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)

In the cyanobacterium Synechococcus elongatus PCC 7942, circadian timing is transmitted from the KaiABC-based central oscillator to the transcription factor RpaA via the KaiC-interacting histidine kinase SasA to activate transcription, thereby generating rhythmic circadian gene expression. However, KaiC can also repress circadian gene expression, including its own. The mechanism and significance of this negative feedback regulation have been unclear. Here, we report a novel gene, labA (low-amplitude and bright), that is required for negative feedback regulation of KaiC. Disruption of labA abolished transcriptional repression caused by overexpression of KaiC and elevated the trough levels of circadian gene expression, resulting in a low-amplitude phenotype. In contrast, overexpression of labA significantly lowered circadian gene expression. Furthermore, genetic analysis indicated that labA and sasA function in parallel pathways to regulate kaiBC expression, whereas rpaA functions downstream from labA for kaiBC expression. These results suggest that temporal information from the KaiABC-based oscillator diverges into a LabA-dependent negative pathway and a SasA-dependent positive pathway, and then converges onto RpaA to generate robust circadian gene expression. It is likely that quantitative information of KaiC is transmitted to RpaA through LabA, whereas SasA mediates the state of the KaiABC-based oscillator.
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PMID:labA: a novel gene required for negative feedback regulation of the cyanobacterial circadian clock protein KaiC. 1721 Jul 89

Two-component systems are predominant signal transduction pathways in prokaryotes, and also exist in many archaea as well as some eukaryotes. A typical TCS consists of a histidine kinase and a cognate response regulator. In this study, a novel gene encoding a response regulator (we designate it drRRA) is identified to be essential for the extreme radioresistance of Deinococcus radiodurans. DrRRA null mutant (we designate it MR) is sensitive to gamma-radiation compared with the wild-type strain. Transcriptional assays show that numerous genes are changed in their transcriptional levels in MR at exponential growth phase under normal or gamma-radiation condition. Most of them are related to stress response and DNA repair. Antioxidant activity assays exhibit that both superoxide dismutases and catalases are decreased in the mutant, whereas Western blotting assays show that RecA and PprA are also reduced in MR, verifying the microarray and quantitative real-time PCR data. Furthermore, pulsed-field gel electrophoresis assay demonstrates that deletion of drRRA results in the delay of genome restitution. These data support the hypothesis that DrRRA contributes to the extreme radioresistance of D. radiodurans through its regulatory role in multiple pathways such as antioxidation and DNA repair pathways.
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PMID:DrRRA: a novel response regulator essential for the extreme radioresistance of Deinococcus radiodurans. 1820 31

A microarray-based approach was used to screen a soil metagenome for the presence of blue light (BL) photoreceptor-encoding genes. The microarray carried 149 different 54-mer oligonucleotides, derived from consensus sequences of light, oxygen and voltage (LOV) domain BL photoreceptor genes. Calibration of the microarrays allowed the detection of minimally 50 ng of genomic DNA against a background of 2-5 microg of genomic DNA. Identification of a positive cosmid clone was still possible for an amount of 0.25 ng against a background of 10 microg of labelled DNA clones. The array could readily identify targets carrying 4% sequence mismatch. Using the LOV microarray, up to 1200 library clones in concentrations of c. 20 ng each with a c. 40 kb insert size could be screened in a single batch. After calibration and reliability controls, the microarray was probed with cosmid-cloned DNA from the thermophilic fraction of a soil sample. From this approach, a novel gene was isolated that encodes a protein consisting of several Per-Arnt-Sim domains, a LOV domain associated to a histidine kinase and a response regulator domain. The novel gene showed highest similarity to a known sequence from Kineococcus radiotolerans SRS30216 (58% identity for the LOV domain only) and to a gene from Methylibium petroleiphilum PM1 (57% identity). The gene, designated as ht-met1 (Hamburg Thermophile Metagenome 1), was isolated and fully sequenced (3615 bp). ht-met1 is followed by a second open reading frame encoding a Fe-chelatase, an arrangement quite frequent for BL photoreceptors. The LOV domain region of ht-met1 was subcloned and expressed yielding a fully functional, flavin-containing LOV domain. Irradiation generated the typical LOV photochemistry, with the transient formation of a flavin-protein photoadduct. The dark recovery lifetime was found as tau(REC) = 120 s (20 degrees C) and is among the fastest ones determined so far for bacterial LOV domains.
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PMID:Novel blue light-sensitive proteins from a metagenomic approach. 1953 4

Addition of nitrate (NO3 (-)) to a suspension of NO3 (-)-depleted Spirulina platensis PCC 7345 restored back the PSII reaction centre efficiency. Using RAPD/RT-PCR differential display, we have detected the upregulation of a novel gene in filaments starved of nitrogen when enriched with NO3 (-). Semiquantitative RT-PCR clearly shows that NO3 (-) repletion induces the expression of this gene. Its nucleotide sequence is homologous to multi sensor histidine kinase (hstk) from Spirulina platensis NIES-39 and Spirulina maxima CS-328 genes. The open reading frame of this gene encodes a protein of 98 amino acids contains sensory domain of PAS domain.
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PMID:Effect of nitrate availability on expression of multi sensor histidine kinase gene in Spirulina platensis PCC 7345. 2357 15

A genome analysis of Pseudomonas pseudoalcaligenes KF707, a PCBs degrader and metal-resistant soil microorganism, revealed the presence of two novel gene clusters named che2 and che3, which were predicted to be involved in chemotaxis-like pathways, in addition to a che1 gene cluster. We herein report that the histidine kinase coding genes, cheA2 and cheA3, have no role in swimming or chemotaxis in P. pseudoalcaligenes KF707, in contrast to cheA1. However, the cheA1 and cheA2 genes were both necessary for cell swarming, whereas the cheA3 gene product had a negative effect on the optimal swarming phenotype of KF707 cells.
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PMID:The Role of cheA Genes in Swarming and Swimming Motility of Pseudomonas pseudoalcaligenes KF707. 2715 56

In this study, we constructed amino acid biosensors that can be used as a high-throughput system to screen microorganisms that produce glutamate. The biosensors are based on two-component regulatory systems (TCRSs) combined with green fluorescent protein (GFP) as a reporter. A chimeric DegS/EnvZ (DegSZ) TCRS was constructed by fusing the N-terminal domain of the sensor kinase DegS from Planococcus sp. PAMC21323 with the catalytic domain of the osmosensor EnvZ from Escherichia coli to control expression of gfp in response to glutamate. gfp was controlled by the ompC promoter through the activated response regulator OmpR-P. The chimeric TCRS-based biosensors showed a 4-fold increase in the fluorescent signal after adding glutamate. A linear correlation was observed between fluorescence intensity and exogenously added glutamate concentration. The chimeric TCRS-based biosensor was used to determine glutamate concentration at the single-cell level by fluorescence-activated cell sorting. Therefore, this biosensor can be used to isolate novel gene products and optimize pathways involved in amino acid production.
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PMID:A Chimeric Two-Component Regulatory System-Based Escherichia coli Biosensor Engineered to Detect Glutamate. 2961 Nov 35