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)

We have independently identified and DNA sequenced the INO2 locus by its close proximity to the KIN1 locus in Saccharomyces cerevisiae. Mutant strains in which the INO2 chromosomal locus has been deleted show pleiotropic phenotypes under growth conditions of inositol/choline availability. Many ino2 delta cells show delocalized cell growth resulting in large cells having aberrant shapes. These mutant cells may display nuclear segregation or positioning defects as well as defects in bud formation. Furthermore, homozygous ino2 delta-1 diploids fail to sporulate. Previous studies have shown that INO2 mutants are defective in phospholipid synthesis due to an inability to derepress the INO1 gene, the structural gene for inositol-1-phosphate synthase. To identify and determine the function of Ino2p in yeast cells, we raised antibodies to a beta-galactosidase/Ino2 fusion protein. The INO2 open reading frame codes for a 304 amino acid protein with a calculated molecular weight of 39.7 kDa. Immunoblot analysis reveals two Ino2-specific proteins of approximately 44 and 46 kDa. The 44 kDa species is localized to the nucleus. Ino2p is believed to function as a positive transcriptional activator in phospholipid synthesis. Our results suggest that it affects additional pathways important to polarized cell growth and division perhaps by functioning as a more general transcriptional factor.
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PMID:INO2, a regulatory gene in yeast phospholipid biosynthesis, affects nuclear segregation and bud pattern formation. 801 48

Overexpression of the YAP1 transcriptional activator renders yeast cells resistant to multiple metabolic inhibitors. In an effort to identify other gene products required for this phenotype we have isolated genomic mutations which neutralize this effect. One such mutation was further characterized and the affected gene was shown to be identical to TPS2 which encodes trehalose phosphate phosphatase, an enzyme catalysing the second step in trehalose biosynthesis. We have analysed the transcriptional regulation of the TPS2 gene and have shown that its transcription is induced by a variety of stressful conditions caused by metabolic inhibitors, osmotic shock and heat shock. This transcriptional activation is mediated by multiple stress promoter elements (C4T) and requires the function of Yap1p as well as reduced activity of the cAMP-regulated protein kinase. Using an appropriate reporter gene we have shown that Yap1p is generally required for transcriptional regulation through the C4T stress element. These results show that the YAP1 protein has a pivotal role in the metabolic stress response and the acquisition of stress tolerance.
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PMID:Yap1p, a yeast transcriptional activator that mediates multidrug resistance, regulates the metabolic stress response. 807 99

In Rhizobium meliloti, transcription of nitrogen fixation genes is induced in oxygen-depleted conditions under the control of the two-component regulatory system FixLJ. FixJ is a transcriptional activator whose activity is dramatically enhanced by phosphorylation, whereas FixL is a hemoprotein kinase that controls the level of phosphorylated FixJ in response to oxygen availability. We have found that a mutant FixJ protein, FixJD54N, in which the presumed site of phosphorylation (aspartate 54) was changed to an asparagine, is strongly affected for phosphorylation by FixL and is not detectably phosphorylated from the low-molecular-weight phosphate donor, acetyl-phosphate. Unexpectedly, FixL strongly enhances the transcriptional activity of the FixJD54N protein both in vivo and in vitro. We present evidence that FixJD54N transcriptional activity is enhanced by phosphorylation of an alternate residue in a reaction that requires FixL and ATP and is not affected by oxygen. We also demonstrate the key role of Asp-54 of FixJ in oxygen signal transduction.
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PMID:FixL of Rhizobium meliloti enhances the transcriptional activity of a mutant FixJD54N protein by phosphorylation of an alternate residue. 814 64

