Genetic and metabolic regulation of Mycobacterium tuberculosis acid growth arrest
Genetic and metabolic regulation of Mycobacterium tuberculosis acid growth arrest
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DOI：
10.1038/s41598-018-22343-4
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发表时间：
2018-03-08
影响因子：
4.6
通讯作者：
Abramovitch, Robert B.
中科院分区：
文献类型：
--
作者：
Baker, Jacob J.;Abramovitch, Robert B.
结核分枝杆菌（Mtb）在感染过程中感知并适应酸性环境。酸性pH依赖性适应包括诱导与回补和特定碳源上的生长停滞相关的代谢基因。在这里，我们报告说，删除异柠檬酸裂解酶或磷酸烯醇丙酮酸羧激酶的结果在酸性pH值和改变代谢产物谱的生长减少，支持的回补代谢的重塑是需要pH值依赖性的适应。在pH 5.7下在含有甘油作为单一碳源的基本培养基中培养的Mtb表现出酸生长停滞表型，其中细菌是非复制的，但有活力和代谢活性。细菌同化和代谢甘油，并在酸生长停滞期间维持ATP库，并对洗涤剂应激和抗生素异烟肼和利福平具有耐受性。正向遗传筛选鉴定了在酸性pH下不抑制其生长的突变体，包括四种在脯氨酸-脯氨酸-谷氨酸（PPE）基因MT3221（也称为ppe 51）中具有三个不同突变的增强酸性生长（eag）突变体。野生型Mtb中MT3221（S211 R）变体蛋白的过表达导致酸生长增强和药物耐受性降低。这些发现支持酸性生长停滞是一种遗传控制的适应性过程，而不仅仅是与酸性pH值相关的生理限制。
Mycobacterium tuberculosis (Mtb) senses and adapts to acidic environments during the course of infection. Acidic pH-dependent adaptations include the induction of metabolic genes associated with anaplerosis and growth arrest on specific carbon sources. Here we report that deletion of isocitrate lyase or phosphoenolpyruvate carboxykinase results in reduced growth at acidic pH and altered metabolite profiles, supporting that remodeling of anaplerotic metabolism is required for pH-dependent adaptation. Mtb cultured at pH 5.7 in minimal medium containing glycerol as a single carbon source exhibits an acid growth arrest phenotype, where the bacterium is non-replicating but viable and metabolically active. The bacterium assimilates and metabolizes glycerol and maintains ATP pools during acid growth arrest and becomes tolerant to detergent stress and the antibiotics isoniazid and rifampin. A forward genetic screen identified mutants that do not arrest their growth at acidic pH, including four enhanced acid growth (eag) mutants with three distinct mutations in the proline-proline-glutamate (PPE) gene MT3221 (also named ppe51). Overexpression of the MT3221(S211R) variant protein in wild type Mtb results in enhanced acid growth and reduced drug tolerance. These findings support that acid growth arrest is a genetically controlled, adaptive process and not simply a physiological limitation associated with acidic pH.