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)

OmpR is a transcriptional activator for the expression of outer membrane porin genes ompF and ompC in Escherichia coli. Its C-terminal half has been identified as the DNA-binding domain (K. Tsung, R. Brissette, and M. Inouye, J. Biol. Chem. 264:10104-10109, 1989). Recent studies have indicated that the N-terminal non-DNA-binding domain of OmpR is involved in modulating OmpR function through interaction with the EnvZ protein, a kinase and phosphatase for OmpR. We isolated and characterized two mutations, G94D and E111K, in the N-terminal domain of OmpR and one mutation, R182C, in the DNA-binding domain of OmpR. All three mutations abolished the ability of OmpR to bind to the ompF and ompC promoters in vivo, thus giving an OmpF- OmpC- phenotype. The decreased DNA-binding ability of the mutant OmpRs was not due to diminished phosphorylation of their N termini, since all the mutant OmpRs were found to be normally phosphorylated by EnvZ in vitro. The mutant OmpRs produced from multicopy plasmids were also found to inhibit completely the production of OmpF and OmpC in wild-type cells, and the complete inhibition depended on the function of EnvZ which was produced in cis or in trans from plasmids. The relationship of the possible alterations in OmpR by the mutations with the observed diminished binding ability is discussed.
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PMID:Mutations in a central highly conserved non-DNA-binding region of OmpR, an Escherichia coli transcriptional activator, influence its DNA-binding ability. 132 Nov 17

We describe a strategy and reagents for study of protein-protein interactions in mammalian cells, termed the karyoplasmic interaction selection strategy (KISS). With this strategy, specific protein-protein interactions are identified by reconstitution of the functional activity of the yeast transcriptional activator GAL4 and the resultant transcription of a GAL4-regulated reporter gene. Reconstitution of GAL4 function results from specific interaction between two chimeric proteins: one contains the DNA-binding domain of GAL4; the other contains a transcriptional activation domain. Transcription of the reporter gene occurs if the two chimeric proteins can form a complex that reconstitutes the DNA-binding and transcriptional activation functions of GAL4. Using the KISS system, we demonstrate specific interactions for sequences from three different pairs of proteins that complex in the cytoplasm. In addition, we demonstrate that reporter genes encoding cell surface or drug-resistance markers can be specifically activated as a result of protein-protein interactions. With these selectable markers, the KISS system can be used to screen specialized cDNA libraries to identify novel protein interactions.
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PMID:Karyoplasmic interaction selection strategy: a general strategy to detect protein-protein interactions in mammalian cells. 138 9

Tax1 of human T-cell leukemia virus type 1 (HTLV-1) is a transcriptional activator for viral gene expression and is also a transforming protein through inducing the expression of several cellular genes under the control of mitogenic signals. We identified the CArG boxes as a Tax1-responsive cis-acting element for the cellular immediate early genes c-fos, egr-1, and egr-2. Using a chimeric protein consisting of the CArG-binding factor p67SRF and the heterologous DNA-binding domain of a yeast transcription factor GAL4, we demonstrated that Tax1 activates the transcriptional activity of p67SRF through the GAL4-binding site. The carboxy-terminal half of p67SRF, which lacks domains for DNA-binding, dimerization, and ternary complex formation with p62TCF, was sufficient for the activation by Tax1. Tax1 produced in Escherichia coli bound p67SRF in vitro. The complex formation in vivo was also indicated by the finding that the acidic activation domain of VP16, by fusion to p67SRF, can complement the transcriptional activation function of a mutant Tax1 in trans. Thus, Tax1 activates CArG-mediated transcription without mitogenic signals through interaction with a CArG-binding factor, p67SRF. This must be one of the primary steps by which Tax1 causes aberration in growth control of the infected cells.
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PMID:Interaction of HTLV-1 Tax1 with p67SRF causes the aberrant induction of cellular immediate early genes through CArG boxes. 142 72

