Investigating the VapBC family of toxin-antitoxin systems in Mycobacterium tuberculosis

研究结核分枝杆菌毒素-抗毒素系统的 VapBC 家族

• 批准号: 9467771
• 负责人: ISABEL NOCEDAL
• 金额: $ 5.67万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-25 至 2020-09-24
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9467771
• 关键词: Address; Adopted; Affinity; Amino Acid Substitution; Amino Acids; Antibiotic Therapy; Antibiotics; Bacteria; Binding; Biological Assay; Cells; Ensure; Environment; Escherichia coli; Event; Evolution; Excision; Family; Gene Duplication; Genes; Goals; Growth; Horizontal Gene Transfer; Individual; Light; Modeling; Molecular; Molecular Evolution; Mutation; Mycobacterium tuberculosis; Operon; Pathogenicity; Phylogenetic Analysis; Play; Prevalence; Proteins; Regulation; Research; Role; Specificity; Stress; System; Testing; Time; Toxin; Work; alpha Toxin; antitoxin; cell growth; duplicate genes; experimental study; member; mutant; novel; pathogen; protein protein interaction; rapid growth; response

Project Summary/Abstract Toxin-antitoxin (TA) systems are important for the ability of many bacteria to respond to environmental stress. These systems typically consist of a stable toxin that inhibits cell growth and an antitoxin that binds and sequesters its cognate toxin. Degradation of the antitoxin can thus liberate the toxin, providing an important mechanism of bacterial growth regulation. TA systems are prevalent across nearly all bacterial species, with many species harboring many copies, often as a result of extensive gene duplication. Despite their abundance, however, there is evidence that toxin- antitoxin interactions are remarkably insulated from each other; i.e. only co-operonic toxins and antitoxins have high-affinity interactions. This suggests that new TA systems deriving from gene duplications must rapidly diverge from one another to ensure that each toxin-antitoxin pair has a unique interaction specificity. How this divergence occurs at the molecular level remains poorly understood, and is crucial to understanding the expansion and prevalence of TA systems in bacteria. Here, I propose to characterize the effect of gene duplications on toxin-antitoxin interactions through study of the VapBC family of TA systems in M. tuberculosis, which has undergone a massive expansion through successive gene/operon duplication events. I will first characterize the interactions between toxins and antitoxins from paralogous M. tuberculosis VapBC systems to determine whether these systems are fully insulated from one another. I will then identify the specific amino acid substitutions responsible for a divergence in binding specificity for paralogous VapBC systems. Finally, I will determine the evolutionary trajectory followed by two VapBC systems post-duplication through the resurrection and characterization of ancestral proteins as well as evolutionary intermediates. Because TA systems are crucial for many bacteria to adopt dormant, "persister" states in response to stress, understanding the large expansion of TA systems that took place in M. tuberculosis will help illuminate the molecular changes required for the evolution of pathogenicity in this species. Additionally, this work will shed important light on the general mechanisms governing the evolution of new protein-protein interactions.

项目摘要/摘要 毒素 - 抗毒素（TA）系统对于许多细菌应对环境压力的能力很重要。 这些系统通常由稳定的毒素组成，该毒素抑制细胞生长和结合和结合的抗毒素 隔离其同源毒素。抗毒素的降解因此可以解放毒素，从而提供重要的 细菌生长调节的机制。 TA系统几乎在所有细菌种类中都普遍存在，许多物种都有许多副本，通常 由于广泛的基因复制。尽管它们丰富，但是有证据表明毒素 - 抗毒素相互作用彼此明显绝缘。即仅合作毒素和抗毒素具有 高亲和力相互作用。这表明从基因重复衍生的新TA系统必须迅速 彼此分歧以确保每个毒素 - 抗毒素对具有独特的相互作用特异性。如何 分子水平上发生分歧仍然知之甚少，并且对于理解理解至关重要 TA系统在细菌中的扩展和流行率。 在这里，我建议通过研究基因重复对毒素 - 抗毒素相互作用的影响 结核分枝杆菌中TA系统的VAPBC家族，通过 连续的基因/操纵子重复事件。我将首先描述毒素和 来自副分枝结核分枝杆菌VAPBC系统的抗毒素，以确定这些系统是否完全 彼此隔热。然后，我将确定负责A的特定氨基酸取代 寄生虫VAPBC系统的结合特异性差异。最后，我将确定进化 轨迹，然后在复活和表征的情况下进行两个VAPBC系统。 祖传蛋白以及进化中间体。 由于TA系统对于许多细菌采用休眠状态至关重要，因此“毅力”状态是为了应对压力， 了解结核分枝杆菌中发生的TA系统的大量扩展将有助于照亮 该物种致病性进化所需的分子变化。此外，这项工作将丢弃 关于管理新蛋白质蛋白相互作用的演变的一般机制的重要光。