The Outer Surface of Vibrio cholerae

描述（由申请人提供）：细菌细胞被膜是一种显著而复杂的结构，可保护细菌免受周围环境的影响。革兰氏阴性菌的一个定义特征是存在包封这些生物体的肽聚糖层的外膜。虽然内膜由甘油磷脂组成，但外膜是一种独特的不对称双层，甘油磷脂局限于内小叶，脂质A是一种独特的糖脂，局限于外小叶。脂质A是LPS的脂质部分并将LPS锚定到细菌表面。细菌已经进化出各种机制来适应其不可预测且通常敌对的环境，包括重塑其膜结构的策略。通常，这些修饰提供对哺乳动物先天免疫系统组分的抗性，并调节宿主对入侵微生物的识别。LPS的脂质A结构域对人是有毒的，并且通过TLR 4-MD 2的识别而有效刺激先天免疫系统。许多革兰氏阴性病原体改变其脂质A结构以逃避宿主检测。此外，脂质A和甘油磷脂的结构改变可以直接影响细菌对先天免疫效应物如宿主抗微生物肽的抗性。 本提案的总体目标是阐明霍乱弧菌（霍乱的病原体）重塑其膜结构的分子机制以及这种重塑在毒力中的作用。本发明的具体目的是：（1）促进抗微生物肽抗性的霍乱弧菌LPS修饰的生物化学和遗传分析;（2）参与向霍乱弧菌LPS添加磷酸甘油部分的酶的表征;（3）阐明霍乱弧菌中磷脂重塑所需的机制;以及（4）霍乱弧菌膜重塑对宿主天然免疫应答的影响。这些目标的完成将直接有助于我们了解脂质重塑/修饰机制如何影响发病机制。最后，从这项工作中不仅可以更好地了解霍乱疾病，而且还可以为疫苗开发提供新的途径，并能够产生可作为潜在佐剂和/或LPS拮抗剂的工程LPS结构。

DESCRIPTION (provided by applicant): The bacterial cell envelope is a remarkable and complex structure that guards bacteria from their surrounding environment. A defining feature of Gram-negative bacteria is the presence of an outer membrane that encapsulates the peptidoglycan layer of these organisms. While the inner membrane is composed of glycerophospholipids, the outer membrane is a unique, asymmetric bilayer with glycerophospholipids confined to the inner leaflet and lipid A, a unique saccharolipid, localized to the outer leaflet. Lipid A is the lipid moiety of LPS and anchors LPS to the bacterial surface. Bacteria have evolved various mechanisms to adapt to their unpredictable and often hostile surroundings, including strategies for remodeling their membrane architecture. Often these modifications provide resistance to components of the mammalian innate immune system and modulate host recognition of the invading microorganism. The lipid A domain of LPS is toxic to humans and potent stimulator of the innate immune system through via recognition by TLR4-MD2. A number of Gram-negative pathogens modify their lipid A structure to evade host detection. Additionally, structural alteration of lipid A and glycerophospholipids can directly impact bacterial resistance to innate immune effectors such as host antimicrobial peptides. The overall objective of this proposal is to unravel the molecular mechanisms by which Vibrio cholerae, the causative agent of the disease cholera, remodels it membrane architecture and the role this remodeling plays in virulence. The specific aims of the current proposal are: (1) biochemical and genetic analysis of V. cholerae LPS modifications promoting antimicrobial peptide resistance; (2) characterization of enzymes involved in the addition of phosphoglycerol moieties to V. cholerae LPS; (3) elucidation of machinery required for phospholipid remodeling in V. cholerae; and (4) impact of V. cholerae membrane remodeling on the host innate immune response. The completion of these Aims will directly contribute to our understanding of how lipid remodeling/modification machinery impacts pathogenesis. Finally, from this work will come not only a better understanding of the disease cholera, but new avenues for vaccine development and the ability to generate engineered LPS structures that could serve as potential adjuvants and/or LPS antagonists.