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)

Kinase A is the sensor histidine kinase responsible for processing postexponential phase information and providing phosphate input to the phosphorelay that activates developmental transcription via phosphorylated Spo0A. A protein inhibitor, KipI, of kinase A was discovered encoded in an operon of genes of unknown function but regulated by the availability of fixed nitrogen. KipI is a potent inhibitor of the autophosphorylation reaction of kinase A but does not inhibit phosphate transfer to the Spo0F response regulator once kinase A is phosphorylated. KipI is an inhibitor of the catalytic domain of kinase A affecting the ATP/ADP reactions and not the phosphotransferase functions of this domain. The inhibitory activity of KipI is counteracted by the product of another gene in the operon, KipA. This protein may bind to KipI, preventing its function as an inhibitor of kinase A. KipI may be the first representative of a new class of signal transduction inhibitors that function by direct interaction with the catalytic domain of histidine kinases to counteract signals influencing the "sensor" domain of such kinases. This inhibitor represents yet another way by which the phosphorelay signal transduction system is affected by negative regulators under the control of metabolic, environmental, or cell cycle influences antithetical to the initiation of developmental transcription.
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PMID:A novel histidine kinase inhibitor regulating development in Bacillus subtilis. 933 21

We have cloned and analysed the sequence of a putative histidine kinase, two-component gene (CaHK1) from Candida albicans. This gene encodes a 2471 amino acid protein (Cahk1p) with an estimated molecular mass of 281.8 kDa. A homology search of Cahk1p with other proteins in the databases showed that Cahk1p exhibits the greatest homology at its C-terminus with both the sensor and regulator components of prokaryotic and eukaryotic two-component histidine kinases. A further analysis of this homology showed that the Cahk1p possessed both sensor and regulator domains in the same polypeptide. Also, Cahk1p is likely to be a soluble protein. The sensor kinase domain of Cahk1p contains conserved motifs that are characteristic of all histidine kinase proteins, including the putative histidine which is believed to be autophosphorylated during activation, ATP binding motifs and others (F- and N-motifs), with unknown function. The Cahk1p regulator domain also contains conserved aspartate and lysine residues and the putative aspartate, which is secondarily phosphorylated by the autophosphorylated histidine. Finally, according to the codon usage frequency of the CaHK1 gene in comparison with other genes from C. albicans, there would appear to be a low level of expression of the gene.
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PMID:Identification of a putative histidine kinase two-component phosphorelay gene (CaHK1) in Candida albicans. 963 13

Natural competence in Streptococcus pneumoniae is regulated by a quorum-sensing mechanism consisting of a competence-stimulating peptide (CSP), its dedicated secretion apparatus (ComAB), its histidine kinase receptor (ComD) and a response regulator (ComE). In this report, we show that ComE is a DNA-binding protein that acts autocatalytically by binding to a region in its own promoter. Two additional ComE binding sites were identified in the pneumococcal genome, one in the promoter region of comAB and the other upstream of an ABC transporter of unknown function. A comparison of the ComE-binding sequences with the sequence motif previously found to be involved in the co-ordinated expression of the late genes revealed that they are unrelated. These findings indicate that ComE activates transcription of the late genes indirectly, i.e. via one or more intermediate factors.
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PMID:Identification of DNA binding sites for ComE, a key regulator of natural competence in Streptococcus pneumoniae. 1044 90

In Escherichia coli, the Cpx two-component regulatory system activates expression of protein folding and degrading factors in response to misfolded proteins in the bacterial envelope (inner membrane, periplasm, and outer membrane). It is comprised of the histidine kinase CpxA and the response regulator CpxR. This response plays a role in protection from stresses, such as elevated pH, as well as in the biogenesis of virulence factors. Here, we show that the Cpx periplasmic stress response is subject to amplification and repression through positive and negative autofeedback mechanisms. Western blot and operon fusion analyses demonstrated that the cpxRA operon is autoactivated. Conditions that lead to elevated levels of phosphorylated CpxR cause a concomitant increase in transcription of cpxRA. Conversely, overproduction of CpxP, a small, Cpx-regulated protein of previously unknown function, represses the regulon and can block activation of the pathway. This repression is dependent on an intact CpxA sensing domain. The ability to autoactivate and then subsequently repress allows for a temporary amplification of the Cpx response that may be important in rescuing cells from transitory stresses and cueing the appropriately timed elaboration of virulence factors.
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PMID:The Cpx envelope stress response is controlled by amplification and feedback inhibition. 1046 96

