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)

The human T cell-specific transcription factor TCF-1 alpha plays a key role in the tissue-specific activation of the T cell receptor (TCR) C alpha enhancer and binds to pyrimidine-rich elements (5'-PyCTTTG-3') present in a variety of other T cell-specific control regions. Using amino acid sequence information derived from the DNA affinity-purified protein, we have now isolated cDNA clones encoding TCF-1 alpha. The TCF-1 alpha cDNA contains a single 68-amino-acid domain that is homologous to a region conserved among high-mobility group (HMG) and nonhistone chromosomal proteins. Expression of full-length and mutant cDNA clones in bacteria reveal that the single HMG motif, which is predicted to contain two extended alpha-helical segments, is sufficient to direct the sequence-specific binding of TCF-1 alpha to DNA. Northern blot experiments demonstrate further that TCF-1 alpha mRNA is highly tissue specific, found primarily in the thymus or T cell lines. The immature CEM T cell line expresses relatively low levels of TCF-1 alpha mRNA, which are increased upon activation of these cells by phorbol esters. Interestingly, the cloned TCF-1 alpha protein is a potent transcriptional activator of the human TCR alpha enhancer in nonlymphoid cell lines, whereas the activity of the endogenous protein in T cell lines is strongly dependent on an additional T cell-specific protein that interacts with the core enhancer. TCF-1 alpha is currently unique among the newly emerging family of DNA-binding regulatory proteins that share the HMG motif in that it is a highly tissue-specific RNA polymerase II transcription factor.
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PMID:A thymus-specific member of the HMG protein family regulates the human T cell receptor C alpha enhancer. 201 90

Expression of the yeast pyrimidine biosynthetic gene, URA3, is induced three- to fivefold in response to uracil starvation, and this regulation is mediated by the transcriptional activator PPR1 (pyrimidine pathway regulator 1). In this study, we have analyzed the regulatory elements of the URA3 promoter by DNase I footprinting, using partially purified yeast cell extracts, by deletion mutagenesis, and by 5'-end mapping of RNA transcripts. Two DNA-binding activities have been detected, and at least four distinct cis-acting regions have been identified. A region rich in poly(dA-dT) serves as an upstream promoter element necessary for the basal level of URA3 expression. A 16-base-pair sequence with dyad symmetry acts acts as a uracil-controlled upstream activating site (UASURA) and shows a specific binding only with cell extracts from strains overproducing PPR1. This in vitro binding does not require dihydroorotic acid, the physiological inducer of URA3. The TATA region appears to be composed of two functionally distinct (constitutive and regulatory) elements. Two G + A-rich regions surrounding this TATA box bind an unidentified factor called GA-binding factor. The 5' copy, GA1, is involved in PPR1 induction and overlaps the constitutive TATA region. The 3' region, GA2, is necessary for maximal expression. Neither of these GA sequences acts as a UAS in a CYC1-lacZ context. The promoters of the unlinked but coordinately regulated URA1 and URA4 genes contain highly conserved copies of the UASURA sequence, which prompted us to investigate the effects of many point mutations within this UASURA sequence on PPR1-dependent binding. In this way, we have identified the most important residues of this binding site and found that a nonsymmetrical change of these bases is sufficient to prevent the specific binding and to suppress the UASURA activity in vivo. In addition, we showed that UASURA contains a constitutive activating element which can stimulate transcription from a heterologous promoter independently of dihydroorotic acid and PPR1.
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PMID:cis- and trans-acting regulatory elements of the yeast URA3 promoter. 220 10

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

We have previously reported that heterogeneous nuclear ribonucleoprotein K (hnRNP K) binds to the pyrimidine-rich strand of the CT element found in the human c-myc gene and activates CT reporter-driven gene expression in vivo. We now characterize the DNA and protein requirements for the interaction of hnRNP K with the CT element. First, hnRNP K is shown to preferentially bind single-stranded DNA over RNA or native double-stranded DNA. Using specific oligoribonucleotide or deoxyribonucleotide probes with specific or nonspecific RNA or DNA competitors, electrophoretic mobility shift assay revealed hnRNP K to be a DNA-binding protein. Specific binding was not simply a reflection of binding to pyrimidine-rich sequences as the number and arrangement of individual CT elements governed interactions with hnRNP K; at least two CT repeats separated by at least three nucleotides are required for binding, indicating the existence of particular stereochemical constraints regulating CT-hnRNP K complex formation. Deletion analysis showed that hnRNP K possesses several nonoverlapping, DNA binding domains, each capable of specific binding with the CT element and preferring DNA over RNA. Each sequence recognition domain is composed of at least one K homology motif, while a larger portion of hnRNP K may be required for stable RNA binding. Additional experiments indicate that the N-terminal 35 residues of hnRNP K are necessary for transactivating the CT element. These results indicate that hnRNP K is a DNA-binding protein and transcriptional activator.
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PMID:Heterogeneous nuclear ribonucleoprotein K is a DNA-binding transactivator. 787 60

