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

Many strains of Escherichia coli express type 1 pili which undergo phase variation during growth in broth, but become uniformly nonpiliated when passaged on agar media. In a previous analysis of these agar phase locked strains, we demonstrated that fimB and fimE, which mediate the site-specific DNA rearrangement involved in phase variation, are differentially transcribed under the two growth conditions. In this study the fimB promoter region was sequenced and characterized in agar phase locked strain J96. Primer extension analysis of the fimB gene identified three putative transcription initiation sites. Transcription starting from two of the sites (P1 and P2) would produce an mRNA that approximates the transcript size of fimB previously detected by Northern blot hybridizations. Gel mobility shift studies revealed the presence of promoter binding activity in broth-grown cell extracts, but not in extracts from agar-grown cells, that reacted specifically with DNA fragments upstream of the P1 and P2 promoter regions. This putative binding protein may be involved in the regulation of fimB, perhaps by acting as a transcriptional activator.
Mol Gen Genet 1994 Mar
PMID:Analysis of the fimB promoter region involved in type 1 pilus phase variation in Escherichia coli. 812 17

Two new yeast genes, named MBR1 and MBR3, were isolated as multicopy suppressors of the growth defect of a strain lacking the HAP2 transcriptional activator. Both genes when overexpressed can also suppress the growth defect of hap3 and hap4 null mutants. However, overexpression of MBR1 cannot substitute for the HAP2/3/4 complex in activation of the CYC1 gene. Nucleotide sequencing of MBR1 and MBR3 revealed that these two genes encode serine-rich, hydrophilic proteins with regions of significant homology. The functional importance of one of these conserved regions was shown by mutagenesis. Disruption of MBR1 leads to a partial growth defect on glycerol medium. Disruption of MBR3 has no major effect but the double disruptant shows a synthetic phenotype suggesting that the MBR1 and MBR3 gene products participate in common function.
Mol Gen Genet 1994 Jun 03
PMID:MBR1 and MBR3, two related yeast genes that can suppress the growth defect of hap2, hap3 and hap4 mutants. 820 48

The aim of this research was to determine whether the structural homology between the O2 gene, a maize transcriptional activator, and the GCN4 gene, a yeast transcriptional factor, is reflected at the level of function. The O2 cDNA was cloned in the yeast expression vector pEMBLyex4 under the control of a hybrid inducible promoter, and used to transform the yeast Saccharomyces cerevisiae. Transformed yeast cells produced O2 mRNA and a polypeptide immunoreactive with anti-O2 antibodies during growth in galactose. The heterologous protein was correctly translocated into the yeast nuclei, as demonstrated by immunofluorescence, indicating that the nuclear targeting sequences of maize are recognized by yeast cells. Further experiments demonstrated the ability of O2 to rescue a gcn4 mutant grown in the presence of aminotriazole, an inhibitor of the HIS3 gene product, suggesting that O2 activates the HIS3 gene, gene normally under control of GCN4. It was shown that the O2 protein is able to trans-activate the HIS4 promoter in yeast cells and binds to it in vitro. The sequence protected by O2, TGACTC, is also the binding site for GCN4. Finally, the expression of O2 protein in yeast did not produce alterations during batch growth at 30 degrees C, while transformants expressing O2 protein showed a conditionally lethal phenotype when grown in galactose at 36 degrees C; this phenotype mimics the behaviour of gcd mutants. The results support the idea that basic mechanisms of transcription control have been highly conserved in eukaryotes.
Mol Gen Genet 1993 Nov
PMID:Functional expression of the transcriptional activator Opaque-2 of Zea mays in transformed yeast. 824 86

In Streptomyces coelicolor A3(2) the whiB and whiG genes are essential for sporulation, their deduced products being a possible transcriptional activator and an RNA polymerase sigma factor, respectively. In a survey of DNA from diverse actinomycetes by Southern blotting, all samples tested hybridized with whiB, but only those representing genera capable of producing sporulating aerial mycelium hybridized with whiG. It is postulated that whiB may play a more intimate role in hyphal fragmentation processes (including sporulation) than whiG. The whiB and whiG homologues (whiB-Stv and whiG-Stv) of Streptoverticillium griseocarneum were cloned and sequenced, and subjected to functional tests in S. coelicolor whiB and whiG mutants. The genes were closely similar, but not identical, to their S. coelicolor counterparts at the DNA and deduced protein levels, and both Stv. griseocarnum gene products could function well in S. coelicolor. However, studies with hybrid transcription units suggested that the promoter region of whiB-Stv is somewhat inefficient in S. coelicolor.
J Gen Microbiol 1993 Nov
PMID:Functional and evolutionary implications of a survey of various actinomycetes for homologues of two Streptomyces coelicolor sporulation genes. 827 42

