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 membrane-bound histidine kinase KdpD is a putative turgor sensor that regulates, together with the response regulator KdpE, expression of the kdpFABC operon. This operon encodes the high affinity K+-uptake system KdpFABC of Escherichia coli. Expression of kdpFABC is induced under K+ limiting growth conditions and in response to an osmotic upshift. Various structural features of KdpD and KdpE, which are important for stimulus perception and/or signal transduction were identified and are described here. Furthermore, various studies undertaken to elucidate the nature of the stimulus for KdpD result in a new model for KdpD stimulus perception. According to this, autophosphorylation activity of KdpD is not a result of changes in turgor per se. Instead, various--mainly intracellular parameters--that are related to changes of environmental conditions influence the activities of KdpD.
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PMID:Towards an understanding of the molecular mechanisms of stimulus perception and signal transduction by the KdpD/KdpE system of Escherichia coli. 1193 51

The HliA protein of the cyanobacterium Synechococcus elongatus PCC 7942 is a small, thylakoid-associated protein that appears to play a role in photoprotection; its transcript rapidly accumulates in response to high-intensity light (HL) and the hli gene family is required for survival of cells in high light. In order to discover regulatory factors involved in HL acclimation in cyanobacteria, a screen was performed for chemically generated mutants unable to properly control expression of the hliA gene in response to HL. One such mutant was identified, and complementation analysis led to the identification of the affected gene, designated nblS. Based on its deduced protein sequence, NblS appears to be a membrane-bound, PAS-domain-bearing, sensor histidine kinase of two-component regulatory systems in bacteria. The nblS mutant was unable to properly control light intensity-mediated expression of several other photosynthesis-related genes, including all three psbA genes and the cpcBA genes. The mutant was also unable to control expression of the hliA and psbA genes in response to low-intensity blue/UV-A light, a response that may be related to the HL-mediated regulation of the genes. Additionally, in response to nutrient deprivation, the nblS mutant was unable to properly control accumulation of the nblA transcript and associated degradation of the light-harvesting phycobilisomes. The nblS mutant dies more rapidly than wild-type cells following exposure to HL or nutrient deprivation, likely due to its inability to properly acclimate to these stress conditions. Thus, the NblS protein is involved in the control of a number of processes critical for altering the photosynthetic apparatus in response to both HL and nutrient stress conditions.
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PMID:nblS, a gene involved in controlling photosynthesis-related gene expression during high light and nutrient stress in Synechococcus elongatus PCC 7942. 1194 63

The Cpx (conjugative plasmid expression) stress response of Escherichia coli is induced in response to extracytoplasmic signals generated in the cell envelope, such as misfolded proteins in the periplasm. Detection of stress is mediated by the membrane-bound histidine kinase, CpxA. Signaling of the response regulator CpxR by activated CpxA results in the expression of several factors required for responding to cell envelope stress. CpxA was originally thought to be required for the expression of the positive regulator of the F plasmid transfer (tra) operon, TraJ. It was later determined that constitutive gain-of-function mutations in cpxA led to activation of the Cpx envelope stress response and decreased TraJ expression. In order to determine the nature of the downregulation of TraJ, the level of expression of TraJ, TraM, and TraY, the F-encoded regulatory proteins of the F tra region, was determined both in a cpxA* background and in a wild-type background in which the Cpx stress response was induced by overexpression of the outer membrane lipoprotein, NlpE. Our results suggest that TraJ downregulation is controlled by a posttranscriptional mechanism that operates in the cytoplasm in response to upregulation of the Cpx stress response by both the cpxA* gain-of-function mutation and the overexpression of NlpE.
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PMID:The positive regulator, TraJ, of the Escherichia coli F plasmid is unstable in a cpxA* background. 1227 Aug 37

Ypd1p, a histidine-containing phosphotransfer protein, plays an important role in a branched His-Asp phosphorelay signal transduction pathway that regulates cellular responses to hyperosmotic stress in Saccharomyces cerevisiae. Ypd1p is required for phosphoryl group transfer from the membrane-bound Sln1p sensor histidine kinase to two downstream response regulator proteins, Ssk1p and Skn7p. To investigate the molecular basis for interaction of Ypd1p with these response regulator domains, we used an approach that coupled alanine-scanning mutagenesis of surface-exposed residues in Ypd1p with a yeast two-hybrid interaction screen. Mutated residues that adversely affected the interaction of Ypd1p with the C-terminal response regulator domain of Ssk1p were identified and found to cluster on or near the alphaA helix in Ypd1p. Our results, supported by analysis of a modeled complex, identify a binding site on Ypd1p for response regulators that is composed of a cluster of conserved hydrophobic residues surrounded by less conserved polar residues. We propose that molecular interactions involving Ypd1p are mediated primarily through hydrophobic contacts, whereas binding specificity and strength of interaction may be influenced by select polar side chain interactions.
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PMID:Ssk1p response regulator binding surface on histidine-containing phosphotransfer protein Ypd1p. 1258 20

