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 phoPR operon encodes a response regulator, PhoP, and a histidine kinase, PhoR, which activate or repress genes of the Bacillus subtilis Pho regulon in response to an extracellular phosphate deficiency. Induction of phoPR upon phosphate starvation required activity of both PhoP and PhoR, suggesting autoregulation of the operon, a suggestion that is supported here by PhoP footprinting on the phoPR promoter. Primer extension analyses, using RNA from JH642 or isogenic sigE or sigB mutants isolated at different stages of growth and/or under different growth conditions, suggested that expression of the phoPR operon represents the sum of five promoters, each responding to a specific growth phase and environmental controls. The temporal expression of the phoPR promoters was investigated using in vitro transcription assays with RNA polymerase holoenzyme isolated at different stages of Pho induction, from JH642 or isogenic sigE or sigB mutants. In vitro transcription studies using reconstituted EsigmaA, EsigmaB, and EsigmaE holoenzymes identified PA4 and PA3 as EsigmaA promoters and PE2 as an EsigmaE promoter. Phosphorylated PhoP (PhoP approximately P) enhanced transcription from each of these promoters. EsigmaB was sufficient for in vitro transcription of the PB1 promoter. P5 was active only in a sigB mutant strain. These studies are the first to report a role for PhoP approximately P in activation of promoters that also have activity in the absence of Pho regulon induction and an activation role for PhoP approximately P at an EsigmaE promoter. Information concerning PB1 and P5 creates a basis for further exploration of the regulatory coordination or overlap of the PhoPR and SigB regulons during phosphate starvation.
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PMID:Autoinduction of Bacillus subtilis phoPR operon transcription results from enhanced transcription from EsigmaA- and EsigmaE-responsive promoters by phosphorylated PhoP. 1520 29

The Bacillus subtilis PhoPR two-component system is directly responsible for activation or repression of Pho regulon genes in response to phosphate deprivation. The response regulator, PhoP, and the histidine kinase, PhoR, are encoded in a single operon with a complex promoter region that contains five known transcription start sites, which respond to at least two regulatory proteins. We report here the identification of another direct regulator of phoPR transcription, carbon catabolite protein A, CcpA. This regulator functions in the presence of glucose or other readily metabolized carbon sources. The maximum derepression of phoPR expression in a ccpA mutant compared to a wild-type stain was observed under excess phosphate conditions with glucose either throughout growth in a high-phosphate defined medium or in a low-phosphate defined medium during exponential growth, a growth condition when phoPR transcription is low in a wild-type strain due to the absence of autoinduction. Either HPr or Crh were sufficient to cause CcpA dependent repression of the phoPR promoter in vivo. A ptsH1 (Hpr) crh double mutant completely relieves phoPR repression during phosphate starvation but not during phosphate replete growth. In vivo and in vitro studies showed that CcpA repressed phoPR transcription by binding directly to the cre consensus sequence present in the promoter. Primer extension and in vitro transcription studies revealed that the CcpA regulation of phoPR transcription was due to repression of P(A6), a previously unidentified promoter positioned immediately upstream of the cre box. Esigma(A) was sufficient for transcription of P(A6), which was repressed by CcpA in vitro. These studies showed direct repression by CcpA of a newly discovered Esigma(A)-responsive phoPR promoter that required either Hpr or Crh in vivo for direct binding to the putative consensus cre sequence located between P(A6) and the five downstream promoters characterized previously.
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PMID:CcpA causes repression of the phoPR promoter through a novel transcription start site, P(A6). 1645 8

Pseudomonas putida KT2440 metabolizes a wide range of carbon and nitrogen sources, including many amino acids. In this study, a sigma54-dependent two-component system that controls the uptake and metabolism of acidic amino acids was identified. The system (designated aau, for acidic amino acid utilization) involves a sensor histidine kinase, AauS, encoded by PP1067, and a response regulator, AauR, encoded by PP1066. aauR and aauS deletion mutants were unable to efficiently utilize aspartate (Asp), glutamate (Glu), and glutamine (Gln) as sole sources of carbon and nitrogen. Growth of the mutants was partially restored when the above-mentioned amino acids were supplemented with glucose or succinate as an additional carbon source. Uptake of Gln, Asp, and asparagine (Asn) by the aauR mutant was moderately reduced, while Glu uptake was severely impaired. In the absence of glucose, the aauR mutant even secreted Glu into the medium. Furthermore, disruption of aauR affected the activities of several key enzymes of Glu and Asp metabolism, leading to the intracellular accumulation of Glu and greatly reduced survival times under conditions of nitrogen starvation. By a proteomics approach, four major proteins were identified that are downregulated during growth of the aauR mutant on Glu. Two of these were identified as periplasmic glutaminase/asparaginase and the solute-binding protein of a Glu/Asp transporter. Transcriptional analysis of lacZ fusions containing the putative promoter regions of these genes confirmed that their expression is indeed affected by the aau system. Three further periplasmic solute-binding proteins were strongly expressed during growth of the aauR deletion mutant on Glu but downregulated during cultivation on glucose/NH4+. These systems may be involved in amino acid efflux.
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PMID:The AauR-AauS two-component system regulates uptake and metabolism of acidic amino acids in Pseudomonas putida. 1702 Dec 7