The NIFA protein activates transcription of nitrogen fixation (nif) operons by the sigma 54-holoenzyme form of RNA polymerase. We purified active NIFA from Klebsiella pneumoniae in the form of a maltose-binding protein (MBP)-NIFA fusion; proteolytic release of MBP yielded inactive and insoluble NIFA. MBP-NIFA activated transcription from the nifHDK promoter in a purified transcription system. Like the related transcriptional activator NTRC, MBP-NIFA catalyzed the ATP-dependent isomerization of closed complexes between sigma 54-holoenzyme and a promoter to open complexes. MBP-NIFA had a broader nucleotide specificity than NTRC, being able to utilize pyrimidine in addition to purine nucleoside triphosphates. Both MBP-NIFA and a purified C-terminal fragment of NIFA bound to the upstream activation sequence for the nifHDK promoter, as assessed by DNAse I footprinting. When assays were performed at 37 degrees C instead of the usual 30 degrees C, transcriptional activation, open complex formation, and DNA binding by MBP-NIFA were all abolished, consistent with the known heat lability of NIFA. However, the purified C-terminal fragment of NIFA still bound the upstream activation sequence at 37 degrees C, indicating that the function of the helix-turn-helix DNA-binding motif is not inherently heat-labile.
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PMID:Activity of purified NIFA, a transcriptional activator of nitrogen fixation genes. 846 Jan 32

SoxS is a transcriptional activator of oxidative stress genes in Escherichia coli. SoxS in vitro binds the promoters of soxRS-regulated genes such as micF, zwf, nfo and sodA, forms multiple protein-DNA complexes, and recruits RNA polymerase to the promoters. E. coli Rob protein, with an N-terminus 55% identical to SoxS, was initially identified by its binding to the oriC replication origin, but Rob in vitro binds some of the same promoters as SoxS and in vivo activates some SoxS-regulated genes. In this work we show that the multiple complexes with SoxS arise from the presence at least two independent binding sites in each of the ++offcF and zwf promoters. SoxS and Rob each form only a single complex with a 20 bp DNA oligonucleotide corresponding to the region immediately upstream of the -35 element of the micF promoter. Methylation interference identified several conserved purine residues required for binding to micF and five other SoxS-binding sites. Together with binding studies using mutated ollgonucleotides and published DNase I footprinting data, this information was used to form a consensus for SoxS sequence specificity: AN2GCAYN7CWA (where N is any base, Y is a pyrimidine, and W is A or T). The sequence requirements for Rob binding differed somewhat from those of SoxS. Using the SoxS-binding consensus, several genes potentially regulated by soxRS were identified in an E. coli genomic database; some of these genes have functions that might contribute to cellular resistance to oxidative stress.
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PMID:Sequence specificity for DNA binding by Escherichia coli SoxS and Rob proteins. 880 47

This study identifies three regions of the human alpha2(I) collagen promoter involved in the binding of nuclear factors. These regions include sequences from -173 to -155 (footprint I), -133 to -119 (footprint II), and -101 to -72 (footprint III). A novel positive cis-element containing a TCCTCC motif was identified within footprint II. In addition, we demonstrated that a pyrimidine-rich region within footprint I is a binding site for a transcriptional repressor, and a CCAAT motif within footprint III is a binding site for a transcriptional activator. Comparative functional analysis of the cis-acting elements within the proximal 350 base pairs of this promoter, including previously characterized Sp1 binding sites at -300, indicates that constitutive activity of this promoter is regulated equivalently by the three positive cis-acting elements at -300, -125, and -80. Mutations in the repressor site at -160 increase constitutive activity by 4-6-fold. However, simultaneous mutations of the repressor site and the cis-regulatory element at either the -300 or -125 sites result in no increase in constitutive transcription activity suggesting interaction between the activators and repressor elements. In contrast, simultaneous mutation of the CCAAT motif and the repressor site results in about a 4-fold increase, suggesting that activation via the CCAAT motif may be independent of this repressor.
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PMID:Transcriptional regulation of the human alpha2(I) collagen gene. Combined action of upstream stimulatory and inhibitory cis-acting elements. 890 Jan 50

