two-component systems
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Eustigmatophyte algae represent an interesting model system for the study of the regulation of the excitation energy flow due to their use of violaxanthin both as a major light-harvesting pigment and as the basis of xanthophyll cycle. Fluorescence induction kinetics was studied in an oleaginous marine alga Nannochloropsis oceanica. Nonphotochemical fluorescence quenching was analyzed in detail with respect to the state of the cellular xanthophyll pool. Two components of nonphotochemical fluorescence quenching (NPQ), both dependent on the presence of zeaxanthin, were clearly resolved, denoted as slow and fast NPQ based on kinetics of their formation. The slow component was shown to be in direct proportion to the amount of zeaxanthin, while the fast NPQ component was transiently induced in the presence of membrane potential on subsecond timescales. The applicability of these observations to other eustigmatophyte species is demonstrated by measurements of other representatives of this algal group, both marine and freshwater.
- MeSH
- fluorescence MeSH
- fotosyntéza MeSH
- mořské řasy chemie MeSH
- Publikační typ
- časopisecké články MeSH
CssRS is a two-component system that plays a pivotal role in mediating the secretion stress response in Bacillus subtilis. This system upregulates the synthesis of membrane-bound HtrA family proteases that cope with misfolded proteins that accumulate within the cell envelope as a result of overexpression or heat shock. Recent studies have shown the induction of CssRS-regulated genes in response to cell envelope stress. We investigated the induction of the CssRS-regulated htrA promoter in the presence of different cell wall- and membrane-active substances and observed induction of the CssRS-controlled genes by glycopeptides (vancomycin and teicoplanin), polymyxins B and E, certain β-lactams, and detergents. Teicoplanin was shown to elicit remarkably stronger induction than vancomycin and polymyxin B. Teicoplanin and polymyxin B induced the spxO gene expression in a CssRS-dependent fashion, resulting in increased activity of Spx, a master regulator of disulfide stress in Bacillus subtilis. The CssRS signaling pathway and Spx activity were demonstrated to be involved in Bacillus subtilis resistance to teicoplanin and polymyxin B.
- MeSH
- antibakteriální látky * farmakologie MeSH
- Bacillus subtilis * genetika účinky léků metabolismus MeSH
- bakteriální proteiny * genetika metabolismus MeSH
- polymyxin B * farmakologie MeSH
- promotorové oblasti (genetika) MeSH
- regulace genové exprese u bakterií * účinky léků MeSH
- signální transdukce MeSH
- teikoplanin * farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
... Market failures and imperfections in health care systems 113 -- Annex 3.A2. ... ... Principal component and cluster analyses 121 -- Annex 3.A4. ... ... Principal component analysis on budget and management approaches 125 -- Chapter 4. ... ... care systems 128 -- Linking health system performance and policy indicators 138 -- Drawing comparisons ... ... Principal component analysis on budget and management indicators 125 -- 4.1. ...
207 s. : il. 30 cm
The ESAT6-like Secretion System (ESS) of the human pathogen Staphylococcus aureus secretes heterodimeric virulence effectors such as EsxB and EsxD. To gain insights into the nature of EsxB-EsxD interaction, randomly mutated esxB generated by error-prone PCR was co-transformed together with esxD as adenylate cyclase fusion constructs into cyclase-deficient Escherichia coli, followed by reverse bacterial two-hybrid screening. Three color species were observed: dark blue, light blue, and white (no EsxB-EsxD interaction). The esxB from white colonies was subjected to standard PCR to check for gene signal, followed by SDS-PAGE for variant stability assessment. The gene coding for a stable EsxB variant that perturbed interaction with EsxD was further subjected to DNA sequencing. A single point mutation in esxB at position 157 was identified, leading to an amino acid change from asparagine to aspartic acid at position 53 in the resulting protein. Structural modeling of EsxB reveals that N53 is surface exposed. Whereas N53S substitution by site-directed mutagenesis retained heterodimerization with EsxD, N53A substitution abrogated such interaction. In addition, N53D change in EsxB did not alter interaction with EssG, another soluble component of the ESS pathway, suggesting minimal impact of the N53D substitution on EsxB stability and solubility. Taken together, these data provide new insights into the nature of EsxB-EsxD interaction and offer a systematic approach for in vivo analysis of protein-protein interactions of pathogenic bacteria in non-pathogenic hosts.
