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)

Transcription of metallothionein genes is activated by heavy metals such as zinc and cadmium, and a DNA element called metal responsive element (MRE) is essential for this process. By mobility-shift assay, we identified a HeLa-cell nuclear protein which specifically binds to MREa of human metallothionein-IIA gene. This protein, named ZRF (zinc-regulatory factor), is present in the cells untreated with heavy metals. Zinc is essential for, and increases in a dose-dependent manner, the binding of ZRF to MREa. Other heavy metals which can also induce metallothioneins, including cadmium, copper and mercury, do not activate ZRF. A MREa-containing oligonucleotide that can bind ZRF confers heavy metal-inducibility to a heterologous promoter, suggesting that ZRF is a zinc-dependent transcriptional activator. In addition to the MRE core sequence, the surrounding sequences are also important for both ZRF binding in vitro, and zinc-dependent transcriptional activation in vivo. MREa by itself responds not only to zinc but also to other metallothionein-inducing heavy metals, indicating that the ZRF protein, not the MREa sequence, is responsible for the zinc specificity.
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PMID:Zinc-specific activation of a HeLa cell nuclear protein which interacts with a metal responsive element of the human metallothionein-IIA gene. 145 36

Copper, zinc superoxide dismutase (SOD1 gene product) (superoxide:superoxide oxidoreductase, EC 1.15.1.1) is a copper-containing enzyme that functions to prevent oxygen toxicity. In the yeast Saccharomyces cerevisiae, copper levels exert some control over the level of SOD1 expression. We show that the ACE1 transcriptional activator protein, which is responsible for the induction of yeast metallothionein (CUP1) in response to copper, also controls the SOD1 response to copper. A single binding site for ACE1 is present in the SOD1 promoter region, as demonstrated by DNase I protection and methylation interference experiments, and is highly homologous to a high-affinity ACE1 binding site in the CUP1 promoter. The functional importance of this DNA-protein interaction is demonstrated by the facts that (i) copper induction of SOD1 mRNA does not occur in a strain lacking ACE1 and (ii) it does not occur in a strain containing a genetically engineered SOD1 promoter that lacks a functional ACE1 binding site.
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PMID:ACE1, a copper-dependent transcription factor, activates expression of the yeast copper, zinc superoxide dismutase gene. 192 15

ACE1 is the transcriptional activator of the metallothionein (CUP1 locus) gene in Saccharomyces cerevisiae. Previous data had implicated the N-terminal domain of ACE1 as responsible for the Cu-dependent specific DNA binding. An expression system in Escherichia coli was constructed to enable the isolation of an ACE1 domain containing the DNA and Cu-binding regions. Here we report the purification and characterization of the Cu-ACE1 truncated molecule. Spectroscopic techniques showed that ACE1 contains an unusual type of DNA binding structure that is based on a polynuclear Cu(I)-cysteinyl thiolate cluster. The cluster consists of six or seven Cu(I) ions coordinated to cysteinyl thiolates in a trigonal geometry distorted from planarity. The Cu(I)-cysteine cluster of Cu-ACE1 exhibits structural properties analogous to the Cu(I)-thiolate polynuclear cluster in yeast Cu-metallothionein itself, suggesting an unusual mechanism for the evolution of this regulatory factor. The Cu cluster organizes and stabilizes the conformation of the N-terminal domain of ACE1 for specific DNA binding.
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PMID:A copper-thiolate polynuclear cluster in the ACE1 transcription factor. 206 93

