Accumulation of inorganic polyphosphate mediates metabolic downshift and antibiotic tolerance in Mycobacterium tuberculosis. Mycobacterium tuberculosis CDC1551

The stringent response, involving the regulatory molecules inorganic polyphosphate (poly P) and (p)ppGpp, is believed to mediate Mycobacterium tuberculosis persistence. In this study, we identified a novel exopolyphosphatase responsible for poly P hydrolysis. Using two different poly P-accumulating M. tuberculosis recombinant strains, we found that increased poly P content drives the organisms into early growth arrest, and contributes to tolerance to the cell wall-active agent isoniazid, increased resistance to stress conditions, and improved survival in macrophages. Transcriptomic and metabolomics analysis revealed metabolic downshift manifested by reduced expression of the transcriptional and translational machinery, and shift from utilization of glucose as a carbon source. In summary, regulation of the poly P balance is critical for persister formation in M. tuberculosis. Overall design: The transcriptome of poly P accumulation strains, Rv1026 knock-down and ppk1 knock-in were compared to empty vector strains by RNA-seq.

严谨反应(stringent response)借助调控分子无机多聚磷酸(inorganic polyphosphate, poly P)与(p)ppGpp发挥功能，被认为可介导结核分枝杆菌(Mycobacterium tuberculosis)的持留状态。本研究中，我们鉴定出一种全新的外聚磷酸酶(exopolyphosphatase)，可催化多聚磷酸的水解反应。本研究使用两株不同的多聚磷酸蓄积型结核分枝杆菌(Mycobacterium tuberculosis)重组菌株，实验结果显示，多聚磷酸含量升高可促使菌体进入早期生长停滞状态，同时可增强其对细胞壁作用剂异烟肼(isoniazid)的耐受性、提升其对抗多种应激条件的抵抗能力，并改善其在巨噬细胞(macrophages)内的存活能力。转录组学与代谢组学分析表明，菌体出现代谢下调特征：转录与翻译系统的表达水平显著降低，且碳源利用模式从葡萄糖切换为其他碳源。综上，多聚磷酸平衡的调控对于结核分枝杆菌的持留菌形成至关重要。整体实验设计：通过RNA测序(RNA-seq)，将多聚磷酸蓄积菌株、Rv1026基因敲低菌株与ppk1基因敲入菌株的转录组与空载体菌株进行对比分析。