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)

Transcription of the hupSL genes, which encode the uptake [NiFe]hydrogenase of Rhodobacter capsulatus, is specifically activated by H(2). Three proteins are involved, namely the H(2)-sensor HupUV, the histidine kinase HupT and the transcriptional activator HupR. hupT and hupUV mutants have the same phenotype, i.e. an increased level of hupSL expression (assayed by phupS::lacZ fusion) in the absence of H(2); they negatively control hupSL gene expression. HupT can autophosphorylate its conserved His(217), and in vitro phosphotransfer to Asp(54) of its cognate response regulator, HupR, was demonstrated. The non-phosphorylated form of HupR binds to an enhancer site (5'-TTG-N(5)-CAA) of phupS localized at -162/-152 nt and requires integration host factor to activate fully hupSL transcription. HupUV is an O(2)-insensitive [NiFe]hydrogenase, which interacts with HupT to regulate the phosphorylation state of HupT in response to H(2) availability. The N-terminal domain of HupT, encompassing the PAS domain, is required for interaction with HupUV. This interaction with HupT, leading to the formation of a (HupT)(2)-(HupUV)(2) complex, is weakened in the presence of H(2), but incubation of HupUV with H(2) has no effect on the stability of the heterodimer/tetramer, HupUV-(HupUV)(2), equilibrium. HupSL biosynthesis is also under the control of the global two-component regulatory system RegB/RegA, which controls gene expression in response to redox. RegA binds to a site close to the -35 promoter recognition site and to a site overlapping the integration host factor DNA-binding site (5'-TCACACACCATTG, centred at -87 nt) and acts as a repressor.
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PMID:Transcriptional regulation of the uptake [NiFe]hydrogenase genes in Rhodobacter capsulatus. 1566 56

In Arabidopsis thaliana, the immediate early response of plants to cytokinin is formulated as the multistep histidine kinase (AHK)-->histidine-containing phosphotransmitter (AHP)-->response regulator (ARR) phosphorelay signaling circuitry, which is initiated by the cytokinin receptor histidine protein kinases. In the hope of finding components (or genes) that function downstream of the cytokinin-mediated His-->Asp phosphorelay signaling circuitry, we carried out genome-wide microarray analyses. To this end, we used a combinatorial microarray strategy by employing not only wild-type plants, but also certain transgenic lines in which the cytokinin-mediated His-->Asp phosphorelay signaling circuitry has been genetically manipulated. These transgenic lines employed were ARR21-overexpressing and ARR22-overexpressing plants, each of which exhibits a characteristic phenotype with regard to the cytokinin-mediated His-->Asp phosphorelay. The results of extensive microarray analyses with these plants allowed us systematically to identify a certain number of genes that were up-regulated at the level of transcription in response to cytokinin directly or indirectly. Among them, some representatives were examined further in wild-type plants to support the idea that certain genes encoding transcription factors are rapidly and specifically induced at the level of transcription by cytokinin in a manner similar to that of the type-A ARR genes, which are the hallmarks of the His-->Asp phosphorelay signaling circuitry. Several interesting transcription factors were thus identified as being cytokinin responsive, including those belonging to the AP2/EREBP family, MYB family, GATA family or bHLH family. Including these, the presented list of cytokinin-up-regulated genes (214) will provide us with valuable bases for understanding the His-->Asp phosphorelay in A. thaliana.
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PMID:Combinatorial microarray analysis revealing arabidopsis genes implicated in cytokinin responses through the His->Asp Phosphorelay circuitry. 1569 62

