Turning Mycobacterium tuberculosis appetite for fatty acids against itself

项目总结 结核病(TB)仍然是全世界发病率和死亡率的主要原因。2020年，预计将有1.5 数百万人死于结核病。这要求改进治疗方案，这将极大地受益于 确定消毒感染的新策略。这一研究的主旋律是颠覆 结核分枝杆菌(结核分枝杆菌)病原体采用的高度适应性策略。有一个 支持结核分枝杆菌利用宿主脂肪酸作为碳源的大量工作。然而，尽管很重要， 为了生长和生存，脂肪酸对结核分枝杆菌也是有毒的。我们实验室以前的工作表明， 缺乏苹果酸合成酶(GlcB)、2型NADH脱氢酶(NDH/NDHA)和EtfD(EtfD)的突变体使 在结核病小鼠模型中，与衰减相关的脂肪酸敏感表型。这表明，它是 有可能改变结核分枝杆菌的优化新陈代谢，以氧化宿主脂肪酸对抗细菌。除了这些特定的 在一些病例中，关于结核分枝杆菌避免脂肪酸毒性所需的遗传决定因素的知识存在差距。至 为了解决这个问题，我们进行了转座子测序(TN-seq)，并比较了转座子突变体 在含有和不含有油酸(一种常用于分枝杆菌的长链脂肪酸)的培养基中产生的文库 培养介质，可能是感染期间的碳源)。该筛选鉴定出NDH和etfD转座子 突变株对油酸敏感，这与我们之前的发现一致。在本提案中，我们将 对我们TN-SEQ筛查的TOP HING的生理功能做一次“深潜”。初步数据显示 CAMP信号、脂肪酸分解代谢和呼吸之间的相互作用影响结核分枝杆菌药物敏感性 和致病性。了解这些不同的细胞过程是如何相互作用的不仅会带来更好的 了解病原体的生物学，但它将揭示消毒结核分枝杆菌感染的新策略。

Project summary Tuberculosis (TB) remains a leading cause of morbidity and mortality worldwide. In 2020, it is estimated that 1.5 million people died from TB. This calls for improved treatment regimens, which will greatly benefit from the identification of novel strategies to sterilize infections. The overarching idea of this line of research is to subvert highly adaptive strategies employed by the etiological agent of TB Mycobacterium tuberculosis (Mtb). There is a large body of work in support of Mtb exploiting host fatty acids as a carbon source. However, although important for growth and survival, fatty acids can also be toxic for Mtb. Previous work from our laboratory showed that mutants devoid of malate synthase (glcB), type-2 NADH dehydrogenase (ndh/ ndhA) and EtfD (etfD) render a fatty acid sensitive phenotype associated with attenuation in the mouse model of TB. This showed that it is possible to turn Mtb’s optimized metabolism to oxidize host fatty acids against the bacilli. Beyond these specific cases, there is a gap in knowledge on the genetic determinants necessary for Mtb to avoid fatty acid toxicity. To address this issue, we have performed transposon sequencing (Tn-seq) and compared transposon mutant libraries generated in medium with and without oleic acid (a long-chain fatty acid commonly used in mycobacteria culture media, and likely a carbon source during infection). This screening identified ndh and etfD transposon mutants as being sensitive to oleic acid, which is consistent with our previous findings. In this proposal we will do a “deep dive” on the physiological function of the top hit of our Tn-seq screening. Preliminary data indicates that an interplay between cAMP signaling, fatty acid catabolism and respiration impacts Mtb drug susceptibility and pathogenicity. Understanding how these different cell processes interact will not only lead to a better understanding of the pathogen’s biology, but it will unveil new strategies to sterilize Mtb infections.