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 C2-H2 zinc-finger is a widely occurring DNA binding motif, usually present as tandem repeats. The majority of C2-H2 zinc-finger proteins that have been studied are derived from animals. Here, we characterize a member of a distinct class of plant C2-H2 zinc-finger proteins in detail. A cDNA clone encoding a DNA binding protein from Arabidopsis was isolated by SouthWestern screening. The protein, termed ZAP1 (Zinc-dependent Activator Protein-1), is encoded by a single copy gene, which is expressed to similar levels in root and flower, to a somewhat lower level in stem and to low levels in leaf and siliques. The optimal binding site was determined by random binding site selection, and the consensus sequence found is CGTTGACCGAG. The homology between ZAP1 and other DNA binding proteins is restricted to a repeated region of a stretch of 24 highly conserved amino acids followed by a zinc-finger motif (C-X4-C-X22-23-H-X1-H). The C-terminal zinc-finger region is essential for DNA binding, whereas deletion of the N-terminal one resulted in 2.5-fold reduced binding affinity. Binding of ZAP1 to DNA was abolished by metal-chelating agents. The activation domain as determined in yeast is adjacent to and possibly overlapping with the DNA binding domain. Particle bombardment experiments with plant cells showed that ZAP1 increases expression of a gusA reporter gene that is under control of ZAP1 binding sites. We conclude that ZAP1 is a plant transcriptional activator with a C2-H2 zinc-finger DNA binding domain.
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PMID:Characterization of a zinc-dependent transcriptional activator from Arabidopsis. 897 46

The Cat8p zinc cluster protein is essential for growth of Saccharomyces cerevisiae with nonfermentable carbon sources. Expression of the CAT8 gene is subject to glucose repression mainly caused by Mig1p. Unexpectedly, the deletion of the Mig1p-binding motif within the CAT8 promoter did not increase CAT8 transcription; moreover, it resulted in a loss of CAT8 promoter activation. Insertion experiments with a promoter test plasmid confirmed that this regulatory 20-bp element influences glucose repression and derepression as well. This finding suggests an upstream activating function of this promoter region, which is Mig1p independent, as delta mig1 mutants are still able to derepress the CAT8 promoter. No other putative binding sites such as a Hap2/3/4/5p site and an Abf1p consensus site were functional with respect to glucose-regulated CAT8 expression. Fusions of Cat8p with the Gal4p DNA-binding domain mediated transcriptional activation. This activation capacity was still carbon source regulated and depended on the Cat1p (Snf1p) protein kinase, which indicated that Cat8p needs posttranslational modification to reveal its gene-activating function. Indeed, Western blot analysis on sodium dodecyl sulfate-gels revealed a single band (Cat8pI) with crude extracts from glucose-grown cells, whereas three bands (Cat8pI, -II, and -III) were identified in derepressed cells. Derepression-specific Cat8pII and -III resulted from differential phosphorylation, as shown by phosphatase treatment. Only the most extensively phosphorylated modification (Cat8pIII) depended on the Cat1p (Snf1p) kinase, indicating that another protein kinase is responsible for modification form Cat8pII. The occurrence of Cat8pIII was strongly correlated with the derepression of gluconeogenic enzymes (phosphoenolpyruvate carboxykinase and fructose-1,6-bisphosphatase) and gluconeogenic PCK1 mRNA. Furthermore, glucose triggered the dephosphorylation of Cat8pIII, but this did not depend on the Glc7p (Cid1p) phosphatase previously described as being involved in invertase repression. These results confirm our current model that glucose derepression of gluconeogenic genes needs Cat8p phosphorylation and additionally show that a still unknown transcriptional activator is also involved.
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PMID:Glucose derepression of gluconeogenic enzymes in Saccharomyces cerevisiae correlates with phosphorylation of the gene activator Cat8p. 911 19

The prolamin box (P-box) is a highly conserved 7-bp sequence element (5'-TGTAAAG-3') found in the promoters of many cereal seed storage protein genes. Nuclear factors from maize endosperm specifically interact with the P-box present in maize prolamin genes (zeins). The presence of the P-box in all zein gene promoters suggests that interactions between endosperm DNA binding proteins and the P-box may play an important role in the coordinate activation of zein gene expression during endosperm development. We have cloned an endosperm-specific maize cDNA, named prolamin-box binding factor (PBF), that encodes a member of the recently described Dof class of plant Cys2-Cys2 zinc-finger DNA binding proteins. When tested in gel shift assays, PBF exhibits the same sequence-specific binding to the P-box as factors present in maize endosperm nuclei. Additionally, PBF interacts in vitro with the basic leucine zipper protein Opaque2, a known transcriptional activator of zein gene expression whose target site lies 20 bp downstream of the P-box in the 22-kDa zein gene promoter. The isolation of the PBF gene provides an essential tool to further investigate the functional role of the highly conserved P-box in regulating cereal storage protein gene expression.
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PMID:A maize zinc-finger protein binds the prolamin box in zein gene promoters and interacts with the basic leucine zipper transcriptional activator Opaque2. 920 53

