BIOSYNTHESIS OF MEMBRANE GLYCOLIPIDS IN RHIZOBIUM

根瘤菌膜糖脂的生物合成

• 批准号: 6910801
• 负责人: Christian R Raetz
• 金额: $ 38.5万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6910801
• 关键词: BIOSYNTHESIS; MEMBRANE; GLYCOLIPIDS; RHIZOBIUM

BB Principal Investigator/Program Director (Last, first, Middle)- Raetz, Christian R.H. DESCRIPTION. State the application's broad, long-term objectives and specific aims, making reference to the health relatedness of the project. Describe concisely the researchdesign and methods for achieving thejMpals. Avoid summaries of past accomplishments and^kpf the first person. This description is meant to serve as a succinct and accurate description of th|^ftposed work when seperated from the application. If^Bpplication is funded, this description, as is, will become public information. Therefore,do not includS^oprietary/confidential information. DONOTEXCEED"MRPACE PROVIDED. Lipopolysaccharides (LPSs) are remarkable glycolipids that comprise the outer surfaces of Gram-negative bacteria, including the symbiotic organism, Rhizobium leguminosamm. In Escherichia coli, the lipid A anchor of LPS is a hexa-acylated disaccharide of glucosamine, bearing phosphate moieties at positions 1 and 4'. The minimal LPS required for growth of E. coli consists of lipid A and two extra sugars. Emerging genomic sequences indicate that the enzymes that make lipid A in E. coli are present in most other Gram-negative bacteria. Lipid A (often termed endotoxin) is also the active component of LPS responsible for the clinical complications of Gram-negative sepsis. Minor modifications in the structure of lipid A can have profound effects on pathogenesis. Some lipid A analogs are actually potent endotoxin antagonists. Compared to E. coli, the chemical structures of the lipid A and core domains of/?, leguminosarum LPS are very unusual. R. leguminosarum lipid A lacks the 1 and 4' phosphates, but is modified with galacturonic acid at position 4'. It is acylated with a peculiar 28 carbon fatty acid, and contains 2-deoxy-2-aminogluconate in place of the proximal glucosamine. The structure of/?, leguminosarum LPS indicates the existence of novel enzymes for generating diverse lipid A and core species. It is now established that the first seven enzymes of lipid A I biosynthesis are in fact the same in E. coli and /?. leguminosarum. The differences arise in the later stages of the pathway. To date, enzymes identified as unique to /?. leguminosarum include a 4'-phosphatase that is also a phosphotransferase, a 1-phosphatase, a long chain acyltransferase with its own acyl carrier protein, and three distinct core glycosyltransferases. Characterization of the /?. leguminosarum system should provide insights into the functions of lipid A-like molecules, including special roles during symbiosis in plants, and affords the opportunity to create novel lipid A hybrids that may have interesting adjuvant or antagonist activities. Some structural features of/?, leguminosarum lipid A are seen in human pathogens. Legionella pneumophila lipid A i contains a C28 chain, while Porphyromonas gingivalis and Helicobacter pylori lipid A lack the 4' phosphate. | In the coming grant period, the specific aims are: I) cloning of the C28 acyltransferase of/?, leguminosarum; i II) analysis of the lipid A 4'-phosphatase/phosphotransferase, especially its ability to synthesize PtdIns-4-P; III) determination of the enzymatic basis for proximal unit diversity in /?. leguminosarum lipid A; and IV) i characterization of enzymes that incorporate the unique inner core sugars of/?, leguminosarum LPS. PERFORMANCE SITE ========================================Section End===========================================

BB首席调查员/计划主管（最后，第一，中间） - 雷茨，克里斯蒂安·R·H·描述。陈述该应用程序的广泛，长期目标和具体目标，以参考项目的健康相关性。简单地描述实现jmpals的研究设计和方法。避免摘要过去的成就和^kpf第一人称。此描述旨在作为与应用程序分开的简洁而准确的描述。如果^bpplication是资助的，那么此描述将成为公共信息。因此，不包括^oprietary/机密信息。 Donotexceed“提供的MRPACE。脂多糖（LPS）是显着的糖脂，包括革兰氏阴性细菌的外表面，包括共生生物体，根瘤菌，豆科植物。在1和4的位置，大肠杆菌的生长需要脂质A和两个额外的糖，这是在大多数革兰氏阴性菌中的脂质序列中的脂质序列，这是较少的脂肪症与大肠杆菌相比，脂质A的结构可以对某些脂质毒性具有深远的作用。它用特殊的28碳脂肪酸酰化，并含有2-脱氧-2-氨基氨基葡萄糖酸酯代替近端葡萄糖胺。 /？，豆科龙LPS的结构表明存在用于产生多种脂质A和核心物种的新型酶。现在已经确定，脂质A I生物合成的前七个酶实际上在大肠杆菌和 /？中是相同的。豆类。这些差异在路径的后期阶段出现。迄今为止，被识别为 /？独有的酶。豆科植物包括一个4'-磷酸酶，它也是一种磷酸转移酶，一种1-磷酸酶，具有其自身酰基载体蛋白的长链酰基转移酶和三种不同的核心糖基转移酶。 /？的特征。豆科植物系统应提供有关脂质A样分子功能的见解，包括在植物中共生期间的特殊作用，并提供了创建新型脂质A杂种的机会，这些杂种可能具有有趣的辅助或拮抗剂活动。在人类病原体中可以看到/？，豆科脂脂A的一些结构特征。肺炎军团脂质脂质A I I含有C28链，而卟啉单胞菌和幽门螺杆菌幽门螺杆菌脂质A缺乏4磷酸盐。 |在即将到来的赠款期间，具体目标是：i）/？femuminosarum的C28酰基转移酶的克隆； I II）分析脂质A 4'-磷酸酶/磷酸转移酶，尤其是其合成PTDINS-4-P的能力； iii）确定 /？中近端单位多样性的酶基础。豆类脂质A; iv）i表征酶，该酶结合了/？，豆科氏菌lps的独特内核糖。 表演站点=============================================================================================