethionine, is an essential protein with WD40 repeats. 852 17

The structural gene for copper- and topa quinone-containing monoamine oxidase (maoA) and an unknown amine oxidase gene have been located at 30.9 min on the Escherichia coli chromosome. Deletion analysis showed that the unknown gene was located within a 1.1-kb cloned fragment adjacent to the maoA gene. The nucleotide sequence of this fragment was determined, and a single open reading frame (maoB) consisting of 903 bp was found. The gene encoded a polypeptide with a predicted molecular mass of 34,619 Da which was correlated with the migration on a sodium dodecyl sulfate-polyacrylamide gel. The predicted amino acid sequence of the MaoB protein was identical to the NH2-terminal amino acid sequence derived by Edman degradation of the protein synthesized under the self-promoter. No homology of the nucleotide sequence of maoB to the sequences of any reported genes was found. However, the amino acid sequence of MaoB showed a high level of homology with respect to the helix-turn-helix motif of the AraC family in its C terminus. The homology search and disruption of maoA on the chromosome led to the conclusion that MaoB is a transcriptional activator of maoA but not an amine oxidase. The consensus sequence of the cyclic AMP-cyclic AMP receptor protein complex binding domain was adjacent to the putative promoter for the maoB gene. By use of lac gene fusions with the maoA and maoB genes, we showed that the maoA gene is regulated by tyramine and MaoB and that the expression of the maoB gene is subject to catabolite repression. Thus, it seems likely that tyramine and the MaoB protein activate the transcription of maoA by binding to the regulatory region of the maoA gene.
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PMID:maoB, a gene that encodes a positive regulator of the monoamine oxidase gene (maoA) in Escherichia coli. 863 85

Genes whose expression is regulated by sulfate starvation in Escherichia coli were identified by generating random translational lacZ fusions in the chromosome with the lambda placMu9 system. Nine lacZ fusion strains which expressed beta-galactosidase after growth under sulfate starvation conditions but not after growth in the presence of sulfate were found. These included two strains with insertions in the dmsA and rhsD genes, respectively, and seven strains in which the insertions were located within a 1.8-kb region downstream of hemB at 8.5 minutes on the E. coli chromosome. Analysis of the nucleotide sequence of this region indicated the presence of four open reading frames designated tauABCD. Disruption of these genes resulted in the loss of the ability to utilize taurine (2-aminoethanesulfonate) as a source of sulfur but did not affect the utilization of a range of other aliphatic sulfonates as sulfur sources. The TauA protein contained a putative signal peptide for transport into the periplasm; the TauB and TauC proteins showed sequence similarity to ATP-binding proteins and membrane proteins, respectively, of ABC-type transport systems; and the TauD protein was related in sequence to a dichlorophenoxyacetic acid dioxygenase. We therefore suggest that the proteins encoded by tauABC constitute an uptake system for taurine and that the product of tauD is involved in the oxygenolytic release of sulfite from taurine. The transcription initiation site was detected 26 to 27 bp upstream of the translational start site of tauA. Expression of the tauD gene was dependent on CysB, the transcriptional activator of the cysteine regulon.
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PMID:Identification of sulfate starvation-regulated genes in Escherichia coli: a gene cluster involved in the utilization of taurine as a sulfur source. 880 33

The Cat8p zinc cluster protein is essential for growth of Saccharomyces cerevisiae with nonfermentable carbon sources. Expression of the CAT8 gene is subject to glucose repression mainly caused by Mig1p. Unexpectedly, the deletion of the Mig1p-binding motif within the CAT8 promoter did not increase CAT8 transcription; moreover, it resulted in a loss of CAT8 promoter activation. Insertion experiments with a promoter test plasmid confirmed that this regulatory 20-bp element influences glucose repression and derepression as well. This finding suggests an upstream activating function of this promoter region, which is Mig1p independent, as delta mig1 mutants are still able to derepress the CAT8 promoter. No other putative binding sites such as a Hap2/3/4/5p site and an Abf1p consensus site were functional with respect to glucose-regulated CAT8 expression. Fusions of Cat8p with the Gal4p DNA-binding domain mediated transcriptional activation. This activation capacity was still carbon source regulated and depended on the Cat1p (Snf1p) protein kinase, which indicated that Cat8p needs posttranslational modification to reveal its gene-activating function. Indeed, Western blot analysis on sodium dodecyl sulfate-gels revealed a single band (Cat8pI) with crude extracts from glucose-grown cells, whereas three bands (Cat8pI, -II, and -III) were identified in derepressed cells. Derepression-specific Cat8pII and -III resulted from differential phosphorylation, as shown by phosphatase treatment. Only the most extensively phosphorylated modification (Cat8pIII) depended on the Cat1p (Snf1p) kinase, indicating that another protein kinase is responsible for modification form Cat8pII. The occurrence of Cat8pIII was strongly correlated with the derepression of gluconeogenic enzymes (phosphoenolpyruvate carboxykinase and fructose-1,6-bisphosphatase) and gluconeogenic PCK1 mRNA. Furthermore, glucose triggered the dephosphorylation of Cat8pIII, but this did not depend on the Glc7p (Cid1p) phosphatase previously described as being involved in invertase repression. These results confirm our current model that glucose derepression of gluconeogenic genes needs Cat8p phosphorylation and additionally show that a still unknown transcriptional activator is also involved.
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PMID:Glucose derepression of gluconeogenic enzymes in Saccharomyces cerevisiae correlates with phosphorylation of the gene activator Cat8p. 911 19


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