Genetic System to Study Virulence in Bacteroides

研究拟杆菌毒力的遗传系统

• 批准号: 6573715
• 负责人: MICHAEL H MALAMY
• 金额: $ 38.97万
• 依托单位: TUFTS UNIVERSITY BOSTON
• 依托单位国家: 美国
• 财政年份: 1983
• 资助国家: 美国
• 起止时间: 1983-01-01 至 2004-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6573715
• 关键词: Bacteroides; anaerobic bacteria; bacteria infection mechanism; bacterial cytopathogenic effect; bacterial genetics; biological transport; cytoplasm; environmental adaptation; exo alpha sialidase; free radical oxygen; glucosamine; granuloma; iron metabolism; laboratory rat; microorganism growth; operon; oxygen; penicillins; periplasm; permease; porphyrin metabolism; sialate; superoxide dismutase; virulence

DESCRIPTION (provided by applicant): This study will focus on factors that allow the obligate anaerobe B.fragilis, although a component of the normal colonic microbiota, to be a successful pathogen. These include its ability to withstand an aerobic environment (aero-tolerance) during early stages of infection; the presence of systems to import heme into the cell for the heme-dependent pathways of central metabolism and defense against reactive oxygen species; the ability of B.fragilis to remove sialic acid residues from host components, and its virtuosity in obtaining nutrients for growth in vivo from complex oligosaccharides and glycoproteins. Specific aims include: 1, to continue to study factors that allow B.fragilis to withstand prolonged oxygen challenge (aerotolerance): We propose that activities in the B.fragilis periplasm serve as the initial line of defense to combat the formation of reactive oxygen species (ROS), protect sensitive targets from ROS challenges and to reverse ROS damage. In addition we have identified specific functions (superoxide dismutase, SOD), and an extensive gene cluster (the Bat operon) that are required for aerotolerance. We will test the hypothesis that the Bat operon plays an important role in exporting reducing potential from the cytoplasm to the periplasm. 2. Acquisition of iron and heme is important for B.fragilis growth in vitro and in vivo. We will study the process of heme uptake in B.fragilis by the heme permease systems whose genes and functions we have described. We will also continue to study the heme-dependent, and Fe-S cluster-containing enzymes in the dual pathways of central metabolism to establish their roles in aerotolerance and in providing energy during oxygen challenge. 3. to investigate the composition, functions and control of operons for the acquisition of growth substrates from the infected host. We will focus on the operon containing the neuraminidase (nanH1) gene and several other glycohydrolases capable of converting the complex Lewis antigen found on the surface of many human cells to individual monosaccharides. We will continue to define the operon for NANA utilization, the NanL1 operon. Is neuraminidase a virulence factor because it supplies NANA for B.fragilis growth, or because its activity alters the surface of host cells during infection, or both? 4.We will develop additional tools to define changes in macromolecular synthesis and stability of DNA, proteins and membranes during 9 oxygen challenge.

描述（由申请人提供）：本研究将集中于允许易厌食症B. fragilis的因素，尽管正常结肠微生物群的组成部分是成功的病原体。其中包括其在感染的早期阶段承受有氧环境（空气耐受性）的能力；在中枢代谢和防御活性氧的防御途径的血红素依赖性途径中，系统的存在将血红素导入细胞中； B. fragilis从宿主成分中去除唾液酸残基的能力，以及从复杂的寡糖和糖蛋白中获得体内生长的养分的特殊性。具体目的包括：1，继续研究允许B. fragilis承受延长的氧气​​挑战（Aerotolerance）的因素：我们提出，B.Fragilis Periplasm中的活动是最初的防御线，以应对反应性氧物种（ROS）的形成（ROS），从而保护敏感靶标，从ROS挑战和反向ROS损坏。此外，我们还确定了碳化性所需的特定功能（超氧化物歧化酶，SOD）和广泛的基因簇（蝙蝠操纵子）。我们将检验以下假设：蝙蝠操纵子在将细胞质的降低潜力降低到周期中起着重要作用。 2。铁和血红素的获取对于体外和体内的B. fragilis生长很重要。我们将通过我们描述的基因和功能的血红素渗透酶系统中研究血红素摄取的过程。 我们还将继续研究中央代谢双重途径中的血红素依赖性和含有Fe-S簇的酶，以确立它们在氧化质量和氧气挑战期间提供能量的作用。 3。研究操纵子的组成，功能和控制，以从受感染的宿主那里获取生长底物。我们将重点关注含有神经氨酸酶（NANH1）基因的操纵子以及能够转化许多人类细胞表面上发现的复杂刘易斯抗原的其他几种糖含量酶，从而将其转化为单个单糖。 我们将继续定义NANA利用率的操纵子NANL1操纵子。神经氨酸酶是毒力因子是因为它为fragilis生长提供了NANA，还是由于其活性在感染过程中改变了宿主细胞的表面，还是两者兼而有之？ 4.我们将开发其他工具来定义9氧气挑战期间DNA，蛋白质和膜的大分子合成和稳定性的变化。