In Saccharomyces cerevisiae, a branched multistep phosphorelay signaling pathway regulates cellular adaptation to hyperosmotic stress. YPD1 functions as a histidine-phosphorylated protein intermediate required for phosphoryl group transfer from a membrane-bound sensor histidine kinase (SLN1) to two distinct response regulator proteins (SSK1 and SKN7). These four proteins are evolutionarily related to the well-characterized "two-component" regulatory proteins from bacteria. Although structural information is available for many two-component signaling proteins, there are very few examples of complexes between interacting phosphorelay partners. Here we report the first crystal structure of a prototypical monomeric histidine-containing phosphotransfer (HPt) protein YPD1 in complex with its upstream phosphodonor, the response regulator domain associated with SLN1.
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PMID:The yeast YPD1/SLN1 complex: insights into molecular recognition in two-component signaling systems. 1465 27

The bacterium Caulobacter crescentus divides asymmetrically as part of its normal life cycle. This asymmetry is regulated in part by the membrane-bound histidine kinase PleC, which localizes to one pole of the cell at specific times in the cell cycle. Here, we track single copies of PleC labeled with enhanced yellow fluorescent protein (EYFP) in the membrane of live Caulobacter cells over a time scale of seconds. In addition to the expected molecules immobilized at one cell pole, we observed molecules moving throughout the cell membrane. By tracking the positions of these molecules for several seconds, we determined a diffusion coefficient (D) of 12 +/- 2 x 10(-3) microm(2)/s for the mobile copies of PleC not bound at the cell pole. This D value is maintained across all cell cycle stages. We observe a reduced D at poles containing localized PleC-EYFP; otherwise D is independent of the position of the diffusing molecule within the bacterium. We did not detect any directional bias in the motion of the PleC-EYFP molecules, implying that the molecules are not being actively transported.
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PMID:Visualization of the movement of single histidine kinase molecules in live Caulobacter cells. 1552 69

A Mg(2+) sensor mutant (PhoQD179L(A)) in which D179 of PhoQ was changed into L or A was isolated and characterized in Escherichia coli. PhoQ-PhoP regulon genes, phoPQ, mgtA and mgrB transcriptions were repressed at a high Mg(2+) concentration in WQ3007 (phoQ-defective strain)/pHO119, but not in WQ3007/pHO179L(A). The in vitro autophosphorylation activity of membrane-bound PhoQ was repressed by Mg(2+) (10 mM), but that of membrane-bound PhoQD179L(A) was not. Furthermore, the phosphotransfer from membrane-bound PhoQ to PhoP was also repressed by Mg(2+), but was not observed in membrane-bound PhoQD179L(A). These results suggest that PhoQD179L(A) is a locked-on mutant that is defective in extracellular Mg(2+)-sensing and that the D179 amino acid residue of PhoQ plays an essential role in signal transfer between the Mg(2+)-sensory and histidine kinase domain of PhoQ.
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PMID:Isolation and molecular characterization of the locked-on mutant of Mg2+ sensor PhoQ in Escherichia coli. 1604 Nov 31

Over the last two decades, the biochemistry and genetics of dimethylsulfoxide (DMSO) and trimethylamine-N-oxide (TMAO) respiration has been characterised, particularly in Escherichia coli marine bacteria of the genus Shewanella and the purple phototrophic bacteria, Rhodobacter sphaeroides and R. capsulatus. All of the enzymes (or catalytic subunits) involved the final step in DMSO and TMAO respiration contain a pterin molybdenum cofactor and are members of the DMSO reductase family of molybdoenzymes. In E. coli, the dimethylsulfoxide reductase (DmsABC) can be purified from membranes as a complex, which exhibits quinol-DMSO oxidoreductase activity. The enzyme is anchored to the membrane via the DmsC subunit and its catalytic subunit DmsA is now considered to face the periplasm. Electron transfer to DmsA involves the DmsB subunit, which is a polyferredoxin related to subunits found in other molybdoenzymes such as nitrate reductase and formate dehydrogenase. A characteristic of the DmsAB-type DMSO reductase is its ability to reduce a variety of S- and N-oxides. E. coli contains a trimethylamine-N-oxide reductase (TorA) that is highly specific for N-oxides. This enzyme is located in the periplasm and is connected to the quinone pool via a membrane-bound penta-haem cytochrome (TorC). DorCA in purple phototrophic bacteria of the genus Rhodobacter is very similar to TorCA with the critical difference that DorA catalyses reduction of both DMSO and TMAO. It is known as a DMSO reductase because the S-oxide is the best substrate. Crystal structures of DorA and TorA have revealed critical differences at the Mo active site that may explain the differences between substrate specificity between the two enzymes. DmsA, TorA and DorA possess a "twin arginine" N-terminal signal sequence consistent with their secretion via the TAT secretory system and not the Sec system. The enzymes are secreted with their bound prosthetic groups: this take place in the cytoplasm and the biogenesis involves a chaperone protein, which is cognate for each enzyme. Expression of the DMSO and TMAO respiratory operons is induced in response to a fall in oxygen tension. dmsABC expression is positively controlled by the oxygen-responsive transcription factor, Fnr and ModE, a transcription factor that binds molybdate. In contrast, torCAD expression is not under Fnr- or ModE-control but is dependent upon a sensor histidine kinase-response regulator pair, TorSR, which activate gene expression under conditions of low oxygen tension in the presence of N- or S-oxide. Regulation of dorCDA expression is similar to that seen for torCAD but it appears that the expression of the sensor histidine kinase-response regulator pair, DorSR is regulated by Fnr and there is an additional tier of regulation involving the ModE-homologue MopB, molybdate and the transcription factor DorX. Analysis of microbial genomes has revealed the presence of dms and tor operons in a wide variety of bacteria and in some archaea and duplicate dms and tor operons have been identified in E. coli. Challenges ahead will include the determination of the significance of the presence of the dms operon in bacterial pathogens and the determination of the significance of DMSO respiration in the global turnover of marine organo-sulfur compounds.
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PMID:Microbial dimethylsulfoxide and trimethylamine-N-oxide respiration. 1622 80