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

The heat shock transcription factor (HSF) of the yeast Saccharomyces cerevisiae is posttranslationally modified. At low growth temperatures, it activates transcription of heat shock genes only poorly; after shift to high temperatures, it activates transcription readily. In an effort to elucidate the mechanism of this regulation, we constructed a series of HSF-VP16 fusions that join the HSF DNA-binding domain to the strong transcriptional activation domain from the VP16 gene of herpes simplex virus. Replacement of the endogenous C-terminal transcriptional activation domain with that of VP16 generates an HSF derivative that exhibits behavior reminiscent of HSF itself: low transcriptional activation activity at normal growth temperature and high activity after heat shock. HSF can thus restrain the activity of the heterologous VP16 transcriptional activation domain. To determine what is required for repression of activity at low temperature, we deleted portions of HSF from this HSF-VP16 fusion to map the regulatory domain. We also isolated point mutations that convert the HSF-VP16 fusion into a constitutive transcriptional activator. We conclude that the central, evolutionarily conserved domain of HSF, encompassing the DNA-binding and multimerization domains, contains a major determinant of temperature-dependent regulation.
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PMID:Temperature-dependent regulation of a heterologous transcriptional activation domain fused to yeast heat shock transcription factor. 154 86

The ALCR protein is the transcriptional activator of the ethanol utilization pathway in the filamentous fungus Aspergillus nidulans. This activator belongs to a family of fungal proteins having a conserved DNA-binding domain containing six cysteines (C6 class) with some striking features. At variance with other motifs of this class, the binding domain of ALCR is strongly asymmetrical in relation to the central cysteines and moreover was predicted to adopt a helix-turn-helix structure. This domain of ALCR was synthesized in Escherichia coli and purified as a glutathione-S-transferase fusion protein. Our results show that the transcriptional activator ALCR is a DNA-binding protein. The DNA-binding motif contains zinc that is necessary for the specific DNA binding. The ALCR peptide binds upstream of the coding region of alcR to two specific targets with different affinities that are characterized by a conserved 5-nucleotide core, 5'-CCGCA-3' (or its reverse). One site, the lower-affinity binding site, is a direct repeat, and the other, the higher-affinity binding site, is a palindromic sequence with dyad symmetry. Therefore, the ALCR binding protein is able to recognize one DNA sequence in two different configurations. An alcR mutant obtained by deletion of the two specific targets in the cis-acting region of the alcR gene is unable to grow on ethanol and does not express any alcohol dehydrogenase activity. These results demonstrate that the binding sites are in vivo functional targets (UASalc) for the ALCR protein in A. nidulans. They corroborate prior evidence that alcR is autoregulated.
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PMID:Identification of the promoter region involved in the autoregulation of the transcriptional activator ALCR in Aspergillus nidulans. 156 30

The Ku (p70/p80) autoantigen, a heterodimer consisting of 70 kDa (p70) and 80 kDa (p80) protein subunits, is one of a group of DNA-associated autoantigens identified as targets of autoantibodies produced by patients with SLE and related disorders. Many of these DNA-protein antigens are involved in organizing the genome into transcriptionally active (euchromatin) and inactive (heterochromatin) domains. The bulk of available evidence indicates that the Ku antigen is also involved in organizing the genome, although its precise role remains unclear. Molecular cloning of the protein subunits of Ku has revealed that the structure of p70 resembles that of certain transcriptional activator proteins, and there is some evidence in vitro that Ku may increase transcriptional activity from at least two promoters. Moreover, examination of the distribution of Ku in the polytene chromosomes of insects suggests an association with transcriptionally active chromatin. The DNA-binding domain of Ku has been localized to the C-terminus of p70, whereas p80 does not appear to bind DNA, and may be involved in interactions with other proteins. Epitope mapping and mutagenesis experiments have shown that the immunodominant epitope of p70 lies within the DNA-binding domain. Surprisingly, this autoepitope is not conserved between humans and mice, raising the possibility that the interaction of Ku with DNA might exhibit species specific functional differences. At least seven additional autoepitopes have been identified on the Ku particle, located on p70, p80, or both subunits. Autoantibodies to p70, p80, and DNA are produced tandemly by patients with SLE, providing evidence for an antigen-driven immune response targeting the entire Ku particle. The multiple specificities of anti-Ku autoantibodies and the tandem production of antibodies to the various constituents of the Ku particle are consistent with a role of either "molecular mimicry" or "intermolecular help" in the generation of autoimmunity to this antigen.
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PMID:Antibodies to the p70/p80 (Ku) antigens in systemic lupus erythematosus. 162 75

