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)

Singlet oxygen (1O2) generated by ultraviolet A irradiation has been reported to induce cytokine-dependent Matrix metalloproteinase-1 (MMP-1) expression in dermal fibroblasts. In the present study, we analyzed the effect of hypericin-based photodynamic therapy (PDT) on MMP-1 expression in two nasopharyngeal cancer (NPC) cell lines and an animal tumor model. MMP-1 protein and mRNA expression were evaluated by Western blot analysis and quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) respectively. Photoactivation of hypericin, a polycyclic phenanthroperylenedione, elicited an increase in MMP-1 protein and mRNA expression in well differentiated HK1 and poorly differentiated CNE-2 NPC cells in vitro. Similarly, there was up-regulation of MMP1 mRNA expression in hypericin-PDT-treated NPC/HK1-tumors. To our knowledge, this is the first time that modulation of MMP-1 expression has been demonstrated as a photodynamic effect of hypericin in NPC cells. This has clinical implications as MMP-1 is known to play an essential role in the biological process of matrix remodeling.
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PMID:Modulation of Matrix metalloproteinase-1 in nasopharyngeal cancer cells by photoactivation of hypericin. 1476 50

The rhizobial FixL/FixJ system, a paradigm of heme-based oxygen sensors, belongs to the ubiquitous two-component signal transduction system. Oxygen-free (deoxy) FixL is autophosphorylated at an invariant histidine residue by using ATP and catalyzes the concomitant phosphoryl transfer to FixJ, but oxygen binding to the FixL heme moiety inactivates the kinase activity. Here we demonstrate that ADP acts as an allosteric effector, reducing the oxygen-binding affinity of the sensor domain in FixL when it is produced from ATP in the kinase reaction. The addition of ADP to a solution of purified wild-type FixL resulted in an approximately 4- to 5-fold decrease in oxygen-binding affinity in the presence of FixJ. In contrast, phosphorylation-deficient mutants, in which the well conserved ATP-binding catalytic site of the kinase domain is impaired, showed no such allosteric effect. This discovery casts light on the significance of homodimerization of two-component histidine kinases; ADP, generated in the phosphorylation reaction in one subunit of the homodimer, enhances the histidine kinase activity of the other, analogous to a two-cylinder reciprocating engine by reducing the ligand-binding affinity.
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PMID:ADP reduces the oxygen-binding affinity of a sensory histidine kinase, FixL: the possibility of an enhanced reciprocating kinase reaction. 1497 Mar 41

Workers in our laboratory have previously identified the staphylococcal respiratory response AB (SrrAB), a Staphylococcus aureus two-component system that acts in the global regulation of virulence factors. This system down-regulates production of agr RNAIII, protein A, and toxic shock syndrome toxin 1 (TSST-1), particularly under low-oxygen conditions. In this study we investigated the localization and membrane orientation of SrrA and SrrB, transcription of the srrAB operon, the DNA-binding properties of SrrA, and the effect of SrrAB expression on S. aureus virulence. We found that SrrA is localized to the S. aureus cytoplasm, while SrrB is localized to the membrane and is properly oriented to function as a histidine kinase. srrAB has one transcriptional start site which results in either an srrA transcript or a full-length srrAB transcript; srrB must be cotranscribed with srrA. Gel shift assays of the agr P2, agr P3, protein A (spa), TSST-1 (tst), and srr promoters revealed SrrA binding at each of these promoters. Analysis of SrrAB-overexpressing strains by using the rabbit model of bacterial endocarditis demonstrated that overexpression of SrrAB decreased the virulence of the organisms compared to the virulence of isogenic strains that do not overexpress SrrAB. We concluded that SrrAB is properly localized and oriented to function as a two-component system. Overexpression of SrrAB, which represses agr RNAIII, TSST-1, and protein A in vitro, decreases virulence in the rabbit endocarditis model. Repression of these virulence factors is likely due to a direct interaction between SrrA and the agr, tst, and spa promoters.
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PMID:Characterization of virulence factor regulation by SrrAB, a two-component system in Staphylococcus aureus. 1506 46