Although most two-component signal transduction systems use a simple phosphotransfer pathway from one histidine kinase (HK) to one response regulator (RR), a multiple-step phosphorelay involving a phosphotransfer scheme of His-Asp-His-Asp was also discovered. Central to this multiple-step-type signal transduction pathway are a hybrid-type HK, containing both an HK domain and an RR receiver domain in a single protein, and a histidine-containing phosphotransfer (HPT) that can exist either as a domain in hybrid-type HKs or as a separate protein. Although multiple-step phosphorelay systems are predominant in eukaryotes, it has been previously suggested that they are less common in prokaryotes. In this study, it was found that putative hybrid-type HKs were present in 56 of 156 complete prokaryotic genomes, indicating that multiple-step phosphorelay systems are more common in prokaryotes than previously appreciated. Large expansions of hybrid-type HKs were observed in 26 prokaryotic species, including photosynthetic cyanobacteria such as Nostoc sp. PCC 7120, and several pathogenic bacteria such as Coxiella burnetii. Phylogenetic analysis indicated that there was no common ancestor for hybrid-type HKs, and their origin and expansion was achieved by lateral recruitment of a receiver domain into an HK molecule and then duplication as one unit. Lateral recruitment of additional sensory domains such as PAS was also evident. HPT domains or proteins were identified in 32 of the genomes with hybrid-type HKs; however, no significant gene expansion was observed for HPTs even in a genome with a large number of hybrid-type HKs. In addition, fewer HPTs than hybrid-type HKs were identified in all prokaryotic genomes.
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PMID:Distribution and evolution of multiple-step phosphorelay in prokaryotes: lateral domain recruitment involved in the formation of hybrid-type histidine kinases. 1600 Jul 7

Taz is a chimeric receptor consisting of the periplasmic, transmembrane and most of the HAMP linker domains of the Escherichia coli aspartate receptor (Tar(Ec)) and the cytoplasmic signalling domain of the E. coli osmosensor EnvZ. Aspartate is one of several attractant ligands normally sensed by Tar and it interacts with Taz to induce OmpR-dependent transcription from the ompC promoter--albeit with reduced sensitivity relative to the chemotactic response it evokes via Tar. By combining Taz with a reporter system that expresses green fluorescent protein (GFP) from the ompC promoter, we were able to examine the interaction of Taz with all 20 natural amino acids. Some amino acids (Leu, Met, Val and Ser) reduced GFP expression, which in the case of leucine is likely attributed to a direct effect on the receptor, rather than an indirect effect through the leucine responsive protein (Lrp). Surprisingly, amino acids like Met and Ser--which are also attractants for Tar--'inhibited' Taz. Moreover, Taz exhibits a higher sensitivity to Leu compared with Asp, which is the inverse of Tar. Our results show the exquisite sensitivity of chemotactic receptors. Small conformational changes induced by making the chimera may have changed the way it responds to different amino acids.
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PMID:Plasticity in amino acid sensing of the chimeric receptor Taz. 1616 63

The Synechococcus elongatus mutant lacking the nrtABCD gene cluster (NA3) is defective in active nitrate transport and requires high nitrate concentrations (>30 mm) for sustained growth. Prolonged incubation of NA3 in medium containing 2 mm nitrate led to isolation of a pseudorevertant (NA3R) capable of transport of millimolar concentrations of nitrate, from which three mutants with improved affinity for nitrate were obtained. We identified three genes responsible for the latent transport activity for nitrate: ltnA, which encodes a response regulator with no effector domain; ltnB, which encodes a hybrid histidine kinase with two receiver domains; and ltnT, which encodes a sulfate permease-like protein with a putative cyclic nucleoside monophosphate (cNMP)-binding domain. Missense mutations of the high affinity derivatives of NA3R were found in ltnT, verifying that LtnT acts as the transporter. Overexpression of truncated LtnT lacking the cNMP-binding domain (but not full-length LtnT) conferred nitrate transport activity on NA3, suggesting that the cNMP-binding domain inhibits transport under normal conditions. A nonsense mutation in ltnB that resulted in elimination of the receiver domains of the encoded protein was responsible for expression of nitrate transport activity in NA3R. Expression of LtnB derivatives lacking the receiver domains also conferred low affinity nitrate transport activity on NA3. The phosphoryl group of the histidine kinase domain of LtnB was transferred to Asp(52) of LtnA in vitro. Overexpression of LtnA (but not LtnA(D52E)) led to manifestation of the latent nitrate transport activity in NA3, indicating involvement of phosphorylated LtnA in activation of the novel transporter.
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PMID:Latent nitrate transport activity of a novel sulfate permease-like protein of the cyanobacterium Synechococcus elongatus. 1640 32

