Iron uptake as a virulence factor in pathogenic vibrios

描述（由申请人提供）：我们的长期研究目标是研究鳗弧菌和创伤弧菌对铁的吸收机制及其表达调控。在鱼类病原体中，pJM1介导的铁摄取系统在全身感染中起重要作用。这个系统是一个很好的模型，因为它与人类败血症有惊人的相似之处，比如由创伤弧菌引起的铁负荷过重的病人。即使在这些高铁条件下，也存在铁限制生态位，其中铁限制诱导的基因在毒力中起着至关重要的作用。在这篇竞争性更新中，我们将完成对鳗鲡质粒介导的铁摄取基因的调控分析，并剖析鳗鲡和创伤鳗鲡铁转运的机制。我们之前已经描述了鳗鲡铁摄取系统的基本成分：铁载体鳗鲡蛋白和控制其合成和运输的蛋白质和调节元件。我们还鉴定了对创伤弧菌毒力至关重要的铁调控基因。我们建议：1。AngR和RNAb调控ITB操纵子的机制。AngR是一种双功能蛋白，可干预铁转运-生物合成（ITB）操纵子的表达，并参与铁转运-生物合成的调控。我们打算：a)完成对AngR调控结构域的分析；b)表征RNAb在ITB操纵子内调控转录的结构功能。2. TonB2介导的铁转运和鳗毒力机制的分子表征。在两种tonB系统中，只有tonB2系统是产生毒力所必需的。由于我们最近解决了TonB2蛋白的结构，我们打算确定对FatA外膜受体TonB2识别重要的残基，并确定FatA中的特定突变如何影响毒力。3. 在鳗鲡和创伤弧菌中，TtpC在tonb2介导的铁转运和毒力中的功能特征。我们在鳗弧菌、创伤弧菌和霍乱弧菌中发现了tonB2上游的一个基因，该基因编码tonB2介导的铁运输所必需的新蛋白。我们将对这种蛋白TtpC进行表征，以了解其在鳗弧菌和创伤弧菌铁转运和毒力中的作用。

DESCRIPTION (provided by applicant): The long-term goal of our research is to dissect the mechanism of iron uptake and the regulation of its expression in the pathogens Vibrio anguillarum and V. vulnificus. In the fish pathogen V. anguillarum the pJM1 mediated iron uptake system plays an essential role in systemic infection. This system is an excellent model due to its striking similarities to human septicemic diseases, such as those caused by V. vulnificus in iron-overloaded patients. Even under these high iron conditions, there are iron-limiting niches at which iron limitation-induced genes play a vital role in virulence. In this competitive renewal we will complete the analysis of the regulation of the plasmid-mediated iron uptake genes of V. anguillarum and dissect the mechanism of iron transport in V. anguillarum and V. vulnificus. We have previously characterized the essential components of the V. anguillarum iron uptake system: the siderophore anguibactin and the proteins and regulatory elements controlling its synthesis and transport. We also characterized iron-regulated genes crucial to the virulence of V. vulnificus. We propose: 1. Mechanism of regulation of the ITB operon by AngR and RNAb. AngR is a bifunctional protein that intervenes in anguibactin biosynthesis and acts in the regulation of expression of the iron transport-biosynthesis (ITB) operon. We intend to: a) complete the analysis of the regulatory domains of AngR and b) characterize the structure-function of RNAb in the regulating transcription within the ITB operon. 2. Molecular characterization of the mechanisms of TonB2- mediated iron transport and virulence in V. anguillarum. Of the two tonB systems available to transduce the energy of the proton motive force of the cytoplasmic membrane of V. anguillarum, only the tonB2 system is required for virulence. Since we recently solved the structure of the TonB2 protein, we intend to identify residues important for the TonB2 recognition of the FatA outer membrane receptor and to identify how specific mutations in FatA affect virulence. 3. Characterization of the TtpC function in the TonB2-mediated iron transport and virulence in V. anguillarum and V. vulnificus. We identified a gene upstream of tonB2 in V. anguillarum, V. vulnificus, and V. cholerae that encodes a novel protein essential for tonB2-mediated iron transport. We will characterize this protein, TtpC, to understand its role in iron transport and virulence of V. anguillarum and V. vulnificus.