Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Specific cysteine residues at possible methyl acceptor sites of the Ada protein of Escherichia coli were converted to other amino acids by site-directed mutagenesis of the cloned ada gene of E. coli. Ada protein with the cysteine residue at 321 replaced by alanine was capable of accepting the methyl group from the methylphosphotriester but not from O6-methylguanine or O4-methylthymine of alkylated DNA, whereas the protein with alanine at position 69 accepted the methyl group from the methylated bases but not from the methylphosphotriester. These two mutants were used to elucidate the biological significance of repair of the two types of alkylation lesions. Introduction of the ada gene with the Ala69 mutation into an ada- cell rendered the cell more resistant to alkylating agents with respect to both killing and induction of mutations, but the gene with the Ala321 mutation exhibited no such activity. Replacement of the cysteine residue at position 69, but not at position 321, abolished the ability of Ada protein to promote transcription of both ada and alkA genes in vitro. These results are compatible with the idea that methylation of the cysteine residue at position 69 renders Ada protein active as a transcriptional regulator, whilst the cysteine residue at position 321 is responsible for repair of pre-mutagenic and lethal lesions in DNA. The actions of mutant Ada proteins on the ada and alkA promoters in vivo were investigated using an artificially composed gene expression system. When the ada gene with the Ala69 mutation was introduced into the cell, there was little induction of expression of either the ada or the alkA genes, even after treatment with an alkylating agent, in agreement with the data obtained from studies in vitro. With the Ala321 mutation, however, a considerable degree of ada gene expression occurred without adaptive treatment. The latter finding suggests that the cysteine residue at position 321, which is located near the C terminus of the Ada protein, is involved in regulating activity, as the transcriptional activator.
 ...
PMID:Functional sites of the Ada regulatory protein of Escherichia coli. Analysis by amino acid substitutions. 304

The Vibrio fischeri luminescence genes are activated by the LuxR protein and a diffusible signal termed the autoinducer. LuxR consists of two domains, a C-terminal transcriptional activator domain, and an N-terminal autoinducer-binding domain, which serves to regulate the function of the C-terminal domain. We have isolated and characterized an intragenic suppressor of a mutation that maps to the N-terminal domain and blocks autoinducer binding. The suppressor changes an alanine residue at position-221 in the C-terminal domain to a valine. In Escherichia coli, the suppressor allows partial activation of the V. fischeri luminescence genes although E. coli containing this protein remains unable to bind autoinducer. To further analyze the influence of the second-site mutation on luxR function, we constructed a luxR gene that coded for a protein with a wild-type N-terminal domain and with the ala-221 to val substitution in the C-terminal domain. This protein activated the luminescence genes in the presence or absence of autoinducer, and it bound autoinducer at levels comparable to the wild-type LuxR protein. Apparently, the alanine to valine substitution at position-221 allows activity of the C-terminal domain in a fashion independent of whether autoinducer is bound to the N-terminal domain.
 ...
PMID:Intragenic suppression of a luxR mutation: characterization of an autoinducer-independent LuxR. 778 94

LAP (NF-IL6 or C/EBP beta), is a liver transcriptional activator protein that confers liver-specific gene expression. Because LAP has a characteristic phosphoacceptor sequence for cAMP-dependent protein kinase A (PKA), we tested if in vitro phosphorylation of LAP by PKA modulates its interaction with specific DNA sequences. The major PKA phosphorylation site of LAP was identified as Ser105, which is a predicted PKA site. As expected, this PKA phosphorylation site disappears after mutation of Ser105 to Ala. Kinetic studies with LAP and LAP Asp105 (which mimics a phosphoserine residue) demonstrated that phosphorylation of Ser105 itself has no effect on DNA binding. Phosphorylation of other sites by PKA, identified in the region between Ser173 and Ser223 and at Ser240, by analysis of truncated and mutated LAP peptides, resulted in an inhibition of DNA binding. LAP was also phosphorylated by purified protein kinase C in vitro, and the major phosphoacceptor was shown to be Ser240 within the DNA-binding domain of LAP. Phosphorylation of LAP at this residue or introduction of a Ser240 to Asp mutation resulted in marked decrease in its binding to DNA. These results suggest that site-specific phosphorylations of LAP modulate transactivation of its target genes.
 ...
PMID:Protein kinase A and C site-specific phosphorylations of LAP (NF-IL6) modulate its binding affinity to DNA recognition elements. 820 Sep 92

