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)

Ypd1p, a 167-residue protein from Saccharomyces cerevisiae, plays a key role in osmosensing phosphorelay signal transduction. It forms part of a multistep phosphorelay system which also includes Sln1p hybrid histidine kinase and two response regulators, Ssk1p and Skn7p. It has been overexpressed in soluble form in Escherichia coli with a His6-tag at its C-terminus. The recombinant protein has been crystallized at room temperature using ammonium sulfate and lithium sulfate as precipitants. Native diffraction data have been collected to 2.3 A using synchrotron radiation. The crystals are triclinic, belonging to the space group P1, with unit-cell parameters a = 65.78, b = 66.74, c = 65.75 A, alpha = 106.60, beta = 106.48, gamma = 115. 53 degrees. The asymmetric unit contains four molecules of the monomeric recombinant Ypd1p, with a corresponding Vm of 2.75 A3 Da-1 and a solvent content of 55.3%.
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PMID:Crystallization and preliminary X-ray analysis of Saccharomyces cerevisiae Ypd1p, a key intermediate in phosphorelay signal transduction. 1032 90

The histidine kinase/response regulator system EnvZ/OmpR of Escherichia coli regulates transcription of the genes ompF and ompC, encoding two porins of the outer membrane. Although the total amount of OmpF and OmpC remains constant, the relative levels of the two proteins fluctuate in a reciprocal manner depending on medium osmolality. The membrane-anchored sensor EnvZ somehow monitors changes in environmental osmolality. To characterize the nature of the stimulus perceived by EnvZ, this protein was overproduced, purified, and reconstituted into proteoliposomes. Autokinase activity of purified and reconstituted EnvZ was stimulated by an increase of the K(+) concentration. Rb(+), Na(+), and NH4(+) also stimulated the activity but to a smaller extent, whereas an osmotic upshift imposed by various sugars or increasing concentrations of glycine betaine, proline, or Tris/MES were without influence. Neither the transfer of the phosphoryl group from EnvZ approximately P to OmpR nor the EnvZ-mediated OmpR approximately P dephosphorylation were affected by one of the tested solutes. Experiments with the reconstructed signal transduction cascade including DNA fragments demonstrated a substantial increase of the amount of phosphorylated OmpR in the presence of K(+) and to a lower extent in the presence of Na(+), Rb(+), and NH4(+). Various K(+) salts were tested indicating that the determined effects were K(+)-specific and not dependent on the anion. In a further in vitro test system, which utilizes right-side-out membrane vesicles, the K(+)-specific activation of EnvZ autokinase from the luminal side was confirmed. These results clearly indicate a regulation of EnvZ autokinase activity by monovalent ions, specifically K(+). Whether K(+) accumulation, which is one of the first responses of E. coli after an osmotic upshift, is related to the stimulation of the EnvZ autokinase activity in vivo is discussed.
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PMID:K+ stimulates specifically the autokinase activity of purified and reconstituted EnvZ of Escherichia coli. 1153 42

The YYCFG two-component signal transduction system (TCSTS) has been shown to be essential to the viability of several gram-positive bacteria. However, the function of the gene pair remains unknown. Interestingly, while both components are essential to Staphylococcus aureus and Bacillus subtilis, only the response regulator (YYCF) is essential to Streptococcus pneumoniae. To study this essential TCSTS further, the S. pneumoniae and S. aureus truncated YycG histidine kinase and full-length YycF response regulator proteins were characterized at a biochemical level. The recombinant proteins from both organisms were expressed in Escherichia coli and purified. The YycG autophosphorylation activities were activated by ammonium. The apparent K(m )(ATP) of S. aureus YycG autophosphorylation was 130 microM and S. pneumoniae was 3.0 microM. Each had similar K(cat )values of 0.036 and 0.024 min(-1), respectively. Cognate phosphotransfer was also investigated indicating different levels of the phosphorylated YycG intermediates during the reaction. The S. pneumoniae YycG phosphorylated intermediate was not detectable in the presence of its cognate YycF, while phosphorylated S. aureus YycG and YycF were detected concurrently. In addition, noncognate phosphotransfer was demonstrated between the two species. These studies thoroughly compare the essential YycFG TCSTS from the two species at the biochemical level and also establish methods for assaying the activities of these antibacterial targets.
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PMID:Biochemical characterization of the first essential two-component signal transduction system from Staphylococcus aureus and Streptococcus pneumoniae. 1286 49