To understand the mechanisms of aluminum (Al) tolerance in wheat (Triticum aestivum L.), suppression subtractive hybridization (SSH) libraries were constructed from Al-stressed roots of two near-isogenic lines (NILs). A total of 1,065 putative genes from the SSH libraries was printed in a cDNA array. Relative expression levels of those genes were compared between two NILs at seven time points of Al stress from 15 min to 7 days. Fifty-seven genes were differentially expressed for at least one time point of Al treatment. Among them, 28 genes including genes for aluminum-activated malate transporter-1, ent-kaurenoic acid oxidase-1, beta-glucosidase, lectin, histidine kinase, and phospoenolpyruvate carboxylase showed more abundant transcripts in Chisholm-T and therefore may facilitate Al tolerance. In addition, a set of genes related to senescence and starvation of nitrogen, iron, and sulfur, such as copper chaperone homolog, nitrogen regulatory gene-2, yellow stripe-1, and methylthioribose kinase, was highly expressed in Chisholm-S under Al stress. The results suggest that Al tolerance may be co-regulated by multiple genes with diverse functions, and those genes abundantly expressed in Chisholm-T may play important roles in enhancing Al tolerance. The down-regulated genes in Chisholm-S may repress root growth and restrict uptake of essential nutrient elements, and lead to root senescence.
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PMID:Transcriptional analysis between two wheat near-isogenic lines contrasting in aluminum tolerance under aluminum stress. 1703 77

Two-component systems, consisting of proteins with histidine kinase and/or response regulator domains, regulate environmental responses in bacteria, Archaea, fungi, slime molds, and plants. Here, we characterize RRG-1, a response regulator protein from the filamentous fungus Neurospora crassa. The cell lysis phenotype of Delta rrg-1 mutants is reminiscent of osmotic-sensitive (os) mutants, including nik-1/os-1 (a histidine kinase) and strains defective in components of a mitogen-activated protein kinase (MAPK) pathway: os-4 (MAPK kinase kinase), os-5 (MAPK kinase), and os-2 (MAPK). Similar to os mutants, Delta rrg-1 strains are sensitive to hyperosmotic conditions, and they are resistant to the fungicides fludioxonil and iprodione. Like os-5, os-4, and os-2 mutants, but in contrast to nik-1/os-1 strains, Delta rrg-1 mutants do not produce female reproductive structures (protoperithecia) when nitrogen starved. OS-2-phosphate levels are elevated in wild-type cells exposed to NaCl or fludioxonil, but they are nearly undetectable in Delta rrg-1 strains. OS-2-phosphate levels are also low in Delta rrg-1, os-2, and os-4 mutants under nitrogen starvation. Analysis of the rrg-1(D921N) allele, mutated in the predicted phosphorylation site, provides support for phosphorylation-dependent and -independent functions for RRG-1. The data indicate that RRG-1 controls vegetative cell integrity, hyperosmotic sensitivity, fungicide resistance, and protoperithecial development through regulation of the OS-4/OS-5/OS-2 MAPK pathway.
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PMID:The response regulator RRG-1 functions upstream of a mitogen-activated protein kinase pathway impacting asexual development, female fertility, osmotic stress, and fungicide resistance in Neurospora crassa. 1739 18

Bacterial pathogens regulate virulence factor gene expression coordinately in response to environmental stimuli, including nutrient starvation. The phosphate (Pho) regulon plays a key role in phosphate homeostasis. It is controlled by the PhoR/PhoB two-component regulatory system. PhoR is an integral membrane signaling histidine kinase that, through an interaction with the ABC-type phosphate-specific transport (Pst) system and a protein called PhoU, somehow senses environmental inorganic phosphate (P(i)) levels. Under conditions of P(i) limitation (or in the absence of a Pst component or PhoU), PhoR activates its partner response regulator PhoB by phosphorylation, which, in turn, up- or down-regulates target genes. Single-cell profiling of PhoB activation has shown recently that Pho regulon gene expression exhibits a stochastic, "all-or-none" behavior. Recent studies have also shown that the Pho regulon plays a role in the virulence of several bacteria. Here, we present a comprehensive overview of the role of the Pho regulon in bacterial virulence. The Pho regulon is clearly not a simple regulatory circuit for controlling phosphate homeostasis; it is part of a complex network important for both bacterial virulence and stress response.
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PMID:The phosphate regulon and bacterial virulence: a regulatory network connecting phosphate homeostasis and pathogenesis. 1824 18

