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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 fadL gene of Escherichia coli codes for an outer membrane protein that is involved in the uptake of long-chain fatty acids. Uptake is regulated by environmental osmolarity, and decreases when the cells are grown under conditions of high osmolarity. A temperature-sensitive mutant that requires fatty acid for growth at 42 degrees C was unable to grow at the high temperature even in the presence of fatty acid if the medium contained 10% sucrose. Promoter activity of the fadL gene in vivo was repressed by high osmolarity in a FadR repressor null mutant. Furthermore, in vitro transcription of the fadL gene was strongly repressed by the addition of OmpR and EnvZ proteins. The results of gel retardation and DNase I protection experiments indicated that OmpR, after incubation with the protein kinase EnvZ, specifically binds to at least four sites around the fadL promoter, two upstream and two downstream from the transcriptional start site. These results suggest that transcription of the fadL gene is osmotically regulated by the OmpR-EnvZ two-component system.
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PMID:Osmoregulation of the fatty acid receptor gene fadL in Escherichia coli. 841 82

A novel protein kinase is induced in rat liver plasma membrane by the administration of peroxisome proliferators. A 36 kDa protein (P36) on the membrane was rapidly phosphorylated in vitro by the kinase and the phosphorylated amino acid was identified as phosphohistidine. Histidine phosphorylation of P36 was activated in vitro by recombinant Ras protein and GTP; both decreased Michaelis constant (Km) for ATP from 1.25 to 0.25 microM. The novel histidine kinase, products of which have been overlooked due to their acid lability, may participate in cellular signaling and peroxisome proliferators may perturb the pathway.
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PMID:A protein histidine kinase induced in rat liver by peroxisome proliferators. In vitro activation by Ras protein and guanine nucleotides. 845 63

A DNA fragment was cloned from Bacteroides fragilis that bestowed low-level tetracycline resistance to Escherichia coli strains harbouring the cloned fragment on a multicopy plasmid. The tetracycline resistance determinant was localized to a 4.3kb Bg/II-PstI subfragment of the original clone. DNA sequence analysis of this fragment revealed that it contained an operon encoding two proteins: one of 519 amino acids, RprX, and a second of 236 amino acids, RprY. Protein sequence analysis revealed that the two proteins shared sequence identity with a family of multicomponent signal-transducing regulatory proteins identified from many diverse bacterial genera. RprX shared identity with the first component of the regulatory system, the histidine protein kinase receptor (for example EnvZ, PhoR, CheA, and VirA). RprY shared identity with the second member of the regulatory protein pair, the regulatory response protein (for example OmpR, PhoB, CheY, and VirG). Expression of these proteins from a multicopy plasmid vector in E. coli resulted in a decrease in the level of the outer membrane porin protein OmpF and an increase in the level of the outer membrane porin protein OmpC. The decrease in OmpF levels correlates with, and may be the cause of, the increased tetracycline resistance. Regulation of the levels of OmpF and OmpC is normally controlled by a multicomponent signal-transducing regulatory pair of proteins, EnvZ and OmpR. The effect RprX and RprY have on OmpF expression is mediated at the level of transcription. Thus, RprX and RprY may be interfering with the normal regulation of OmpF by OmpR and EnvZ.
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PMID:Cloning and identification of a two-component signal-transducing regulatory system from Bacteroides fragilis. 846 17

A putative two-component system, mtrA-mtrB, was isolated from M. tuberculosis H37Rv by using phoB from Pseudomonas aeruginosa as a hybridization probe. The predicted gene product of mtrA displayed high similarity with typical response regulators, including AfsQ1, PhoB, PhoP, and OmpR. The predicted gene product of mtrB displayed similarities with the histidine protein kinases AfsQ2, PhoR, and EnvZ and other members of this class of proteins. Expression analysis in the T7 system showed that mtrA encoded a polypeptide with an apparent molecular mass of 30 kDa. MtrA was overproduced, purified, and demonstrated to participate in typical phosphotransfer reactions using a heterologous histidine protein kinase, CheA, as a phosphoryl group donor. Mycobacterium bovis BCG, harboring an mtrA-gfp (green fluorescent protein cDNA) transcriptional fusion, was used to monitor mtrA expression in infected J774 monolayers. Flow cytometric and fluorescence microscopic analyses indicated that the mtrA promoter was activated upon entry and incubation in J774 macrophages. In contrast, the hsp60-gfp fusion displayed no change in expression under the growth conditions tested. These results suggest a potential role for mtrA in adaptation of the M. tuberculosis complex organisms to environmental changes which may include intracellular conditions.
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PMID:Elements of signal transduction in Mycobacterium tuberculosis: in vitro phosphorylation and in vivo expression of the response regulator MtrA. 865 13

