Iron Uptake as a Virulence Factor in Pathogenic Vibrios

描述(由申请人提供)：这项研究的长期目标是剖析鳗弧菌毒力相关基因表达调控的复杂机制。质粒介导的铁摄取系统是S毒力谱系的主要组成部分，在宿主-细菌相互作用导致全身感染和死亡中发挥着重要作用。这一系统是研究的极好模型。 由于这种感染的发病机制与其他弧菌引起的人类败血症疾病有惊人的相似之处，因此对铁清除在人类系统性感染中所起的作用进行了研究。我们已经确定了这个铁摄取系统的基本成分：铁载体angibactin，运输蛋白，以及控制其合成和运输的调节元件。在……里面 在这个系统中，我们发现了一个铁转运生物合成操纵子，它的表达受正调控因子AngR和TAF的控制，它们的作用区域包括该操纵子的启动子。我们还鉴定了两个反义RNA，RNApha和RNAbeta，它们在转录后作用于铁运输-生物合成操纵子的负控制。RNApha在FATA-Farb间隔区的表达控制中起作用，而RNAβ起作用 一种相对于操纵子上游基因的血管紧张素受体表达的衰减剂。因此，我们建议：(1)鉴定两个反义RNAs作为基因表达的负调控因子的作用，并研究影响其稳定性、活性和对毒力的影响的分子和结构参数。(2)研究正性调控因子AngR和TAFR在铁的表达中的作用 运输-生物合成操纵子，愈创木蛋白生产，和毒力。我们打算在AngR基因和TAFR区域产生定点和缺失突变，以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。对中国传统文化的剖析 这种病原体中铁摄取系统表达的分子相互作用将为探索理解人类系统性感染细菌病原学过程的新途径提供范例。从长远来看，我们的发现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.