Evolutionary Conservation of Interacting Effector Complexes in P. Syringae

描述（由申请人提供）：细菌采用多种机制与真核宿主定殖并共存。许多共生细菌和致病菌相互作用的基础是多种效应物通过三型分泌系统（TTSS）易位进入真核细胞环境。动物和植物相关微生物之间的TTSS的保存突出了这种结构对跨界传递效应物的重要性。然而，菌株内效应物套件的多样化和进化决定了与宿主相互作用的性质和特异性。最近的研究表明，一株细菌可以含有多达30种效应因子，而这些毒力因子的组成在同一物种的分离株之间可能有很大差异。尽管效应器在建立人类病原体沙门氏菌和耶尔森菌以及植物病原体丁香假单胞菌的成功感染方面具有重要意义，但在菌株中形成效应器组合的进化力量尚未得到很好的理解。效应器是否通常相互独立作用而引起毒力，或者致病机制是宿主内效应器群之间复杂相互作用的结果？本提案的目的是了解是否和如何对效应相互作用，以促进感染假单胞菌的丁香。进化分析将用于确定在丁香假单胞菌不同病原之间相互关联的效应物。此外，将通过使用寡核苷酸微阵列对遗传和地理上不同的分离物进行广泛采样，确定一种病原体中效应库的保守和可变部分。效应物存在的相关性通过病原体内部和之间的进化时间表明，这些效应物在宿主内相互作用引起感染。一旦确定了可能相互作用的效应物对，将创建含有单突变体和双突变体的菌株，以便在宿主感染期间对毒力的影响进行功能测试。与公共卫生相关：在许多细菌感染期间，如人类病原体沙门氏菌和耶尔森氏菌，疾病的发展完全依赖于利用效应蛋白从细菌到宿主的易位的保守机制。本研究计划的目标是利用植物病原体丁香假单胞菌的进化分析来识别在宿主内潜在相互作用的效应物对，并在感染期间功能性地验证这些相互作用。因此，这项研究将更好地了解促进细菌物种内部和物种之间效应物多样性的进化力量，从而了解人类和植物宿主内的毒力。

DESCRIPTION (provided by applicant): Bacteria employ diverse mechanisms to colonize and co-exist with their eukaryotic hosts. The basis of interaction for many symbiotic and pathogenic bacteria is translocation of multiple effectors into the eukaryotic cellular environment via a type three secretion system (TTSS). Conservation of the TTSS between animal and plant associated microbes highlights the importance of this structure for delivery of effectors across kingdoms. However, it is diversification and evolution of suites of effectors within strains that determines the nature and specificity of interactions with a host. Recent efforts have shown that single strains of bacteria can contain up to 30 effectors, and that the composition of these virulence factors can differ dramatically between isolates of the same species. Despite the importance of effectors in establishing successful infection for human pathogens Salmonella and Yersinia as well as the plant pathogen Pseudomonas syringae, the evolutionary forces that shape the composition of suites of effectors within strains are not well understood. Do effectors generally act independently of one another to cause virulence, or is pathogenesis the outcome of complex interactions between groups of effectors within a host? The goal of this proposal is to understand if and how pairs of effectors interact to promote infection in Pseudomonas syringae. Evolutionary analyses will be used to identify effectors that co-associate with one another between different pathovars of P. syringae. Furthermore, conserved and variable portions of the effector repertoire within one pathovar will be identified through extensive sampling of genetically and geographically diverse isolates using oligonucleotide micro-arrays. Correlation in the presence of effectors through evolutionary time within and between pathovars implies that these effectors interact within the host to cause infection. Once potentially interacting pairs of effectors have been identified, strains containing single and double mutants will be created in order to functionally test for effects on virulence during infection of a host. Relevance To Public Health: Development of disease during infection by many bacteria, such as the human pathogens Salmonella and Yersinia, is entirely dependent on a conserved mechanism employing the translocation of effector proteins from bacterium to host. The goals of this research program are to use evolutionary analyses with the plant pathogen Pseudomonas syringae to identify pairs of effectors that potentially interact within the host and to functionally verify these interactions during infection. This research will therefore provide a greater understanding of the evolutionary forces promoting diversity in suites of effectors within and between bacterial species, and thus virulence within both human and plant hosts.