Tn-seq analysis.

Bacterial persisters contribute significantly to clinical treatment failure and relapse. These cells could resist antibiotic treatment via transient phenotypic and gene expression alterations. We conducted a high-throughput screening of Salmonella Typhimurium transposon mutants to identify key genes for intramacrophage antibiotic persistence. The results show that a sulfur transferase complex encoded by yheM, yheL, yheN, trmU and yhhP are involved in bacterial intramacrophage antibiotic persistence. Salmonella could persist in macrophages by downregulating the expression of the sulfur transferase complex during exposure to high concentrations of antibiotics, and even in a persistent infection mouse model. Mechanistically, deletion of yheM increases reactive nitrogen species (RNS) in the exponential phase, which inhibits bacterial respiration and ATP generation. In contrast, absence of yheM promotes persister formation by elevating (p)ppGpp levels in the stationary phase. Taken together, our data demonstrate that bacteria use the sulfur transferase to coordinate intramacrophage replication and persistence for adaptation to various environmental stresses. These findings reveal the role of the sulfur transferase complex in bacterial intramacrophage persistence and provide a promising target for antibacterial infection therapy.

细菌持留菌（Bacterial persisters）是引发临床治疗失败与疾病复发的关键因素。此类细胞可通过瞬时表型与基因表达改变，耐受抗生素治疗。本研究针对鼠伤寒沙门氏菌（Salmonella Typhimurium）转座子突变体开展高通量筛选，以鉴定巨噬细胞内抗生素持留相关的关键基因。
研究结果显示，由yheM、yheL、yheN、trmU及yhhP编码的硫转移酶复合物，参与细菌的巨噬细胞内抗生素持留过程。在高浓度抗生素暴露条件下，甚至在持续性感染小鼠模型中，沙门氏菌可通过下调该硫转移酶复合物的表达，实现在巨噬细胞内的持留。
从机制层面分析，敲除yheM会在指数生长期提升活性氮物种（reactive nitrogen species, RNS）水平，进而抑制细菌呼吸作用与三磷酸腺苷（ATP）生成；与之相反，yheM缺失会在稳定生长期升高(p)ppGpp水平，从而促进持留菌形成。
综上，本研究数据证实，细菌可通过硫转移酶复合物协调巨噬细胞内的复制与持留过程，以适应不同环境胁迫。上述研究结果揭示了硫转移酶复合物在细菌巨噬细胞内持留中的作用，为抗菌感染治疗提供了极具潜力的干预靶点。