Pseudomonas sp. strain CF600 can degrade phenol and some of its methylated derivatives via a plasmid (pVI150)-encoded pathway. The metabolic route involves hydroxylation by a multi-component phenol hydroxylase and a subsequent meta-cleavage pathway. All 15 structural genes involved are clustered in an operon that is regulated by a divergently transcribed transcriptional activator. The multi-component nature of the phenol hydroxylase is unusual since reactions of this type are usually accomplished by single component flavoproteins. We have isolated and analysed a number of marine bacterial isolates capable of degrading phenol and a range of other aromatic compounds as sole carbon and energy sources. Southern hybridization and enzyme assays were used to compare the catabolic pathways of these strains and of the archetypal phenol-degrader Pseudomonas U, with respect to known catabolic genes encoded by Pseudomonas CF600. All the strains tested that degraded phenol via a meta-cleavage pathway were found to have DNA highly homologous to each of the components of the multicomponent phenol hydroxylase. Moreover, DNA of the same strains also strongly hybridized to probes specific for pVI150-encoded meta-pathway genes and the specific regulator of its catabolic operon. These results demonstrate conservation of structural and regulatory genes involved in aromatic catabolism within strains isolated from diverse geographical locations (UK, Norway and USA) and a range of habitats that include activated sludge, sea water and fresh-water mud.
J Gen Microbiol 1993 Nov
PMID:Conservation of regulatory and structural genes for a multi-component phenol hydroxylase within phenol-catabolizing bacteria that utilize a meta-cleavage pathway. 827 53

In the budding yeast Kluyveromyces lactis glucose repression of genes involved in lactose and galactose metabolism is primarily mediated by LAC9 (or K1GAL4) the homologue of the well-known Saccharomyces cerevisiae transcriptional activator GAL4. Phenotypic difference in glucose repression existing between natural strains are due to differences in the LAC9 gene (Breunig, 1989, Mol.Gen.Genet. 261, 422-427). Comparison between the LAC9 alleles of repressible and non-repressible strains revealed that the phenotype is a result of differences in LAC9 gene expression. A two-basepair alteration in the LAC9 promoter region produces a promoter-down effect resulting in slightly reduced LAC9 protein levels under all growth conditions tested. In glucose/galactose medium any change in LAC9 expression drastically affects expression of LAC9 controlled genes e.g. those encoding beta-galactosidase or galactokinase revealing a strong dependence of the kinetics of induction on the LAC9 concentration. We propose that in tightly repressible strains the activator concentration drops below a critical threshold that is required for induction to occur. A model is presented to explain how small differences in activator levels are amplified to produce big changes in expression levels of metabolic genes.
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PMID:Glucose repression of lactose/galactose metabolism in Kluyveromyces lactis is determined by the concentration of the transcriptional activator LAC9 (K1GAL4) [corrected]. 844 21

Transcription of the PHO84 gene encoding a Pi transporter in Saccharomyces cerevisiae is regulated by the Pi concentration in the medium. The promoter region of PHO84 bears five copies of the motif 5'-CACGT(G/T)-3', a candidate for the upstream activation site (UAS) that binds the transcriptional activator protein of the phosphatase regulon, Pho4p. These motifs are found at nucleotides -880 (site A), -587 (B), -436 (C), -414 (D), and -262 (E) relative to the putative ATG codon of PHO84. The Pho4p binds to all five 6-bp motifs with various affinities. Deletion analysis of the PHO84 promoter using a PHO84-lacZ fusion gene and base substitutions in the 6-bp motif revealed that two copies of the 6-bp motif, either C or D, and E, are necessary and sufficient for full regulation of the PHO84 gene. Results of expression studies with a CYC1-lacZ fusion gene with various 36-bp oligonucleotides including the 30-bp sequences around site D or E, or with modified sequences, inserted in the CYC1 promoter region indicated that the 6-bps motif flanked by a thymine nucleotide at its 5' end is much less effective as a UAS site for Pho4p in vivo than other versions. Thus, the consensus sequences for phosphatase regulation are 5'-GCACGTGGG-3' and 5'-GCACGTTTT-3' which differ from the binding sequences for the Cpflp protein required for transcription of the genes in methionine biosynthesis and for centromere function. However, Pho4p binding in vitro was unaffected by modification of the 5' or 3' flanking sites of the 6-bp motif, while modification inside the 6-bp motif affected it severely. The UAS function of the GCACGTTTT motif with respect to the Pi signal depends on its orientation in the promoter sequence.
Mol Gen Genet 1995 Dec 10
PMID:Structure and distribution of specific cis-elements for transcriptional regulation of PHO84 in Saccharomyces cerevisiae. 855 45

