The Mycobacterium Tuberculosis Dormancy Program

结核分枝杆菌休眠计划

基本信息

批准号：
8628025
负责人：
MARTIN Inua VOSKUIL
金额：
$ 37.54万
依托单位：
UNIVERSITY OF COLORADO DENVER
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-06-01 至 2016-02-29
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8628025
关键词：
ATP Synthesis Pathway Aerobic Aerobic Bacteria Anaerobic Bacteria Anti-Bacterial Agents Antibiotics Antimycobacterial Agents Assimilations Bacillus (bacterium)Bacteria Bacterial Infections Biochemical Carbon Carbon Dioxide Carbon Monoxide Catabolism Categories Cavia Cell Respiration Cessation of life Citric Acid Cycle Data Dendritic Cells Disease Outbreaks Drug Combinations Drug Design Electron Transport Energy-Generating Resources Environment Enzymes Equilibrium Evolution Exhibits Gene Expression Genes Goals Granuloma Growth Human Humanities Hypoxia Immigration Infection Lesion Lipids Lung Metabolic Metabolic Pathway Metabolism Modeling Mycobacterium tuberculosis Necrosis Nitric Oxide Nutrient Oxidation-Reduction Oxygen Pathway interactions Pharmaceutical Preparations Population Production Proteins Protocols documentation Reaction Regulon Research Respiration Role Route Seeds Signal Transduction Site Source Structure Succinates System Testing Tuberculosis Work antimicrobial base chemotherapy cytokine design extracellular in vivo interest killings latent infection macromolecule macrophage metabolomics mouse model novel pathogen programs public health relevance yeast two hybrid system

项目摘要

DESCRIPTION (provided by applicant): A third of the world's population is infected with Mycobacterium tuberculosis (Mtb), and most of these infections are latent. Tubercle bacilli can remain inactive in lung lesions only to emerge decades later to seed new outbreaks of tuberculosis. In addition, tuberculosis is one of the most difficult bacterial infections to treat and continues to cause more deaths than any other bacterial infection. Bacilli exist in replicating and non-replicating states in a range of microenvironments that vary in oxygen concentration and nutrient availability. The bacilli that survive during latent infection likely exist in a non-replicating state and antimicrobials, effective against actively growing bacteria, are often not effective against non-replicating bacteria. Little is known about the metabolic mechanisms employed by Mtb to survive latent infection or the hostile microenvironment of necrotic caseous tubercle lesions where oxygen is limited and nutrient sources suboptimal. Mtb cannot grow but endures in the absence of aerobic respiration. Therefore, the non-replicating anaerobic state is considered a prime model for persistent bacilli in vivo. In the absence of aerobic respiration Mtb requires a functional electron transport system to drive ATP synthesis. However, the core metabolic mechanisms by which the bacilli maintain redox balance are unknown. Therefore, our central research question is "What metabolic mechanisms are employed by Mtb when aerobic respiration is inhibited?" At least three factors limit Mtb aerobic respiration: the inhibitory effect of macrophage-produced nitric oxide and carbon monoxide, and the structure of mature granulomas. All three of these conditions strongly induce the DosR regulon, a regulon essential for anaerobic survival. However, the regulon does not encode a complete recognizable intermediary metabolic pathway. Our expression analysis and biochemical data strongly indicate that Mtb - an obligate aerobe - maintains a unique multifaceted intermediary pathway for metabolism in the absence of aerobic respiration. Thus, throughout the evolution of Mtb as a frank human pathogen, it has maintained an extensive array of enzymes which appear to be geared specifically for anaerobic metabolic functions. The pathway predicts that Mtb has the potential to metabolize lipids and all other major carbon sources anaerobically. Antimicrobials designed to kill non-replicating anaerobic bacilli are sorely needed. Our research directly supports this goal. New antimycobacterial drugs and drug combinations are routinely tested against hypoxic/anaerobic bacilli, but questions about the proper protocol and our limited understanding of relevant intermediary metabolic pathways limit a rational approach to drug design. Our preliminary data suggests we are at the brink of a fundamental understanding of Mtb anaerobic metabolism. Our working hypothesis is: Mtb employs a novel anaerobic metabolic cycle in conjunction with the DosR regulon to confer survival during non- respiring conditions within TB lesions. To test this hypothesis we will investigate key aspects of the proposed anaerobic metabolic pathway.

描述（由申请人提供）：世界三分之一的人口感染了结核分枝杆菌（MTB），其中大多数感染是潜在的。结节杆菌在肺部病变中可能保持不活跃，只有几十年后才能播种新的结核病暴发。此外，结核病是治疗的最困难的细菌感染之一，并继续造成比任何其他细菌感染更多的死亡。杆菌存在于在氧气浓度和养分供应方面变化的一系列微环境中的复制和非复制状态。在潜在感染期间生存的杆菌可能存在于非复制状态和抗菌剂中，可有效防止积极生长的细菌，通常无效地抵抗非复制细菌。关于MTB在潜在感染中生存的代谢机制或氧化有限且营养源次优的坏死性结节病变的敌对微环境，几乎没有知识。 MTB不能生长，但是在没有有氧呼吸的情况下忍受。因此，非复制的厌氧状态被认为是体内持续性杆菌的主要模型。在没有有氧呼吸的情况下，MTB需要一个功能性电子传输系统才能驱动ATP合成。但是，杆菌维持氧化还原平衡的核心代谢机制尚不清楚。因此，我们的中心研究问题是“抑制有氧呼吸时，MTB采用了哪些代谢机制？”至少三个因素限制了MTB有氧呼吸：巨噬细胞产生的一氧化氮和一氧化碳的抑制作用以及成熟的肉芽瘤的结构。这三个条件都强烈诱导DOSR调节，这是厌氧存活至关重要的调节。但是，调节子没有编码完整的可识别中间代谢途径。我们的表达分析和生化数据强烈表明，MTB（一种强大的动孔）在没有有氧呼吸的情况下维持了独特的多方面中介途径，用于代谢。因此，在MTB作为坦率的人类病原体的整个演变中，它一直保持着广泛的酶，这些酶似乎是专门用于厌氧代谢功能的。该途径预测，MTB有可能通过厌氧代谢脂质和所有其他主要的碳源。迫切需要设计用于杀死非复发性厌氧菌的抗菌剂。我们的研究直接支持这一目标。常规测试了针对低氧/厌氧菌的新抗菌药物和药物组合，但是有关适当方案的问题以及我们对相关中介代谢途径的有限理解限制了对药物设计的合理方法。我们的初步数据表明，我们对MTB厌氧代谢的基本了解处于边缘。我们的工作假设是：MTB与DOSR调节型一起采用了一种新型的厌氧代谢周期，以在TB病变内的非呼吸条件下赋予生存。为了检验这一假设，我们将研究提出的厌氧代谢途径的关键方面。