The Cpx envelope stress response of Escherichia coli is controlled by a two-component regulatory system that senses misfolded proteins in extracytoplasmic compartments and responds by inducing the expression of envelope protein folding and degrading factors. We have proposed that in the absence of envelope stress the pathway is maintained in a downregulated state, in part through interactions between the periplasmic inhibitor molecule CpxP and the sensing domain of the histidine kinase CpxA. In this study, we show that depletion of the periplasmic contents of the cell by spheroplast formation does indeed lead to induction of the Cpx envelope stress response. Further, removal of CpxP is an important component of this induction because tethering an MBP-CpxP fusion protein to the spheroplast inner membranes prevents full activation by this treatment. Spheroplast formation has previously been demonstrated to induce the expression of a periplasmic protein of unknown function, Spy. Analysis of spy expression in response to spheroplast formation by Western blot analysis and by lacZ operon fusion in various cpx mutant backgrounds demonstrated that spy is a member of the Cpx regulon. Interestingly, although the only known spy homologue is cpxP, Spy does not appear to perform the same function as CpxP as it is not involved in inhibiting the Cpx envelope stress response. Rather, deletion of spy leads to activation of the sigmaE stress response. Because the sigmaE response is specifically affected by alterations in outer membrane protein biogenesis, we think it possible that Spy may be involved in this process.
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PMID:Tethering of CpxP to the inner membrane prevents spheroplast induction of the cpx envelope stress response. 1097 35

Two-component systems are signal transduction systems which enable bacteria to regulate cellular functions in response to changing environmental conditions. In most cases regulation is accomplished on the transcriptional level by a response regulator protein, which, according to the phosphorylation state of its receiver domain, displays different affinities for its target promoters. Here we describe identification of genes regulated by the two-component system HP166-HP165 of Helicobacter pylori and characterization of the corresponding target promoters. We demonstrated that expression of the HP166-HP165 two-component system is negatively autoregulated under conditions favoring autophosphorylation of the histidine kinase. Furthermore, we found that response regulator HP166 activates transcription of genes encoding a protein family with an unknown function present in H. pylori 26695, as well as an operon composed of five H. pylori-specific genes. While open reading frame HP166 is an essential gene, the target genes of the response regulator are not required for growth under in vitro culture conditions.
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PMID:Identification of target genes regulated by the two-component system HP166-HP165 of Helicobacter pylori. 1175 11

The Listeria monocytogenes two-component signal transduction system, LisRK, initially identified in strain LO28, plays a significant role in the virulence potential of this important food-borne pathogen. Here, it is shown that, in addition to its major contribution in responding to ethanol, pH, and hydrogen peroxide stresses, LisRK is involved in the ability of the cell to tolerate important antimicrobials used in food and in medicine, e.g., the lantibiotic nisin and the cephalosporin family of antibiotics. A (Delta)lisK mutant (lacking the LisK histidine kinase sensor component) displays significantly enhanced resistance to the lantibiotic nisin, a greatly enhanced sensitivity to the cephalosporins, and a large reduction in the expression of three genes thought to encode a penicillin-binding protein, another histidine kinase (other than LisK), and a protein of unknown function. Confirmation of the role of LisRK was obtained when the response regulator, LisR, was overexpressed using both constitutive and inducible (nisin-controlled expression) systems. Under these conditions we observed a reversion of the (Delta)lisK mutant to wild-type growth kinetics in the presence of nisin. It was also found that overexpression of LisR complemented the reduced expression of two of the aforementioned genes. These results demonstrate the important role of LisRK in the response of L. monocytogenes to a number of antimicrobial agents.
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PMID:The LisRK signal transduction system determines the sensitivity of Listeria monocytogenes to nisin and cephalosporins. 1218 29