Taz1 is a hybrid receptor in the Escherichia coli cytoplasmic membrane, consisting of the N-terminal ligand binding domain of Tar (a chemoreceptor for aspartate) and the C-terminal signaling domain of EnvZ (an osmosensor). The binding of aspartate to an extra cytoplasmic domain induces the transmembrane signal to the cytoplasmic signaling domain. The signaling domain functioning as a protein kinase evokes a response by transferring a phosphate from an intracellular histidine to OmpR. This domain also encodes an OmpR-specific phosphatase whose action is crucial in completing the OmpR phosphorylation cycle. Phosphorylated OmpR acts as a transcriptional activator for the ompC gene. A number of mutations were introduced into the signaling domain in conserved sequences of the prokaryotic histidine kinase family. All Taz1 mutants lost the ability to both autophosphorylate the histidine residue and transfer the phosphate to OmpR. These mutated receptors were unable to activate ompC-lacZ expression. However, ompC-lacZ was able to be activated by complementation of Taz1 mutants. In some combinations, two different defective Taz1 mutants could restore both OmpR kinase and phosphatase activities when co-expressed. In other combinations only kinase activity was restored. Aspartate-inducible ompC-lacZ expression was restored only in the former cases, while in the latter cases ompC-lacZ expression became constitutive. These results indicate that the kinase activity is essential to activate ompC expression while the phosphatase activity is required to regulate ompC gene expression in a ligand-dependent manner.
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PMID:Requirement of both kinase and phosphatase activities of an Escherichia coli receptor (Taz1) for ligand-dependent signal transduction. 838 84

The transcriptional activator NUC-1 controls the transcription of the genes for phosphorus acquisition enzymes, and its activity is regulated by the negative regulatory factors, PREG and PGOV In this report, we describe the cloning and molecular analysis of the preg+ gene. In Neurospora crassa, as in higher eukaryotes, transformation frequently results in nonhomologous integration of transforming DNA. Insertion of transforming DNA into host genes mutates the gene and provides a molecular tag for cloning it. We obtained two mutants that have an insertion in the preg+ and pgov+ genes, respectively, among 2 x 10(5) transformants. The preg+ gene was cloned by screening a Neurospora genomic DNA library with DNA sequences flanking the transforming DNA of the rescued plasmid. Northern analysis showed that the transcription of the preg+ gene is not regulated by phosphate. The carboxy-terminal half of PREG shows strong homology with Saccharomyces cerevisiae PHO80 whose function is analogous to that of PREG. The pregc mutations are located in the well conserved residues which may directly interact with the residues in the regulatory domain of NUC-1.
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PMID:Insertional mutagenesis in Neurospora crassa: cloning and molecular analysis of the preg+ gene controlling the activity of the transcriptional activator NUC-1. 843 69

By making operon fusions with lambda placMu53, we identified, cloned, and analyzed the phoH gene belonging to the phosphate (pho) regulon. We mapped the phoH gene at 23.6 min in the Escherichia coli genomic library (Y. Kohara, K. Akiyama, and K. Isono, Cell 50:495-508, 1987). Its nucleotide sequence revealed an open reading frame of 354 amino acids which contains sequences for nucleotide-binding motifs. From comparison of the DNA sequences, phoH was found to be identical to psiH, which had been identified as a phosphate starvation-inducible gene (W.W. Metcalf, P.M. Steed, and B.L. Wanner, J. Bacteriol. 172:3191-3200, 1990). The PhoH protein was overproduced by the T7 promoter system, identified as a protein of about 39 kDa, and purified. The amino-terminal amino acid sequence of the PhoH protein agreed with the one deduced from the DNA sequence. We demonstrated that PhoH has an ATP-binding activity by a photoaffinity labeling experiment. Two transcriptional initiation sites (P1 and P2) were identified by S1 nuclease mapping. The upstream P1 promoter contains a pho box, the conserved sequence shared by the pho regulon genes. The region containing the pho box was bound by PhoB protein, the transcriptional activator of the pho regulon, as revealed by footprinting. Regulation of phoH expression in vivo was studied by constructing plasmids containing transcriptional fusions of the phoH promoters with a promoterless gene for chloramphenicol acetyltransferase. Transcription from the P1 promoter required the phoB function and was induced by phosphate limitation, while transcription from the P2 promoter was independent of phoB and constitutive under tested conditions.
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PMID:Molecular analysis of the phoH gene, belonging to the phosphate regulon in Escherichia coli. 844 94

