Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transcription of Rhodobacter capsulatus genes encoding the nitrogenase polypeptides (nifHDK) is repressed by fixed nitrogen and oxygen. R. capsulatus nifA1 and nifA2 encode identical NIFA proteins that activate transcription of nifHDK and other nif genes. In this study, we report that nifA1-lacZ and nifA2-lacZ fusions are repressed in the presence of NH3 and activated to similar levels under nitrogen-deficient conditions. This nitrogen-controlled activation was dependent on R. capsulatus ntrC (which encodes a transcriptional activator) but not rpoN (which encodes an RNA polymerase sigma factor). We have used primer extension analyses of nifA1, nifA2 and nifH and deletion analyses of nifA1 and nifA2 upstream regions to define likely promoters and cis upstream activation sequences required for nitrogen control of these genes. Primer extension mapping confirmed that ntrC but not rpoN is required for nifA1 and nifA2 activation, and that nifA1 and nifA2 do not possess typical RPON-activated promoters.
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PMID:Analysis of the promoters and upstream sequences of nifA1 and nifA2 in Rhodobacter capsulatus; activation requires ntrC but not rpoN. 137 28

Affinity cleaving proteins have been synthesized based on the DNA-binding domain of the yeast transcriptional activator GCN4 with the DNA cleaving moiety Fe.EDTA attached at the NH2 terminus [Oakley, M. G., & Dervan, P. B. (1990) Science 248, 847]. Cleavage patterns generated by Fe-EDTA-GCN4(226-281) bound to the DNA sites 5'-CTGACTAAT-3' and 5'-ATGACTCTT-3' reveal that the NH2 termini of the GCN4 DNA-binding domain are located in the major groove of DNA, 9-10 base pairs apart, consistent with a Y-shaped dimeric structure. 1-Methylimidazole-2-carboxamide netropsin (2-ImN) is a designed synthetic peptide which binds in the minor groove of DNA at 5'-TGACT-3' sites as an antiparallel, side-by-side dimer [Mrksich, M., Wade, W. S., Dwyer, T. J., Geierstanger, B. H., Wemmer, D.E., & Dervan, P. B. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 7586]. Through the use of Fe.EDTA-GCN4(226-281) as a sequence-specific footprinting agent, it is shown that the dimeric protein GCN4-(226-281) and the dimeric peptide 2-ImN can simultaneously occupy their common binding site in the major and minor grooves of DNA, respectively. The association constants for 2-ImN in the presence and in the absence of Fe.EDTA-GCN4(226-281) are found to be similar, suggesting that the binding of the two dimers is not cooperative.
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PMID:Evidence that a minor groove-binding peptide and a major groove-binding protein can simultaneously occupy a common site on DNA. 144 35

As part of a study of transcriptional regulation by viral proteins, we examined whether an acidic region from a regulatory protein of an RNA virus could function as a trans-activator. The NH2-terminal highly acidic domain I of the phosphoprotein (P) of vesicular stomatitis virus (VSV) was fused to the DNA-binding domain of the yeast trans-activator, GAL4. In transient transfection assays, the resulting chimeric protein failed to activate transcription of a reporter CAT gene. However, mutation of basic amino acid residues located at positions 6 and 8 or the alteration of eight amino acids within the acidic domain to eight different amino acids converted the chimeric protein into a transcriptional activator comparable to wild-type GAL4. When subjected to SDS-polyacrylamide gel electrophoresis, the P proteins containing trans-activation-positive mutations in domain I showed an altered mobility, suggesting that these mutations may have caused a conformational change that is critical for trans-activation. Since the acidity of P domain I is not sufficient to activate transcription, additional features of this region must play an important role in GAL4-mediated trans-activation. None of the trans-activation-positive mutants supported VSV RNA transcription in vitro. These results suggest that the amino acid residues within P domain I that can be made to function in the trans-activation of DNA-dependent RNA transcription are distinct from those involved in VSV RNA-dependent RNA transcription.
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PMID:Alteration of specific amino acid residues in the acidic domain I of VSV phosphoprotein (P) converts a GAL4-P(I) hybrid into a transcriptional activator. 165 11

The substrate specificity of the cAMP-dependent protein kinase (cAPK) from Saccharomyces cerevisiae has been investigated using synthetic peptides corresponding to the local phosphorylation site sequence around Ser-230 in the yeast transcriptional activator ADR1. ADR1 is required for the expression of the glucose-repressible alcohol dehydrogenase. Yeast cAPK (encoded by the TPK1 gene) phosphorylated Ser-230 in the synthetic peptide ADR1-217-234, VRKRYLKKLTRRASFSAQ-NH2, with a Km of 5.3 microM compared with 46 microM for LRRASLG (Kemptide). Porcine heart cAPK phosphorylated the ADR1 peptide and Kemptide with the considerable lower Km values of 0.23 and 1.6 microM, respectively. These results indicate that the ADR1 peptide is an excellent substrate for cAPK. Both the yeast and mammalian protein kinases qualitatively shared a number of substrate specificity determinants in common involving residues on the proximal NH2-terminal side and up to the +4 position of the COOH-terminal side of the phosphoacceptor. The mammalian enzyme, however, had a much higher affinity for its substrates than did the yeast enzyme. In addition, the yeast and mammalian enzymes displayed several quantitative differences in their preferences for particular peptide substrates. In particular, the mammalian enzyme strongly preferred substrates with NH2-terminal extensions beyond the -4 position relative to the phosphoacceptor. These results suggest that all eukaryotic cAPKs recognize similar but not identical substrate specificity determinants. They also suggest that the different affinities for substrates that inhere to the individual enzymes could influence their physiological roles.
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PMID:Substrate specificities for yeast and mammalian cAMP-dependent protein kinases are similar but not identical. 191 32

