Vibrio fischeri as a model of bacterial colonization

许多动物上皮组织被良性的、通常是必需的细菌共生体定殖，例如口腔中的那些以及沿着内衬肠道和呼吸道的细胞的顶端表面的沿着的那些。 这些组织发生在环境和身体之间的界面处，也是许多细菌病原体（例如，流感嗜血杆菌和脑膜炎奈瑟菌）。 在致病性和合作性联合体中，细菌和宿主细胞最常见的通信是通过它们的表面分子的相互作用或通过分泌其他生物活性化合物。 模型之间的共生关系的鱿鱼Euprymna的上皮组织和革兰氏阴性，发光的细菌协会费氏弧菌被利用作为一个系统，通过该系统来表征这些跨域细胞-细胞相互作用，并提供洞察有益的和致病的动物-细菌协会之间的关键差异。最近的研究表明，该系统的脂多糖（LPS），革兰氏阴性菌的主要表面分子和产品负责最显着的哺乳动物对感染性细菌的反应，诱导特定的变化在鱿鱼宿主的细胞生物学和形态学的初始阶段的关系。 此外，宿主对LPS的反应的表征已经揭示了该分子与由共生体输出的蛋白质化合物协同作用。 由这些费氏弧菌衍生因子诱导的宿主细胞“行为”的类型包括：产生粘液以促进易感组织的定殖，以及开始形态发生程序，该程序将宿主组织从未定殖的幼年体的形态特征转变为成熟、成年体联合体的一个特征。 宿主细胞对费氏弧菌的其他几种鉴定的反应也可能受到这些化合物的影响。这个跨学科项目的目标是表征V. fischeri的生物活性分子，特别是LPS和与LPS协同工作的肽，这些肽在鱿鱼-弧菌协会的早期阶段介导宿主组织反应。 本研究的具体目标是：（1）鉴定野生型费氏弧菌LPS和直接来源于共生的LPS的结构，以及鉴定来源于与受损宿主反应相关的特定LPS合成突变体的LPS;（2）确定与LPS协同作用的细菌分子的精确生物化学特性和活性;和（3）确定LPS结构的哪些方面在赋予对宿主抗微生物肽的抗性中起作用。

Many animal epithelial tissues are colonized by benign, often essential, bacterial symbionts, such as those in the oral cavity and along the apical surfaces of the cells lining the intestinal and respiratory tracts. These tissues, which occur at the interface between the environment and the body, are also the sites of infection by many bacterial pathogens (e.g., Haemophilus influenzae and Neisseria meningitidis). In both pathogenic and cooperative associations the bacteria and host cells communicate most commonly through interactions of their surface molecules or through the secretion of other bioactive compounds. The model symbiosis between the epithelial tissues of the squid Euprymna scolopes and its Gram-negative, luminous bacterial associate Vibrio fischeri is being exploited as a system by which to characterize these cross-Domain cell-cell interactions and to provide insight into the critical differences between beneficial and pathogenic animal-bacterial associations. Recent studies of this system have shown that lipopolysaccharide (LPS), the principal surface molecule of Gram-negative bacteria and the product responsible for the most dramatic mammalian responses to infective bacteria, induces specific changes in the squid host's cell biology and morphology during the initial stages of the relationship. In addition, characterization of host responses to LPS has revealed that this molecule works synergistically with proteinaceous compounds exported by the symbiont. The types of host cell 'behaviors' induced by these V. fischeri-derived factors include: the production of mucus to facilitate colonization of susceptible tissues, and the onset of a morphogenetic program that transforms host tissues from a morphology characteristic of the uncolonized juvenile to one characteristic of the mature, adult association. Several other identified responses of host cells to V. fischeri may also be affected by these compounds. The goal of this interdisciplinary project is to characterize bioactive molecules of V. fischeri, specifically LPS and the peptides that work in concert with LPS, that mediate host tissue responses during the early phases of the squid-vibrio association. The specific aims of this proposal are to: (1) characterize the structures of wild-type V. fischeri LPS and the LPS derived directly from the symbiosis, as well as characterize LPS derived from specific LPS-synthesis mutants that are associated with compromised host responses; (2) determine the precise biochemical identity and activity of bacterial molecules that act synergistically with LPS; and, (3) determine what aspects of LPS structure play a role in conferring resistance to host antimicrobial peptides.