Novel inhibitors of cholesterol degradation in Mycobacterium tuberculosis reveal how the bacterium's metabolism is constrained by the intracellular environment.
Novel inhibitors of cholesterol degradation in Mycobacterium tuberculosis reveal how the bacterium's metabolism is constrained by the intracellular environment.
复制标题
DOI：
10.1371/journal.ppat.1004679
复制
发表时间：
2015-02
期刊：
影响因子：
6.7
通讯作者：
Russell DG
中科院分区：
文献类型：
--
作者：
VanderVen BC;Fahey RJ;Lee W;Liu Y;Abramovitch RB;Memmott C;Crowe AM;Eltis LD;Perola E;Deininger DD;Wang T;Locher CP;Russell DG
结核分枝杆菌（Mtb）依赖于一组专门的代谢途径来支持巨噬细胞的生长。通过进行广泛的、无偏见的化学筛选以鉴定抑制巨噬细胞内Mtb代谢的小分子，我们鉴定了大量限制巨噬细胞和含有胆固醇作为主要碳源的培养基中Mtb生长的新型化合物。基于这一观察结果，我们开发了一种化学拯救策略，以鉴定靶向参与胆固醇代谢的代谢酶的化合物。该方法鉴定了两种抑制HsaAB酶复合物的化合物，所述HsaAB酶复合物是胆固醇A/B环完全降解所需的。该策略还确定了PrpC的抑制剂，2-甲基柠檬酸合酶，这是胆固醇衍生的丙酰辅酶A同化到TCA循环所必需的。这些化学探针代表了具有新型作用模式的新型抑制剂，并靶向支持Mtb在其宿主细胞中生长所需的代谢途径。筛选还揭示了一组结构多样的化合物，其靶向胆固醇利用的其他阶段。对这类化合物有抗性的突变体在细菌腺苷酸环化酶Rv 1625/Cya中是有缺陷的。这些数据表明环腺苷酸（cAMP）在调节结核分枝杆菌的胆固醇利用，并与已发表的报告表明，丙酸代谢受cAMP水平的调节是一致的。有趣的是，逆转的胆固醇依赖性的生长抑制所造成的这一子集的化合物可以通过补充培养基与乙酸盐，但不与葡萄糖，表明结核分枝杆菌是由胆固醇的存在诱导的代谢约束的独特形式。人类是M.结核病（Mtb），并且估计目前有18亿人感染Mtb。这种感染的一个重要方面是Mtb通过在巨噬细胞内复制来维持感染的能力。在巨噬细胞内，结核分枝杆菌利用一组专门的代谢途径来利用宿主来源的营养素，如脂肪酸和/或胆固醇，用于能量产生。关于感染期间Mtb代谢的许多细节仍然未知。在这里，我们采用化学方法来鉴定小分子探针，其靶向巨噬细胞感染期间的Mtb代谢。我们发现，我们鉴定的许多小分子抑制剂需要胆固醇才能起作用。在这里，我们报告了一种新的化学救援方法，以确定三种新型抑制剂的代谢靶点，并发现cAMP信号与Mtb中的胆固醇利用有关。总之，这些数据表明胆固醇对巨噬细胞内的Mtb代谢发挥主导作用。此外，本研究中鉴定的新型抑制剂将有助于评价胆固醇代谢作为化疗干预的靶点。
Mycobacterium tuberculosis (Mtb) relies on a specialized set of metabolic pathways to support growth in macrophages. By conducting an extensive, unbiased chemical screen to identify small molecules that inhibit Mtb metabolism within macrophages, we identified a significant number of novel compounds that limit Mtb growth in macrophages and in medium containing cholesterol as the principle carbon source. Based on this observation, we developed a chemical-rescue strategy to identify compounds that target metabolic enzymes involved in cholesterol metabolism. This approach identified two compounds that inhibit the HsaAB enzyme complex, which is required for complete degradation of the cholesterol A/B rings. The strategy also identified an inhibitor of PrpC, the 2-methylcitrate synthase, which is required for assimilation of cholesterol-derived propionyl-CoA into the TCA cycle. These chemical probes represent new classes of inhibitors with novel modes of action, and target metabolic pathways required to support growth of Mtb in its host cell. The screen also revealed a structurally-diverse set of compounds that target additional stage(s) of cholesterol utilization. Mutants resistant to this class of compounds are defective in the bacterial adenylate cyclase Rv1625/Cya. These data implicate cyclic-AMP (cAMP) in regulating cholesterol utilization in Mtb, and are consistent with published reports indicating that propionate metabolism is regulated by cAMP levels. Intriguingly, reversal of the cholesterol-dependent growth inhibition caused by this subset of compounds could be achieved by supplementing the media with acetate, but not with glucose, indicating that Mtb is subject to a unique form of metabolic constraint induced by the presence of cholesterol. Human beings are the sole ecological niche for M. tuberculosis (Mtb), and it is estimated that 1.8 billion people are currently infected with Mtb. An important aspect of this infection is Mtb’s ability to maintain infection by replicating within macrophages. Within macrophages, Mtb exploits a specialized set of metabolic pathways to utilize host-derived nutrients, such as fatty acids and/or cholesterol, for energy production. Many details regarding Mtb metabolism during infection remain unknown. Here we took a chemical approach to identify small molecule probes, which target Mtb metabolism during infection in macrophages. We found that many of the small molecule inhibitors that we identified require cholesterol for activity. Here we report a novel chemical rescue approach to identify the metabolic targets of three novel inhibitors, and discovered that cAMP signaling is linked to cholesterol utilization in Mtb. Together, these data demonstrate that cholesterol exerts a dominant effect on Mtb metabolism within macrophages. Additionally, the novel inhibitors identified in this study will facilitate evaluation of cholesterol metabolism as a target for chemotherapeutic intervention.
登录
查看更多内容
影响因子：
82.9
作者：
Muñoz-Elías, EJ;McKinney, JD
通讯作者：
McKinney, JD
影响因子：
4.8
作者：
Dresen, Carola;Lin, Leo Y. -C.;Eltis, Lindsay D.
通讯作者：
Eltis, Lindsay D.
影响因子：
4.9
作者：
Charpentier, Charlotte;Roquebert, Benedicte;Descamps, Diane
通讯作者：
Descamps, Diane
影响因子：
4.8
作者：
Lee, Wonsik;VanderVen, Brian C.;Russell, David G.
通讯作者：
Russell, David G.
影响因子：
4.8
作者：
Capyk, Jenna K.;Casabon, Israeel;Eltis, Lindsay D.
通讯作者：
Eltis, Lindsay D.