The NH2-terminal locations of a dimer containing the DNA binding domain of the yeast transcriptional activator GCN4 have been mapped on the binding sites 5'-CTGACTAAT-3' and 5'-ATGACTCTT-3'. Affinity cleaving was effected by synthetic GCN4 proteins with Fe.EDTA moieties at the NH2-terminus. Analysis of the DNA cleavage patterns for dimers of the Fe.EDTA-proteins corresponding to GCN4 residues 222 to 281 and 226 to 281 revealed that the NH2-termini were in the major groove nine to ten base pairs apart and were symmetrically displaced four to five base pairs from the central C of the recognition site. This result is consistent with the Y-shaped scissor grip-leucine zipper model recently proposed for a class of DNA binding proteins important in the regulation of gene expression.
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PMID:Structural motif of the GCN4 DNA binding domain characterized by affinity cleaving. 211 78

The ada gene of Escherichia coli encodes a 39-kDa protein which serves both as a transcriptional activator of the adaptive response to alkylating agents and as a DNA repair enzyme demethylating O6-methyl-guanine and phosphotriester residues. Here, the isolated Ada protein was found to be readily cleaved into two fragments of similar size by treatment with trypsin, chymotrypsin, subtilisin, or V8 protease. The fragments retained their respective methyltransferase activities. The Ada protein is, therefore, comprised of two stable active domains united by a central hinge region of about 10 amino acids. Post-translational modification of the Ada protein by methylation of a specific cysteine residue in the NH2-terminal domain is known to convert it to an efficient transcriptional activator. This residue has now been identified as Cys-69.
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PMID:Functional domains and methyl acceptor sites of the Escherichia coli ada protein. 316 36

The amino acid sequence of the Bradyrhizobium japonicum nitrogen fixation regulatory protein NifA, as derived from the nucleotide sequence of the nifA gene, was aligned to the corresponding protein sequences from Klebsiella pneumoniae, Rhizobium meliloti and Rhizobium leguminosarum biovar viciae. High conservation was found in the central domain and in the COOH-terminal, putative DNA binding domain, whereas very little homology was present within the first 250 amino acids from the NH2-terminus. Upon deletion of the first 218 amino acids (37% of the protein) and expression of the remainder as a Cat'-'NifA hybrid protein, a fully active, nif-specific transcriptional activator protein was obtained which also retained oxygen sensitivity, a characteristic property of the wild-type B. japonicum NifA protein. In contrast, an unaltered COOH-terminal domain was required for an active NifA protein. Between the central and the DNA binding domains, a so-called interdomain linker region was identified which was conserved in all rhizobial species but missing in the K.pneumoniae NifA protein. Two conserved cysteine residues in this region were changed to serine residues, by oligonucleotide-directed mutagenesis. This resulted in absolutely inactive NifA mutant proteins. Similar null phenotypes were obtained by altering two closely adjacent cysteine residues in the central domain to serine residues. Nif gene activation in vivo by the B.japonicum NifA protein, but not by the K.pneumoniae NifA protein, was sensitive to treatment with chelating agents, and this inhibition could be overcome by the addition of divalent metal ions. On the basis of these observations and previous data on oxygen sensitivity we raise the hypothesis that at least some, if not all, of the four essential cysteine residues may be involved in oxygen reactivity or metal binding or both.
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PMID:Essential and non-essential domains in the Bradyrhizobium japonicum NifA protein: identification of indispensable cysteine residues potentially involved in redox reactivity and/or metal binding. 335 73

We have purified the phage lambda transcriptional activator protein cII. The procedure described allows cII to be obtained in both high purity and yield, and thus allows detailed physical and chemical analysis. We demonstrate that cII in solution is a tetrameric protein and that it undergoes specific processing at its NH2-terminal end. In addition, the protein is characterized as to its molar extinction coefficient, molecular weight, amino acid composition, isoelectric point, alpha-helical content, and antigenic capability.
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PMID:Purification and properties of a transcriptional activator. The cII protein of phage lambda. 621 85

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

Nitrogen regulation of transcription in Escherichia coli requires sensation of the intracellular nitrogen status and control of the dephosphorylation of the transcriptional activator NRI-P. This dephosphorylation is catalyzed by the bifunctional kinase/phosphatase NRII in the presence of the dissociable PII protein. The ability of PII to stimulate the phosphatase activity of NRII is regulated by a signal transducing uridylyltransferase/uridylyl-removing enzyme (UTase/UR), which converts PII to PII-UMP under conditions of nitrogen starvation; this modification prevents PII from stimulating the dephosphorylation of NRI approximately P. We used purified components to examine the binding of small molecules to PII, the effect of small molecules on the stimulation of the NRII phosphatase activity by PII, the retention of PII on immobilized NRII, and the regulation of the uridylylation of PII by the UTase/UR enzyme. Our results indicate that PII is activated upon binding ATP and either 2-ketoglutarate or glutamate, and that the liganded form of PII binds much better to immobilized NRII. We also demonstrate that the concentration of glutamine required to inhibit the uridylyltransferase activity is independent of the concentration of 2-ketoglutarate present. We hypothesize that nitrogen sensation in E. coli involves the separate measurement of glutamine by the UTase/UR protein and 2-ketoglutarate by the PII protein.
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PMID:The Escherichia coli PII signal transduction protein is activated upon binding 2-ketoglutarate and ATP. 762 80


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