Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India.
Sci Rep. 2022 Jul 30;12(1):13127. doi: 10.1038/s41598-022-17051-z.
In this study, we probe the role of secondary messenger c-di-AMP in drug tolerance, which includes both persister and resistant mutant characterization of Mycobacterium smegmatis. Specifically, with the use of c-di-AMP null and overproducing mutants, we showed how c-di-AMP plays a significant role in resistance mutagenesis against antibiotics with different mechanisms of action. We elucidated the specific molecular mechanism linking the elevated intracellular c-di-AMP level and high mutant generation and highlighted the significance of non-homology-based DNA repair. Further investigation enabled us to identify the unique mutational landscape of target and non-target mutation categories linked to intracellular c-di-AMP levels. Overall fitness cost of unique target mutations was estimated in different strain backgrounds, and then we showed the critical role of c-di-AMP in driving epistatic interactions between resistance genes, resulting in the evolution of multi-drug tolerance. Finally, we identified the role of c-di-AMP in persister cells regrowth and mutant enrichment upon cessation of antibiotic treatment.
在这项研究中，我们探究了第二信使 c-di-AMP 在药物耐受性中的作用，包括分枝杆菌耐持久和耐药突变体的特征。具体来说，我们使用 c-di-AMP 缺失和过表达突变体，展示了 c-di-AMP 如何在针对具有不同作用机制的抗生素的耐药性突变中发挥重要作用。我们阐明了将细胞内 c-di-AMP 水平升高与高突变体产生联系起来的特定分子机制，并强调了非同源性 DNA 修复的重要性。进一步的研究使我们能够确定与细胞内 c-di-AMP 水平相关的靶标和非靶标突变类别的独特突变景观。在不同的菌株背景下，我们估计了独特靶标突变的总体适应度成本，然后表明 c-di-AMP 在驱动耐药基因之间的上位性相互作用方面起着关键作用，导致多药耐受性的进化。最后，我们确定了 c-di-AMP 在抗生素治疗停止后，持久细胞重新生长和突变体富集中的作用。