Myxococcus xanthus undergoes a complex starvation-induced developmental program that results in cells forming multicellular fruiting bodies by aggregating into mounds and then differentiating into spores. This developmental program requires at least 72 h and is mediated by a temporal cascade of gene regulators in response to intra- and extracellular signals. espA mutants, encoding an orphan hybrid histidine kinase, alter the timing of this developmental program, greatly accelerating developmental progression. Here, we characterized EspA and demonstrated that it autophosphorylates in vitro on the conserved histidine residue and then transfers the phosphoryl group to the conserved aspartate residue in the associated receiver domain. The conserved histidine and aspartate residues were both required for EspA function in vivo. Analysis of developmental gene expression and protein accumulation in espA mutants indicated that the expression of the A-signal-dependent spi gene was not affected but that the MrpC transcriptional regulator accumulated earlier, resulting in earlier expression of its target, the FruA transcriptional regulator. Early expression of FruA correlated with acceleration of both the aggregation and sporulation branches of the developmental program, as monitored by early methylation of the FrzCD chemosensory receptor and early expression of the sporulation-specific dev and Mxan_3227 (Omega7536) genes. These results show that EspA plays a key role in the timing of expression of genes necessary for progression of cells through the developmental program.
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PMID:EspA, an orphan hybrid histidine protein kinase, regulates the timing of expression of key developmental proteins of Myxococcus xanthus. 1846 9

A two-component system formed by a sensor histidine kinase and a response regulator has been identified as an element participating in cell density signal transduction in Pseudomonas putida KT2440. It is a homolog of the Pseudomonas aeruginosa RoxS/RoxR system, which in turn belongs to the RegA/RegB family, described in photosynthetic bacteria as a key regulatory element. In KT2440, the two components are encoded by PP_0887 (roxS) and PP_0888 (roxR), which are transcribed in a single unit. Characterization of this two-component system has revealed its implication in redox signaling and cytochrome oxidase activity, as well as in expression of the cell density-dependent gene ddcA, involved in bacterial colonization of plant surfaces. Whole-genome transcriptional analysis has been performed to define the P. putida RoxS/RoxR regulon. It includes genes involved in sugar and amino acid metabolism and the sulfur starvation response and elements of the respiratory chain (a cbb3 cytochrome oxidase, Fe-S clusters, and cytochrome c-related proteins) or genes participating in the maintenance of the redox balance. A putative RoxR recognition element containing a conserved hexamer (TGCCAG) has also been identified in promoters of genes regulated by this two-component system.
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PMID:A two-component regulatory system integrates redox state and population density sensing in Pseudomonas putida. 1882 16

When exposed extreme environmental conditions such as sea water, bacteria have been shown different survival strategy for continue their life. One of this strategy known as viable but nonculturable (VBNC) state which is very important for nondifferiation bacteria. VBNC cells cause serious human health problems. Little is known, however, about the genetic mechanisms underlying the VBNC state. Under different environmental conditions, porins are important in the survival strategy of bacteria. EnvZ/OmpR work together as regulators of ompF and ompC gene expression. It is known that the EnvZ system has a role in VBNC state. In this study we tried to find out the viability of EnvZ, OmpC and OmpF mutant E. coli under stress effect of osmolarity, pH and starvation. Bacteria were suspended in filtered-autoclaved sea water microcosms and numbers determined over 25 day incubation periods by plate count (PC), direct viable count (DVC) and count of cells capable of respiration (RCC). As regard to results, alkaline pH affected E. coli more than acidic pH, which led to decline in number. On the contrary glycine betaine addition to sea water protected E. coli porin mutants and also reduced the death rate of bacteria. Under the effect of pH, osmotic stress and starvation stress, wild type E. coli and porin mutants entered a dormant state or became VBNC with the exception of MSZ31 (envZ mutant) E. coli cells which did not enter the VBNC state under the three tested stress conditions. This study is the first report to demonstrate that E. coli could not enter the VBNC state in the lack of EnvZ product under the stress of osmolarity, pH and starvation and the relationship between EnvZ and VBNC state are not affected by pH, osmolarity and starvation.
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PMID:Viable but non-culturable state (VBNC) of Escherichia coli related to EnvZ under the effect of pH, starvation and osmotic stress in sea water. 2038 Jan 41

The gene product of histidine kinase DR2244 (putative phoR) encoded by Deinococcus radiodurans has been suggested to be involved in the PhoR-PhoB two-component regulatory system. This two-component signalling system is activated upon phosphate starvation in several bacteria, including D. radiodurans. Single crystals were obtained from a recombinant preparation of the catalytic/ATP-binding (CA) domain of D. radiodurans PhoR (79-224) overexpressed in Escherichia coli. The crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 46.9, b = 81.8, c = 204.6 A. The crystals contained six molecules in the asymmetric unit. Diffraction data were collected to 2.4 A resolution on beamline ID23-2 of the European Synchrotron Radiation Facility.
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PMID:Crystallization and preliminary X-ray characterization of a catalytic and ATP-binding domain of a putative PhoR histidine kinase from the gamma-radioresistant bacterium Deinococcus radiodurans. 2038 8


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