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)

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 DNA sequence upstream of the dhlB gene encoding the haloalkanoic acid dehalogenase of Xanthobacter autotrophicus GJ10 was determined and contained an open reading frame, designated dhlC, which encoded a protein with a significant similarity with the family of Na(+)-dependent symport proteins. The dhlC gene was subcloned under control of a T7 promoter, and found to encode a polypeptide of 45 kDa on SDS-PAGE. Upstream of dhlC, a -24/-12 promoter sequence was found. Further upstream, in the opposite direction of transcription, another open reading frame, designated dhlR, with homology with the family of sigma 54-dependent transcriptional activator proteins was detected. The dhlR gene was cloned and expressed under the control of a T7 promoter and encoded a polypeptide of 51 kDa on SDS-PAGE. The genetic organization of the dhlB region suggested that the expression of dhlC and dhlB was controlled by the product of dhlR and sigma 54 which may explain the observed overexpression of the haloalkanoic acid dehalogenase under starvation conditions.
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PMID:Sequence analysis of the upstream region of dhlB, the gene encoding haloalkanoic acid dehalogenase of Xanthobacter autotrophicus GJ10. 758

Nucleoside diphosphate kinases (NDPKs) catalyze the transfer of high-energy phosphates from nucleoside triphosphates to nucleoside diphosphates and may be involved in the regulation of growth, development, and signal transduction processes. We report here the purification and characterization of NDPK from detergent-solubilized extracts of dark-grown oat (Avena) tissue. The purification was achieved primarily through adsorption to GTP-agarose, followed by elution with ATP. SDS-polyacrylamide gel electrophoresis and gel filtration chromatography indicated that the purified protein is composed of six 18 kDa subunits. Substrate specificity experiments indicated that the purified kinase is capable of using all tested nucleosides as substrates. N-terminal sequencing of the Avena protein revealed that 87% of the 23 amino acids sequenced were identical to the human Nm23 protein, a nucleoside diphosphate kinase identified as a possible tumor metastasis suppressor and transcriptional activator of the myc oncogene.
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PMID:A plant nucleoside diphosphate kinase homologous to the human Nm23 gene product: purification and characterization. 803 16

The sequences of two previously known tail genes, R and S, of the temperate bacteriophage P2 and the sequence of an additional open reading frame (orf-30) located between S and V, were determined. Amber mutations mapping within R and S, Ram3, Ram42, Ram23, Sam75, and Sam89 were sequenced and found to be within their corresponding open reading frames. We constructed overproducing plasmids for R and S and identified these proteins by SDS-PAGE of whole-cell lysates and Coomassie blue staining. The predicted molecular masses of proteins R and S were M(r) 17,400 and 17,300, respectively, although both polypeptides migrated more slowly during gel electrophoresis than would be expected from the sequence data. orf-30 occupies the strand opposite from RS and V and is preceded by several weak potential sigma 70-RNA polymerase promoters, some of which overlap with the V promoter. A construct that had the putative orf-30 promoter region upstream of the lacZ gene produced low levels of beta-galactosidase activity in vivo. Expression from the orf-30 promoter was not stimulated by the phage P4 transcriptional activator protein, delta, which acts at all the known P2 and P4 late promoters. Insertion mutagenesis showed that orf-30 was not an essential gene for P2 growth in Escherichia coli. None of the gene or protein sequences exhibited extensive homology to sequences in the nucleic acid and protein databases. However, the R protein contains a small region homologous to one in the phage T4 tail protein gp15, which is required for T4 tails to bind heads. We propose that R and S are tail completion proteins that are essential for stable head joining.
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PMID:Molecular cloning and characterization of bacteriophage P2 genes R and S involved in tail completion. 817 26

A genomic gene of tritin, a ribosome-inactivating protein (RIP) from Triticum aestivum, was cloned using a barley RIP gene as a probe. The 5'-non-coding region has potential TATA boxes and three sequences homologous to the binding sequence of the transcriptional activator protein Opaque-2 which activates maize RIP gene expression. The cloned DNA encoded tritin consists of 275 amino acids with no secretion signal sequence. The coding region of tritin was expressed in Escherichia coli using lac promoter and yielded a protein similar to the native one, as determined by SDS-polyacrylamide gel electrophoresis and immunological analysis.
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PMID:Nucleotide sequence of a genomic gene encoding tritin, a ribosome-inactivating protein from Triticum aestivum. 849 16

Stabilization of mRNA is important in the regulation of CYP2a5 expression but the factors involved in the process are not known [Aida and Negishi (1991) Biochemistry 30, 8041-8045]. In this paper, we describe, for the first time, a protein that binds specifically to the 3'-untranslated region of CYP2a5 mRNA and which is inducible by pyrazole, a compound known to increase the half-life of CYP2a5 mRNA. We also demonstrate that pyrazole treatment causes an elongation of the CYP2a5 mRNA poly(A) tail, and that phenobarbital, which is transcriptional activator of the CYP2a5 gene that does not affect the mRNA half-life, neither induces the RNA-binding protein nor affects the poly(A) tail size. SDS/PAGE of the UV-cross-linked RNA-protein complex demonstrated that the RNA-binding protein has an apparent molecular mass of 44 kDa. The protein-binding site was localized to a 70-nucleotide region between bases 1585 and 1655. Treatment of cytoplasmic extracts with an SH-oxidizing agent, diamide, an SH-blocking agent, N-ethylmaleimide or potato acid phosphatase abolished complex-formation, suggesting that the CYP2a5 mRNA-binding protein is subject to post-translational regulation. Subcellular fractionation showed that the 44 kDa protein is present in polyribosomes and nuclei, and that its apparent induction is much stronger in polyribosomes than in nuclear extracts. We propose that this 44 kDa RNA-binding protein is involved in the stabilization of CYP2a5 mRNA by controlling the length of the poly(A) tail.
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PMID:Identification and characterization of a 44 kDa protein that binds specifically to the 3'-untranslated region of CYP2a5 mRNA: inducibility, subcellular distribution and possible role in mRNA stabilization. 861 Nov 42

