LIPID A MODIFICATION SYSTEMS IN GRAM-NEGATIVE BACTERIA

革兰氏阴性细菌中的脂质 A 修饰系统

• 批准号: 7253418
• 负责人: Christian R Raetz
• 金额: $ 36.51万
• 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/7253418
• 关键词: Acyl Carrier Protein; Acyltransferase; Adjuvant; Anabolism; Animals; Appearance; Bacteria; Biochemical; Carbon; Chemical Structure; Clinical; Cloning; Cosmids; DNA; Development; Disaccharides; Endotoxins; Enteral; Enzymes; Epitopes; Escherichia coli; Facility Construction Funding Category; Fatty Acids; Figs - dietary; Genes; Genetic; Genomics; Glucosamine; Glycolipids; Gram-Negative Bacteria; Grant; Growth; Haemophilus influenzae; Helicobacter pylori; Human; Hybrids; Infection; Laboratories; Lead; Legionella pneumophila; Life; Lipid A; Lipids; Lipopolysaccharides; Minor; Modification; Monosaccharides; Nitrogen; Nodule; O Antigens; Organism; Pathogenesis; Pathway interactions; Phosphatidylinositols; Phosphoric Monoester Hydrolases; Phosphotransferases; Plants; Play; Porphyromonas gingivalis; Positioning Attribute; Reaction; Reagent; Reporting; Rhizobium; Role; Salmonella typhimurium; Sepsis; Staging; Standards of Weights and Measures; Structure; Structure-Activity Relationship; Surface; Symbiosis; System; Techniques; Transferase; analog; base; enzyme activity; galacturonic acid; genetic analysis; glycosyltransferase; inorganic phosphate; insight; interest; lipid A 4' -phosphatase; mutant; novel; pathogen; sugar

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.

脂多糖（LPSS）是杰出的糖脂，包括革兰氏阴性的外表面 细菌，包括共生生物，根瘤菌。在大肠杆菌中，脂质的锚 LPS的葡萄糖是葡萄糖的二糖，在1和4'位置含有磷酸盐部分。这 大肠杆菌生长所需的最小LP由脂质A和两种额外的糖组成。新兴基因组 序列表明使大肠杆菌中脂质A的酶中存在 细菌。脂质A（通常称为内毒素）也是负责临床的LP的活性成分 革兰氏阴性败血症的并发症。脂质A结构中的微小修饰可以具有深刻的 对发病机理的影响。某些脂质A类似物实际上是有效的内毒素拮抗剂。 与大肠杆菌相比，脂质A和核心域的化学结构是/？ 非常不寻常。 R.豆类脂质A缺乏1和4磷酸盐，但用半乳糖酸在 位置4'。它用特殊的28碳脂肪酸酰化，并在适当的 近端葡萄糖胺。 /？，豆科氏菌的结构表明存在新酶 用于产生多种脂质A和核心物种。现在确定脂质A的前七个酶 我的生物合成实际上在大肠杆菌和 /？中是相同的。豆类。差异在后期 路径。迄今为止，被识别为 /？独有的酶。豆科植物包括一个4'-磷酸酶，也是一个 磷酸转移酶，一种1-磷酸酶，一种具有自己的酰基载体蛋白的长链酰基转移酶，三个 独特的核心糖基转移酶。 /？的特征。豆类系统应提供见解 进入脂质A样分子的功能，包括植物中共生期间的特殊作用，并提供 创建可能具有有趣的辅助或对手活动的新型脂质的杂种。一些 在人类病原体中可以看到/？，豆科脂脂A的结构特征。军团肺脂脂a 我包含一个C28链，而卟啉单胞菌和幽门螺杆菌脂质缺乏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;和iv） 我表征了包含/？的独特内核糖的酶。