Methylglyoxal (MG) is a typical 2-oxoaldehyde derived from glycolysis. We have recently found that MG activates transcription factors such as Yap1 and Msn2, and triggers a Hog1 mitogen-activated protein kinase cascade in Saccharomyces cerevisiae. Regarding the activation of Hog1 by MG, we found that Sln1, an osmosensor possessing histidine kinase activity, functions as a sensor of MG (Maeta, K., Izawa, S., and Inoue, Y. (2005) J. Biol. Chem. 280, 253-260). To gain further insight into the role of MG as a signal initiator, here we analyze the response of Schizosaccharomyces pombe to extracellular MG. Spc1, a stress-activated protein kinase (SAPK), was phosphorylated following the treatment with MG. No phosphorylation was observed in a wis1Delta mutant. The His-to-Asp phosphorelay system consisting of three histidine kinases (Phk1, Phk2, and Phk3), a phosphorelay protein (Spy1), and a response regulator (Mcs4) exists upstream of the Spc1-SAPK pathway. The phosphorylation of Spc1 following MG treatment was observed in phk1Deltaphk2Deltaphk3Delta and spy1Delta cells, but not in mcs4Delta cells. These results suggest that S. pombe has an alternative module(s) that directs the MG signal to the SAPK pathway via Mcs4. Additionally, we found that the transcription factor Pap1 is concentrated in the nucleus in response to MG, independent of the Spc1-SAPK pathway.
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PMID:Methylglyoxal as a signal initiator for activation of the stress-activated protein kinase cascade in the fission yeast Schizosaccharomyces pombe. 1646 60

Using a yeast two-hybrid assay system, it was demonstrated that the four-helix bundle of the Rhodobacter sphaeroides PrrB histidine kinase both serves as the interaction site for the regulatory domain of its cognate response regulator PrrA and is the primary determinant of the interaction specificity. The alpha-helix 1 and its flanking turn region within the dimerization domain (DD) of the PrrB histidine kinase appear to play an important role in conferring the recognition specificity for the PrrA response regulator on the DD. The catalytic ATP-binding domain of the histidine kinase, which functions as the catalytic unit for the phosphotransfer reaction from ATP to the conserved histidine residue in the DD, also appears to contribute to the enhancement of the recognition specificity conferred by the DD. It was also revealed that replacement of Asp-63 and Lys-113 of the PrrA response regulator by alanine abolished protein-protein interactions between PrrA and its cognate histidine kinase PrrB, whereas mutations of Asp-19, Asp-20 and Thr-87 to alanine did not affect protein-protein interactions, indicating that among the active site residues of PrrA, Asp-63 and Lys-113 are important not only in the function of PrrA but also for protein-protein interactions between PrrA and PrrB.
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PMID:Interacting specificity of a histidine kinase and its cognate response regulator: the PrrBA system of Rhodobacter sphaeroides. 1684 10

Ehrlichia chaffeensis, the etiologic agent of human monocytic ehrlichiosis, replicates in early endosomes by avoiding lysosomal fusion in monocytes and macrophages. In E. chaffeensis we predicted three pairs of putative two-component regulatory systems (TCSs) designated PleC-PleD, NtrY-NtrX, and CckA-CtrA based on amino acid sequence homology. In the present study to determine biochemical pairs and specificities of the TCSs, the recombinant proteins of the three putative histidine kinase (HK) kinase domains (rPleCHKD, rNtrYHKD, and MBP-rCckAHKD) and the full-length forms of three putative response regulators (RRs) (rPleD, rNtrX, and rCtrA) as well as the respective mutant recombinant proteins (rPleCHKDH244A, rNtrYHKDH498A, MBP-rCckAHKDH449A, rPleDD53A, rNtrXD59A, and rCtrAD53A) were expressed and purified as soluble proteins. The in vitro HK activity, the specific His residue-dependent autophosphorylation of the kinase domain, was demonstrated in the three HKs. The specific Asp residue-dependent in vitro phosphotransfer from the kinase domain to the putative cognate RR was demonstrated in each of the three RRs. Western blot analysis of E. chaffeensis membrane and soluble fractions using antibodies specific for each recombinant protein detected PleC and CckA in the membrane fraction, whereas it detected NtrY, NtrX, and PleD in the soluble fraction. CtrA was found in the two fractions at similar levels. E. chaffeensis was sensitive to closantel, an HK inhibitor. Closantel treatment induced lysosomal fusion of the E. chaffeensis inclusion in a human monocytic leukemia cell line, THP-1 cells, implying that functional TCSs are essential in preventing lysosomal fusion of the E. chaffeensis inclusion compartment.
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PMID:Biochemical activities of three pairs of Ehrlichia chaffeensis two-component regulatory system proteins involved in inhibition of lysosomal fusion. 1692 92