In the maize endosperm, the Opaque2 (O2) basic leucine zipper transcriptional activator regulates the expression of a subset of the zein seed storage protein gene family. Immunodetection of wild-type or mutant O2 polypeptides fractionated by SDS-PAGE resolved a closely spaced doublet migrating in the 68- to 72-kD range, whereas by using isoelectric focusing, seven to nine isoforms were detected for each allele. Phosphatase treatment simplified the protein patterns to a single band corresponding to the nonphosphorylated component. In vivo and in vitro labeling confirmed that O2 can be phosphorylated. In protein gel blots probed with DNA, only the nonphosphorylated and hypophosphorylated O2 polypeptides were able to bind an oligonucleotide containing the O2 binding sequence. Upon in situ dephosphorylation of the focused isoforms by phosphatase treatment of the isoelectric focusing filter, the hyperphosphorylated forms acquired DNA binding activity. The ratio among the various isoforms remained constant throughout the developmental stages of endosperm growth but changed from daytime to nighttime, with a significant increase of the hyperphosphorylated forms during the night period. These results indicate that O2 exists in vivo as a pool of differently phosphorylated polypeptides and demonstrate that O2 DNA binding activity is modulated by a phosphorylation/dephosphorylation mechanism that appears to be influenced by environmental conditions.
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PMID:Phosphorylation of Opaque2 changes diurnally and impacts its DNA binding activity. 901 67

The promoter of the amyloid beta-protein precursor (APP) gene directs high levels of cell type-specific transcription with 94 base pairs 5' to the main transcriptional start site. An essential activator domain in this proximal APP promoter is a nuclear factor binding site designated as APBbeta. The recognition domain for the APBbeta binding factor is located between position -93 and -82 relative to the main transcriptional start site. The nuclear factor that binds to the APBbeta site was partially purified by multiple steps of ion exchange and hydroxyapatite chromatography. Based on UV cross-linking results, a protein with an apparent molecular mass of 140 kDa was selected as the putative APBbeta binding protein. After the final purification step consisting of preparative SDS-polyacrylamide gel electrophoresis, partial peptide sequences were obtained that completely matched the transcriptional factor CTCF. This protein is a known regulator of c-myc and lysozyme gene expression, and it binds to a variety of diverse DNA sequences. The binding of CTCF to the APBbeta domain was further established by competition with CTCF binding oligonucleotides in mobility shift electrophoresis. The identity was also confirmed by the observation that the APBbeta binding factor is recognized by antibodies against C- and N-terminal sequences of CTCF. In addition, oligonucleotide competition during in vitro transcription affirmed that CTCF acts as a transcriptional activator in the APP gene promoter.
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PMID:The zinc finger protein CTCF binds to the APBbeta domain of the amyloid beta-protein precursor promoter. Evidence for a role in transcriptional activation. 940 28

The noncovalent association of transmembrane alpha-helices is a fundamental event in the folding of helical membrane proteins. In this work, a system (TOXCAT) is developed for the study of transmembrane helix-helix oligomerization in a natural membrane environment. This assay uses a chimeric construct composed of the N-terminal DNA binding domain of ToxR (a dimerization-dependent transcriptional activator) fused to a transmembrane domain (tm) of interest and a monomeric periplasmic anchor (the maltose binding protein). Association of the tms results in the ToxR-mediated activation of a reporter gene encoding chloramphenicol acetyltransferase (CAT). The level of CAT expression indicates the strength of tm association. The assay distinguishes between a known dimerizing tm and a mutant in which dimerization is disrupted. In addition, modulation of the chimera concentration shows that the dimerization exhibits concentration dependence in membranes. TOXCAT also is used to select oligomeric tms from a library of randomized sequences, demonstrating the potential of this system to reveal novel oligomerization motifs. The TOXCAT system has been used to investigate glycophorin A tm-mediated dimerization. Although the overall sensitivity of glycophorin A tm dimerization to mutagenesis is found to be similar in membranes and in detergent micelles, several significant differences exist. Mutations to polar residues, which are generally disruptive in SDS, exhibit sequence specificity in membranes, demonstrating both the limitations of detergent micelles and the wider range of application of the TOXCAT system.
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PMID:TOXCAT: a measure of transmembrane helix association in a biological membrane. 992 59

The OxyR protein is a transcriptional activator for a subset of peroxide stress-inducible genes, most of which are involved in defense systems against oxidative stress. Recently, it was demonstrated that purified OxyR has one intramolecular disulfide bond, which led to the proposal that the reversible disulfide bond formation regulates the activity of OxyR as a transcription factor in response to peroxide stress. In this study, I demonstrated by SDS-PAGE under non-reducing conditions that an intramolecular disulfide bond is formed in OxyR upon exposure of the cells to hydrogen peroxide in vivo. Experiments using strains expressing mutant OxyR proteins with Cys to Ser single amino acids substitutions confirmed that the disulfide bond is formed between the Cys-199 and -208. Kinetic analyses indicated that the formation of the disulfide bond is rapid and transient, oxidized within 30 s and re-reduced within 5 min after the addition of hydrogen peroxide in the wild-type strain. These results provide evidence for the regulatory role of the reversible oxidation of dithiol to disulfide in sensing peroxide stress in vivo and signal transduction to the transcription apparatus by OxyR.
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PMID:In vivo oxidation-reduction kinetics of OxyR, the transcriptional activator for an oxidative stress-inducible regulon in Escherichia coli. 1048 70


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