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)

We identified four histidine kinase (HK) genes of a cytokinin receptor family, two histidine-containing phosphotransmitter (HPt) genes, thirteen A-type response regulator (RR) genes and six B-type RR genes in the rice genome. The HK genes (OHK2, OHK3, OHK4 and OHK5 for Oryza sativa HK), the HPt genes (OHP1 and OHP2 for O. sativa HPt) and the B-type RR genes (ORR1, ORR2, ORR3, ORR4 and ORR6 for O. sativa RR) except one (ORR5) showed expression in various organs. ORR5 was expressed in callus and flower. Three A-type RR genes (OsRR4, OsRR9 and OsRR10 for O. sativa RR) showed cytokinin-induced expression, and three (OsRR8, OsRR12 and OsRR13) showed expression in flower. We also identified two other genes named OHK1 and CHARK (CHASE domain Receptor-like serine/threonine Kinase). OHK1 encodes an HK similar to Arabidopsis CKI1, which is involved in female gametophyte development. CHARK encodes a protein with an extracellular cytokinin-perceiving CHASE domain and a cytoplasmic serine/threonine kinase domain which are connected with a single transmembrane domain. The presence of all four gene families and CHARK in the rice genome suggests that a cytokinin signal is transduced by the phosphotransfer mechanism as is the case in Arabidopsis, and that rice may have an additional novel signalling pathway involving serine/threonine phosphorylation.
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PMID:Identification and characterization of cytokinin-signalling gene families in rice. 1691 2

Signal transducing mechanisms are essential for regulation of gene expression in both prokaryotic and eukaryotic organisms. Regulation of gene expression in eukaryotes is accomplished by serine/threonine and tyrosine kinases and cognate phosphatases. In contrast, gene expression in prokaryotes is controlled by two-component systems that comprise a sensor histidine kinase and a cognate DNA binding response regulator. Pathogenic bacteria utilize two-component systems to regulate expression of their virulence factors and for adaptive responses to the external environment. We have previously shown that the human pathogen Streptococcus agalactiae (Group B Streptococci, GBS) encodes a single eukaryotic-type serine/threonine kinase Stk1, which is important for virulence of the organism. In this study, we aimed to understand how Stk1 contributes to virulence of GBS. Our results indicate that Stk1 expression is important for resistance of GBS to human blood, neutrophils and oxidative stress. Consistent with these observations, Stk1 positively regulates transcription of a cytotoxin, beta-haemolysin/cytolysin (beta-H/C) that is critical for survival of GBS in the bloodstream and for resistance to oxidative stress. Interestingly, positive regulation of beta-H/C by Stk1 requires the two-component regulator CovR. Further, we show that Stk1 can negatively regulate transcription of CAMP factor in a CovR-dependent manner. As Stk1 phosphorylates CovR in vitro, these data suggest that serine/threonine phosphorylation impacts CovR-mediated regulation of GBS gene expression. In summary, our studies provide novel information that a eukaryotic-type serine/threonine kinase regulates two-component-mediated expression of GBS cytotoxins.
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PMID:Regulation of cytotoxin expression by converging eukaryotic-type and two-component signalling mechanisms in Streptococcus agalactiae. 1700 13

The Pho regulon is controlled by the histidine kinase-response regulator pair SphS-SphR in many cyanobacteria and up-regulation of the Pho regulon can be monitored by measuring alkaline phosphatase activity. However, the mechanism regulating signal transduction between SphS and SphR has not been described. We have created a cyanobacterial strain allowing the introduction of mutations into the transmitter domain of SphS. Mutations at Thr-167, adjacent to the H motif of SphS, introduce elevated alkaline phosphatase activity in the presence of phosphate and an enhancement of alkaline phosphatase activity, when compared to the control strain, in phosphate-limiting media. SphU acts as a negative regulator of the SphS-SphR system in Synechocystis sp. PCC 6803 and we show that constitutive alkaline phosphatase activity in the absence of SphU requires signal transduction through SphS and SphR. However, constitutive activity in the absence of SphU is severely attenuated in the DeltaSphU:SphS-T167N mutant. Our data suggest that Thr-167 contributes to the mechanism underlying regulation by SphU. We have also assembled a deletion mutant system allowing the introduction of mutations into SphR and show that Gly-225 and Trp-236, which are both conserved in SphR from cyanobacteria, are essential for activation of the Pho regulon under phosphate-limiting conditions.
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PMID:Phosphate sensing in Synechocystis sp. PCC 6803: SphU and the SphS-SphR two-component regulatory system. 1754 76

