UNIPROT:P51532 - FACTA Search

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

The sulfur regulatory system of Neurospora crassa is composed of a set of structural genes involved in sulfur catabolism controlled by a genetically defined set of trans-acting regulatory genes. These sulfur regulatory genes include cys-3+, which encodes a basic region-leucine zipper transcriptional activator, and the negative regulatory gene scon-2+. We report here that the scon-2+ gene encodes a polypeptide of 650 amino acids belonging to the expanding beta-transducin family of eukaryotic regulatory proteins. Specifically, SCON2 protein contains six repeated G beta-homologous domains spanning the C-terminal half of the protein. SCON2 represents the initial filamentous fungal protein identified in the beta-transducin group. Additionally, SCON2 exhibits a specific amino-terminal domain that potentially defines another subfamily of beta-transducin homologs. Expression of the scon-2+ gene has been examined using RNA hybridization and gel mobility-shift analysis. The dependence of scon-2+ expression on CYS3 function and the binding of CYS3 to the scon-2+ promoter indicate the presence of an important control loop within the N. crassa sulfur regulatory circuit involving CYS3 activation of scon-2+ expression. On the basis of the presence of beta-transducin repeats, the crucial role of SCON2 in the signal-response pathway triggered by sulfur limitation may be mediated by protein-protein interactions.
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PMID:The sulfur controller-2 negative regulatory gene of Neurospora crassa encodes a protein with beta-transducin repeats. 772 64

The uaY gene codes for a transcriptional activator mediating the induction of a number of unlinked genes involved in purine utilization in Aspergillus nidulans. Here we present the complete genomic and cDNA nucleotide sequence of this gene. The gene contains two introns. The derived polypeptide of 1060 residues contains a typical zinc binuclear cluster domain and shows a number of similarities with the PPR1 regulatory gene of Saccharomyces cerevisiae. These similarities are most striking in the putative linker and dimerization regions following the zinc cluster. Gel-shift and DNase I footprinting experiments have been carried out for three genes subject to UaY-mediated induction. The binding sequence is 5'-TCGG-6X-CCGA, which is identical to the proposed PPR1 binding sites. Nevertheless, the identity of the base immediately 3' of the 5'-TCGG sequence clearly affects the affinity of the site. The site upstream of the uapA gene has been shown to be active in vivo. Binding to this site has been analysed by a number of interference techniques. There is an interesting chemical similarity between the co-inducer of the purine utilization pathway (uric acid) and that of the genes of the pyrimidine biosynthetic pathway (dihydroorotic acid) and we show that dihydroorotic acid can act as a poor inducer of at least one activity under UaY control. These striking similarities, together with the unique pattern of regulation of pyrimidine biosynthesis in S. cerevisiae, suggest that PPR1 evolved through recruitment into the pyrimidine biosynthetic pathway of an ancestral gene related to uaY.
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PMID:The sequence and binding specificity of UaY, the specific regulator of the purine utilization pathway in Aspergillus nidulans, suggest an evolutionary relationship with the PPR1 protein of Saccharomyces cerevisiae. 772 21

SoxR protein governs the soxRS (superoxide response) regulon of Escherichia coli by becoming a transcriptional activator when the cells are exposed to compounds that mediate univalent redox reactions, many of which produce superoxide as a by-product. SoxR was overproduced and purified to near homogeneity from a strain bearing an expression vector. It could bind specifically to the soxS operator even in the absence of RNA polymerase. The aerobically purified protein, which is readily autooxidized, could activate the transcription of soxS DNA even without exposure to known inducing agents. SoxR is a globular homodimer. It contains one [2Fe-2S] cluster per polypeptide chain, as demonstrated by optical and EPR spectroscopy combined with stoichiometric analysis of iron content, unpaired-electron-spin density, and reduction by dithionite. The protein is active in its oxidized ([2Fe-2S]2+) state. The presence of a prosthetic group capable of univalent redox reactions may help to explain the activation of the regulon in vivo by compounds that can mediate such reactions.
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PMID:Overproduction and physical characterization of SoxR, a [2Fe-2S] protein that governs an oxidative response regulon in Escherichia coli. 773 Mar 38

Infected-cell polypeptide 4 (ICP4) of herpes simplex virus is both a transcriptional activator and a repressor. It has been previously demonstrated that both SP1-activated transcription and USF-activated transcription are repressed by ICP4 without affecting basal transcription (B. Gu, R. Rivera-Gonzalez, C. A. Smith, and N. A. DeLuca, Proc. Natl. Acad. Sci. USA 90:9528-9532, 1993; R. Rivera-Gonzalez, A. N. Imbalzano, B. Gu, and N.A. DeLuca, Virology 202:550-564, 1994). In this study, it was found that ICP4 repressed the activation function of two other activators, VP16 and ICP4 itself, in vitro. ICP4 inhibited transcription by interfering with the formation of transcription initiation complexes without affecting transcription elongation. Repression of activator function required that an ICP4 DNA binding site was present in one orientation within approximately 45 bp 3' to the TATA box. DNA binding by ICP4 was necessary but not sufficient for repression. ICP4 has been shown to form tripartite complexes cooperatively with the TATA box-binding protein and TFIIB on DNA containing an ICP4 binding site and a TATA box (C. A. Smith, P. Bates, R. Rivera-Gonzalez, B. Gu, and N. DeLuca, J. Virol. 67:4676-4687, 1993). A region of ICP4 that enables the molecule to form tripartite complexes was also required in addition to the DNA binding domain for efficient repression. Moreover, repression was observed only when the ICP4 binding site was in a position that resulted in the formation of tripartite complexes. Together, the data suggest that ICP4 represses transcription by binding to DNA in a precise way so that it may interact with the basal transcription complex and inhibit some general step involved in the function of activators. The steps or interactions involved in transcriptional activation that are inhibited by ICP4 are discussed.
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PMID:Repression of activator-mediated transcription by herpes simplex virus ICP4 via a mechanism involving interactions with the basal transcription factors TATA-binding protein and TFIIB. 779 69

