Iron Uptake as a Virulence Factor in Pathogenic Vibrios

描述（由申请方提供）：本研究的长期目标是剖析病原体鳗弧菌中毒力相关基因表达调控的复杂机制。质粒介导的铁吸收系统是这种细菌的主要组成部分？的毒力库，发挥重要作用，在宿主-细菌相互作用，导致全身感染和死亡率。这一制度是一个很好的研究模式 铁清除在人类全身感染中的作用，因为这种感染的发病机制与其他弧菌引起的人类败血症有惊人的相似之处。我们已经表征了这个铁吸收系统的基本组成部分：铁载体anguibactin、转运蛋白以及控制其合成和转运的调节元件。在 在该系统中，我们鉴定了一种铁转运-生物合成操纵子，其表达受作用于包括该操纵子启动子的区域的正调节因子AngR和TAF控制。我们还表征了两种反义RNA，RNAalpha和RNAbeta，其在转录后作用于铁转运生物合成操纵子的负控制。RNA α在fatA-farB基因间区域的表达控制中起作用，RNA β在fatA-farB基因间区域的表达控制中起作用。 与操纵子中的上游基因相比，是angR表达的衰减剂。因此，我们建议：（1）研究RNA α和RNA β这两种反义RNA作为基因表达负调控因子的作用，并研究影响其稳定性、活性和毒力的分子和结构参数。(2)为了表征正调节因子AngR和TAFr在铁表达中的作用， 转运-生物合成操纵子、anguibactin生产和毒力。我们打算在angR基因和TAFr区域中产生定点突变体和缺失突变体，以便剖析对调控和毒力至关重要的基因。这些成分控制病原体-宿主相互作用的具体机制将进一步阐明。解剖 这种病原体中铁吸收系统表达的分子相互作用将作为探索新途径的范例，以了解细菌病原体的系统性人类感染过程。从长远来看，我们的研究结果将有助于制定控制败血症疾病的措施。

DESCRIPTION (provided by the applicant): The long-term goal of this research is to dissect the complex mechanism of regulation of virulence-associated gene expression in the pathogen Vibrio anguillarum. The plasmid-mediated iron uptake system is a major component of this bacterium?s virulence repertoire, playing an essential role in the host-bacteria interaction leading to systemic infection and mortality. This system serves as an excellent model for the study of the role that iron scavenging plays in systemic infections of humans since the pathogenesis of this infection shows striking similarities to human septicemic disease caused by other vibrios. We have characterized the essential components of this iron uptake system: the siderophore anguibactin, transport proteins, and regulatory elements controlling its synthesis and transport. In this system we identified an iron transport-biosynthesis operon whose expression is controlled by the positive regulators AngR and TAF that act at regions that include the promoter of this operon. We also characterized two antisense RNAs, RNAalpha and RNAbeta, that act post-transcriptionally in the negative control of the iron transport-biosynthesis operon. RNAalpha acts in the control of expression at the fatA-farB intergenic region and RNA beta acts as an attenuator of the expression of angR as compared to upstream genes in the operon. Therefore, we propose: (1) to characterize the roles of the two antisense RNAs, RNAalpha and RNA beta, as negative regulators of gene expression and to investigate the molecular and structural parameters that affect their stability, activity and influence on virulence. (2) To characterize the role of the positive regulators, AngR and TAFr, in the expression of the iron transport-biosynthesis operon, anguibactin production, and virulence. We intend to generate site-directed and deletion mutants in the angR gene and in the TAFr region in order to dissect the genes that are essential for regulation and virulence. The specific mechanisms by which these components govern the pathogen-host interaction will be further elucidated. Dissection of the molecular interactions underlying the expression of the iron uptake system in this pathogen will serve as a paradigm to the exploration of new avenues in understanding the process of systemic human infection of a bacterial etiology. In the long term, our findings will aid in the development of measures for the control of septicemic diseases.