The HAMP domain plays an essential role in signal transduction not only in histidine kinase but also in a number of other signal-transducing receptor proteins. Here we expressed the EnvZ HAMP domain (Arg(180)-Thr(235)) with the R218K mutation (termed L(RK)) or with L(RK) connected with domain A (Arg(180)-Arg(289)) (termed LA(RK)) of EnvZ, an osmosensing transmembrane histidine kinase in Escherichia coli, by fusing it with protein S. The L(RK) and LA(RK) proteins were purified after removing protein S. The CD analysis of the isolated L protein revealed that it consists of a random structure or is unstructured. This suggests that the EnvZ HAMP domain by itself is unable to form a stable structure and that this structural fragility may be important for its role in signal transduction. Interestingly the substitution of Ala(193) in the EnvZ HAMP domain with valine or leucine in Tez1A1, a chimeric protein of Tar and EnvZ, caused a constitutive OmpC phenotype. The CD analysis of LA(RK)(A193L) revealed that this mutated HAMP domain possesses considerable secondary structures and that the thermostability of this entire LA(RK)(A193L) became substantially lower than that of LA(RK) or just domain A, indicating that the structure of the HAMP domain with the A193L mutation affects the stability of downstream domain A. This results in cooperative thermodenaturation of domain A with the mutated HAMP domain. These results are discussed in light of the recently solved NMR structure of the HAMP domain from a thermophilic bacterium (Hulko, M., Berndt, F., Gruber, M., Linder, J. U., Truffault, V., Schultz, A., Martin, J., Schultz, J. E., Lupas, A. N., and Coles, M. (2006) Cell 126, 929-940).
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PMID:Structural and functional studies of the HAMP domain of EnvZ, an osmosensing transmembrane histidine kinase in Escherichia coli. 1763 23

The signal transduction systems of eukaryotes are different from those of prokaryotes with respect to their structures and mechanisms. The main signal transduction system of prokaryotes called the two-component system (TCS) is a one-step phosphorelay system composed of a histidine kinase (HK) while the central signal transduction system of eukaryotes called the mitogen-activated protein kinase (MAPK) cascade system (MCS) is a multi-step phosphorelay system composed of serine/threonine/tyrosine kinases (STYKs). The two signal transduction systems are also different in their transphosphorylation mechanisms. HK in the TCS transfers its own phosphate group to the response regulator protein while STYKs in the MCS phosphorylate other proteins using ATP. We were intrigued by the different dynamics resulting from such differences and wondered why STYKs instead of HKs have been evolutionarily selected in eukaryotic signaling cascades. In this paper, we compared the dynamical characteristics of two mathematical models which reflect such differences between the TCS and the MCS, and found that STYKs are more appropriate for cascade structures in eukaryotic signal transduction than HK with respect to the duration and settling time of response signals.
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PMID:Why have serine/threonine/tyrosine kinases been evolutionarily selected in eukaryotic signaling cascades? 1844 Aug 68

Whereas phosphoesters of serine, threonine, and tyrosine are present in great abundance in mammalian cells, only limited information is available for other amino acids modified by a phosphate group. Phosphohistidine in proteins has been discovered in mammalian cells, but no enzyme with histidine kinase activity has been reported to date. The present study demonstrates for the first time the histidine kinase activity of a mammalian protein. Branched-chain alpha-ketoacid dehydrogenase kinase, a mitochondrial enzyme, has high sequence similarity with histidine kinases from lower organisms but has been classified as a serine/threonine kinase. Our studies indicate that in addition to a serine this enzyme also autophosphorylates a histidine residue. This finding suggests that histidine kinases are not restricted to lower organisms.
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PMID:Branched-chain 6-ketoacid dehydrogenase kinase: A mammalian enzyme with histidine kinase activity. 1949 89

In Streptococcus pneumoniae, stkP and phpP, encoding the eukaryotic-type serine-threonine kinase and PP2C phosphatase, respectively, form an operon. PhpP has the features of a so-called "soluble" protein, whereas StkP protein is membrane associated. Here we provide the first genetic and physiological evidence that PhpP and StkP, with antagonist enzymatic activities, constitute a signaling couple. The StkP-PhpP couple signals competence upstream of the competence-specific histidine kinase ComD, receptor for the oligopeptide pheromone "competence stimulating peptide." We show that PhpP activity is essential in a stkP(+) genetic background, suggesting tight control of StkP activity by PhpP. Proteins PhpP and StkP colocalized to the cell membrane subcellular fraction and likely belong to the same complex, as revealed by coimmunoprecipitation in cellular extracts. Specific coimmunoprecipitation of the N-kinase domain of StkP and PhpP recombinant proteins by PhpP-specific antibodies demonstrates direct interaction between these proteins. Consistently, flow cytometry analysis allowed the determination of the cytoplasmic localization of PhpP and of the N-terminal kinase domain of StkP, in contrast to the periplasmic localization of the StkP C-terminal PASTA (penicillin-binding protein and serine-threonine kinase associated) domain. A signaling route involving interplay between serine, threonine, and histidine phosphorylation is thus described for the first time in this human pathogen.
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PMID:The StkP/PhpP signaling couple in Streptococcus pneumoniae: cellular organization and physiological characterization. 1950 4