The DNA binding domain of the yeast transcriptional activator CYP1(HAP1) contains a zinc-cluster structure. The structures of the DNA binding domain-DNA complexes of two other zinc-cluster proteins (GAL4 and PPR1) have been studied by X-ray crystallography. Their binding domains present, besides the zinc cluster, a short linker peptide and a dimerization element. They recognize, as homodimers, two rotationally symmetric CGG trinucleotides, the linker peptide and the dimerization element playing a crucial role in binding specificity. Surprisingly, CYP1 recognizes degenerate forms of a direct repeat, CGGnnnTAnCGGnnnTA, and the role of its linker is under discussion. To better understand the binding specificity of CYP1, we have studied, by NMR, the interaction between the CYP1(55-126) peptide and two DNA fragments derived from the CYC1 upstream activation sequence 1B. Our data indicate that CYP1(55-126) interacts with a CGG and with a thymine 5 bp downstream. The CGG trinucleotide is recognized by the zinc cluster in the major groove, as for GAL4 and PPR1, and the thymine is bound in the minor groove by the N-terminal region, which possesses a basic stretch of arginyl and lysyl residues. This suggests that the CYP1(55-126) N-terminal region could play a role in the affinity and/or specificity of the interaction with its DNA targets, in contrast to GAL4 and PPR1.
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PMID:NMR analysis of CYP1(HAP1) DNA binding domain-CYC1 upstream activation sequence interactions: recognition of a CGG trinucleotide and of an additional thymine 5 bp downstream by the zinc cluster and the N-terminal extremity of the protein. 922 3

The egr-type zinc-finger transcription factor encoded by the Drosophila gene stripe (sr) is expressed in a subset of epidermal cells to which muscles attach during late stages of embryogenesis. We report loss-of-function and gain-of-function experiments indicating that sr activity provides ectodermal cells with properties required for the establishment of a normal muscle pattern during embryogenesis and for the differentiation of tendon-like epidermal muscle attachment sites (EMA). Our results show that sr encodes a transcriptional activator which acts as an autoregulated developmental switch gene. sr activity controls the expression of EMA-specific target genes in cells of ectodermal but not of mesodermal origin. sr-expressing ectodermal cells generate long-range signals that interfere with the spatial orientation of the elongating myotubes.
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PMID:Epidermal muscle attachment site-specific target gene expression and interference with myotube guidance in response to ectopic stripe expression in the developing Drosophila epidermis. 923 24

The solution structure and backbone dynamics of the transcriptional activator PUT3 (31-100) has been characterized using NMR spectroscopy. PUT3 (31-100) contains three distinct domains: a cysteine zinc cluster, linker, and dimerization domain. The cysteine zinc cluster of PUT3 closely resembles the solution structure of GAL4, while the dimerization domain forms a long coiled-coil similar to that observed in the crystal structures of GAL4 and PPR1. However, the residues at the N-terminal end of the coiled-coil behave very differently in each of these proteins. A comparison of the structural elements within this region provides a model for the DNA binding specificity of these proteins. Furthermore, we have characterized the dynamics of PUT3 to find that the zinc cluster and dimerization domains have very diverse dynamics in solution. The dimerization domain behaves as a large protein, while the peripheral cysteine zinc clusters have dynamic properties similar to small proteins.
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PMID:Structure and mobility of the PUT3 dimer. 930 3

Chromosomal translocations resulting in chimaeric transcription factors underlie specific malignancies, but few authentic target genes regulated by these fusion proteins have been identified. Desmoplastic small round-cell tumour (DSRT) is a multiphenotypic primitive tumour characterized by massive reactive fibrosis surrounding nests of tumour cells. The t(11;22)(p13;q12) chromosomal translocation that defines DSRT produces a chimaeric protein containing the potential transactivation domain of the Ewing-sarcoma protein (EWS) fused to zinc fingers 2-4 of the Wilms tumour suppressor and transcriptional repressor WT1 (refs 2,3). By analogy with other EWS fusion products, the EWS-WT1 chimaera may encode a transcriptional activator whose target genes overlap with those repressed by WT1 (ref. 4). To characterize its functional properties, we generated osteosarcoma cell lines with tightly regulated inducible expression of EWS-WT1. Expression of EWS-WT1 induced the expression of endogenous platelet-derived growth factor-A (PDGFA), a potent secreted mitogen and chemoattractant whose promoter contains the many potential WT1-binding sites. Native PDGFA was not regulated by wild-type WT1, indicating a difference in target gene specificity between this tumour suppressor and its oncogenic derivative. PDGFA was expressed within tumour cells in primary DSRT specimens, but it was absent in Wilms tumours expressing WT1 and Ewing sarcomas with an EWS-Fli translocation. We conclude that the oncogenic fusion of EWS to WT1 in DSRT results in the induction of PDGFA, a potent fibroblast growth factor that contributes to the characteristic reactive fibrosis associated with this unique tumour.
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PMID:The EWS-WT1 translocation product induces PDGFA in desmoplastic small round-cell tumour. 935 95

