Leon Gabrielle, Brynildsen Mark P
Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, United States of America.
Omenn-Darling Bioengineering Institute, Princeton University, Princeton, New Jersey, United States of America.
PLoS Genet. 2025 Sep 2;21(9):e1011840. doi: 10.1371/journal.pgen.1011840. eCollection 2025 Sep.
Studies have shown that DNA damage repair systems, including homologous recombination (HR) and the SOS response, are important for fluoroquinolone (FQ) persistence of Escherichia coli, which has been the workhorse organism of persister research. We sought to explore whether those systems are also important for FQ persistence of Pseudomonas aeruginosa, a common cause of lung infections in cystic fibrosis patients, which can be treated with FQs such as ciprofloxacin (CIP). Notably, P. aeruginosa has important differences in its DNA damage repair capabilities compared to E. coli that include the machinery needed to conduct non-homologous end-joining (NHEJ), Ku and LigD. Using a genetic approach, we found that loss of HR significantly depressed persister levels of P. aeruginosa to CIP during stationary-phase, but not in exponential-phase. This differed from E. coli grown in identical conditions, where loss of HR reduced survival in both stationary- and exponential-phase populations. Similarly, an inability to induce the SOS response reduced survival during both growth phases for E. coli but only in stationary-phase for P. aeruginosa. Loss of NHEJ machinery in P. aeruginosa did not impact persister levels during stationary- or exponential-phase, whereas overexpression of NHEJ machinery in P. aeruginosa had toxic effects. In addition, the generality of findings to another FQ, levofloxacin, and a recent clinical isolate, MRSN 1612, were confirmed. These results demonstrate that HR and the SOS response are important to CIP persistence of stationary-phase P. aeruginosa, dispensable to CIP persisters in growing P. aeruginosa cultures, and that the contributions of systems to E. coli persistence do not directly translate to persisters of P. aeruginosa.
研究表明，包括同源重组（HR）和SOS应答在内的DNA损伤修复系统，对于大肠杆菌的氟喹诺酮（FQ）持续性很重要，大肠杆菌一直是持留菌研究的主要对象。我们试图探究这些系统对于铜绿假单胞菌的FQ持续性是否也很重要，铜绿假单胞菌是囊性纤维化患者肺部感染的常见病因，可用环丙沙星（CIP）等FQ进行治疗。值得注意的是，与大肠杆菌相比，铜绿假单胞菌在DNA损伤修复能力方面存在重要差异，包括进行非同源末端连接（NHEJ）所需的机制、Ku和LigD。通过遗传学方法，我们发现HR缺失在稳定期显著降低了铜绿假单胞菌对CIP的持留菌水平，但在指数期没有。这与在相同条件下生长的大肠杆菌不同，在大肠杆菌中，HR缺失降低了稳定期和指数期群体的存活率。同样，无法诱导SOS应答降低了大肠杆菌在两个生长阶段的存活率，但仅降低了铜绿假单胞菌在稳定期的存活率。铜绿假单胞菌中NHEJ机制的缺失在稳定期或指数期均未影响持留菌水平，而铜绿假单胞菌中NHEJ机制的过表达具有毒性作用。此外，还证实了这些发现对于另一种FQ左氧氟沙星以及一株近期临床分离株MRSN 1612的普遍性。这些结果表明，HR和SOS应答对于稳定期铜绿假单胞菌的CIP持续性很重要，对于生长中的铜绿假单胞菌培养物中的CIP持留菌是可有可无的，并且这些系统对大肠杆菌持续性的贡献并不能直接转化为铜绿假单胞菌的持留菌。