The 72 kDa 1E1 protein of human cytomegalovirus (HCMV) is one of a few viral regulatory proteins expressed immediately after infection of a host cell. Although it is now well-established that 1E1 is a potent transcriptional activator of the human immunodeficiency virus (HIV) long terminal repeat (LTR), the identity of the nucleotide sequence responsive to 1E1 remains elusive and the molecular mechanism of this interaction is not well-understood. We have constructed various LTR mutants and tested them for their ability to be activated by 1E1 using transient transfection assays. Mutations in the NF-kappa B sites, of either a few changes in the nucleotide sequence or a deletion of the entire region, abrogated 1E1-driven transactivation. Deletion of the Tat-responsive element (TAR) had no significant effect on reporter expression. Mutations in the Sp1 sites or the TATA box significantly lowered LTR activity, but this is probably due to an effect on the general transcription system, as these elements are also required for the transactivation of the LTR by many stimulators including Tat, tumour necrosis factor alpha (TNF-alpha). E1A/E1B and phorbol myristate acetate (PMA). In addition, gel retardation analysis demonstrated that NF- kappa B activity was significantly increased in human T lymphoid H9 and monocytic U937 cell lines constitutively expressing 1E1. Taken together, these data suggest that NF- kappa B plays a central role in the 1E1 transactivation of the HIV LTR.
J Gen Virol 1996 Jan
PMID:Essential role of NF-kappa B in transactivation of the human immunodeficiency virus long terminal repeat by the human cytomegalovirus 1E1 protein. 855 31

Several sites of nuclear protein interaction within the promoter region of the Antirrhinum majus floral meristem identity gene SQUAMOSA were detected using an electrophoretic mobility shift assay. One of these sites displayed a particularly clear interaction with nuclear protein extracted from inflorescences but not with nuclear protein extracted from young, nonflowering plants. This site could thus represent a binding motif for a transcriptional activator. A South-western screen of an inflorescence cDNA expression library resulted in the isolation of several cDNAs representing two different genes named SBP1 and SBP2 (for SQUAMOSA-pROMOTER BINDING PROTEIN gene 1 and 2). Both genes encode highly similar protein domains which were found to be necessary and sufficient for binding DNA in a sequence-specific manner. This DNA-binding domain showed no similarity to known proteins in the databases. However, it is characteristic for a small family of gene products in A. majus and other plant species. Expression of SBP1 and 2 is developmentally regulated and their transcriptional activation precedes that of SQUAMOSA. The data presented support the idea that members of the newly identified SBP gene family function as transcription factors involved in the control of early flower development.
Mol Gen Genet 1996 Jan 15
PMID:A new family of DNA binding proteins includes putative transcriptional regulators of the Antirrhinum majus floral meristem identity gene SQUAMOSA. 856 90

A short non-coding region (SNR) commonly exists between the E5 and L2 open reading frames of human papillomaviruses (HPVs). Except for the poly(A) signal for early gene transcripts, no biological functions have been discovered for the SNR. To test a possible promoter-like activity of the SNR, we carried out CAT reporter assays using constructs containing the SNRs from HPV-16, -18 and -33 linked to a promoterless CAT gene. We reproducibly observed enhanced expression of CAT gene by the SNRs. Co-expression of a transcriptional activator (LAP/NF-IL6) or deletion of the poly(A) signal augmented the promoter-like activity of the SNRs. RNase protection assays revealed a LAP-inducible CAT mRNA properly initiated from the HPV-16 SNR. These results may suggest that the SNR has a promoter activity that is regulated by keratinocyte differentiation.
J Gen Virol 1996 Mar
PMID:Evidence for a promoter-like activity in the short non-coding region of human papillomaviruses. 860 81


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