LuxR, the Vibrio fischeri luminescence gene (lux) activator, is the best-studied member of a family of bacterial transcription factors required for cell density-dependent expression of specific genes involved in associations with eukaryotic hosts. Neither LuxR nor any other LuxR homolog has been shown to bind DNA directly. We have purified the LuxR C-terminal transcriptional activator domain from extracts of recombinant Escherichia coli in which this polypeptide was expressed. The purified polypeptide by itself binds to lux regulatory DNA upstream of the lux box, a 20-bp palindrome that is required for LuxR activity in vivo, but it does not bind to the lux box. However, the LuxR C-terminal domain together with RNA polymerase protects a region including the lux box and the lux operon promoter from DNase I cleavage. There is very little protection of the lux operon promoter region from DNase I digestion in the presence of RNA polymerase alone. Apparently, there is a synergistic binding of the LuxR C-terminal domain and RNA polymerase to the promoter region. The upstream binding region for the purified polypeptide encompasses a binding site for cAMP receptor protein (CRP). Under some conditions, CRP binding can block the binding of the LuxR C-terminal domain to the upstream binding region, and it can also block the synergistic binding of the LuxR C-terminal domain and RNA polymerase to the lux box and luminescence gene promoter region. This description of DNA binding by the LuxR C-terminal domain should lead to an understanding of the molecular interactions of the LuxR family of transcriptional activators with regulatory DNA.
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PMID:Synergistic binding of the Vibrio fischeri LuxR transcriptional activator domain and RNA polymerase to the lux promoter region. 780 88

A 33 membered polypeptide corresponding to the leucine zipper region of the yeast transcriptional activator GCN4 was synthesized by solid phase chemical synthesis and characterized. Asparagine in the hydrophobic core of the molecule is replaced by valine in the synthetic variant. The correctness of amino acid sequence of the preparation is corroborated by direct sequencing. High-speed equilibrium ultracentrifugation, ultraviolet circular dichroism spectroscopy and scanning microcalorimetry have been employed to demonstrate that in solution the peptide forms a highly stable triple-stranded alpha-helical coiled coil. The stability of the mutant form is 40 degrees C higher than the dimeric form of natural peptide under similar conditions. It was proposed that location of some polar groups in the 'a' and 'd' positions of natural two-stranded coiled coils may be regarded as protection against alternative triple- and multistranded conformations.
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PMID:Synthesis and properties of the peptide corresponding to the mutant form of the leucine zipper of the transcriptional activator GCN4 from yeast. 783 Dec 80

Alveolar rhabdomyosarcomas are pediatric solid tumors with a hallmark cytogenetic abnormality: translocation of chromosomes 2 and 13 [t(2;13) (q35;q14)]. The genes on each chromosome involved in this translocation have been identified as the transcription factor-encoding genes PAX3 and FKHR. The NH2-terminal paired box and homeodomain DNA-binding domains of PAX3 are fused in frame to COOH-terminal regions of the chromosome 13-derived FKHR gene, a novel member of the forkhead DNA-binding domain family. To determine the role of the fusion protein in transcriptional regulation and oncogenesis, we identified the PAX3-FKHR fusion protein and characterized its function(s) as a transcription factor relative to wild-type PAX3. Antisera specific to PAX3 and FKHR were developed and used to examine PAX3 and PAX3-FKHR expression in tumor cell lines. Sequential immunoprecipitations with anti-PAX3 and anti-FKHR sera demonstrated expression of a 97-kDa PAX3-FKHR fusion protein in the t(2;13)-positive rhabdomyosarcoma Rh30 cell line and verified that a single polypeptide contains epitopes derived from each protein. The PAX3-FKHR protein was localized to the nucleus in Rh30 cells, as was wild-type PAX3, in t(2;13)-negative A673 cells. In gel shift assays using a canonical PAX binding site (e5 sequence), we found that DNA binding of PAX3-FKHR was significantly impaired relative to that of PAX3 despite the two proteins having identical PAX DNA-binding domains. However, the PAX3-FKHR fusion protein was a much more potent transcriptional activator than PAX3 as determined by transient cotransfection assays using e5-CAT reporter plasmids. The PAX3-FKHR protein may function as an oncogenic transcription factor by enhanced activation of normal PAX3 target genes.
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PMID:The PAX3-FKHR fusion protein created by the t(2;13) translocation in alveolar rhabdomyosarcomas is a more potent transcriptional activator than PAX3. 786 45

