Inhibition of tRNA Synthetases Induces Persistence in Chlamydia
Inhibition of tRNA Synthetases Induces Persistence in Chlamydia
复制标题
DOI：
10.1128/iai.00943-19
复制
发表时间：
2020-04-01
影响因子：
3.1
通讯作者：
Ouellette, Scot P.
中科院分区：
文献类型：
--
作者：
Hatch, Nathan D.;Ouellette, Scot P.
沙眼衣原体是细菌性传播感染的主要原因，肺炎衣原体导致社区获得性呼吸道感染。在体内，宿主免疫系统会释放干扰素(IFN-Gamma)来对抗感染。干扰素能激活人体细胞产生色氨酸(Trp)分解酶吲哚-2，3-双加氧酶(IDO)。因此，在干扰素-γ激活的宿主细胞中，胞浆色氨酸减少。在进化为细胞内依赖的过程中，衣原体显著减少了其基因组大小和含量，因为它依赖宿主细胞获得各种营养。重要的是，沙眼衣原体和肺炎衣原体是色氨酸营养缺陷菌，当人类宿主细胞暴露在干扰素-γ下时，它们会饥饿地缺乏这种必要的营养。为了生存下来，衣原体进入了一种称为持久性的替代发育状态。衣原体持续存在的特征是分裂周期停止，形态异常，在干扰素诱导的持续存在的情况下，转录中依赖色氨酸密码子的变化。我们假设这些转录变化依赖于特定的氨基酸饥饿状态。为了研究当其他氨基酸变得有限时衣原体反应的机制，我们测试了原核生物特异性tRNA合成酶抑制剂吲哚霉素和AN3365分别模拟色氨酸和亮氨酸饥饿的效果。我们发现这些药物抑制了衣原体的生长，并诱导了与持久性一致的形态和转录变化。重要的是，当从培养液中去除这些化合物时，生长抑制被逆转。根据这些数据，我们发现吲哚霉素和AN3365是有效的工具，可以用来模拟持久状态，而不依赖于干扰素-γ。
Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infections, and Chlamydia pneumoniae causes community-acquired respiratory infections. In vivo, the host immune system will release gamma interferon (IFN-gamma) to combat infection. IFN-gamma activates human cells to produce the tryptophan (Trp)-catabolizing enzyme indoleamine 2,3-dioxygenase (IDO). Consequently, there is a reduction in cytosolic Trp in IFN-gamma-activated host cells. In evolving to obligate intracellular dependence, Chlamydia has significantly reduced its genome size and content, as it relies on the host cell for various nutrients. Importantly, C. trachomatis and C. pneumoniae are Trp auxotrophs and are starved for this essential nutrient when the human host cell is exposed to IFN-gamma. To survive this, chlamydiae enter an alternative developmental state referred to as persistence. Chlamydial persistence is characterized by a halt in the division cycle, aberrant morphology, and, in the case of IFN-gamma-induced persistence, Trp codon-dependent changes in transcription. We hypothesize that these changes in transcription are dependent on the particular amino acid starvation state. To investigate the chlamydial response mechanisms acting when other amino acids become limiting, we tested the efficacy of prokaryote-specific tRNA synthetase inhibitors, indolmycin and AN3365, to mimic starvation of Trp and leucine, respectively. We show that these drugs block chlamydial growth and induce changes in morphology and transcription consistent with persistence. Importantly, growth inhibition was reversed when the compounds were removed from the medium. With these data, we find that indolmycin and AN3365 are valid tools that can be used to mimic the persistent state independently of IFN-gamma.