The GAL4 protein belongs to a large class of fungal transcriptional activator proteins encoding within their DNA-binding domains (DBD) six cysteines that coordinate two atoms of zinc (the Zn2Cys6 domain). In an effort to characterize the interactions between the Zn2Cys6 class transcriptional activator proteins and their DNA-binding sites, we have replaced in the full-length GAL4 protein small regions of the Zn2Cys6 domain with the analogous regions of another Zn2Cys6 protein called PPR1 an activator of pyrimidine biosynthetic genes. Alterations between the first and third cysteines abolished binding to GAL4 (upstream activation sequence of GAL (UASG)) or PPR1 (upstream acitvation sequence of UAS) DNA-binding sites and severely reduced transcriptional activation in yeast. In contrast, alterations between the third and fourth cysteines had only minor effects on binding to UASG but led to substantial decreases in activation in both yeast and a mammalian cell line. In the crystal structure of the GAL4 DBD-UASG complex (Marmorstein, R., Carey, M., Ptashne, M., and Harrison, S. C. (1992) Nature 356, 408-414), this region is facing away from the DNA, making it likely that there exists within the GAL4 DBD an accessible domain important in activation.
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PMID:Alterations in the GAL4 DNA-binding domain can affect transcriptional activation independent of DNA binding. 959 20

The effect of extracellular adenine and the role of the transcriptional activator Bas1p on expression of the yeast genome was assessed by two-dimensional (2D) analysis of the yeast proteome. These data combined with LacZ fusions and northern blot analysis allow us to show that synthesis of enzymes for all 10 steps involved in purine de novo synthesis is repressed in the presence of adenine and requires BAS1 and BAS2 for optimal expression. We also show that expression of ADE12 and ADE13, the two genes required for synthesis of AMP from inosine 5'monophosphate (IMP), is co-regulated with the de novo pathway genes. The same combined approach, used to study histidine biosynthesis gene expression, showed that HIS1 and HIS4 expression is co-regulated with purine biosynthesis genes whereas HIS2, HIS3, HIS5 and HIS6 expression is not. This work, together with previously published data, gives the first comprehensive overview of the regulation of purine and histidine pathways in a eukaryotic organism. Finally, the expression of two pyrimidine biosynthesis genes URA1 and URA3 was found to be severely affected by bas1 and bas2 mutations in the absence of adenine, establishing a regulatory link between the two nucleotide biosynthesis pathways.
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PMID:Role of the myb-like protein bas1p in Saccharomyces cerevisiae: a proteome analysis. 982 21

Saccharomyces cerevisiae responds to pyrimidine starvation by increasing the expression of four URA genes, encoding the enzymes of de novo pyrimidine biosynthesis, three- to eightfold. The increase in gene expression is dependent on a transcriptional activator protein, Ppr1p. Here, we investigate the mechanism by which the transcriptional activity of Ppr1p responds to the level of pyrimidine biosynthetic intermediates. We find that purified Ppr1p is unable to promote activation of transcription in an in vitro system. Transcriptional activation by Ppr1p can be observed, however, if either dihydroorotic acid (DHO) or orotic acid (OA) is included in the transcription reactions. The transcriptional activation function and the DHO/OA-responsive element of Ppr1p localize to the carboxyl-terminal 134 amino acids of the protein. Thus, Ppr1p directly senses the level of early pyrimidine biosynthetic intermediates within the cell and activates the expression of genes encoding proteins required later in the pathway. These results are discussed in terms of (i) regulation of the pyrimidine biosynthetic pathway and (ii) a novel mechanism of regulating gene expression.
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PMID:Activation of transcription by metabolic intermediates of the pyrimidine biosynthetic pathway. 985 11


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