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

We have cloned a regulatory gene for amylase synthesis in Aspergillus oryzae. This gene, amyR, encodes a 604-amino acid transcriptional activator with a Cys6 zinc cluster, that shows extensive homology to the DNA binding domain of GAL4 from Saccharomyces cerevisiae. The DNA binding domain of amyR binds to two types of sequences found in a number of promoters from Aspergillus genes coding for starch-degrading enzymes. One type of binding site is characterized by two CGG triplets separated by eight nucleotides. The other type has only one CGG triplet, which is followed by the sequence AAATTTAA.
Mol Gen Genet 1999 Dec
PMID:A new transcriptional activator for amylase genes in Aspergillus. 1062 49

The yeast transcriptional activator Cat8p has been identified as a factor that is essential for the derepression of genes involved in gluconeogenesis (like FBP1, PCK1, ACR1, ICL1 and MLS1) when only nonfermentable carbon sources are provided. Cat8p-dependent expression is mediated by cis-acting elements in the respective promoters, which are named UAS/CSREs (upstream activating sequence/carbon source responsive element). To establish whether the function of Cat8p is restricted to the activation of gluconeogenesis or is also involved in the regulation of a greater variety of genes, we investigated the transcriptional regulation of two genes, IDP2 and JEN1, which exhibit a similar expression pattern to gluconeogenic genes, although IDP2 at least is not linked directly to the gluconeogenic pathway. We identified functional UAS/CSRE elements in the promoters of both genes. Expression studies revealed that JEN1 is regulated negatively by the repressors Mig1p and Mig2p, and that Cat8p is needed for full derepression of the gene under non-fermentative growth conditions. Furthermore, we showed that Mig2p is also involved in the repression of CAT8 itself. The results presented in this study support a model in which Cat8p-dependent gene activation is not restricted to gluconeogenesis, but targets a wide variety of genes which are strongly derepressed under non-fermentative growth conditions.
Mol Gen Genet 1999 Dec
PMID:Cat8p, the activator of gluconeogenic genes in Saccharomyces cerevisiae, regulates carbon source-dependent expression of NADP-dependent cytosolic isocitrate dehydrogenase (Idp2p) and lactate permease (Jen1p). 1062 72

The timed destruction of cell cycle regulatory proteins is of key importance in controlling cell cycle progression in eukaryotes. Recently, Skp1 from yeast (Saccharomyces cerevisiae) was shown to play an important role in the ubiquitin-mediated proteolysis of these proteins via the Skp1-Cdc53-F-box (SCF) pathway. Here we describe the fortuitous cloning of cDNAs for two Skp1 homologues from the plant Arabidopsis thaliana on account of their ability to activate reporter gene expression in yeast directed by the cyt-1 element from the promoter of the Agrobacterium tumefaciens T-cyt gene, which is essential for expression of the gene in plants. This element is strikingly similar in sequence to the binding site for the yeast Migl protein, a transcriptional repressor of genes involved in the utilisation of carbohydrates other than glucose. We report that Mig1 protein binds to the cyt-1 element with similar specificity as a previously described plant nuclear protein factor, and that the cyt-1 element is a target for an unknown yeast transcriptional activator when Mig1 itself is inactivated. Interestingly, our data further indicate that A. thaliana Skp1 inactivates Mig1 by destabilising the yeast F-box protein Grr1, which is required for cyclin degradation and is thus involved in control of the cell cycle, and for glucose-regulated gene repression. Our results suggest that the plant counterpart of yeast Skp1 is probably also instrumental in ubiquitin-mediated proteolysis of specific proteins via an SCF-like pathway.
Mol Gen Genet 2000 Mar
PMID:Overexpression of Arabidopsis thaliana SKP1 homologues in yeast inactivates the Mig1 repressor by destabilising the F-box protein Grr1. 1077 50

Using a modified TAIL-PCR technique, the 5'-flanking regions of the phenylalanine ammonia lyase (Pal) genes of a yam species, Dioscorea bulbifera, and the phosphoglucose isomerase (Pgi) gene of D. tokoro were successfully isolated. Two novel modifications of the TAIL-PCR procedure introduced here, namely (1) the use of a battery of random 10-mers (RAPD primers) as short arbitrary primers, and (2) the use of a total of five nested, gene-specific primers, allow the rapid isolation of the 5'-flanking region of any gene from organisms with large genomes. Isolated 5'-flanking regions were fused to the gus gene, and tested for transient expression in tobacco BY2 cells. All the isolated 5'-flanking regions were shown to drive reporter gene expression. Three Pal promoters responded to salicylic acid, presumably as a result of the binding of a MYB transcriptional activator to the multiple MREs (Myb Recognition Elements) present in these regions.
Mol Gen Genet 2000 Apr
PMID:Rapid isolation of promoter sequences by TAIL-PCR: the 5'-flanking regions of Pal and Pgi genes from yams (Dioscorea). 1082 Nov 91