Nucleoside-diphosphate kinase (NDP kinase), a key enzyme in nucleotide metabolism, is also known to be involved in growth and developmental control and tumor metastasis suppression. Interestingly, we find that coexpression of NDP kinase with Taz1, a Tar/EnvZ chimera, in the absence of its native signal, can activate a porin gene ompC-lacZ expression in Escherichia coli. Further studies show that NDP kinase can act as a protein kinase to phosphorylate histidine protein kinases such as EnvZ and CheA which are members of the His-Asp phosphorelay signal transduction systems in E. coli. Instead of ATP, the exclusive phosphodonor for histidine kinases, GTP can be utilized in vitro in the presence of NDP kinase to phosphorylate EnvZ and CheA, which then transfer the phosphoryl group to OmpR and CheY, the respective response regulators. The direct involvement of GTP for the phosphorylation of EnvZ through NDP kinase was further demonstrated by the use of a mutant EnvZ, which lost ability to be autophosphorylated with ATP. Phospho-OmpR thus formed can bind specifically to an ompF promoter sequence. These results suggest that NDP kinase may play a physiological role in signal transduction.
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PMID:Nucleoside-diphosphate kinase-mediated signal transduction via histidyl-aspartyl phosphorelay systems in Escherichia coli. 895 29

The histidyl-aspartyl phosphorelay, formerly described as the two-component system, is the predominant mode of signal transduction in bacteria. Adaptation to environmental changes occurs through a sensor histidine protein kinase and a response regulator. The histidine protein kinase is usually a transmembrane receptor and the response regulator is a cytoplasmic protein. Together the histidyl-aspartyl phosphorelay proteins mediate reversible phosphorylation events that control downstream effectors. Following autophosphorylation at a conserved histidine residue, the histidine kinase serves as a phospho-donor for the response regulator. Once phosphorylated, the response regulator mediates changes in gene expression or cellular locomotion. The EnvZ-OmpR phosphorelay system in Escherichia coli, which monitors external osmolarity and responds by differentially modulating the expression of the OmpF and OmpC major outer membrane porins, will be described as a model system. While histidine kinases were thought to be present only in prokaryotes, they have recently been identified in eukaryotic systems. Here, we review the unique and conserved features of this growing family of signal transducers.
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PMID:Signal transduction via the histidyl-aspartyl phosphorelay. 918 55

Autophosphorylating histidine kinases are an ancient conserved family of enzymes that are found in eubacteria, archaebacteria and eukaryotes. They are activated by a wide range of extracellular signals and transfer phosphate moieties to aspartates found in response regulators. Recent studies have shown that such two-component signal transduction pathways mediate osmoregulation in Saccharomyces cerevisiae, Dictyostelium discoideum and Neurospora crassa. Moreover, they play pivotal roles in responses of Arabidopsis thaliana to ethylene and cytokinin. A transmembrane histidine kinase encoded by dhkA accumulates when Dictyostelium cells aggregate during development. Activation of DhkA results in the inhibition of its response regulator, RegA, which is a cAMP phosphodiesterase that regulates the cAMP dependent protein kinase PKA. When PKA is activated late in the differentiation of prespore cells, they encapsulate into spores. There is evidence that this two-component system participates in a feedback loop linked to PKA in prestalk cells such that the signal to initiate encapsulation is rapidly amplified. Such signal transduction pathways can be expected to be found in a variety of eukaryotic differentiations since they are rapidly reversible and can integrate disparate signals.
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PMID:Histidine kinases in signal transduction pathways of eukaryotes. 919 Oct 38