The Rcs signalling pathway controls a variety of physiological functions like capsule synthesis, cell division or motility in prokaryotes. The Rcs regulation cascade, involving a multi-step phosphorelay between the two membrane-bound hybrid sensor kinases RcsC and RcsD and the global regulator RcsB, is, up to now, one of the most complicated regulatory systems in bacteria. To understand the structural basis of Rcs signal transduction, NMR spectroscopy was employed to determine the solution structure of the RcsC C terminus, possessing a phosphoreceiver domain (RcsC-PR), and a region previously described as a long linker between the histidine kinase domain of RcsC (RcsC-HK) and the RcsC-PR. We have found that the linker region comprises an independent structural domain of a new alpha/beta organization, which we named RcsC-ABL domain (Alpha/Beta/Loop). The ABL domain appears to be a conserved and unique structural element of RcsC-like kinases with no significant sequence homology to other proteins. The second domain of the C terminus, the RcsC-PR domain, represents a well-folded CheY-like phosphoreceiver domain with the central parallel beta-sheet covered with two alpha-helical layers on both sides. We have mapped the interaction of RcsC-ABL and RcsC-PR with the histidine phosphotransfer domain (HPt) of RcsD. In addition we have characterized the interaction with and the conformational effects of Mg2+ and the phosphorylation mimetic BeF(-)(3) on RcsC-ABL and RcsC-PR.
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PMID:A new structural domain in the Escherichia coli RcsC hybrid sensor kinase connects histidine kinase and phosphoreceiver domains. 1700 98

The number of known protein structures is growing exponentially (Berman et al., 2000), but the structural mapping of essential domain-domain and protein-protein interaction surfaces has advanced more slowly. It is particularly difficult to analyze the interaction surfaces of membrane proteins on a structural level, both because membrane proteins are less accessible to high-resolution structural analysis and because the membrane environment is often required for native complex formation. The Protein-Interactions-by-Cysteine-Modification (PICM) method is a generalizable, in vitro chemical scanning approach that can be applied to many protein complexes, in both membrane-bound and soluble systems. The method begins by engineering Cys residues on the surface of a protein of known structure, then a bulky probe is coupled to each Cys residue. Next, the effects of both Cys substitution and bulky probe attachment are measured on the assembly and the activity of the target complex. Bulky probe coupling at an essential docking site disrupts complex assembly and/or activity, while coupling outside the site typically has little or no effect. PICM has been successfully applied to the core signaling complex of the E. coli and S. typhimurium chemotaxis pathway, where it has mapped out essential docking surfaces on transmembrane chemoreceptor (Tar) and histidine kinase (CheA) components (Bass and Falke, 1998; Mehan et al., 2003; Miller et al., 2006). The approach shares similarities with other important scanning methods like alanine and tryptophan scanning (Cunningham and Wells, 1989; Sharp et al., 1995a), but has two unique features: (1) functional effects are determined for both small volume (Cys) and large volume (bulky probe) side chain substitutions in the same experiment, and (2) nonperturbing positions are identified at which Cys residues and bulky probes can be introduced for subsequent biochemical and biophysical studies, without significant effects on complex assembly or activity.
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PMID:The PICM chemical scanning method for identifying domain-domain and protein-protein interfaces: applications to the core signaling complex of E. coli chemotaxis. 1760 25


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