Xu Yuanyuan, Ehrt Sabine, Schnappinger Dirk, Beites Tiago
Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA.
bioRxiv. 2023 Apr 10:2023.04.10.536268. doi: 10.1101/2023.04.10.536268.
Type 2 NADH dehydrogenase (Ndh-2) is an oxidative phosphorylation enzyme discussed as a promising drug target in different pathogens, including and (). To kill , Ndh-2 needs to be inactivated together with the alternative enzyme type 1 NADH dehydrogenase (Ndh-1), but the mechanism of this synthetic lethality remained unknown. Here, we provide insights into the biology of NADH dehydrogenases and a mechanistic explanation for Ndh-1 and Ndh-2 synthetic lethality in . NADH dehydrogenases have two main functions: maintaining an appropriate NADH/NAD+ ratio by converting NADH into NAD+ and providing electrons to the respiratory chain. Heterologous expression of a water forming NADH oxidase (Nox), which catalyzes the oxidation of NADH, allows to distinguish between these two functions and show that Nox rescues Mtb from Ndh-1/Ndh-2 synthetic lethality, indicating that NADH oxidation is the essential function of NADH dehydrogenases for viability. Quantification of intracellular levels of NADH, NAD, ATP, and oxygen consumption revealed that preventing NADH oxidation by Ndh-2 depletes NAD(H) and inhibits respiration. Finally, we show that Ndh-1/ Ndh-2 synthetic lethality can be achieved through chemical inhibition.
2型NADH脱氢酶（Ndh-2）是一种氧化磷酸化酶，在包括结核分枝杆菌和麻风分枝杆菌在内的不同病原体中被视为一种有前景的药物靶点（参考文献）。为了杀死结核分枝杆菌，Ndh-2需要与替代酶1型NADH脱氢酶（Ndh-1）一起被灭活，但其合成致死的机制仍不清楚。在此，我们深入了解了NADH脱氢酶的生物学特性，并对结核分枝杆菌中Ndh-1和Ndh-2的合成致死性给出了机制解释。NADH脱氢酶有两个主要功能：通过将NADH转化为NAD+来维持适当的NADH/NAD+比率，并为呼吸链提供电子。催化NADH氧化的产水NADH氧化酶（Nox）的异源表达，使得区分这两种功能成为可能，并表明Nox可将结核分枝杆菌从Ndh-1/Ndh-2合成致死性中拯救出来，这表明NADH氧化是NADH脱氢酶对结核分枝杆菌生存能力的基本功能。对细胞内NADH、NAD、ATP水平以及氧气消耗的定量分析表明，阻止Ndh-2对NADH的氧化会耗尽NAD(H)并抑制呼吸作用。最后，我们表明可以通过化学抑制实现Ndh-1/Ndh-2合成致死性。
