Mechanism of CsrA-Mediated Global Control

描述（由申请人提供）：通过研究全球调控的新范式，即大肠杆菌的碳储存调控（Csr）系统，将寻求对转录后调控机制的深入了解。Csr包括CsrA，这是一种RNA结合蛋白，可调节靶mrna的翻译和/或稳定性。CsrB和证监会是一种非编码调控rna，通过隔离CsrA蛋白来拮抗CsrA， CsrD是一种特异性靶向CsrB和证监会的蛋白，可被RNase e降解。在大肠杆菌中，CsrA在大范围内影响代谢、生理、运动和多细胞行为，抑制从指数期向固定期过渡期间表达的某些基因，激活指数期表达的各种基因。CsrA同源物广泛分布于真细菌中，并调节植物和动物病原体中毒力因子的表达。因此，所提出的研究也将提供对细菌生理和发病机制的基本理解，并可能为细菌感染的治疗提供新的方法。本课题的具体目的是：1)阐明CsrA激活或抑制基因表达的分子机制。这一目标将包括对CsrA介导的自动调节的分析，以及对影响CsrA靶转录物稳定性的因素的研究。2)结合生物信息学、基因组学、分子遗传学和生物化学等方法，建立企业社会责任全球调控机制。3) CsrA-RNA复合物的化学计量学和结构表征。这一目标将包括核磁共振结构的模型CsrA靶RNA的确定，以及CsrA-RNA复合物的x射线晶体学结构。4)阐明CsrD作用的分子机制。我们将通过实验来阐明CsrD特异性靶向CsrB和证监会被RNase e降解的机制。这些研究的长期目标是充分了解Csr系统的调控成分、遗传电路、分子机制和生物学功能。深入了解转录后调控机制将寻求通过研究全球遗传调控的新范式，大肠杆菌的碳储存调控（Csr）系统。Csr在广泛的范围内控制着细菌的代谢、生理、运动和生物膜的发育，并调节植物和动物病原体中毒力因子的表达。因此，所提出的研究将提供对细菌生理和发病机制的基本理解，并可能为细菌感染的治疗提供新的方法。

DESCRIPTION (provided by applicant): Insight into post-transcriptional regulatory mechanisms will be sought through the study of a novel paradigm in global regulation, the carbon storage regulatory (Csr) system of Escherichia coli. Csr includes CsrA, an RNA binding protein that regulates translation and/or modulates the stability of target mRNAs. CsrB and CsrC are non-coding regulatory RNAs that antagonize CsrA by sequestering this protein and CsrD is a protein that specifically targets CsrB and CsrC for degradation by RNase E. In E. coli, CsrA affects metabolism, physiology, motility and multicellular behavior on a broad scale, repressing certain genes expressed during the transition from exponential to stationary phase growth and activating various genes expressed during exponential phase. CsrA homologues are widely distributed among eubacteria and regulate the expression of virulence factors in both plant and animal pathogens. Thus, the proposed studies will also provide fundamental understanding of the regulation of bacterial physiology and pathogenesis, and may suggest novel therapeutic approaches for bacterial infections. The specifc aims of this proposal are: 1) Elucidate the molecular mechanisms by which CsrA activates or inhibits gene expression. This aim will include an analysis of CsrA-mediated autoregulation, as well as an investigation into the factors that influence the stability of CsrA target transcripts. 2) Establish the Csr global regulon using a combination of bioinformatic, genomic, molecular genetic and biochemical approaches. 3) Stoichiometric and structural characterization of CsrA-RNA complexes. This aim will include NMR structural determination of a model CsrA target RNA, as well as the structure of CsrA-RNA complexes by X-ray crystallography. 4) Elucidate the molecular mechanism of CsrD action. We will conduct experiments to elucidate the mechanism by which CsrD specifically targets CsrB and CsrC for degradation by RNase E. The long-range objectives of these studies are to fully understand the regulatory components, genetic circuitry, molecular mechanisms, and biological functions of the Csr system. Insight into post-transcriptional regulatory mechanisms will be sought through the study of a novel paradigm in global genetic regulation, the carbon storage regulatory (Csr) system of Escherichia coli. Csr controls bacterial metabolism, physiology, motility and biofilm development on a broad scale, and regulates the expression of virulence factors in both plant and animal pathogens. Thus, the proposed studies will provide fundamental understanding of the regulation of bacterial physiology and pathogenesis, and may suggest novel therapeutic approaches for bacterial infections.