Antibiotic Bactericidal Activity Is Countered by Maintaining pH Homeostasis in Mycobacterium smegmatis.
Antibiotic Bactericidal Activity Is Countered by Maintaining pH Homeostasis in Mycobacterium smegmatis.
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DOI：
10.1128/msphere.00176-16
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发表时间：
2016-07
期刊：
影响因子：
4.8
通讯作者：
Voskuil MI
中科院分区：
文献类型：
--
作者：
Bartek IL;Reichlen MJ;Honaker RW;Leistikow RL;Clambey ET;Scobey MS;Hinds AB;Born SE;Covey CR;Schurr MJ;Lenaerts AJ;Voskuil MI
自从发现抗生素以来，由于细菌感染导致的死亡率急剧下降。然而，来自难以治疗的细菌如结核分枝杆菌和多重耐药病原体的感染一直在上升。对特定药物-靶标相互作用下游导致细胞死亡的级联事件的理解还不清楚。我们已经发现，通过维持细菌细胞内的pH平衡来停止几类抗生素的杀伤，这与抗生素杀伤的共同机制一致。我们的研究结果表明，抗生素的杀伤机制源于抗生素通过破坏质子进入而不影响质子泵出细胞来增加细菌细胞内pH值的能力。了解抗生素杀灭所需的核心机制可能对开发新的致命抗生素以及治疗难治性和耐药性病原体产生重大影响。抗生素针对细菌生长所必需的特定生物合成过程。有趣的是，几个共同点将看似不同的抗生素的杀菌活性联系起来，例如赋予广谱抗生素耐受性的许多条件。抗生素是否以其特定靶标特有的方式或通过通用机制杀死是一个关键和有争议的主题。在此，我们证明了不同抗生素对耻垢分枝杆菌和四种进化上不同的细菌病原体的杀菌活性被维持细胞内pH稳态的条件所阻断。单细胞pH值分析表明，抗生素增加了耻垢分枝杆菌的胞质pH值，而促进质子进入胞质的条件下，防止细胞内碱化和抗生素杀伤。这些发现导致了一个假设，即假定抗生素致死性发生在抗生素阻碍ATP消耗生物合成过程时，而代谢驱动的质子流出持续，尽管通过ATP合酶的质子流入损失。因此，在没有伴随的呼吸质子流出减少的情况下，由于细胞内碱化而发生细胞死亡。我们的研究结果表明，抗生素对pH稳态的影响应被认为是抗生素致死的潜在机制。重要性自从抗生素的发现，由于细菌感染的死亡率已经大大降低。然而，来自难以治疗的细菌如结核分枝杆菌和多重耐药病原体的感染一直在上升。对特定药物-靶标相互作用下游导致细胞死亡的级联事件的理解还不清楚。我们已经发现，通过维持细菌细胞内的pH平衡来停止几类抗生素的杀伤，这与抗生素杀伤的共同机制一致。我们的研究结果表明，抗生素的杀伤机制源于抗生素通过破坏质子进入而不影响质子泵出细胞来增加细菌细胞内pH值的能力。了解抗生素杀灭所需的核心机制可能对开发新的致命抗生素以及治疗难治性和耐药性病原体产生重大影响。
Since the discovery of antibiotics, mortality due to bacterial infection has decreased dramatically. However, infections from difficult to treat bacteria such as Mycobacterium tuberculosis and multidrug-resistant pathogens have been on the rise. An understanding of the cascade of events that leads to cell death downstream of specific drug-target interactions is not well understood. We have discovered that killing by several classes of antibiotics was stopped by maintaining pH balance within the bacterial cell, consistent with a shared mechanism of antibiotic killing. Our findings suggest a mechanism of antibiotic killing that stems from the antibiotic’s ability to increase the pH within bacterial cells by disrupting proton entry without affecting proton pumping out of cells. Knowledge of the core mechanism necessary for antibiotic killing could have a significant impact on the development of new lethal antibiotics and for the treatment of recalcitrant and drug-resistant pathogens. Antibiotics target specific biosynthetic processes essential for bacterial growth. It is intriguing that several commonalities connect the bactericidal activity of seemingly disparate antibiotics, such as the numerous conditions that confer broad-spectrum antibiotic tolerance. Whether antibiotics kill in a manner unique to their specific targets or by a universal mechanism is a critical and contested subject. Herein, we demonstrate that the bactericidal activity of diverse antibiotics against Mycobacterium smegmatis and four evolutionarily divergent bacterial pathogens was blocked by conditions that worked to maintain intracellular pH homeostasis. Single-cell pH analysis demonstrated that antibiotics increased the cytosolic pH of M. smegmatis, while conditions that promoted proton entry into the cytosol prevented intracellular alkalization and antibiotic killing. These findings led to a hypothesis that posits antibiotic lethality occurs when antibiotics obstruct ATP-consuming biosynthetic processes while metabolically driven proton efflux is sustained despite the loss of proton influx via ATP synthase. Consequently, without a concomitant reduction in respiratory proton efflux, cell death occurs due to intracellular alkalization. Our findings indicate the effects of antibiotics on pH homeostasis should be considered a potential mechanism contributing to antibiotic lethality. IMPORTANCE Since the discovery of antibiotics, mortality due to bacterial infection has decreased dramatically. However, infections from difficult to treat bacteria such as Mycobacterium tuberculosis and multidrug-resistant pathogens have been on the rise. An understanding of the cascade of events that leads to cell death downstream of specific drug-target interactions is not well understood. We have discovered that killing by several classes of antibiotics was stopped by maintaining pH balance within the bacterial cell, consistent with a shared mechanism of antibiotic killing. Our findings suggest a mechanism of antibiotic killing that stems from the antibiotic’s ability to increase the pH within bacterial cells by disrupting proton entry without affecting proton pumping out of cells. Knowledge of the core mechanism necessary for antibiotic killing could have a significant impact on the development of new lethal antibiotics and for the treatment of recalcitrant and drug-resistant pathogens.