Modification of Helicobacter pylori Lipid A

幽门螺杆菌脂质 A 的修饰

• 批准号: 6570247
• 负责人: Michael Stephen Trent
• 金额: $ 15.97万
• 依托单位: EAST TENNESSEE STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2005-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6570247
• 关键词: Helicobacter; acylation; bacteria infection mechanism; bacterial DNA; bacterial genetics; endotoxins; enzyme activity; enzyme structure; functional /structural genomics; lipase; lipid biosynthesis; lipid structure; lipopolysaccharides; mass spectrometry; molecular cloning; nuclear magnetic resonance spectroscopy; plasmids; polymerase chain reaction; protein purification

DESCRIPTION (provided by applicant): The outer membrane of Gram-negative bacteria consists of a unique molecule known as lipid A that serves as the membrane anchor for lipopolysaccharide (LPS). Lipid A (endotoxin) is the component of LPS responsible for the stimulation of the host innate immune system involved in Gram- negative sepsis. The lipid A of Escherchia coli is a hexa-acylated disaccharide of glucosamine that is substituted at the 1- and 4'- positions with phosphate and glycosylated at the 6' position with two Kdo (3-deoxy-D-manno-octulosonic acid) moieties. Nine enzymes are required for biosynthesis of Kdo2- lipid A, the minimal LPS required for E. coli growth under normal laboratory conditions. Since lipid A is required for bacterial growth, it has become an interesting target for the design of novel antibacterial agents. Although single copies of the lipid A biosynthetic genes are found in nearly all Gram-negative bacterial genomes including those of Helicobacter pylori, the lipid A of the latter is underacylated with the phosphate groups either absent or modified. The primary focus of the present study is the identification of novel enzymes required for the modification of H. plyori lipid A and initial studies to evaluate the importance of such modifications during infection. Secondly, the lipid A structure of Helicobacter heilmannii will be investigated. H. pylori is now considered the causative agent of gastric and duodenal ulcers and H. heilmannii has recently been found associated with human gastritis. The specific aims of the current proposal are: (I) characterization and cloning of lipid A deacylases of H. pylori; (II) characterization and cloning of genes required for modification of the phosphates of H. pylori lipid A; (III) relevance of H. pylori lipid A modifications during infection; and (IV) isolation, purification, and structural characterization of key lipid A species of H. heilmannii. The completion of these aims will not only further the understanding of the lipid A biosynthetic pathway in H. pylori and H. heihnannii but also lay the foundation for new molecular insights into the pathogenesis of these unique organisms.

描述（由申请人提供）：革兰氏阴性细菌的外膜由一种被称为脂质A的独特分子组成，该分子用作脂多糖（LPS）的膜锚。脂质A（内毒素）是负责刺激涉及革兰氏阴性败血症的宿主先天免疫系统的LP的组成部分。大肠杆菌的脂质A是葡萄糖的六酰化二糖，在1和4'-位置用磷酸盐和4'-位置取代，并用两个KDO（3-二氧基 - 曼诺 - 辛托旋转剂）在6'位置进行糖基化。 KDO2-脂质A的生物合成需要9种酶，这是正常实验室条件下大肠杆菌生长所需的最小LPS。由于细菌生长需要脂质A，因此它已成为新型抗菌剂设计的有趣靶标。 尽管在几乎所有革兰氏阴性细菌基因组中都发现了脂质A生物合成基因的单个副本，包括幽门螺杆菌的幽门螺杆菌的基因，但后者的脂质a的磷酸基团不足或没有修饰。本研究的主要重点是鉴定了修饰h. plyori脂质A和初步研究所需的新型酶，以评估感染过程中这种修饰的重要性。其次，将研究脂质的螺旋杆菌结构。幽门螺杆菌现在被认为是胃溃疡和十二指肠溃疡的病因，最近发现Heilmannii与人类胃炎有关。当前建议的具体目的是：（i）脂质雌性雌性脂的表征和克隆； （ii）修饰幽门螺杆菌A磷酸盐所需的基因的表征和克隆； （iii）感染过程中幽门螺杆菌脂质A修饰的相关性； （iv）关键脂质的孤立，纯化和结构表征Ah。Heilmannii物种。这些目标的完成不仅将进一步理解幽门螺杆菌和H. heihnannii中的脂质A生物合成途径，而且还为对这些独特生物的发病机理的新分子见解奠定了基础。