Nutrient-starved, non-replicating Mycobacterium tuberculosis requires respiration, ATP synthase and isocitrate lyase for maintenance of ATP homeostasis and viability
Nutrient-starved, non-replicating Mycobacterium tuberculosis requires respiration, ATP synthase and isocitrate lyase for maintenance of ATP homeostasis and viability
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DOI：
10.1099/mic.0.033084-0
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发表时间：
2010-01-01
期刊：
影响因子：
2.8
通讯作者：
Dick, Thomas
中科院分区：
文献类型：
--
作者：
Gengenbacher, Martin;Rao, Srinivasa P. S.;Dick, Thomas
尽管广泛的化疗，结核分枝杆菌在其人类宿主中持续存在的能力被认为是基于非复制表型耐药杆菌的亚群。为了研究不生长的病原体，在富营养培养基中缺氧（Wayne模型）或富氧培养基中营养剥夺（Loebel模型）产生静止生物的培养模型已经被开发出来。与韦恩杆菌的能量代谢相比，人们对洛贝尔杆菌的了解甚少。在这里，我们分析了营养饥饿条件下的结核分枝杆菌。在转移到非复制状态后，病原体保持细胞内ATIP水平降低了五倍，但保持不变。对F(0)F(1) ATIP合成酶的化学探测证明了该酶对ATP稳态和营养匮乏生物体的生存能力的重要性。令人惊讶的是，特异性ATIP合成酶抑制剂TMC207不影响生存能力，只是适度降低营养匮乏生物体的细胞内ATIP水平。氧气的耗尽杀死了洛贝尔杆菌，而硝酸盐则阻止了死亡，这表明呼吸和外源电子受体是维持生存能力所必需的。缺乏乙醛酸分流酶异柠檬酸裂解酶的营养饥饿杆菌未能降低细胞内ATIP水平而死亡，从而建立了ATIP控制与中间代谢之间的联系。我们得出结论，ATIP水平的降低可能是结核分枝杆菌适应非生长生存的重要一步。
The ability of Mycobacterium tuberculosis to persist in its human host despite extensive chemotherapy is thought to be based on subpopulations of non-replicating phenotypically drug-resistant bacilli. To study the non-growing pathogen, culture models that generate quiescent organisms by either oxygen depletion in nutrient-rich medium (Wayne model) or nutrient deprivation in oxygen-rich medium (Loebel model) have been developed. In contrast to the energy metabolism of Wayne bacilli, little is known about Loebel bacilli. Here we analysed M. tuberculosis under nutrient-starvation conditions. Upon shifting to the non-replicating state the pathogen maintained a fivefold reduced but constant intracellular ATIP level. Chemical probing of the F(0)F(1) ATIP synthase demonstrated the importance of this enzyme for ATP homeostasis and viability of the nutrient-starved organism. Surprisingly, the specific ATIP synthase inhibitor TMC207 did not affect viability and only moderately reduced the intracellular ATIP level of nutrient-starved organisms. Depletion of oxygen killed Loebel bacilli, whereas death was prevented by nitrate, suggesting that respiration and an exogenous electron acceptor are required for maintaining viability. Nutrient-starved bacilli lacking the glyoxylate shunt enzyme isocitrate lyase failed to reduce their intracellular ATIP level and died, thus establishing a link between ATIP control and intermediary metabolism. We conclude that reduction of the ATIP level might be an important step in the adaptation of M. tuberculosis to non-growing survival.