The tryptophan synthase-encoding gene, trpB, of Aspergillus nidulans was cloned and characterized. It was mapped to chromosome I, between the gene medA, which is required for sexual and asexual development, and an ORF encoding a protein with significant similarity to subunit B of vacuolar ATP synthases. The 5' untranslated region was found to be at least 142 nucleotides (nt) long, the poly(A) addition site was localized at position + 216 relative to the stop codon by sequencing of several independent cDNA clones. The trpB gene contains two exons separated by an intron of 105 nt, which is located close to the 5' end of the ORF. Directly upstream of the transcriptional start site, one well conserved potential binding site for the cross-pathway control transcriptional activator CPCA was found. The level of trpB transcript was shown to be regulated by cross-pathway control. A knockout mutant for trpB displays tryptophan auxotrophy, no trpB transcript is detectable, and development is perturbed to an extent that is dependent on the amount of tryptophan added to the medium. The trpB gene encodes a protein of 723 amino acids, with a calculated molecular weight of 77.6 kDa. The deduced amino acid sequence shows 72.6% similarity to the tryptophan synthase of Neurospora crassa. Most amino acid residues essential for catalytic activity in the tryptophan synthase of Salmonella typhimurium are conserved. The linker region joining the two domains of the enzyme is 13 residues longer than the longest connector found so far in tryptophan synthases from fungi.
Mol Gen Genet 2000 Jun
PMID:The tryptophan synthase-encoding trpB gene of Aspergillus nidulans is regulated by the cross-pathway control system. 1090 54

The yeast Kluyveromyces lactis is can utilise a wide range of non-fermentable carbon compounds as sole sources of carbon and energy, and differs from Saccharomyces cerevisiae in being able to carry out oxidative and fermentative metabolism simultaneously. In S. cerevisiae, growth on all non-fermentable carbon sources requires Cat8p, a transcriptional activator that controls the expression of gluconeogenic and glyoxylate cycle genes via CSREs (Carbon Source Responsive Elements). The down-regulation of Cat8p by fermentable carbon sources is the primary factor responsible for the tight repression of gluconeogenesis by glucose in S. cerevisiae. To analyse the regulation of gluconeogenesis in K. lactis, we have cloned and characterised the K. lactis homologue of CAT8 (KlCAT8). The gene was isolated by multicopy suppression of a fog2/klsnf1 mutation, indicating a similar epistatic relationship between KlSNF1 and KlCAT8 as in the case of the S. cerevisiae homologues. KlCAT8 encodes a protein of 1445 amino acids that is 40% identical to ScCat8p. The most highly conserved block is the putative Zn(II)2Cys6 DNA-binding domain, but additional conserved regions shared with members of the zinc-cluster family from Aspergillus define a subfamily of Cat8p-related proteins. KlCAT8 complements the growth defect of a Sccat8 mutant on non-fermentable carbon sources. In K. lactis, deletion of KlCAT8 severely impairs growth on ethanol, acetate and lactate, but not on glycerol. Derepression of enzymes of the glyoxylate cycle--malate synthase and particularly isocitrate lyase--was impaired in a Klcat8 mutant, whereas Northern analysis revealed that derepression of KlFBP1 and KlPCK1 does not require KlCat8p. Taken together, our results indicate that in K. lactis gluconeogenesis is not co-regulated with the glyoxylate cycle, and only the latter is controlled by KlCat8p.
Mol Gen Genet 2000 Sep
PMID:Differences in regulation of yeast gluconeogenesis revealed by Cat8p-independent activation of PCK1 and FBP1 genes in Kluyveromyces lactis. 1101 49

The E6 oncoprotein of bovine papillomavirus type 1 (BPV-1) can transform cells independently of p53 degradation. The precise mechanisms underlying this transformation are not yet completely understood. Here it is shown that BPV-1 E6 interacts with CBP/p300 in the same way as described for the E6 proteins of oncogenic human papillomaviruses. This interaction results in an inhibition of the transcriptional coactivator function of CBP/p300 required by p53 and probably by other transcription factors. The comparison of the CBP/p300-binding properties of BPV-1 E6 mutants previously characterized in transcription and transformation studies suggests (i) that the E6-CBP/p300 interaction may be necessary, but not sufficient, for cell transformation, and (ii) that the transcriptional activator function, inherent to the E6 protein, is not derived from forming a complex with CBP/p300.
J Gen Virol 2000 Nov
PMID:Interaction with CBP/p300 enables the bovine papillomavirus type 1 E6 oncoprotein to downregulate CBP/p300-mediated transactivation by p53. 1103 72

