IRON UPTAKE AS A VIRULENCE FACTOR IN PATHOGENIC VIBRIOS

这项研究的长期目标是研究遗传学和 质粒介导铁的毒性相关特性的分子生物学 摄取，这在许多侵袭性疾病的发病机制中起着重要作用。 人类和家畜的败血症疾病。 我们目前使用的是 一个模型系统，鱼类病原体鳗弧菌，导致终端 出血性败血症 质粒介导的毒力特性 决定簇使其成为研究宿主细菌的一个非常有吸引力的模型 互动。 我们已经使用转座诱变，分子克隆， DNA测序以确定pJM 1的至少四个组分 质粒介导的铁摄取系统：铁载体;铁受体 铁-铁载体复合物，即86 kd外膜蛋白OM 2; a 调节性反式作用因子和RSV 1重复序列，其侧翼为 pJM 1质粒中的铁摄取区。 每个人的具体角色 这四种成分在铁吸收过程的调节中起作用， 在鳗弧菌中的毒力将通过提出的 调查 实现这些目标的具体目标是：1。 鳗弧菌铁载体的分离与结构测定。 2.克隆的pJM 1铁摄取区域的互补分析。 3. 克隆的OM 2蛋白基因的表征。 4.克隆及 表征的反式作用的调节因子，提高了 铁载体活性的产生。 5.调查非法贩运的性质 增加的铁载体生产和V的高铁吸收能力。 鳗分离物及其与鳗串联重复的关系 的两个重复序列侧翼的pJM 1铁吸收区。 被鉴定为IS 1样元件的重复序列，位于铁摄取的侧翼 另一种在人类中发现的毒力相关质粒pCo 1V-K30的区域 大肠杆菌入侵菌株。 铁吸收基因在 侧翼为重复序列的区域似乎非常保守， pCo 1V-K30和pJM 1质粒，以及其它质粒， 染色体 这些重复序列的存在 毒力决定因素可能有助于它们的重组 迁移率 因此，该项目不仅将阐明铁的作用， 在侵袭性细菌疾病的发病机制中， 有助于了解这些毒力的机制， 这些因素在自然界中以流行病学的方式传播。

The long term objective of this research is to investigate the genetics and molecular biology of a virulence-associated property, plasmid-mediated iron uptake, which plays an important role in the pathogenesis of many invasive septicemic diseases of man and domestic animals. We are presently using as a model system the fish pathogen Vibrio anguillarum which causes a terminal hemorrhagic septicemia. The features of the plasmid-mediated virulence determinant makes it a very attactive model to study host bacterial interacions. We have used transposition mutagenesis, molecular cloning and DNA sequencing to define at least four components of the pJM1 plasmid-mediated iron uptake system: a siderophore; a receptor for iron-siderophore complexes which is the 86 kd outer membrane protein OM2; a regulatory trans-acting factor and RSV1 repeated sequences that flank the iron uptake region in the pJM1 plasmid. The specific roles that each of these four components play in the regulation of the iron uptake process and virulence in V. anguillarum will be elucidated by the proposed investigation. The specific aims to achieve these objectives are: 1. Isolation and structure determination of the V. anguillarum siderophore. 2. Complementation analysis of cloned pJM1 iron uptake regions. 3. Characterization of the cloned OM2 protein gene. 4. Cloning and characterization of the trans-acting regulatory factor that enhances the production of siderophore activity. 5. Investigation of the nature of the increased siderophore production and high iron uptake proficiency of a V. anguillarum isolate and its relationship to the tandem duplication of one of the two repeated sequences flanking the pJM1 iron uptake region. Repeated sequences identified as IS1-like elements, flank the iron uptake region of another virulence associated plasmid, pCo1V-K30, found in human invasive strins of Escherichia coli. The iron uptake genes within the region flanked by the repeated sequences appeared to be very conserved in both the pCo1V-K30 and the pJM1 plasmids, as well as in other plasmids and chromosomes. The existence of the repeated sequences bracketing these virulence determinants may have contributed to their recombinational mobility. Thus, this project will not only elucidate the role of iron uptake in the pathogenesis of invasive bacterial disease, but will also contribute to the understanding of the mechanisms by which these virulence factors have spread epidemiologically in nature.