CUP2 is a copper-dependent transcriptional activator of the yeast CUP1 metallothionein gene. In the presence of Cu+ and Ag+) ions its DNA-binding domain is thought to fold as a cysteine-coordinated Cu cluster which recognizes the palindromic CUP1 upstream activation sequence (UASc). Using mobility shift, methylation interference, and DNase I and hydroxyl radical footprinting assays, we examined the interaction of wild-type and variant CUP2 proteins produced in Escherichia coli with the UASc. Our results suggest that CUP2 has a complex Cu-coordinated DNA-binding domain containing different parts that function as DNA-binding elements recognizing distinct sequence motifs embedded within the UASc. A single-amino-acid substitution of cysteine 11 with a tyrosine results in decreased Cu binding, apparent inactivation of one of the DNA-binding elements and a dramatic change in the recognition properties of CUP2. This variant protein interacts with only one part of the wild-type site and prefers to bind to a different half-site from the wild-type protein. Although the variant has about 10% of wild-type DNA-binding activity, it appears to be completely incapable of activating transcription.
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PMID:A single amino acid change in CUP2 alters its mode of DNA binding. 216 39

CUP2 is a regulatory gene controlling expression of CUP1, which encodes the Cu-binding yeast metallothionein. CUP2, which is identical to the ACE1 gene, encodes a Cu-regulated DNA-binding protein. The CUP2 protein contains a cysteine-rich DNA-binding domain dependent on Cu+ and Ag+ ions which bind the cysteine residues and direct the refolding of the metal-free apoprotein. CUP2 mutant alleles from Cu-sensitive yeast strains have point mutations affecting the DNA-binding activity. These results establish CUP2 as the primary sensor of intracellular Cu+ in the yeast Saccharomyces cerevisiae, functioning as a Cu+-regulated transcriptional activator.
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PMID:The CUP2 gene product, regulator of yeast metallothionein expression, is a copper-activated DNA-binding protein. 267 88

Human T-cell leukemia virus type I has a unique sequence pX and the product p40x was proposed to be a specific trans-acting transcriptional activator of expression of the viral gene. Recently, a second pX protein p27x-III in addition to p40x was identified; these two proteins are encoded by overlapping frames III and IV (x-lor). For determination of which product is the trans-acting activator, site-directed mutations were introduced into the pX sequence which was placed under the metallothionein promoter. On cotransfection with pLTR-CAT (a plasmid containing the LTR of HTLV-I and chloramphenicol acetyltransferase gene), only the mutations that affected p40x expression inactivated the transcriptional activation from the LTR.
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PMID:The p40x of human T-cell leukemia virus type I is a trans-acting activator of viral gene transcription. 300 3

We examined in the H4IIE rat hepatoma cell line the relationship between butyrate-induced changes in the nuclease sensitivity of chromatin and changes in transcriptional activity of specific genes. The butyrate-inducible metallothionein I (MT-I) gene underwent a dramatic increase in DNase I sensitivity after 3 h of butyrate treatment. However, genes not transcribed in H4IIE cells underwent the same changes in DNase I sensitivity. Thus, butyrate-induced increases in DNase I sensitivity are not sufficient for the transcriptional activation of a gene. Butyrate treatment has also been reported to alter the sensitivity of sequences to micrococcal nuclease (MNase) in a manner reflecting their tissue-specific expression. Butyrate exposure caused increased digestion of the MT-I gene by MNase. However, butyrate-induced MNase sensitivity also occurred for genes which are neither transcribed in untreated cells nor butyrate inducible. Moreover, cadmium, a potent transcriptional activator of the MT-I gene, does not alter the sensitivity of the MT-I gene to MNase. Thus, the butyrate-induced alterations in MNase sensitivity are neither sufficient for, necessary for, nor indicative of transcriptional activation.
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PMID:Butyrate-induced changes in nuclease sensitivity of chromatin cannot be correlated with transcriptional activation. 343 45