Cells that overexpress PKA as a consequence of carrying multiple copies of the gene encoding the catalytic subunit can be induced to sporulate when developing as single cells. A peptide phosphorylated by PKA, termed SDF-1, has recently been shown to stimulate this process (Anjard et al., 1997). Several genes have been implicated in a signal transduction pathway by which prestalk cells induce encapsulation of prespore cells during terminal differentiation including a prestalk-specific putative membrane protease (TagC) and a two-component system consisting of a receptor-histidine kinase (DhkA) and a response regulator with cAMP phosphodiesterase activity (RegA). To determine whether SDF-1 uses this pathway, strains carrying null mutations in the pertinent genes were transformed with a pkaC plasmid such that they can overexpress PKA. Since these mutant strains all sporulated efficiently when SDF-1 was added, it appears that other gene products mediate the response. However, we found that regA- mutant cells release a distinct factor, SDF-2, that rapidly induces encapsulation of test cells overexpressing pkaC. Since cells in which tagC is disrupted do not form SDF-2 and cells in which dhkA is disrupted do not respond to SDF-2, this peptide appears to use the two-component system that regulates PKA activity. SDF-2 is a small peptide released by prestalk cells in a manner dependent on TagC. It appears to act on prespore cells through the DhkA receptor to inhibit the cAMP phosphodiesterase of RegA, thereby activating PKA via cAMP. The process of induction by SDF-2 can be shown to be distinct from that by SDF-1. SDF-2 appears to stimulate prestalk cells to release additional SDF-2 by acting through a signal transduction pathway that also involves DhkA, RegA, and PKA. Based on these results we present a model for the signal transduction cascade regulating spore differentiation.
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PMID:Signal transduction pathways leading to spore differentiation in Dictyostelium discoideum. 947 20

In Arabidopsis thaliana, signal transduction of the hormone ethylene involves at least two receptors, ETR1 and ERS, both of which are members of the two-component histidine protein kinase family that is prevalent in prokaryotes. The pathway also contains a negative regulator of ethylene responses, CTR1, which closely resembles members of the Raf protein kinase family. CTR1 is thought to act at or downstream of ETR1 and ERS based on double mutant analysis; however, the signaling mechanisms leading from ethylene perception to the regulation of CTR1 are unknown. By using the yeast two-hybrid assay, we detected a specific interaction between the CTR1 amino-terminal domain and the predicted histidine kinase domain of ETR1 and ERS. We subsequently verified these interactions by using an in vitro protein association assay(s). In addition, we determined that the amino-terminal domain of CTR1 can associate with the predicted receiver domain of ETR1 in vitro. Based on deletion analysis, the portion of CTR1 that interacts with ETR1 roughly aligns with the regulatory region of Raf kinases. These physical associations support the genetic evidence that CTR1 acts in the pathway of ETR1 and ERS and suggest that these interactions could be involved in the regulation of CTR1 activity.
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PMID:Association of the Arabidopsis CTR1 Raf-like kinase with the ETR1 and ERS ethylene receptors. 956 Feb 88

Spore germination is a defined developmental process that marks a critical point in the life cycle of Dictyostelium discoideum. Upon germination the environmental conditions must be conducive to cell growth to ensure survival of emerged amoebae. However, the signal transduction pathways controlling the various aspects of spore germination in large part remain to be elucidated. We have used degenerate PCR to identify dhkB, a two-component histidine kinase, from D. discoideum. DhkB is predicted to be a transmembrane hybrid sensor kinase. The dhkB-null cells develop with normal timing to give what seem to be mature fruiting bodies by 22 to 24 h. However, over the next several hours, the ellipsoidal and encapsulated spores proceed to swell and germinate in situ within the sorus and thus do not respond to the normal inhibitors of germination present within the sorus. The emerged amoebae dehydrate due to the high osmolarity within the sorus, and by 72 h 4% or less of the amoebae remain as spores, while most cells are now nonviable. Precocious germination is suppressed by ectopic activation of or expression of cAMP-dependent protein kinase A. Additionally, at 24 h the intracellular concentration of cAMP of dhkB- spores is 40% that of dhkB+ spores. The results indicate that DHKB regulates spore germination, and a functional DHKB sensor kinase is required for the maintenance of spore dormancy. DHKB probably acts by maintaining an active PKA that in turn is inhibitory to germination.
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PMID:The hybrid histidine kinase dhkB regulates spore germination in Dictyostelium discoideum. 957 30


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