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Sensor Histidine Kinase (sensor + histidine_kinase)
Selected AbstractsListeria monocytogenes response regulators important for stress tolerance and pathogenesisFEMS MICROBIOLOGY LETTERS, Issue 1 2001Birgitte H. Kallipolitis Abstract Environmental sensing by two-component signal transduction systems is likely to play a role for growth and survival of Listeria monocytogenes both during transmission in food products and within a host organism. Two-component systems typically consist of a membrane-associated sensor histidine kinase and a gene regulatory protein, the response regulator (RR). We have identified seven putative RR genes in L. monocytogenes LO28 by PCR using degenerate oligonucleotide primers. By insertional inactivation we obtained data suggesting that three of the putative RRs contribute to the pathogenicity of L. monocytogenes in mice. Strikingly, the mutants that were attenuated in virulence also had a decreased ability to grow in the presence of various stress conditions potentially encountered in an infection process. Thus, our data point to a connection between the ability of the putative two-component systems to sense and respond to certain environmental stimuli, and the virulence of L. monocytogenes. [source] Novel domains of the prokaryotic two-component signal transduction systemsFEMS MICROBIOLOGY LETTERS, Issue 1 2001Michael Y. Galperin Abstract The archetypal two-component signal transduction systems include a sensor histidine kinase and a response regulator, which consists of a receiver CheY-like domain and a DNA-binding domain. Sequence analysis of the sensor kinases and response regulators encoded in complete bacterial and archaeal genomes revealed complex domain architectures for many of them and allowed the identification of several novel conserved domains, such as PAS, GAF, HAMP, GGDEF, EAL, and HD-GYP. All of these domains are widely represented in bacteria, including 19 copies of the GGDEF domain and 17 copies of the EAL domain encoded in the Escherichia coli genome. In contrast, these novel signaling domains are much less abundant in bacterial parasites and in archaea, with none at all found in some archaeal species. This skewed phyletic distribution suggests that the newly discovered complexity of signal transduction systems emerged early in the evolution of bacteria, with subsequent massive loss in parasites and some horizontal dissemination among archaea. Only a few proteins containing these domains have been studied experimentally, and their exact biochemical functions remain obscure; they may include transformations of novel signal molecules, such as the recently identified cyclic diguanylate. Recent experimental data provide the first direct evidence of the participation of these domains in signal transduction pathways, including regulation of virulence genes and extracellular enzyme production in the human pathogens Bordetella pertussis and Borrelia burgdorferi and the plant pathogen Xanthomonas campestris. Gene-neighborhood analysis of these new domains suggests their participation in a variety of processes, from mercury and phage resistance to maintenance of virulence plasmids. It appears that the real picture of the complexity of phosphorelay signal transduction in prokaryotes is only beginning to unfold. [source] Regulation of virulence determinants in Staphylococcus aureus: complexity and applicationsFEMS MICROBIOLOGY REVIEWS, Issue 2 2004Stéphane Bronner Abstract The virulence of Staphylococcus aureus is essentially determined by cell wall associated proteins and secreted toxins that are regulated and expressed according to growth phases and/or growth conditions. Gene expression is regulated by specific and sensitive mechanisms, most of which act at the transcriptional level. Regulatory factors constitute numerous complex networks, driving specific interactions with target gene promoters. These factors are largely regulated by two-component regulatory systems, such as the agr, saeRS, srrAB, arlSR and lytRS systems. These systems are sensitive to environmental signals and consist of a sensor histidine kinase and a response regulator protein. DNA-binding proteins, such as SarA and the recently identified SarA homologues (SarR, Rot, SarS, SarT, SarU), also regulate virulence factor expression. These homologues might be intermediates in the regulatory networks. The multiple pathways generated by these factors allow the bacterium to adapt to environmental conditions rapidly and specifically, and to develop infection. Precise knowledge of these regulatory mechanisms and how they control virulence factor expression would open up new perspectives for antimicrobial chemotherapy using key inhibitors of these systems. [source] The Photoreaction of the Photoactive Yellow Protein Domain in the Light Sensor Histidine Kinase Ppr is Influenced by the C-terminal Domains,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2008Hironari Kamikubo To study the role of the C-terminal domains in the photocycle of a light sensor histidine kinase (Ppr) having a photoactive yellow protein (PYP) domain as the photosensor domain, we analyzed the photocycles of the PYP domain of Ppr (Ppr-PYP) and full-length Ppr. The gene fragment for Ppr-PYP was expressed in Escherichia coli, and it was chemically reconstituted with p- coumaric acid; the full-length gene of Ppr was coexpressed with tyrosine ammonia-lyase and p -coumaric acid ligase for biosynthesis in cells. The light/dark difference spectra of Ppr-PYP were pH sensitive. They were represented as a linear combination of two independent difference spectra analogous to the PYPL/dark and PYPM/dark difference spectra of PYP from Halorhodospira halophila, suggesting that the pH dependence of the difference spectra is explained by the equilibrium shift between the PYPL - and PYPM -like intermediates. The light/dark difference spectrum of Ppr showed the equilibrium shift toward PYPL compared with that of Ppr-PYP. Kinetic measurements of the photocycles of Ppr and Ppr-PYP revealed that the C-terminal domains accelerate the recovery of the dark state. These observations suggest an interaction between the C-terminal domains and the PYP domain during the photocycle, by which light signals captured by the PYP domain are transferred to the C-terminal domains. [source] Cloning, purification, crystallization and preliminary X-ray analysis of the receiver domain of the histidine kinase CKI1 from Arabidopsis thalianaACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 5 2009Klumpler The receiver domain (RD) of a sensor histidine kinase (HK) catalyses the transphosphorylation reaction during the action of HKs in hormonal and abiotic signalling in plants. Crystals of the recombinant RD of the Arabidopsis thaliana HK CYTOKININ-INDEPENDENT1 (CKI1RD) have been obtained by the hanging-drop vapour-diffusion method using ammonium sulfate as a precipitant and glycerol as a cryoprotectant. The crystals diffracted to approximately 2.4,Å resolution on beamline BW7B of the DORIS-III storage ring. The diffraction improved significantly after the use of a non-aqueous cryoprotectant. Crystals soaked in Paratone-N diffracted to at least 2.0,Å resolution on beamline BW7B and their mosaicity decreased more than tenfold. The crystals belonged to space group C2221, with unit-cell parameters a = 54.46, b = 99.82, c = 79.94,Å. Assuming the presence of one molecule of the protein in the asymmetric unit gives a Matthews coefficient VM of 2.33,Å3,Da,1. A molecular-replacement solution has been obtained and structure refinement is in progress. [source] | ||||||||||