Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.13.3 (histidine kinase)
2,405 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of the genes encoding the major outer membrane porin proteins OmpF and OmpC in Escherichia coli is regulated by ompR, which encodes the transcriptional activator protein OmpR, and envZ, which encodes a receptorlike protein located in the inner membrane. To examine the role of EnvZ in the expression of the osmoregulated porin genes, we analyzed the production of OmpF and OmpC in cells that lack envZ function. We show that EnvZ is required for the maximal production of OmpC in cells grown in minimal medium but is not essential for the efficient induction of OmpC that occurs during a shift to a high-osmolarity medium. In contrast, the production of OmpF in cells that lack envZ function was similar to that of the parent strain, whereas OmpF repression during a shift to a high-osmolarity medium was incomplete in the absence of EnvZ. These results are discussed in the context of the putative role of EnvZ in the expression of ompF and ompC.
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PMID:Regulation of ompC and ompF expression in Escherichia coli in the absence of envZ. 284 9

Sakacin A is a small, heat-stable, antilisterial bacteriocin produced by Lactobacillus sake Lb706. The nucleotide sequence of a 8,668-bp fragment, shown to contain all information necessary for sakacin A production and immunity, was determined. The sequence revealed the presence of two divergently transcribed operons. The first encompassed the structural gene sapA (previously designated sakA) and saiA, which encoded a putative peptide of 90 amino acid residues. The second encompassed sapK (previously designated sakB), sapR, sapT, and sapE. sapK and sapR presumably encoded a histidine kinase and a response regulator with marked similarities to the AgrB/AgrA type of two-component signal-transducing systems. The putative SapT and SapE proteins shared similarity with the Escherichia coli hemolysin A-like signal sequence-independent transport systems. SapT was the HlyB analog with homology to bacterial ATP-binding cassette exporters implicated in bacteriocin transport. Frameshift mutations and deletion analyses showed that sapK and sapR were necessary for both production and immunity, whereas sapT and sapE were necessary for production but not for immunity. The putative SaiA peptide was shown to be involved in the immunity to sakacin A. The region between the operons contained IS1163, a recently described L. sake insertion element. IS1163 did not appear to be involved in expression of the sap genes. Northern (RNA) blot analysis revealed that the putative SapK/SapR system probably acts as a transcriptional activator on both operons. A 35-bp sequence, present upstream of the putative sapA promoter, and a similar sequence (30 of 35 nucleotides identical) upstream of sapK were shown to be necessary for proper expression and could thus be possible targets for transcriptional activation.
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PMID:The genes involved in production of and immunity to sakacin A, a bacteriocin from Lactobacillus sake Lb706. 772 4

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 Bacillus subtilis pstS operon and phoA gene are members of the Pho regulon that is controlled by PhoR, a histidine kinase, and PhoP, a response regulator. Footprinting analysis showed that phosphorylated PhoP extended the PhoP protected region in pstS and phoA promoters, and also bound to a separate site within the coding region of each gene. Our previous in vivo studies have shown that, in contrast to other Pho regulon promoters that are not expressed in either phoP or phoR mutants, a low-level induction from the pstS promoter (25% of parent strain) can be detected in a phoR mutant. In this study, by using an in vitro transcription system, we demonstrate that (i) only phosphorylated PhoP is a transcriptional activator of the pstS operon and of the phoA gene; (ii) phosphorylated PhoP and RNA polymerase sigmaA holoenzyme are sufficient for in vitro transcription of the pstS promoter and the phoA promoter; (iii) the activation of the pstS promoter requires lower concentrations of phosphorylated PhoP than does the phoA promoter for transcription; and (iv) PhoP binding sites in both the pstS promoter core binding region and in the 5' coding region of the gene, which have been identified by footprinting analysis, are important for the transcription of the pstS promoter in vitro.
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PMID:PhoP-P and RNA polymerase sigmaA holoenzyme are sufficient for transcription of Pho regulon promoters in Bacillus subtilis: PhoP-P activator sites within the coding region stimulate transcription in vitro. 968 Feb 8

