Genetic Systems to Study Virulence in Bacteroides

研究拟杆菌毒力的遗传系统

• 批准号: 6889578
• 负责人: MICHAEL H MALAMY
• 金额: $ 39.82万
• 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 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6889578
• 关键词: Bacteroides; anaerobiosis; bacteria infection mechanism; bacterial genetics; bacterial proteins; enzyme activity; enzyme mechanism; exo alpha sialidase; free radical oxygen; gene expression; genetic promoter element; genetic regulation; heme; host organism interaction; iron metabolism; laboratory rat; membrane activity; microorganism growth; northern blottings; operon; protein metabolism; protein transport; reporter genes; tissue /cell culture; transposon /insertion element; virulence

DESCRIPTION (provided by applicant): This study will focus on factors that allow the obligate anaerobe Bacteroides 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 forms a multi-protein complex in the cell membrane that 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 analyze the operon for NANA utilization, the NanLET operon and to define the sites in the three NanR repressed promoters for NanR binding. We will determine if neuraminidase is a virulence factor because it supplies NANA for growth, or because its activity alters the surface of host cells, or both.

描述（由申请人提供）：本研究将集中在允许易厌食菌菌的脆弱性脆弱的因素上，尽管正常结肠微生物群的成分可以成为成功的病原体。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；脆弱芽孢杆菌从宿主成分中去除唾液酸残基的能力及其在从复杂的寡糖和糖蛋白中获得体内生长的养分的精炼。具体目的包括：1，继续研究允许B. fragilis承受长时间的氧挑战（Aerotolerance）的因素：我们建议在脆弱的B. fragilis Periplasm中作为最初的防御线，以应对反应性氧物种的形成（ROS），保护敏感靶标（ROS挑战）免受ROS挑战和反向ROS损害。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：蝙蝠操纵子在细胞膜中形成多蛋白质复合物，该络合物在将细胞质的降低潜力中的降低潜力中起着重要作用。 2。铁和血红素的获取对于体外和体内的脆弱芽孢杆菌生长很重要。我们将通过血红素渗透酶系统研究血红素份的血红素摄取过程，我们所描述的基因和功能我们还将继续研究中心代谢的双重途径中的血红素依赖性和含有Fe-s簇的酶，以在空气稳定性和在氧气中提供能量的作用。 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。我们将继续分析NANA利用率，Nanlet操纵子的操纵子，并在三个NANR抑制启动子中定义NANR结合的启动子中的位点。我们将确定神经酰胺酶是否是毒力因子，因为它为NANA提供了生长，或者其活性会改变宿主细胞的表面，或两者兼而有之。