Resistance to multiple antibiotics and certain oxidative stress compounds was conferred by three independently selected mutations (marR1, soxQ1, and cfxB1) that mapped to 34 min on the Escherichia coli chromosome. Mutations at this locus can activate the marRAB operon, in which marR encodes a putative repressor of mar transcription and marA encodes a putative transcriptional activator of defense genes against antibiotics and oxidants. Overexpression of the wild-type MarR protein reversed the phenotypes (antibiotic resistance and increased antioxidant enzyme synthesis) of all three mutants. DNA sequence analysis showed that, like marR1, the other two mutations were alterations of marR: a 285-bp deletion in cfxB1 and a GC-->AT transition at codon 70 (Ala-->Thr) in soxQ1. All three mutations cause increased amounts of mar-specific RNA, which supports the hypothesis that MarR has a repressor function in the expression of the marRAB operon. The level of mar RNA was further induced by tetracycline in both the marR1 and soxQ1 strains but not in the cfxB1 deletion mutant. In the cfxB1 strain, the level of expression of a truncated RNA, with or without tetracycline exposure, was the same as the fully induced level in the other two mutants. Overproduction of MarR in the cfxB1 strain repressed the transcription of the truncated RNA and restored transcriptional inducibility by tetracycline. Thus, induction of the marRAB operon results from the relief of the repression exerted by MarR. The marRAB operon evidently activates both antibiotic resistance and oxidative stress genes.
 ...
PMID:Repressor mutations in the marRAB operon that activate oxidative stress genes and multiple antibiotic resistance in Escherichia coli. 828 90

In the yeast Saccharomyces cerevisiae, genetic studies suggest that the RIM1 gene encodes a positive regulator of meiosis. rim1 mutations cause reduced expression of IME1, which is required for expression of many meiotic genes, and thus lead to a partial defect in meiosis and spore formation. We report the sequence of RIM1 and functional analysis of its coding region. The RIM1 gene product (RIM1) contains three regions similar to C2H2 zinc fingers. Serine substitutions for cysteine in each of the putative zinc fingers abolish RIM1 function. The carboxyl-terminus of RIM1 is enriched in acidic amino acids and is required for full RIM1 activity. RIM1 also contains two putative cAMP-dependent protein kinase (cAPK) phosphorylation sites. At one site, substitution of alanine for serine does not affect RIM1 activity; at the other site, this substitution impairs activity. This analysis of RIM1 suggests that the protein may function as a transcriptional activator. We have used the cloned RIM1 gene to create a complete rim1 deletion. This null allele, like previously isolated rim1 mutations, causes a partial meiotic defect. In addition to RIM1, maximum IME1 expression requires the MCK1 and IME4 gene products. Defects associated with rim1, mck1, and ime4 mutations in expression of a meiotic reporter gene (ime2-lacZ) and in sporulation are additive. These findings suggest that RIM1 acts independently of MCK1 and IME4 to stimulate IME1 expression.
 ...
PMID:Molecular characterization of the yeast meiotic regulatory gene RIM1. 836 97

Active E1 component of Pseudomonas putida branched-chain-oxoacid dehydrogenase was purified from P. putida strains carrying pJRS84 which contains bkdR (encoding the transcriptional activator) and bkdA1 and bkdA2 (encoding the alpha and beta subunits). Expression was inducible, however, 45-, 39- and 37-kDa proteins were produced instead of the expected 45-kDa and 37-kDa proteins. The 45-kDa protein was identified as E1 alpha and the 37-kDa and 39-kDa proteins were identified as separate translational products of bkdA2 by their N-terminal sequences. The N-terminal amino acid of the 39-kDa protein was leucine instead of methionine. The 45-, 39- and 37-kDa proteins were also produced in wild-type P.putida. Translation of bkdA1 and bkdA2 from an Escherichia coli expression plasmid produced only 45-kDa and 39-kDa proteins, with N-terminal methionine on the 39-kDa protein. The insertion of guanine residues 5' to the first ATG of bkdA2 did not affect expression of E1 beta in P. putida including the N-terminal leucine which appears to eliminate the possibility of ribosome jumping. The Z-average molecular mass of the E1 component was determined by sedimentation equilibrium to be 172 +/- 9 kDa compared to a calculated value of 166 kDa for the heterotetramer and a Stokes radius of 5.1 nm. E1 alpha Ser313, which is homologous to the phosphorylated residue of rat liver E1 alpha, was converted to alanine resulting in about a twofold increase in Km, but no change in Kcat. S315A and S319A mutations had no effect on Km or Kcat indicating that these residues do not play a major part in catalysis of E1 alpha beta 2.
 ...
PMID:Purification of active E1 alpha 2 beta 2 of Pseudomonas putida branched-chain-oxoacid dehydrogenase. 852 48

Previously, we demonstrated that ABP-1 (arylphorin gene-specific binding protein-1), which is suggested to be the transcriptional activator of the arylphorin gene of Sarcophaga peregrina, is present in NIH-Sape-4 cells, which do not express arylphorin. As well as ABP-1, these cells were found to contain another protein (ABP-2) that probably binds to the same sequence as that to which ABP-1 binds [Adachi, N., Kubo, T., and Natori, S. (1993) J. Biochem. 114, 55-60]. We purified ABP-2 from a nuclear extract of NIH-Sape-4 cells and compared its DNA-binding activity with that of ABP-1. Both ABP-1 and ABP-2 were found to bind to the same sequence in the arylphorin gene with the same affinity and stability, but an ABP-2-specific hypersensitive site was detected by DNase I footprinting analysis. Analyses of proteolytic fragments suggested that both ABP-1 and ABP-2 have Zn fingers showing high similarity with that of AEF-1, a transcriptional repressor of the Drosophila melanogaster alcohol dehydrogenase gene that binds to a sequence very similar to that binding ABP-1 and ABP-2. We isolated a candidate cDNA for ABP-2, and the protein it encoded contained nine Zn fingers and regions rich in alanine, glutamine, serine/threonine, glycine, histidine, and asparagine.
 ...
PMID:Purification, characterization, and cDNA cloning of ABP-2 (arylphorin gene-specific binding protein-2) that specifically binds to the ABP-1-binding sequence in the arylphorin gene of Sarcophaga peregrina. 901 Jul 76