The Wilms' tumor suppressor gene, WT1, encodes a transcription factor in the zinc finger family, which binds to GC-rich sequences and functions as a transcriptional activator or repressor. The WT1 protein plays a crucial role in urogenital development in mammals and its function is thought to be conserved during vertebrate evolution. Although accumulating evidence suggests that WT1 regulates a subset of genes including growth factor and growth factor receptor genes, little is known about regulators or signal cascades that could modulate the function of WT1. In this study, we show that the WT1 protein expressed exogenously in fibroblasts was phosphorylated in vivo, and that treatment with forskolin, which activates the cAMP-dependent protein kinase (PKA) in vivo, induced phosphorylation of additional sites in WT1. We identified the forskolin-induced phosphorylation sites as Ser-365 and Ser-393, which lie in the zinc finger domain in zinc fingers 2 and 3, respectively. PKA phosphorylated WT1 at Ser-365 and Ser-393 in vitro, as well as at additional sites, and this phosphorylation abolished the DNA-binding activity of WT1 in vitro. Using WT1 mutants in which Ser-365 and Ser-393 were mutated to Ala individually and in combination, we showed that phosphorylation of these sites was critical for inhibition of DNA binding in vivo. Thus, coexpression of the PKA catalytic subunit with wild type WT1 reduced the level of WT1 DNA-binding activity detected in nuclear extracts, and decreased transcriptional repression activity in vivo. In contrast to wild type WT1, all of the phosphorylation site mutants retained significant DNA-binding activity and repression activity in the presence of PKA. Analysis of the mutants showed that phosphorylation of Ser-365 and Ser-395 had additive inhibitory effects on WT1 DNA-binding in vivo and that phosphorylation at both sites was required for neutralization of repression activity. Therefore, we conclude that PKA modulates the activity of WT1 in vivo through phosphorylation of Ser-365 and Ser-393, which inhibits DNA binding. This in turn results in a decrease in WT1 transcriptional repression. Our findings provide the first evidence that the function of WT1 can be modulated by its phosphorylation in vivo.
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PMID:Inhibition of the DNA-binding and transcriptional repression activity of the Wilms' tumor gene product, WT1, by cAMP-dependent protein kinase-mediated phosphorylation of Ser-365 and Ser-393 in the zinc finger domain. 936 17

The facB gene of Aspergillus nidulans encodes a DNA binding transcriptional activator required for growth on acetate as a sole carbon source. FacB contains N-terminal GAL4-like Zn(II)2Cys6 (or C6 zinc) binuclear cluster DNA binding and leucine zipper-like heptad repeat motifs and central and C-terminal acidic alpha-helical regions. facB recessive loss of function mutants are deficient in acetate induction of acetyl-CoA synthase, isocitrate lyase, malate synthase, acetamidase, and NADP-isocitrate dehydrogenase. Characterization of lesions in facB mutant alleles has localized important functional regions of the FacB protein. Two extreme mutants are shown to lack the C-terminal region of the protein. Two temperature sensitive mutants contain amino acid substitutions in the DNA binding domain and are shown to affect acetate induction of amdS-lacZ expression and confer temperature sensitive in vitro DNA binding. Two temperature sensitive facB mutations result in thermolability of acetyl-CoA synthase, isocitrate lyase, and malate synthase but not acetamidase or NADP-isocitrate dehydrogenase in crude extracts. This suggests that FacB may have a structural role in acetate metabolism in addition to its regulatory function.
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PMID:Molecular characterization of mutants of the acetate regulatory gene facB of Aspergillus nidulans. 936 56

AlcR is the transcriptional activator of the ethanol utilization pathway in Aspergillus nidulans. The zinc DNA-binding domain contains ligands of zinc, six cysteines (Zn2Cys6) or five cysteines and one histidine (Zn2Cys5His). The utilisation of complementary approaches such as X-ray absorption spectroscopy, mutational analysis, zinc content evaluation, determination of specific binding connecting structural and biological data, have allowed to determine zinc environment and to analyse the involvement of amino acids. The determination by EXAFS of zinc ligands (four sulphur atoms), the Zn content in the protein (2:1), the evaluation of the distance between two zinc atoms (3.16 +/- 0.02 angstroms), together with the total loss of specific DNA-binding activity when one cysteine ligand is mutated, are in favour of a zinc cluster model in which six cysteine sulphurs ligate two zinc atoms. XANES spectra of wild type and H10A AlcR protein are virtually identical indicating that Histidine 10 does not have a direct contribution in zinc ligation but electrophoretic mobility shift assays show that His10 is involved in DNA-binding. In contrast, proline 25 does not seem to play any direct role in the DNA-binding activity but XANES spectra of Pro25A AlcR protein are slightly modified comparing to the wild type protein spectra. This suggests a role of the proline in the stabilisation of the Zn cluster structure. AlcR DNA-binding domain belongs to the zinc binuclear class family (Zn2Cys6) with unique characteristics resulting from its primary and secondary structures and its binding specificity toward direct and inverted repeat target.
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PMID:First experimental evidence of a zinc binuclear cluster in AlcR protein, mutational and X-ray absorption studies. 943 11


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