In Rhizobium meliloti, transcription of the key nitrogen-fixation regulatory genes nifA and fixK is induced in response to microaerobiosis through the action of the FixL and FixJ proteins. These two proteins are sensor and regulator homologues, respectively, of a large family of bacterial two-component systems involved in sensing and responding to environmental changes. A soluble, truncated form of the membrane protein FixL, FixL*, has been shown to be a hemoprotein that phosphorylates and dephosphorylates FixJ in response to oxygen tension. Here we use an in vitro transcription system to prove that FixJ is a transcriptional activator of both nifA and fixK and that phosphorylation of FixJ markedly increases its activity. Phosphorylation was achieved either by preincubating FixJ with FixL* and ATP or by exposing FixJ to the inorganic phospho donor ammonium hydrogen phosphoramidate. Both FixJ and FixJ-phosphate formed heparin-resistant complexes under the assay conditions used. Lastly, we were able to show that anaerobiosis, in the presence of FixL* and ATP, greatly stimulates FixJ activity at the nifA promoter with either Escherichia coli or R. meliloti RNA polymerase. This use of atmospheric oxygen to control nifA transcription in vitro represents a reconstitution of a bacterial two-component signal transduction system in its entirety, from effector to ultimate target, by the use of purified components.
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PMID:Oxygen regulation of nifA transcription in vitro. 847 99

Phosphoribosyl diphosphate-lacking (delta prs) mutant strains of Escherichia coli require NAD, guanosine, uridine, histidine, and tryptophan for growth. NAD is required by phosphoribosyl diphosphate-lacking mutants because of lack of one of the substrates for the quinolinate phosphoribosyltransferase reaction, an enzyme of the NAD de novo pathway. Several NAD-independent mutants of a host from which prs had been deleted were isolated; all of them were shown to have lesions in the pstSCAB-phoU operon, in which mutations lead to derepression of the Pho regulon. In addition NAD-independent growth was dependent on a functional quinolinate phosphoribosyltransferase. The prs suppressor mutations led to the synthesis of a new phosphoryl compound that may act as a precursor for a new NAD biosynthetic pathway. This compound may be synthesized by the product of an unknown phosphate starvation-inducible gene of the Pho regulon because the ability of pst or phoU mutations to suppress the NAD requirement requires PhoB, the transcriptional activator of the Pho regulon.
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PMID:Phosphoribosyl diphosphate synthetase-independent NAD de novo synthesis in Escherichia coli: a new phenotype of phosphate regulon mutants. 855 May 5

It was demonstrated previously that a deoxyribophosphodiesterase (dRpase) activity is associated with the DNA repair enzyme exonuclease I, and that this activity is stimulated by the addition of the E. coli single-stranded DNA-binding protein (Ssb). This activity catalyzes the release of deoxyribose-phosphate groups at apurinic/apyrimidinic (AP) sites in the DNA that have been cleared by the action of an AP endonuclease. We have now used the yeast two-hybrid system to demonstrate that a protein-protein interaction occurs between exonuclease I and Ssb. When the E. coli ssb gene was fused in frame to the DNA-activating domain of the GAL4 transcriptional activator and the exonuclease I gene was fused in frame to the DNA-binding domain, a functional GAL4 transcriptional activator was produced as determined by growth of yeast on selective medium and the measurement of beta-galactosidase activity. We have also demonstrated that Ssb can stimulate the dRpase activity of exonuclease I using double-stranded bacteriophage M13 DNA containing several strand interruptions at incised AP sites. These results suggest that Ssb may be required for efficient base-excision repair in bacteria.
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PMID:Protein-protein interactions between the Escherichia coli single-stranded DNA-binding protein and exonuclease I. 861 28

In Bordetella pertussis, transcription of virulence-associated genes is regulated by the BvgS and BvgA proteins, members of the bacterial two-component signal-transduction family. BvgS is the transmembrane sensor and BvgA, in its phosphorylated form, is believed to be the key transcriptional activator in B. pertussis. However, the BvgA recognition sites in most virulence promoters have not yet been identified. To investigate the interaction of BvgA with the upstream region of cyaA, the gene encoding adenylate cyclase haemolysin, we have produced large amounts of BvgA in Escherichia coli. The protein was purified from inclusion bodies and then phosphorylated by acetyl phosphate. Using electrophoretic mobility-shift and footprinting assays, we provide evidence that BvgA cannot bind to the cyaA promoter unless it is phosphorylated. The phosphorylated form of BvgA (BvgA-P) is able to bind specifically to the upstream region of cyaA. Analysis of this region revealed that an unexpectedly large sequence, from -137 to -51, appears to be the target for BvgA-P binding, and probably contains multiple binding sites.
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PMID:Phosphorylation-dependent binding of BvgA to the upstream region of the cyaA gene of Bordetella pertussis. 873 28


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