Rta, mainly encoded by open reading frame 50 (ORF50), is the product of an immediate-early gene of human herpesvirus-8 (HHV-8)/Kaposi's sarcoma-associated herpesvirus. Rta is a transcriptional activator that is both necessary and sufficient to disrupt viral latency and activate the expression of downstream viral lytic genes. We report that ectopically expressed Rta protein could also activate the rta promoter on a reporter plasmid up to 144-fold, both in latently infected B cells and in uninfected epithelial cells, and that this activation was dose-dependent. Furthermore, by analysing the 5' untranslated region using ribonuclease protection assays, we demonstrated that transfection of an Rta expression plasmid into latently infected cells activated the expression of rta transcripts from endogenous viral genomes. We propose that auto-activation of the immediate-early gene, rta, is an important strategy for HHV-8 to effectively respond to environmental stimuli and maximally activate the virus lytic cycle.
J Gen Virol 2000 Dec
PMID:Auto-activation of the rta gene of human herpesvirus-8/Kaposi's sarcoma-associated herpesvirus. 1108 35

The chimeric transcriptional activator TGV mediates dexamethasone (dx)-inducible and tetracycline (tc)-repressible transgene expression in tobacco (dx-on/ tc-off system). The expression profiles of four different synthetic target promoters, comprising multiple TGV binding sites upstream of a core promoter, were characterised using the sensitive luciferase assay. Induction factors of over 1,000 were measured in roots and leaves of over 30% of the transgenic plants, irrespective of the promoter used. Promoters PTF and PTax, which carry the -48 to +1 region of the Cauliflower Mosaic Virus 35S promoter, showed higher expression levels in both the uninduced and induced states than PTop10 and PTFM, which harbour several point mutations in this region. Moreover, PTax expressed higher background activities than PTF, indicating that the sequence of the synthetic regulatory region can influence background levels. The usefulness of the dx-on/tc-off system for experiments addressing gene function was demonstrated by using it to control the expression of isopentenyl transferase. This enzyme catalyses the rate-limiting step in cytokinin biosynthesis and causes phenotypic effects even at low expression levels. Only dx-induced transgenic plants displayed phenotypic alterations indicative for increased cytokinin synthesis (e.g. outgrowth of lateral buds). Simultaneous treatment of selected buds with the antiinducer tc suppressed bud growth. This result suggests that cytokinins cannot serve as mobile signals to elicit the release of apical dominance in tissues compromised for enhanced cytokinin synthesis.
Mol Gen Genet 2001 Feb
PMID:Characterisation of novel target promoters for the dexamethasone-inducible/tetracycline-repressible regulator TGV using luciferase and isopentenyl transferase as sensitive reporter genes. 1125 34

The hepatitis B virus (HBV) X protein (HBx) was originally suggested to be a viral transcriptional activator, but its functional mechanisms are still unclear. In this study we have analysed the intracellular localization of HBx in transfected cells and demonstrate that its compartmentalization is dependent on overall expression levels. HBx was exclusively or predominantly localized in the nuclei in weakly expressing cells. However, elevated cellular levels correlated with its accumulation in the cytoplasm, suggesting that the capacity of HBx for nuclear compartmentalization might be limited. Cytoplasmic HBx was detected either as punctate granular staining or in dispersed, finely granular patterns. We have further analysed the detailed cytoplasmic compartmentalization, using confocal microscopy, and show no association with the endoplasmic reticulum, plasma membrane or lysosomes, but a substantial association of HBx with mitochondria. However, a major fraction of cytoplasmic HBx did not localize in mitochondria, indicating the presence of two distinctly compartmentalized cytoplasmic populations. Furthermore, high levels of HBx expression led to an abnormal mitochondrial distribution, involving clumping and organelle aggregation, which was not observed at lower expression levels. The data presented here provide novel insights into the compartmentalization of HBx and may prove important for future evaluations of its functions, both in the viral life-cycle and in the pathology of HBV-related liver disease.
J Gen Virol 2001 Apr
PMID:Intracellular localization of the hepatitis B virus HBx protein. 1125 93


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