Photodynamic therapy (PDT) is a new modality of treatment for cancer. Hypericin is a photosensitizer, which is known to generate reactive oxygen species upon activation with light. We observed that photoactivated hypericin induces the generation of reactive oxygen intermediates in nasopharyngeal cancer (NPC) cells in vitro. There was also significant reduction of Glutathione S-transferase (GST) activity in HK1 and CNE-2 NPC cells and in tumor tissues from the NPC/HK1 murine tumor model by hypericin-mediated PDT. As antioxidants protect cells against phototoxicity, down-regulation of GST activity would potentiate the efficacy of hypericin-PDT treatment.
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PMID:Photoactivation of hypericin down-regulates glutathione S-transferase activity in nasopharyngeal cancer cells. 1507 26

We review and analyze the growing family of bacterial proteins carrying the LOV (light oxygen voltage) motif, a flavin-binding photoactive domain first characterized in plant blue-light receptors, the phototropins. A total of 29 sequences encoding LOV-proteins can be detected in the genomes of 24 bacterial species. In the bacterial LOV domains, the majority of the amino acids known to interact with the flavin mononucleotide (FMN) chromophore in phototropin LOVs are conserved, supporting the suggestion of their possible role as blue-light sensors. The Bacillus subtilis protein YtvA has been the first bacterial LOV-protein shown to bind FMN and to undergo the same light-induced reactions as plant phototropins. The photocycle involves the reversible formation of a covalent adduct between FMN and a conserved cysteine. In this work we report preliminary results on a Caulobacter crescentus LOV-kinase, that undergoes the same photochemistry as YtvA. The bacterial LOV-proteins exhibit a variety of effector domains associated to the light-responsive LOV-domain, e.g. histidine kinase, transcriptional regulators, putative phosphodiesterases and regulators of stress factors, pointing to their physiological role as sensing and signalling proteins.
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PMID:The bacterial counterparts of plant phototropins. 1517 Apr 86

We have deleted a gene for a sensor histidine kinase, dspA (or hik33), in the cyanobacterium Synechocystis sp. strain PCC6803. In low and moderate light, the mutant grew slowly under photoautotrophic conditions, with a doubling time of approximately 40 h, and had severely reduced photosynthetic oxygen evolution. When the mutant was maintained in low or moderate light in the presence of glucose, its growth rate was only somewhat lower than that of wild-type cells. However, the mutant was light sensitive and rapidly died in high light. Furthermore, levels of many transcripts encoding genes associated with photosynthesis were altered in the mutant relative to wild-type Synechocystis sp. strain PCC6803 both in low light and following exposure to high light. There was constitutive expression of several high-light-inducible genes, including hli, psbAIII, and gpx2; there was little increased accumulation of sodB mRNA in high light; and the cells failed to accumulate cpcBA and psaAB mRNAs in low light in the presence of glucose, although a normal decline in the levels of these mRNAs was observed during exposure to high light. These results suggest that DspA is involved in controlling sets of photosynthetic and high-light-responsive genes, either directly or indirectly. These and other results, some of which are presented in a companion paper (C.-J. Tu, J. Shrager, R. Burnap, B. L. Postier, and A. R. Grossman, J. Bacteriol. 186:3889-3902, 2004), suggest that DspA acts as a global regulator that helps coordinate cellular metabolism with growth limitations imposed by environmental conditions.
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PMID:Control of photosynthetic and high-light-responsive genes by the histidine kinase DspA: negative and positive regulation and interactions between signal transduction pathways. 1517 2

The PrrBA two-component system in Rhodobacter sphaeroides 2.4.1, which is composed of the PrrB histidine kinase and the PrrA response regulator, controls the expression of all of the photosynthesis genes, either directly or indirectly, in response to changes in oxygen tension. In vivo under aerobic conditions it is the cbb(3) cytochrome c oxidase which generates an inhibitory signal preventing the accumulation of activated PrrA. Using purified cbb(3) cytochrome c oxidase, PrrB, and PrrA, we demonstrate in vitro that the cbb(3) oxidase inhibits PrrB activity by apparently increasing the intrinsic PrrB phosphatase activity, which dephosphorylates phosphorylated PrrA without alteration of the PrrB kinase activity. The transmembrane domain of PrrB is required for the enhancement of PrrB phosphatase activity by the cbb(3) oxidase. Full-length PrrB has a significantly greater ability to phosphorylate PrrA than does truncated PrrB lacking the transmembrane domain. This is at least in part due to the lower autophosphorylation rate of the truncated PrrB relative to the full-length PrrB. This finding provides evidence that the sensing domain (transmembrane domain) of PrrB plays an important role not only in optimally sensing the state of the cbb(3) oxidase but also in maintaining the correct conformation of PrrB, providing optimal autokinase activity.
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PMID:Reconstitution of the Rhodobacter sphaeroides cbb3-PrrBA signal transduction pathway in vitro. 1519 36

