Rhizobial Lipopolysaccharides Essential for Infection

感染必需的根瘤菌脂多糖

• 批准号: 6730568
• 负责人: RUSSELL W CARLSON
• 金额: $ 26.94万
• 依托单位: UNIVERSITY OF GEORGIA
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-06-01 至 2006-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6730568
• 关键词: Leguminoseae; Rhizobiaceae; bacteria infection mechanism; carbohydrate structure; chemical structure function; lipid biosynthesis; lipopolysaccharides; mutant; symbiosis; Leguminoseae; Rhizobiaceae; bacteria infection mechanism; carbohydrate structure; chemical structure function; lipid biosynthesis; lipopolysaccharides; mutant; symbiosis

DESCRIPTION (provided by applicant): Rhizobia are Gram-negative soil bacteria that form nitrogen-fixing symbioses with legumes. A specific rhizobial species recognizes and infects a specific host plant. Rhizobial cell surface lipopolysaccharides (LPSs) are important for endocytotic invasion of host root nodule cells and differentiation into nitrogen-fixing bacteroids within a host-derived intracellular compartment known as the symbiosome. The symbiosome membrane is derived from the Golgi and endoplasmic reticulum of the host cell and is both acidic and low in O2. Rhizobial symbionts are analogous to animal bacterial pathogens that survive in phagosome-derived intracellular compartments and cause chronic infections; e.g. Brucella. The LPSs from members of the Rhizobiaceae have a very long chain lipid-A fatty acid, 27-OHC28:0, (as does the pathogen, Brucella abortus). Also, LPSs from R. etli (Re) (a bean symbiont) and from R. leguminosarum bv. vicae (Rlv) (a pea symbiont) have unique lipid-A, and core oligosaccharide; e.g. they are devoid of phosphate and contain galacturonic acid. During symbiosis, modifications are made to the O-chain polysaccharide (e.g. methylation) and lipid-A. In the case of Rlv, both LPS and the entire bacterium become hydrophobic. This increase in hydrophobicity is due primarily to a doubling of the lipid-A 27-OHC28:0 moiety. It is proposed that the LPS O-chain modifications are required for adherence of the bacterium to the host membrane, and that the 27-OHC28:0 moiety is required to maintain membrane stability during endocytosis and symbiosome formation. The aims of this proposal are to structurally characterize the O-chain modifications, and to determine the functions of the Re and Rlv unique structural features with regard to both symbiosis and LPS biosynthesis. This will be accomplished through the creation and analysis of Re and Rlv mutants that are specifically altered in these unique structural features (e.g. defective in 27-OHC28:0 incorporation), and by the isolation and characterization of LPS fragments that bind to specific monoclonal antibodies whose LPS epitopes change during symbiosis.

描述（由申请人提供）：根瘤菌是革兰氏阴性菌 这种形成了固定氮与豆类的共生。特定的根瘤菌 识别并感染特定的宿主植物。根瘤细胞表面 脂多糖（LPSS）对于宿主根的内吞侵袭很重要 结节细胞并分化为固定固定菌类细菌 宿主衍生的细胞内室被称为共生室。共生 膜源自宿主细胞的高尔基体和内质网 并且在O2中既酸性又低。根瘤菌共生体类似于动物 在吞噬体衍生的细胞内生存的细菌病原体 车厢并引起慢性感染；例如布鲁氏菌。会员的LPSS Rhizobiaceae的长链脂质-A脂肪酸，27-OHC28：0，（AS 病原体是布鲁氏菌堕胎）。另外，来自R. etli（re）的LPS（豆 Symbiont）和R. leguminosarum bv。 vicae（rlv）（豌豆共生体） 独特的脂质-A和核心寡糖；例如它们没有磷酸盐和 含有半乳酸酸。在共生期间，对 O链多糖（例如甲基化）和脂质-A。在RLV的情况下 LPS和整个细菌变为疏水。这增加了 疏水性主要是由于脂质A 27-OHC28：0部分的加倍。 建议遵守LPS O-chain修改 宿主膜的细菌，需要27-OHC28：0部分 在内吞作用和共生形成期间保持膜稳定性。这 该建议的目的是在结构上表征O链 修改并确定RE和RLV唯一的功能 关于共生和LP的生物合成的结构特征。这 将通过对RE和RLV突变体的创建和分析来完成 这些在这些独特的结构特征（例如 在27-OHC28：0融合中有缺陷），并通过隔离和 与特定单克隆抗体结合的LPS片段的表征 在共生期间，其LPS的表现会发生变化。