Characterization of cyclic-GMP-cAMP regulation in Vibrio cholerae

摘要 霍乱弧菌是一种能够引起全球大流行的病原体，包括 科学记录。第七次大流行El Tor生物型取代了经典的 导致前六次大流行的生物型在基因上有许多不同 核苷酸多态与七号弧菌两个大基因岛的获得 大流行岛屿I和II(VSP-I和VSP-II)。VSP-I岛编码11个基因， 包括dncv，它编码一种二核苷酸环化酶，产生环状- GMP-AMP(CGAMP)分子。对感染幼鼠模型的毒力研究揭示 Dncv是VSP-I中唯一的基因，当突变时，具有竞争劣势。 与亲本菌株相比。这为DncV和cGAMP提供了强有力的证据 对致死性很重要。CGAMP如何调节下游途径增强毒力 仍然悬而未决。最近，一项研究发现，VSP-I中的另一个基因称为capV，即 紧邻dncv，编码一种磷脂酶，通过结合激活 CGAMP。这些结果表明，cGAMP通过与细胞内蛋白受体结合而作用于细胞。 在概念上类似于其他环二核苷酸的方式。而CapV的发现 解释了DncV和cGAMP对霍乱弧菌脂代谢的影响，以及 CGAMP对毒力、MSHA表达和趋化性表达的影响尚不清楚。这 建议假设额外的蛋白受体(S)直接与cGAMP结合介导 MSHA的下游调控、趋化作用和发病机制。我们将检验我们的假设 通过使用生化和遗传方法，包括：目标1.识别相互作用 CGAMP和AIM的蛋白质2.cGAMP下调MSHA的特性 歌剧。总之，完成这一目标的结果将揭示cGAMP信号如何 出现在霍乱弧菌中，并揭示了cGAMP和cGMP-di-GMP之间的交点 (C-di-GMP)，霍乱弧菌也使用的另一种环二核苷酸分子。此外, 揭示霍乱弧菌中的信号分子网络将有助于更好地理解 当病原体通过水平基因转移获得cGAMP信号时，它们可以适应。

ABSTRACT Vibrio cholerae is a pathogen capable of causing worldwide pandemics including seven in the scientific record. The seventh pandemic El Tor biotype that displaced the classical biotype responsible for the first six pandemics differ genetically by many single nucleotide polymorphisms and the acquisition of two large genetic islands called Vibrio seventh pandemic islands I and II (VSP-I and VSP-II). The VSP-I island encodes eleven genes, including dncV which encodes a dinucleotide cyclase enzyme that produces the cyclic- GMP-AMP (cGAMP) molecule. Virulence studies in the infant mice model of infection revealed that dncV is the only gene in VSP-I, that when mutated, has a competitive disadvantage compared to the parental strain. This provides strong evidence that DncV and cGAMP is important for virulence. How cGAMP regulated downstream pathways to enhance virulence remained unresolved. Recently, a study revealed that another gene in VSP-I called capV, that is immediately adjacent to dncV, encodes a phospholipase that is activated by binding to cGAMP. These results suggest that cGAMP acts on the cell by binding protein receptors in a manner similar in concept of other cyclic dinucleotides. While the discover of CapV explained the effect of DncV and cGAMP on lipid metabolism in V. cholerae, the effect of cGAMP on virulence, MSHA expression and chemotaxis expression are unexplained. This proposal hypothesizes that additional protein receptor(s) bind directly to cGAMP to mediate downstream regulation of MSHA, chemotaxis and pathogenesis. We will test our hypothesis by using biochemical and genetic approaches including: Aim 1. Identifying interacting proteins of cGAMP and Aim 2. Characterizing cGAMP down regulation of the MSHA operons. Together, results from the completion of this aim will reveal how cGAMP signaling occurs in V. cholerae and shed light on the intersection between cGAMP and cyclic-di-GMP (c-di-GMP), another cyclic dinucleotide molecule also used by V. cholerae. In addition, revealing the network of signaling molecules in V. cholerae will allow better understand of pathogens can adapt when they acquire cGAMP signaling via horizontal gene transfer.