Soluble guanylate cyclase (sGC) is a nitric oxide- (NO-) sensing hemoprotein that has been found in eukaryotes from Drosophila to humans. Prokaryotic proteins with significant homology to the heme domain of sGC have recently been identified through genomic analysis. Characterization of two of these proteins is reported here. The first is a 181 amino acid protein cloned from Vibrio cholerae (VCA0720) that is encoded in a histidine kinase-containing operon. The ferrous unligated form of VCA0720 is 5-coordinate, high-spin. The CO complex is low-spin, 6-coordinate, and the NO complex is high-spin and 5-coordinate. These ligand-binding properties are very similar to those of sGC. The second protein is the N-terminal 188 amino acids of Tar4 (TtTar4H), a predicted methyl-accepting chemotaxis protein (MCP) from the strict anaerobe Thermoanaerobacter tengcongensis. TtTar4H forms a low-spin, 6-coordinate ferrous-oxy complex, the first of this sGC-related family that binds O2. TtTar4H has ligand-binding properties similar to those of the heme-containing O2 sensors such as AxPDEA1. sGC does not bind O2 despite having a porphyrin with a histidyl ligand like the globins. The results reported here, with sequence-related proteins from prokaryotes but in the same family as the sGC heme domain, show that these proteins have evolved to discriminate between ligands such as NO and O2; hence, we term this family H-NOX domains (heme-nitric oxide/oxygen).
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PMID:Spectroscopic characterization of the soluble guanylate cyclase-like heme domains from Vibrio cholerae and Thermoanaerobacter tengcongensis. 1528 48

The ability of motile bacteria to swim toward or away from specific environmental stimuli, such as nutrients, oxygen, or light provides cells with a survival advantage, especially under nutrient-limiting conditions. This behavior, called chemotaxis, is mediated by the bacteria changing direction by briefly reversing the direction of rotation of the flagellar motors. A sophisticated signal transduction system, consisting of signal transducer proteins, a histidine kinase, a response regulator, a coupling protein, and enzymes that mediate sensory adaptation, relates the input signal to the flagellar motor. Chemotaxis has been extensively studied in bacteria such as Escherichia coli and Salmonella enterica serovar Typhimurium, and depends on the activity of single copies of proteins in a linear pathway. However, growing evidence suggests that chemotaxis in other bacteria is more complex with many bacterial species having multiple paralogues of the various chemotaxis genes found in E. coli and, in most cases, the detailed functions of these potentially redundant genes have not been elucidated. Although the completed genome of Vibrio cholerae, the causative agent of cholera, predicted a multitude of genes with homology to known chemotaxis-related genes, little is known about their relative contribution to chemotaxis or other cellular functions. Furthermore, the role of chemotaxis during the environmental or infectious phases of this organism is not yet fully understood. This review will focus on the complex relationship between chemotaxis and virulence in V. cholerae.
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PMID:Chemotaxis in Vibrio cholerae. 1545 Oct 94

The Rhizobium leguminosarum bv. viciae VF39 FixL protein belongs to a distinct group of hybrid regulatory sensor proteins that bear a covalently linked C-terminal receiver domain. FixL has an unorthodox histidine kinase domain, which is shared with many other hybrid regulators. The purified FixL protein had autophosphorylation activity. A truncated protein, lacking the receiver domain, had a much-reduced autophosphorylation activity. However, this truncated protein still efficiently phosphorylated the purified receiver domain in trans. This indicates that, in the full-length FixL protein, the conserved histidine residue in the kinase domain is phosphorylated only transiently and that most of the phosphoryl label accumulates in the C-terminal receiver domain. Gene-fusion studies showed that the fixL gene is required for free-living microaerobic induction of the fnrN promoter. The presence of a functional fixK gene is not required. An R. leguminosarum strain lacking fixL could not be complemented with a truncated copy of the gene lacking the receiver domain. This indicates that the C-terminal receiver domain is an intermediate in the signal transduction pathway that links oxygen limitation to induction of the fnrN promoter in R. leguminosarum bv. viciae VF39.
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PMID:The C-terminal receiver domain of the Rhizobium leguminosarum bv. viciae FixL protein is required for free-living microaerobic induction of the fnrN promoter. 1552 57


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