REQUIREMENTS FOR BACTERIAL COLONIZATION OF ANIMAL TISSUE

描述（由申请人提供）：我们研究的长期目标是定义允许细菌与宿主交流的信号，并确定它们对宿主环境做出反应的途径。夏威夷乌贼（Euprymna scolopes）和它的细菌伙伴费氏弧菌（Vibrio fischeri）之间的共生关系，为研究细菌与动物的相互作用提供了一个简单、优雅的模型系统。只有V. fischeri在乌贼中定居。迄今为止的证据表明，费氏弧菌积极参与实现观察到的特异性关联。然而，决定这种特异性的因素尚不清楚。我们已经确定了fischeri弧菌启动共生所需的一组基因（syp，共生多糖位点），以及控制syp转录的非连锁传感器激酶调节因子rscS。提出或已知的另外四种调节因子也控制syp转录，包括a ？54依赖的响应调节器，SypG，和2个额外的2组分调节器。因此，syp由至少3种蛋白质控制，这些蛋白质被预测能够感知和响应环境。特定等位基因（rscS*）的多拷贝表达导致V. fischeri表达与细胞-细胞相互作用改变一致的syp依赖性新表型：在固体复杂培养基上的褶皱菌落和在液体最小培养基上的膜形成。我们建议阐明控制syp转录的主要调控机制，并确定与syp依赖表型相关的其他基因。我们将鉴定由syp位点产生的多糖，并鉴定细胞表面性质的任何差异。最后，我们将更详细地研究syp突变体共生缺陷的本质，并探讨可能的解释。这里提出的实验将扩大我们对定植是如何开始的以及在建立长期关联过程中原核生物和真核生物之间如何发生信号交换的理解。与公共卫生的相关性在于该模型系统揭示细菌与动物宿主相互作用的新机制的潜力。这些信息可能有助于设计新的抗菌剂。我们的研究生物与引起人类胃肠炎的细菌密切相关，包括新兴病原体，副溶血性弧菌和创伤弧菌。研究这一模型也可能导致预防、减少或治疗这类感染的方法。

DESCRIPTION (provided by applicant): The long-term objective of our research is to define signals that allow bacteria to communicate with a host and to identify the pathways by which they respond to the host environment. The symbiotic association between the Hawaiian squid, Euprymna scolopes, and its bacterial partner, Vibrio fischeri, provides a simple, elegant model system for studying bacteria-animal interactions. Only V. fischeri colonizes the squid. The evidence to date suggests that V. fischeri actively participates in achieving the observed specificity of the association. The factors that dictate this specificity, however, are not yet understood. We have identified a cluster of genes (syp, symbiosis polysaccharide locus) that is required for V. fischeri to initiate symbiosis, and an unlinked sensor kinase regulator, rscS, that controls syp transcription. Four additional regulators are proposed or known to also control syp transcription, including a ?54-dependent response regulator, SypG, and 2 additional 2-component regulators. Thus, syp is controlled by at least 3 proteins that are predicted to sense and respond to the environment. Multi-copy expression of a particular allele (rscS*) causes V. fischeri to express syp-dependent novel phenotypes consistent with altered cell-cell interactions: wrinkled colonies on solid complex media and pellicle formation in liquid minimal medium. We propose to elucidate the major regulatory mechanisms controlling syp transcription and identify additional genes associated with syp-dependent phenotypes. We will identify the polysaccharide produced by the syp locus and identify any differences in cell surface properties. Finally, we will examine in more detail the nature of the symbiosis defect of syp mutants and explore possible explanations to account for it. The experiments proposed here will expand our understanding of how colonization is initiated and how signal exchange occurs between a prokaryote and a eukaryote during the establishment of a long-term association. The relevance to public health lies in the potential of this model system to reveal novel mechanisms by which bacteria interact with an animal host. Such information could potentially allow the design of new antimicrobial agents. Our research organism is closely related to bacteria that cause gastroenteritis in humans, including the emerging pathogens, V. parahaemolyticus and V. vulnificus. Studying this model may also lead to approaches that prevent, reduce or treat such infections.