A sudden decrease in ambient temperature induces the expression of a number of genes in poikilothermic organisms. We report here that the cold inducibility of gene expression in Synechocystis sp. PCC 6803 was enhanced by the rigidification of membrane lipids that was engineered by disruption of genes for fatty acid desaturases. DNA microarray analysis revealed that cold-inducible genes could be divided into three groups according to the effects of the rigidification of membrane lipids. The first group included genes whose expression was not induced by cold in wild-type cells but became strongly cold-inducible upon rigidification of membrane lipids. This group included certain heat-shock genes, genes for subunits of the sulfate transport system, and the hik34 gene for a histidine kinase. The second group consisted of genes whose cold inducibility was moderately enhanced by the rigidification of membrane lipids. Most genes in this group encoded proteins of as yet unknown function. The third group consisted of genes whose cold inducibility was unaffected by the rigidification of membrane lipids. This group included genes for an RNA helicase and an RNA-binding protein. DNA microarray analysis also indicated that the rigidification of membrane lipids had no effect on the heat inducibility of gene expression. Hik33, a cold-sensing histidine kinase, regulated the expression of most genes in the second and third groups but of only a small number of genes in the first group, an observation that suggests that the cold-inducible expression of genes in the first group might be regulated by a cold sensor that remains to be identified.
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PMID:Gene-engineered rigidification of membrane lipids enhances the cold inducibility of gene expression in synechocystis. 1250 18

Transposon tagging with modified maize Ds-GUS constructs was used to isolate genes induced by oxygen deprivation in Arabidopsis thaliana. Seedlings of 800 gene-trap (DsG) and 600 enhancer-trap (DsE) lines were grown on vertically positioned plates for 1 week, oxygen deprived for up to 24 h and stained for GUS activity. Oxygen deprivation induced intricate patterns of gene expression in seedlings of 65 lines. The insertion site and phenotypes of 15 lines were examined. Surprisingly, none of the insertions were into genes that encode known anaerobic polypeptides. Insertions were identified within or adjacent to genes encoding proteins of regulatory, enzymatic, mitochondrial protein import and unknown function, as well as adjacent to genes encoding a putative receptor-like kinase and putative sensor-histidine kinase. Four lines had significantly lower ADH activity after 24 h of oxygen deprivation and three of these showed reduced stress tolerance. Two lines with wild-type levels of ADH were low-oxygen intolerant. Paradoxically, several lines had significantly higher ADH activity after 12 h of oxygen deprivation but reduced stress tolerance. Caffeine treatment, which increased ADH specific activity in wild-type seedlings under aerobic conditions, was sufficient to increase GUS staining in seven of the 15 lines, providing evidence that these genes may be regulated by cytosolic calcium levels. These results demonstrate the effectiveness of the Ds-GUS tagging system in the identification of genes that are regulated in response to oxygen deprivation and a calcium second messenger.
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PMID:Gene and enhancer trap transposable elements reveal oxygen deprivation-regulated genes and their complex patterns of expression in Arabidopsis. 1250 34

It was previously shown that enhanced nisin resistance in some mutants was associated with increased expression of three genes, pbp2229, hpk1021, and lmo2487, encoding a penicillin-binding protein, a histidine kinase, and a protein of unknown function, respectively. In the present work, we determined the direct role of the three genes in nisin resistance. Interruption of pbp2229 and hpk1021 eliminated the nisin resistance phenotype. Interruption of hpk1021 additionally abolished the increase in pbp2229 expression. The results indicate that this nisin resistance mechanism is caused directly by the increase in pbp2229 expression, which in turn is brought about by the increase in hpk1021 expression. We also found a degree of cross-protection between nisin and class IIa bacteriocins and investigated possible mechanisms. The expression of virulence genes in one nisin-resistant mutant and two class IIa bacteriocin-resistant mutants of the same wild-type strain was analyzed, and each mutant consistently showed either an increase or a decrease in the expression of virulence genes (prfA-regulated as well as prfA-independent genes). Although the changes mostly were moderate, the consistency indicates that a mutant-specific change in virulence may occur concomitantly with bacteriocin resistance development.
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PMID:pbp2229-mediated nisin resistance mechanism in Listeria monocytogenes confers cross-protection to class IIa bacteriocins and affects virulence gene expression. 1500 92


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