The histidine kinase DhkC controls a phosphorelay involved in regulating the slug versus culmination choice during the multicellular developmental program of Dictyostelium discoideum. When the relay is active, slug migration is favored due to the activation of a cyclic AMP (cAMP) phosphodiesterase and the resultant lowering of the intracellular and extracellular levels of cAMP. Ammonia signaling represents one input into the DhkC phosphorelay, and previous studies indicated that the ammonium transporter C inhibits the relay in response to low ammonia levels. Evidence is presented that another member of the family of ammonium transporters, AmtA, also regulates the slug/culmination choice. Under standard conditions of development, the wild-type strain requires a transitional period of 2 to 3 h to go from fingers to culminants, with some slugs forming and migrating briefly prior to culmination. In contrast, amtA null cells, like cells that lack DhkC, possessed a transitional period of only 1 to 2 h and rarely formed slugs. Disruption of amtA in an amtC null strain overcame the slugger phenotype of that strain and restored its ability to culminate. Strains lacking AmtA were insensitive to the ability of ammonia to promote and prolong slug migration. These findings lead to the proposal that AmtA functions in ammonia sensing as an activator of the DhkC phosphorelay in response to perceived high ammonia levels.
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PMID:Function of ammonium transporter A in the initiation of culmination of development in Dictyostelium discoideum. 1683 43

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

The receiver domain (RD) of a sensor histidine kinase (HK) catalyses the transphosphorylation reaction during the action of HKs in hormonal and abiotic signalling in plants. Crystals of the recombinant RD of the Arabidopsis thaliana HK CYTOKININ-INDEPENDENT1 (CKI1(RD)) have been obtained by the hanging-drop vapour-diffusion method using ammonium sulfate as a precipitant and glycerol as a cryoprotectant. The crystals diffracted to approximately 2.4 A resolution on beamline BW7B of the DORIS-III storage ring. The diffraction improved significantly after the use of a non-aqueous cryoprotectant. Crystals soaked in Paratone-N diffracted to at least 2.0 A resolution on beamline BW7B and their mosaicity decreased more than tenfold. The crystals belonged to space group C222(1), with unit-cell parameters a = 54.46, b = 99.82, c = 79.94 A. Assuming the presence of one molecule of the protein in the asymmetric unit gives a Matthews coefficient V(M) of 2.33 A(3) Da(-1). A molecular-replacement solution has been obtained and structure refinement is in progress.
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PMID:Cloning, purification, crystallization and preliminary X-ray analysis of the receiver domain of the histidine kinase CKI1 from Arabidopsis thaliana. 1940 81

HP1043 of Helicobacter pylori is an orphan response regulator (RR) with a highly degenerate receiver sequence incapable of phosphorylation, which is essential for cell viability. In contrast, the orthologous RR protein of Helicobacter pullorum, an enterohepatic Helicobacter species mainly isolated from poultry, harbours a consensus receiver sequence and is associated with a cognate histidine kinase (HK). Here, we show that this two-component system of H. pullorum, denoted HPMG439/HPMG440, is involved in the control of nitrogen metabolism by regulating the expression of glutamate dehydrogenase, an AmtB ammonium transporter and a PII protein. However, the role of the RR HPMG439 is not restricted to nitrogen regulation since, in contrast with the HK HPMG440, HPMG439 is essential for growth of H. pullorum under nutrient-rich conditions.
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PMID:Novel function assignment to a member of the essential HP1043 response regulator family of epsilon-proteobacteria. 2347 51

Sensing and uptake of external ammonium is essential for anaerobic ammonium-oxidizing (anammox) bacteria, and is typically the domain of the ubiquitous Amt/Rh ammonium transporters. Here, we report on the structure and function of an ammonium sensor/transducer from the anammox bacterium "Candidatus Kuenenia stuttgartiensis" that combines a membrane-integral ammonium transporter domain with a fused histidine kinase. It contains a high-affinity ammonium binding site not present in assimilatory Amt proteins. The levels of phosphorylated histidine in the kinase are coupled to the presence of ammonium, as conformational changes during signal recognition by the Amt module are transduced internally to modulate the kinase activity. The structural analysis of this ammonium sensor by X-ray crystallography and small-angle X-ray-scattering reveals a flexible, bipartite system that recruits a large uptake transporter as a sensory module and modulates its functionality to achieve a mechanistic coupling to a kinase domain in order to trigger downstream signaling events.
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PMID:Signaling ammonium across membranes through an ammonium sensor histidine kinase. 2932 12