The delta-proteobacterium Myxococcus xanthus coordinates its motility during aggregation and fruiting body formation. While searching for chemotaxis genes in M. xanthus, we identified a third chemotaxis-like gene cluster, the che3 cluster, encoding homologs to two methyl-accepting chemotaxis proteins (MCPs), a CheW, a hybrid CheA, a CheB, a CheR, but no CheY. Mutations in mcp3A, mcp3B, and cheA3 did not show obvious defects in motility or chemotaxis but did affect the timing of entry into development. Mutations in these genes caused early aggregation of starving cells, even at low cell densities. Furthermore, these mutants showed pronounced overexpression of the developmentally regulated Tn5lac fusions Omega4403, Omega4411, and Omega4521 as well as overexpression of mbhA and tps, markers for peripheral rods and aggregating cells, respectively. Divergently transcribed from the che3 promoter region is another gene, crdA (chemosensory regulator of development), predicted to encode a transcriptional activator of sigma(54)-dependent promoters. To test the hypothesis that CrdA functions as the cognate response regulator for the histidine kinase CheA3, CrdA and CheA3 were assayed and found to interact strongly in the yeast two-hybrid system. Mutant analysis showed that crdA cells were delayed in development (12-24 h) and delayed in MbhA production relative to the wild type. An mcp3BcrdA double mutant displayed the crdA phenotype, indicating that crdA is epistatic to mcp3B. We conclude that the Che3 chemotaxis-like system functions to control developmental gene expression by regulating a sigma(54) transcriptional activator, CrdA.
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PMID:Chemosensory regulation of developmental gene expression in Myxococcus xanthus. 1256 62

Transcription of the hupSL genes, which encode the uptake [NiFe]hydrogenase of Rhodobacter capsulatus, is specifically activated by H(2). Three proteins are involved, namely the H(2)-sensor HupUV, the histidine kinase HupT and the transcriptional activator HupR. hupT and hupUV mutants have the same phenotype, i.e. an increased level of hupSL expression (assayed by phupS::lacZ fusion) in the absence of H(2); they negatively control hupSL gene expression. HupT can autophosphorylate its conserved His(217), and in vitro phosphotransfer to Asp(54) of its cognate response regulator, HupR, was demonstrated. The non-phosphorylated form of HupR binds to an enhancer site (5'-TTG-N(5)-CAA) of phupS localized at -162/-152 nt and requires integration host factor to activate fully hupSL transcription. HupUV is an O(2)-insensitive [NiFe]hydrogenase, which interacts with HupT to regulate the phosphorylation state of HupT in response to H(2) availability. The N-terminal domain of HupT, encompassing the PAS domain, is required for interaction with HupUV. This interaction with HupT, leading to the formation of a (HupT)(2)-(HupUV)(2) complex, is weakened in the presence of H(2), but incubation of HupUV with H(2) has no effect on the stability of the heterodimer/tetramer, HupUV-(HupUV)(2), equilibrium. HupSL biosynthesis is also under the control of the global two-component regulatory system RegB/RegA, which controls gene expression in response to redox. RegA binds to a site close to the -35 promoter recognition site and to a site overlapping the integration host factor DNA-binding site (5'-TCACACACCATTG, centred at -87 nt) and acts as a repressor.
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PMID:Transcriptional regulation of the uptake [NiFe]hydrogenase genes in Rhodobacter capsulatus. 1566 56

We have measured the transcription of several genes that have been implicated as virulence factors in Aspergillus fumigatus, including fos-1, a histidine kinase, two-component signal protein, rhbA, a ras-related protein required for signaling, pksP, a polyketide synthase involved in biosynthesis of melanin, pabA synthetase, an enzyme catalyzing a late step in the biosynthesis of folate, lysF, a homoconitase related to lysine biosynthesis, and cpcA, the transcriptional activator of the cross-pathway control system of amino acid biosynthesis. Transcription levels were determined from in vitro grown organism as well as from lung tissue from mice infected with A. fumigatus. Our data indicate that fos-1 and rhbA transcription increased significantly during the infection in mice, compared to the other genes whose transcription remained the same (pksP, cpcA, pabA) or decreased slightly (lysF). In vitro measurements of transcription compared to transcription in infected lung tissue demonstrated low levels of fos-1 and rhbA, 20-40-fold increases (cpcA, lysF, pabA), while pksP was not detected from cultures. Our data demonstrate that transcription of these genes differs in vitro versus during disease.
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PMID:Expression of Aspergillus fumigatus virulence-related genes detected in vitro and in vivo with competitive RT-PCR. 1620 68