Yeast metallothionein, encoded by the CUP1 gene, and its copper-dependent transcriptional activator ACE1 play a key role in mediating copper resistance in Saccharomyces cerevisiae. Using an ethyl methanesulfonate mutant of a yeast strain in which CUP1 and ACE1 were deleted, we isolated a gene, designated CUP9, which permits yeast cells to grow at high concentrations of environmental copper, most notably when lactate is the sole carbon source. Disruption of CUP9, which is located on chromosome XVI, caused a loss of copper resistance in strains which possessed CUP1 and ACE1, as well as in the cup1 ace1 deletion strain. Measurement of intracellular copper levels of the wild-type and cup9-1 mutant demonstrated that total intracellular copper concentrations were unaffected by CUP9. CUP9 mRNA levels were, however, down regulated by copper when yeast cells were grown with glucose but not with lactate or glycerol-ethanol as the sole carbon source. This down regulation was independent of the copper metalloregulatory transcription factor ACE1. The DNA sequence of CUP9 predicts an open reading frame of 306 amino acids in which a 55-amino-acid sequence showed 47% identity with the homeobox domain of the human proto-oncogene PBX1, suggesting that CUP9 is a DNA-binding protein which regulates the expression of important copper homeostatic genes.
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PMID:Identification and analysis of a Saccharomyces cerevisiae copper homeostasis gene encoding a homeodomain protein. 796 20

Using the anticoagulant, hirudin, from the leech Hirudo medicinalis as a secreted reporter protein, the influence of physiological parameters on activity and regulation of the yeast (Saccharomyces cerevisiae) metallothionein (CUP1) promoter was studied. Induction of CUP1-directed hirudin expression from 2 mu-based vectors was possible at any time point during diauxic batch growth, even in cells approaching stationary phase. The highest titers of hirudin were obtained when the CUP1 promoter was activated immediately following inoculation of the cultures. If such a pseudo-constitutive fermentation strategy was adopted, the promoter was superior to an optimized variant (GAPFL) of the strong, constitutive GAPDH promoter. This superiority was primarily due to the relative independence of CUP1 promoter activity of the physiological status of host cells: whilst the maximal strength of the CUP1 and GAPFL promoters was comparable, CUP1-directed hirudin expression was high in all phases of diauxic batch growth, whereas hirudin production from the GAPFL promoter declined in post-diauxic cultures. High activity of the CUP1 promoter was observed on both a fermentable (glucose) and a non-fermentable (ethanol) carbon source. Hirudin expression could be adjusted to different levels by varying the amount of inducer (cupric sulphate) added to cultures. The copper concentrations required for maximal promoter induction had no negative effects on host growth and interfered with neither hirudin secretion nor with the biological activity of the peptide. Overexpression of the transcriptional activator, ACE1, resulted in increased levels of hirudin mRNA. Hirudin titers increased in parallel to mRNA concentrations in cultures grown in the presence of low concentrations of copper. In contrast, at high copper doses, elevated levels of the ACE1 protein resulted in inferior hirudin production. Cells overexpressing ACE1 while harbouring a CUP1-drived hirudin expression cassette showed slow growth and poor plasmid maintenance. It was tested whether this might be the result of a block in the secretory pathway; however, measurements of intracellular hirudin did not support this hypothesis. The data rather indicated that hirudin production was limited by a metabolic constraint downstream of transcription but upstream of the secretory pathway.
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PMID:Physiological characterization of the yeast metallothionein (CUP1) promoter, and consequences of overexpressing its transcriptional activator, ACE1. 801 99

A construct, MRE-beta Geo, with five metal response elements fused to a selectable reporter gene was transfected into BHK cells and a stable clone that could be induced up to 100-fold by zinc, cadmium, bismuth, silver, cobalt, copper, mercury, or nickle was isolated. Some, and perhaps all, of these metals induce MRE-beta Geo by displacing zinc. Transfection of these cells with a construct encoding the transcriptional activator MTF-1 resulted in constitutive expression of MRE-beta Geo, whereas expression of an antisense MTF-1 construct in these cells prevented induction by all of the metals. A variant cell line with high constitutive expression in the absence of added metals was isolated; normal regulation was restored by cell fusion. These results suggest that regulation of metallothionein genes by metals is mediated by MTF-1 interacting with metal response elements and that zinc functions to release MTF-1 from an inhibitor.
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PMID:Regulation of metallothionein genes by heavy metals appears to be mediated by a zinc-sensitive inhibitor that interacts with a constitutively active transcription factor, MTF-1. 810 90


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