The expression of virulence factor genes in Bordetella pertussis is mediated by the BvgA-BvgS two-component signal transduction system. The response regulator, BvgA, acts directly as a transcriptional activator at the loci encoding pertussis toxin (ptx) and filamentous hemagglutinin (fha). Previous studies have demonstrated that these two loci are differentially regulated by BvgA. As an initial step in gaining insight into the mechanism underlying this differential regulation, we initiated DNA binding and in vitro transcription analyses to examine the activities of BvgA and RNA polymerase (RNAP) purified from both B. pertussis and Escherichia coli at the fha promoter. We discovered that unphosphorylated BvgA binds to a single region (-100 to -70, relative to the start of transcription), whereas phosphorylated BvgA binds both this region and another, farther downstream, that extends to the -35 nucleotide. In the absence of BvgA, RNAP binds a region farther upstream than expected (-104 to -35). However, occupation of both sites by BvgA phosphate repositions RNAP to the site used in vivo. The binding of BvgA phosphate to the downstream site correlates with in vitro transcriptional activity at the fha promoter. As the DNA binding and transcription activities of the E. coli-derived RNAP are similar to those observed for the B. pertussis enzyme, we employed several mutant E. coli proteins in in vitro transcription analyses. We observed that polymerases carrying either a deletion of the C-terminal domain of the alpha subunit or substitution of alanine at either of two critical residues within this domain were severely impaired in the ability to mediate BvgA-activated transcription at fha.
 ...
PMID:Nature of DNA binding and RNA polymerase interaction of the Bordetella pertussis BvgA transcriptional activator at the fha promoter. 904 38

The ZEBRA protein from Epstein-Barr virus (EBV) activates a switch from the latent to the lytic expression program of the virus. ZEBRA, a member of the bZIP family of DNA-binding proteins, is a transcriptional activator capable of inducing expression from viral lytic cycle promoters. It had previously been thought that ZEBRA's capacity to disrupt EBV latency resided primarily in its ability to activate transcription of genes that encode products required for lytic replication. We generated a point mutant of ZEBRA, Z(S186A), that was not impaired in its ability to activate transcription; however, this mutation abolished its ability to initiate the viral lytic cascade. The mutant, containing a serine-to-alanine substitution in the DNA-binding domain of the protein, bound to several known ZEBRA-binding sites and activated transcription from reporters bearing known ZEBRA-responsive promoters but did not disrupt latency in EBV-infected cell lines. Therefore, initiation of the EBV lytic cycle by the ZEBRA protein requires a function in addition to transcriptional activation; a change of serine 186 to alanine in the DNA-binding domain of ZEBRA abolished this additional function and uncovered a new role for the ZEBRA protein in disruption of EBV latency. The additional function that is required for initiation of the lytic viral life cycle is likely to require phosphorylation of serine 186 of the ZEBRA protein, which may influence either DNA recognition or transcriptional activation of lytic viral promoters in a chromatinized viral episome.
 ...
PMID:Alteration of a single serine in the basic domain of the Epstein-Barr virus ZEBRA protein separates its functions of transcriptional activation and disruption of latency. 906 Jun 66

Different mechanisms of transcriptional activation may be required for distinct classes of promoters and cellular conditions. The Epstein-Barr virus (EBV)-encoded transcriptional activator Zta recruits the general transcription factors IID (TFIID) and IIA (TFIIA) to promoter DNA and induces a TATA box-binding protein (TBP)-associated factor-dependent footprint downstream of the transcriptional initiation site. In this study, we investigated the functional significance of TFIID-TFIIA (D-A complex) recruitment by Zta. Alanine substitution mutations in the Zta activation domain which eliminate the ability of Zta to stimulate the D-A complex were examined. These Zta mutants were defective in the ability to activate transcription from an EBV-derived promoter (BHLF1) but activated a highly responsive synthetic promoter (Z7E4T). Both the number of activator binding sites and the core promoter region contribute to the requirement for D-A complex recruitment. These functionally distinct core promoters had significant differences in affinity for TBP and TFIID binding. The D-A complex-recruiting activity of Zta was found to be important for promoter selection in the presence of a competitor template. Conditions which limit TFIID binding to the TATA element or compromise the ability of TFIIA to bind TBP required activator stimulation of the D-A complex. These results indicate that D-A complex recruitment is one of at least two activation pathways utilized by Zta and is the essential pathway for a subset of promoters and conditions which limit TFIID binding to the TATA element.
 ...
PMID:Requirement for transcription factor IIA (TFIIA)-TFIID recruitment by an activator depends on promoter structure and template competition. 934 26


<< Previous 1 2 3 4 5 6 7 8 9 Next >>