FixL is a heme-based O2 sensor protein, which responds to low O2 concentrations by activating the transcriptional activator FixJ. Signal transduction is initiated by the dissociation of O2 from the sensor domain of FixL, resulting in protein conformational changes that are transmitted to a histidine kinase domain. To gain insight into the FixL sensing mechanism, we monitored changes in the protein's structure in the picosecond to millisecond time frame, following the dissociation of the ligand using time-resolved resonance Raman spectroscopy. This study presents the time-resolved resonance Raman spectra of Sinorhizobium meliloti FixL upon O2 dissociation, as well as upon CO dissociation. The FixL spectra show that there are three steps in the dynamic structural changes that result from ligand dissociation. Ligand-dependent structural dynamics are observed in the earliest step. On the basis of comparisons of these structural changes, a scheme for the signal transduction of FixL is proposed which supports the FG loop switch mechanism. Similar spectral changes were observed both for the sensor domain and for the full-length protein, although structural changes occurred faster with the former than with the latter. This difference in rate suggests that the structural changes occurring in the heme pocket are coupled to those of the kinase domain. The implications of these results for FixL's sensing mechanism are discussed.
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PMID:Resonance Raman observation of the structural dynamics of FixL on signal transduction and ligand discrimination. 1746 99

Phosphate import is required for the growth of mycobacteria and is regulated by environmental inorganic phosphate (P(i)) concentrations, although the mechanism of this regulation has not been characterized. The expression of genes involved in P(i) acquisition is frequently regulated by two-component regulatory systems (2CRs) consisting of a sensor histidine kinase and a DNA-binding response regulator. In this work, we have identified the senX3-regX3 2CR as a P(i)-dependent regulator of genes involved in phosphate acquisition in Mycobacterium smegmatis. Characterization of senX3 mutants with different PhoA phenotypes suggests a dual role for SenX3 as a phosphatase or a phosphodonor for the response regulator RegX3, depending upon P(i) availability. Expression of PhoA activity required phosphorylation of RegX3, consistent with a role for phosphorylated RegX3 (RegX3 approximately P) as a transcriptional activator of phoA. Furthermore, purified RegX3 approximately P bound to promoter sequences from phoA, senX3, and the high-affinity phosphate transporter component pstS, demonstrating direct transcriptional control of all three genes. DNase I footprinting and primer extension analyses have further defined the DNA-binding region and transcriptional start site within the phoA promoter. A DNA motif consisting of an inverted repeat was identified in each of the promoters bound by RegX3 approximately P. Based upon our findings, we propose a model for P(i)-regulated gene expression mediated by SenX3-RegX3 in mycobacteria.
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PMID:The two-component regulatory system senX3-regX3 regulates phosphate-dependent gene expression in Mycobacterium smegmatis. 1752 10

Mucoidy, or overproduction of the exopolysaccharide known as alginate, in Pseudomonas aeruginosa is a poor prognosticator for lung infections in cystic fibrosis. Mutation of the anti-sigma factor MucA is a well-accepted mechanism for mucoid conversion. However, certain clinical mucoid strains of P. aeruginosa have a wild-type (wt) mucA. Here, we describe a loss-of-function mutation in kinB that causes overproduction of alginate in the wt mucA strain PAO1. KinB is the cognate histidine kinase for the transcriptional activator AlgB. Increased alginate production due to inactivation of kinB was correlated with high expression at the alginate-related promoters P(algU) and P(algD). Deletion of alternative sigma factor RpoN (sigma(54)) or the response regulator AlgB in kinB mutants decreased alginate production to wt nonmucoid levels. Mucoidy was restored in the kinB algB double mutant by expression of wt AlgB or phosphorylation-defective AlgB.D59N, indicating that phosphorylation of AlgB was not required for alginate overproduction when kinB was inactivated. The inactivation of the DegS-like protease AlgW in the kinB mutant caused loss of alginate production and an accumulation of the hemagglutinin (HA)-tagged MucA. Furthermore, we observed that the kinB mutation increased the rate of HA-MucA degradation. Our results also indicate that AlgW-mediated MucA degradation required algB and rpoN in the kinB mutant. Collectively, these studies indicate that KinB is a negative regulator of alginate production in wt mucA strain PAO1.
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PMID:The Pseudomonas aeruginosa sensor kinase KinB negatively controls alginate production through AlgW-dependent MucA proteolysis. 1916 21


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