The hybrid sensor kinase RpfC positively regulates the expression of a range of virulent genes and negatively modulates the synthesis of the quorum sensing signal diffusible signal factor (DSF) in Xanthomonas campestris. Three conserved amino acid residues of RpfC implicated in phosphorelay (His(198) in the histidine kinase domain, Asp(512) in the receiver domain, and His(657) in the histidine phosphotransfer domain) were essential for activation of the production of extracellular enzymes and extracellular polysaccharide (EPS) virulence factors but were not essential for repression of DSF biosynthesis. Domain deletion and subsequent in trans expression analysis revealed that the receiver domain of RpfC alone was sufficient to repress DSF overproduction in an rpfC deletion mutant. Further deletion and alanine scanning mutagenesis analyses identified a peptide of 107 amino acids and three amino acid residues (Gln(496), Glu(504), and Ile(552)) involved in modulating DSF production. Co-immunoprecipitation and far Western blot analyses suggested an interaction between the receiver domain and RpfF, the enzyme involved in DSF biosynthesis. These data support a model in which RpfC modulates two different functions (virulence factor synthesis and DSF synthesis) by utilization of a conserved phosphorelay system and a novel domain-specific protein-protein interaction mechanism, respectively. This latter mechanism represents an added dimension to conventional two-component signaling paradigms.
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PMID:Dual signaling functions of the hybrid sensor kinase RpfC of Xanthomonas campestris involve either phosphorelay or receiver domain-protein interaction. 1694 Feb 95

Nitrate transport activity of the LtnT permease of the cyanobacterium Synechococcus elongatus is activated when LtnA, a response regulator without an effector domain, is phosphorylated by LtnB, a hybrid histidine kinase. We identified a protein (LtnC) that is required for activation of LtnT. LtnC consists of an N-terminal histidine-containing phosphoacceptor (HisKA) domain, a receiver domain, and a unique C-terminal domain found in some cyanobacterial proteins. Because LtnC lacks an ATP-binding kinase domain of a histidine kinase, it is incapable of autophosphorylation, but LtnC is phosphorylated by LtnA. The histidine residue in the HisKA domain but not the aspartate residue in the receiver domain is essential for phosphorylation of LtnC and activation of LtnT. LtnC phosphorylation leads to oligomerization of the protein. Fusion of the C-terminal domain of LtnC to glutathione S-transferase, which forms oligomers, also activates LtnT, suggesting that oligomerization of the LtnC C-terminal domain causes LtnT activation. These results indicate that the C-terminal domain of LtnC acts as an effector domain that directs the output of the signal from the phosphorelay system. The two-step (His-Asp-His) phosphorelay system, composed of the LtnB, LtnA, and LtnC proteins, is distinct from the known phosphorelay systems, namely, the typical two-component system (His-Asp) and the multistep phosphorelay system (His-Asp-His-Asp), because the HisKA domain of LtnC is the terminal phosphoacceptor that determines the signal output. LtnC is a new class of signal transducer in His-Asp phosphorelay systems that contains a HisKA domain and an effector domain.
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PMID:A new class of signal transducer in His-Asp phosphorelay systems. 1704 Sep 12


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