We have replaced the polyomavirus (Py) enhancer, which is an essential component of the Py origin of DNA replication (ori), with five repeats of a 17-bp oligonucleotide including the yeast GAL4 upstream activating sequence (5xGAL4 sites). Plasmids containing this modified Py ori, designated test plasmids, and plasmids encoding either the GAL4 transcriptional activator protein or various derivatives of this protein were cotransfected into mouse cells which constitutively synthesize a temperature-sensitive Py large tumor antigen (T-Ag). Replication of the test plasmids was monitored by Southern blot determinations of the amounts of plasmid DNA that became resistant to cleavage by the enzyme DpnI. These studies showed that in the presence of a functional T-Ag, the GAL4 protein, and hybrid proteins including the GAL4 DNA-binding domain and the activating domain of the adenovirus E1a or herpesvirus VP16 protein transactivated the modified Py ori. A truncated protein including just the GAL4 DNA-binding domain was inactive in these assays. The authentic GAL4 protein was found to be a more efficient replication transactivator than the hybrid proteins. In contrast, chloramphenicol acetyltransferase assays showed that the hybrid proteins were more efficient transcriptional activators than the GAL4 protein. The extent of the GAL4-dependent replication of a plasmid in which the Py early promoter was deleted was 55% lower than that of a plasmid including the promoter. However, the extents of replication of plasmids including two tandem repeats of the remaining Py origin core and 5xGAL4 sites or two origin cores flanking a single cluster of 5xGAL4 sites were 4.8- and 1.6-fold higher than that of the plasmid including a single copy of each element. The replication of a plasmid including two clusters of 5xGAL4 sites flanking a single origin core was below the limit of detection of our assays. These results indicate that the GAL4 and hybrid transactivators do not activate the Py ori by virtue of their interactions with transcription factors that bind promoter elements. Rather, it appears that these activator proteins may interact with the replication initiation complexes, thereby facilitating or inhibiting the initiation of replication.
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PMID:The yeast GAL4 protein transactivates the polyomavirus origin of DNA replication in mouse cells. 164 81

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

Epstein-Barr virus nuclear protein 2 (EBNA-2) increases mRNA levels of specific viral and cellular genes through direct or indirect effects on upstream regulatory elements. The EBNA-2 domains essential for these effects have been partially defined and correlate with domains important for B-cell growth transformation. To determine whether EBNA-2 has a direct transcriptional activating domain, gene fusions between the DNA-binding domain of GAL4 and EBNA-2 were tested in CHO and B-lymphoma cells for the ability to activate transcription from target plasmids containing GAL4 recognition sites upstream of an adenovirus or murine mammary tumor virus promoter. In B-lymphoma cells, a 37-amino-acid EBNA-2 domain previously identified to be essential for transformation was nearly as strong a transcriptional activator as the activating domain of herpes simplex virus trans-inducing factor VP16. A quadradecapeptide had about 25% of the activating activity of the longer peptide. This first evidence that EBNA-2 directly activates transcription should facilitate the identification of nuclear factors with which EBNA-2 interacts in transactivation and transformation.
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PMID:An Epstein-Barr virus nuclear protein 2 domain essential for transformation is a direct transcriptional activator. 165 76


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