Cui Peng, Niu Hongxia, Shi Wanliang, Zhang Shuo, Zhang Wenhong, Zhang Ying
Key Lab of Molecular Virology, Institute of Medical Microbiology, Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China.
Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States.
Front Microbiol. 2018 Mar 6;9:413. doi: 10.3389/fmicb.2018.00413. eCollection 2018.
Persister cells are metabolically quiescent multi-drug tolerant fraction of a genetically sensitive bacterial population and are thought to be responsible for relapse of many persistent infections. Persisters can be formed naturally in the stationary phase culture, and also can be induced by bacteriostatic antibiotics. However, the molecular basis of bacteriostatic antibiotic induced persister formation is unknown. Here, we established a bacteriostatic antibiotic induced persister model and screened the single gene deletion mutant library for mutants with defect in rifampin or tetracycline induced persistence to ofloxacin. Thirsty-seven and nine genes were found with defects in rifampin- and tetracycline-induced persister formation, respectively. Six mutants were found to overlap in both rifampin and tetracycline induced persister screens: , , , , , and . Interestingly, four of these mutants (, , and ) mapped to DNA repair pathway, one mutant mapped to global transcriptional regulator () and one to efflux (). The stationary phase culture of the identified mutants and parent strain BW25113 were subjected to different antibiotics including ofloxacin, ampicillin, gentamicin, and stress conditions including starvation and acid pH 4.0. All the six mutants showed less tolerance to ofloxacin, but only some of them were more sensitive to other specific stress conditions. Complementation of five of the six common mutants restored the persister level to that of the parent strain in both stationary phase and static antibiotic-induced conditions. In addition to the DNA repair pathways shared by both rifampin and tetracycline induced persisters, genes involved in rifampin-induced persisters map also to transporters, LPS biosynthesis, flagella biosynthesis, metabolism (folate and energy), and translation, etc. These findings suggest that persisters generated by different ways may share common mechanisms of survival, and also shed new insight into the molecular basis of static antibiotic induced antagonism of cidal antibiotics.
持留菌是遗传敏感细菌群体中代谢静止的多药耐受部分，被认为是许多持续性感染复发的原因。持留菌可在稳定期培养物中自然形成，也可由抑菌抗生素诱导形成。然而，抑菌抗生素诱导持留菌形成的分子基础尚不清楚。在此，我们建立了一个抑菌抗生素诱导持留菌模型，并筛选单基因缺失突变体文库，以寻找在利福平或四环素诱导对氧氟沙星产生持留性方面存在缺陷的突变体。分别发现37个和9个基因在利福平和四环素诱导持留菌形成方面存在缺陷。在利福平和四环素诱导持留菌筛选中发现6个突变体重叠： 、 、 、 、 和 。有趣的是，这些突变体中的4个（ 、 、 和 ）映射到DNA修复途径，1个突变体映射到全局转录调节因子（ ），1个映射到外排（ ）。对鉴定出的突变体和平行菌株BW25113的稳定期培养物施加不同抗生素，包括氧氟沙星、氨苄青霉素、庆大霉素，以及应激条件，包括饥饿和酸性pH 4.0。所有6个突变体对氧氟沙星的耐受性均降低，但只有其中一些对其他特定应激条件更敏感。6个常见突变体中的5个的互补在稳定期和静态抗生素诱导条件下均将持留菌水平恢复到亲本菌株的水平。除了利福平和四环素诱导持留菌共有的DNA修复途径外，参与利福平诱导持留菌的基因还映射到转运蛋白、脂多糖生物合成、鞭毛生物合成、代谢（叶酸和能量）以及翻译等。这些发现表明，通过不同方式产生的持留菌可能共享共同的存活机制，也为抑菌抗生素诱导对杀菌抗生素拮抗作用的分子基础提供了新的见解。