The investigation of protein histidine phosphorylation has required the development of a number of methods that differ from traditional methods of phosphoprotein analysis that were developed to study phosphorylation of serine, threonine, and tyrosine, which are, unlike phosphohistidine, acid-stable. The investigation of histidine phosphorylation is further complicated by the fact that in mammalian proteins, phosphorylation appears to occur at either 1-N or 3-N positions of the imidazole ring, depending on the source of the kinase. In this review, we describe methods developed for phosphoamino acid analysis to detect phosphohistidine, including the determination of the isoform present, using chromatographic and mass spectrometric analysis of phosphoprotein hydrolysates and 1H- and 31P NMR analysis of intact phosphoproteins and phosphopeptides. We also describe methods for the assay of protein histidine kinase activity, including a quantitative assay of alkali-stable, acid-labile protein phosphorylation, and an in-gel kinase assay applied to histidine kinases. Most of the detailed descriptions of methods are as they are applied in our laboratory to the investigation of histone H4 phosphorylation and histone H4 histidine kinases, but which can be applied to the phosphorylation of any proteins and to any such histidine kinases.
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PMID:Histidine phosphorylation in histones and in other mammalian proteins. 2094 59

Ethylene plays important roles in plant growth, development and stress responses. Its receptor genes have been studied in dicots such asArabidopsis, tobacco and tomato. However, no research has been reported for the ethylene receptors from monocots currently. In the present study, we cloned an ethylene receptor geneOSPK2 from rice and found that its encoded protein was divergent from the ethylene receptors from dicots. OSPK2 had a long extension in its N-terminal, followed by three transmembrane segments, a GAF domain, a putative kinase domain and a putative receiver domain. Although most of the domains were conserved, the expected phosphorylation site His and the phosphate receiver Asp have been replaced by Gln and Asn, respectively. This fact indicates that OSPK2 may not function as a histidine kinase in a phosphorelay manner, but rather play roles by other mechanism, probably through Ser/Thr kinase activity. The expression of theOSPK2 gene was investigated by RT-PCR method under different conditions. We found that this gene was apparently induced by wounding and PEG treatment, but not significantly affected by salt and ABA treatments. The differential expression of theOSPK2 gene may reflect its roles in mediating different abiotic stress responses, consistent with our previous studies on tobacco ethylene receptors.
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PMID:Characterization of an ethylene receptor homolog gene from rice. 2107 9

Two-component signal transduction mediates a wide range of phenotypes in microbes and plants. The sensor transmitter module controls the phosphorylation state of the cognate-response-regulator receiver domain. Whereas the two-component autokinase and phosphotransfer reactions are well-understood, the mechanism by which sensors accelerate the rate of phospho-response regulator dephosphorylation, termed "transmitter phosphatase activity," is unknown. We identified a conserved DxxxQ motif adjacent to the phospho-accepting His residue in the HisKA_3 subfamily of two-component sensors. We used site-specific mutagenesis to make substitutions for these conserved Gln and Asp residues in the nitrate-responsive NarX sensor and analyzed function both in vivo and in vitro. Results show that the Gln residue is critical for transmitter phosphatase activity, but is not essential for autokinase or phosphotransfer activities. The documented role of an amide moiety in phosphoryl group hydrolysis suggests an analogous catalytic function for this Gln residue in HisKA_3 members. Results also indicate that the Asp residue is important for both autokinase and transmitter phosphatase activities. Furthermore, we noted that sensors of the HisKA subfamily exhibit an analogous E/DxxT/N motif, the conserved Thr residue of which is critical for transmitter phosphatase activity of the EnvZ sensor. Thus, two-component sensors likely use similar mechanisms for receiver domain dephosphorylation.
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PMID:Conserved mechanism for sensor phosphatase control of two-component signaling revealed in the nitrate sensor NarX. 2107 95


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