- MeSH
- bakteriální proteiny chemie genetika metabolismus MeSH
- faktory virulence genetika metabolismus MeSH
- konformace proteinů MeSH
- mutace MeSH
- mutageneze * MeSH
- polymerázová řetězová reakce MeSH
- sekreční systém typu VII genetika metabolismus MeSH
- sekvenční seřazení MeSH
- Staphylococcus aureus genetika metabolismus MeSH
- techniky dvojhybridového systému MeSH
- vazba proteinů MeSH
- Publikační typ
- časopisecké články MeSH
... and Evolution -- The Regulatory Apparatus Encoded in the DNA 2 -- The Genes and Gene Regulatory Components ... ... Transduced into Spatial -- Patterns of Gene Expression -- Operating Principles for cis -Regulatory Systems ... ... Developmental Specification Events 26 -- Spatial Repression in cis -Regulatory specification 28 -- Two ... ... The Last Routines: Calling in Differentiation Programs 146 -- Specification of Peripheral Nervous System ... ... Changes that Make New Forms: Gene Regulatory Systems and the Evolution of Body Plans -- Some Examples ...
1st ed. xii, 261 s.
To elucidate the physiological meaning of OmpR-dependent expression of invasin gene (inv) inhibition in Yersinia enterocolitica, the function of the EnvZ/OmpR regulatory pathway in osmoregulation of inv expression was analyzed in detail. The osmoregulation of inv expression was found to be a multifaceted process involving both OmpR-dependent and -independent mechanisms. Analysis of inv transcription in strains lacking OmpR or EnvZ proteins indicated that kinase EnvZ is not the only regulator of OmpR phosphorylation. Using the transcriptional inv::lacZ fusion in a heterologous system (Escherichia coli) we tried to clarify the role of OmpR in the inv regulatory circuit composed of negative (H-NS) and positive (RovA) regulators of inv gene transcription. We were able to show a significant increase in inv expression in E. coli ompR background under H-NS( Ecoli )-repressed condition. Moreover, H-NS-mediated inv repression was relieved when RovA of Y. enterocolitica was expressed from a plasmid. Furthermore, we showed that RovA may activate inv expression irrespective on the presence of H-NS protein. Using this strategy we showed that OmpR of Y. enterocolitica decrease RovA-mediated inv activation.
- MeSH
- bakteriální adheziny genetika MeSH
- bakteriální chromozomy genetika MeSH
- bakteriální proteiny genetika metabolismus MeSH
- Escherichia coli genetika metabolismus MeSH
- fúze genů MeSH
- genetická transkripce MeSH
- lac operon genetika MeSH
- osmolární koncentrace MeSH
- promotorové oblasti (genetika) MeSH
- regulace genové exprese u bakterií MeSH
- transaktivátory genetika metabolismus MeSH
- Yersinia enterocolitica genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
We propose a new framework for rigorous robustness analysis of stochastic biochemical systems that is based on probabilistic model checking techniques. We adapt the general definition of robustness introduced by Kitano to the class of stochastic systems modelled as continuous time Markov Chains in order to extensively analyse and compare robustness of biological models with uncertain parameters. The framework utilises novel computational methods that enable to effectively evaluate the robustness of models with respect to quantitative temporal properties and parameters such as reaction rate constants and initial conditions. We have applied the framework to gene regulation as an example of a central biological mechanism where intrinsic and extrinsic stochasticity plays crucial role due to low numbers of DNA and RNA molecules. Using our methods we have obtained a comprehensive and precise analysis of stochastic dynamics under parameter uncertainty. Furthermore, we apply our framework to compare several variants of two-component signalling networks from the perspective of robustness with respect to intrinsic noise caused by low populations of signalling components. We have successfully extended previous studies performed on deterministic models (ODE) and showed that stochasticity may significantly affect obtained predictions. Our case studies demonstrate that the framework can provide deeper insight into the role of key parameters in maintaining the system functionality and thus it significantly contributes to formal methods in computational systems biology.
- MeSH
- antigeny bakteriální MeSH
- bakteriální proteiny MeSH
- DNA bakterií analýza MeSH
- faktory virulence MeSH
- finanční podpora výzkumu jako téma MeSH
- genomové ostrovy genetika MeSH
- lidé MeSH
- regulace genové exprese u bakterií MeSH
- Streptococcus agalactiae genetika patogenita MeSH
- Streptococcus pneumoniae genetika MeSH
- těhotenství MeSH
- Check Tag
- lidé MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
