Turning Mycobacterium tuberculosis appetite for fatty acids against itself

项目摘要 结核病（TB）仍然是全世界发病率和死亡率的主要原因。到2020年，预计1.5 100万人死于结核病。这就要求改进治疗方案，这将大大受益于 确定新的消毒感染的策略。这项研究的总体思路是颠覆 结核分枝杆菌（Mtb）病原体采用的高度适应性策略。有一个 大量工作支持Mtb利用宿主脂肪酸作为碳源。然而，尽管重要 对于生长和存活，脂肪酸也可能对结核分枝杆菌有毒。我们实验室以前的工作表明， 缺乏苹果酸合酶（glcB）、2型NADH脱氢酶（ndh/ ndhA）和EtfD（etfD）的突变体提供了一种 在TB小鼠模型中与减毒相关的脂肪酸敏感表型。这表明它是 可能将Mtb的优化代谢转化为氧化宿主脂肪酸对抗杆菌。除了这些具体的 然而，在结核分枝杆菌避免脂肪酸毒性所需的遗传决定因素方面存在知识空白。到 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 在含有和不含油酸（分枝杆菌中常用的长链脂肪酸）的培养基中产生的文库 培养基，并且可能是感染期间的碳源）。该筛选鉴定了ndh和etfD转座子 突变体对油酸敏感，这与我们以前的发现一致。在本提案中，我们将 对我们Tn-seq筛选的热门生理功能做一个“深潜”。初步数据表明 cAMP信号传导、脂肪酸催化剂和呼吸作用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如何相互作用，不仅会导致更好的 这一发现不仅有助于了解结核病病原体的生物学，而且将揭示消灭结核病感染的新策略。

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.