The timing of asexual fruiting body formation during Aspergillus nidulans colony development is precisely regulated so that conidiophores are typically produced 1-2 mm behind the growing edge of the colony. Mutations in any of four A. nidulans genes, flbB, flbC, flbD, or flbE, result in colonies that are delayed at least 24 hr in their ability to initiate conidiophore development resulting in fluffy colonies with conidiophores forming in the center, at least 12-15 mm behind the growing edge. The requirement for each of these four genes in determining the timing of developmental initiation precedes transcriptional activation of the primary developmental regulatory gene brlA, indicating a possible role for each gene in developmentally regulated activation of brlA expression. The wild-type flbD gene was isolated and shown to encode an approximately 1.6-kb mRNA that is present throughout the A. nidulans life cycle. The deduced FlbD protein sequence predicts a 314-amino-acid polypeptide with significant identity at its amino terminus to the DNA-binding domain of the Myb family of transcription factors indicating that FlbD probably functions as a sequence-specific transcriptional activator. Although conidiophore development does not normally occur in submerged culture, forced overexpression of flbD in submerged hyphae caused inappropriate activation of brlA expression and resulted in production of complex conidiophores that produced all of the distinct cell types observed in wild-type conidiophores including viable spores. This ability of flbD overexpression to activate conidiation requires brlA, flbB, and flbA (another early developmental regulator) but does not require flbC or flbE. We propose that FlbD functions during normal development by activating transcription of other genes required for development (such as brlA) and that FlbD activity is normally controlled post-transcriptionally by an unknown mechanism.
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PMID:flbD encodes a Myb-like DNA-binding protein that coordinates initiation of Aspergillus nidulans conidiophore development. 788 70

The NS-1 gene of the parvovirus minute virus of mice (MVM) (prototype strain, MVMp) was fused in phase with the sequence coding for the DNA-binding domain of the bacterial LexA repressor. The resulting chimeric protein, LexNS-1, was tested for its transcriptional activity by using various target promoters in which multiple LexA operator sequences had been introduced. Under these conditions, NS-1 was shown to stimulate gene expression driven by the modified long terminal repeat promoters (from the retroviruses mouse mammary tumor virus and Rous sarcoma virus) and P38 promoter (from MVMp), indicating that the NS-1 protein is a potent transcriptional activator. It is noteworthy that in the absence of LexA operator-mediated targeting, the genuine mouse mammary tumor virus and Rous sarcoma virus promoters were inhibited by NS-1. Together these data strongly suggest that NS-1 contains an activating region able to induce promoters with which this protein interacts but also to repress transcription from nonrecognized promoters by a squelching mechanism similar to that described for other activators. Deletion mutant analysis led to the identification of an NS-1 domain that exhibited an activating potential comparable to that of the whole polypeptide when fused to the DNA-binding region of LexA. This domain is localized in the carboxy-terminal part of NS-1 and corresponds to one of the two regions previously found to be responsible for toxicity. These results argue for the involvement of the regulatory functions of NS-1 in the cytopathic effect of this parvovirus product.
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PMID:Targeting of promoters for trans activation by a carboxy-terminal domain of the NS-1 protein of the parvovirus minute virus of mice. 796 88

The equine herpesvirus type 1 (EHV-1) immediate-early (IE) gene product, an ICP4 homolog, is the major regulatory protein encoded by EHV-1 during cytolytic infection. The IE gene product has been demonstrated to induce reporter gene expression directed by both homologous and heterologous viral promoters, including the EHV-1 thymidine kinase (tk) promoter, the herpes simplex virus type 1 (HSV-1) tk and ICP4 promoters, and the simian virus 40 early promoter. In this report, the transcriptional activation domain of the EHV-1 IE gene product was mapped to within an acidic, 87-amino-acid region (amino acids 3 to 89) at the amino-terminus of the IE molecule. It is demonstrated that the IE transcriptional activation domain, when fused to the DNA-binding domain of the yeast transcriptional activator GAL4, can activate gene expression in cell lines derived from at least two different species. Moreover, it is shown that the EHV-1 IR2 gene product (Harty and O'Callaghan, J. Virol. 65, 3829-3838, 1991), a truncated form of the IE polypeptide lacking IE amino acid residues 1-322 (and, therefore lacks the deduced transcriptional activation domain), fails to transactivate the EHV-1 tk promoter, but retains the ability to down-regulate the EHV-1 IE promoter. Fusion of the acidic transcriptional activation domain of the HSV-1 virion protein VP16 to the transactivation-deficient IR2 gene product restored the ability of this truncated IE polypeptide to transactivate the EHV-1 tk promoter. These findings suggest a role for the IR2 protein as a trans-repressor of EHV-1 gene expression.
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PMID:The equine herpesvirus type 1 immediate-early gene product contains an acidic transcriptional activation domain. 803 Feb 39

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