Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.13.3 (histidine kinase)
 2,405 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chemotaxis of enteric bacteria in spatial gradients toward a source of chemoattractant is accomplished by increases in the length of swimming runs up the gradient. Biochemical components of the intracellular signal pathway have been identified, but mechanisms for achieving the high response sensitivity remain unknown. Binding of attractant ligand to its receptor inactivates a receptor-associated histidine kinase, CheA, which phosphorylates the signal protein CheY. The reduction in phospho-CheY, CheY-P, levels prolongs swimming runs. Here, the stimulus-response relation has been determined by measurement of excitation responses mediated by the Tar receptor to defined concentration jumps of the attractant, aspartate, administered within milliseconds by photolysis of a photolabile precursor. The bacteria responded to <1% changes in Tar occupancy when adapted to aspartate over concentrations spanning three orders of magnitude. Response amplitudes increased approximately logarithmically with stimulus strength, extending responsiveness over a greater stimulus range. The extent and form of this relation indicates that, in contrast to mechanisms for adaptive recovery, excitation signal generation involves amplification based on cooperative interactions. These interactions could entail inactivation of multiple receptor-CheA signaling complexes and/or simultaneous activation of CheY-P dephosphorylation.
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PMID:Response tuning in bacterial chemotaxis. 1050 Jan 2

The human pathogen Candida albicans encodes at least three putative two-component histidine kinase signal transduction proteins, including Chk1p and a response regulator protein (Cssk1p). Strains deleted in CHK1 are avirulent in a murine model of hematogenously disseminated disease. The specific function of Chk1p has not been established, but hyphae of the chk1 mutant exhibit extensive flocculation while yeast forms are less adherent to reconstituted human esophageal tissue, indicating that this protein may regulate cell surface properties. Herein, we analyze glucan, mannan and chitin profiles in strains deleted in chk1 (CHK21) compared to a gene-reconstituted strain (CHK23) and a parental strain CAF2. Total alkali-soluble hexose from the cell wall of the chk1 mutant (strain CHK21) was significantly reduced. Western blots of cell wall extracts from CHK21, CHK23 and CAF2 reacted with a Mab to the acid-stable mannan fraction revealed extensive staining of lower molecular mass species in strain CHK21 only. FACE (fluorophore assisted carbohydrate electrophoresis) was used to characterize the oligosaccharide side chains of beta-eliminated (O-linked), acid-hydrolyzed (acid-labile phosphomannan) and acetolysis (acid-stable mannan) extracted fractions of total mannan. The profiles of O-linked as well as the acid-labile oligosaccharides were similar in both CAF2 and CHK21, but the acid-stable oligosaccharide side chains were significantly truncated. We also characterized the beta-glucan from each strain using NMR, and found that both the degree of polymerization and the ratio of (1-3)/(1-6) linkages was lower in CHK21 relative to wild-type cells. The sensitivity of CHK21 to antifungal drugs and inhibitors was unaffected. In summary, our data have identified a new function for a histidine kinase two-component signal protein in a human pathogenic fungus.
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PMID:The role of the Candida albicans histidine kinase [CHK1) gene in the regulation of cell wall mannan and glucan biosynthesis. 1268 36

We have measured the transcription of several genes that have been implicated as virulence factors in Aspergillus fumigatus, including fos-1, a histidine kinase, two-component signal protein, rhbA, a ras-related protein required for signaling, pksP, a polyketide synthase involved in biosynthesis of melanin, pabA synthetase, an enzyme catalyzing a late step in the biosynthesis of folate, lysF, a homoconitase related to lysine biosynthesis, and cpcA, the transcriptional activator of the cross-pathway control system of amino acid biosynthesis. Transcription levels were determined from in vitro grown organism as well as from lung tissue from mice infected with A. fumigatus. Our data indicate that fos-1 and rhbA transcription increased significantly during the infection in mice, compared to the other genes whose transcription remained the same (pksP, cpcA, pabA) or decreased slightly (lysF). In vitro measurements of transcription compared to transcription in infected lung tissue demonstrated low levels of fos-1 and rhbA, 20-40-fold increases (cpcA, lysF, pabA), while pksP was not detected from cultures. Our data demonstrate that transcription of these genes differs in vitro versus during disease.
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PMID:Expression of Aspergillus fumigatus virulence-related genes detected in vitro and in vivo with competitive RT-PCR. 1620 68