A HigB-like toxin induces non-replicating Salmonella inside macrophages by inhibiting RNase III-dependent rRNA maturation [sehA_RNA-Seq]. A HigB-like toxin induces non-replicating Salmonella inside macrophages by inhibiting RNase III-dependent rRNA maturation [sehA_RNA-Seq]

Many bacteria are often resistant to antibiotic treatment and drugs because, even if these drugs are effective, bacteria can slow down their growth rate and thus attenuate the effectiveness of the drug. A similar growth-rate control is detected in pathogenic bacteria that infect and persist inside their hosts. The bacterial growth rate within host cells can be regulated by multiple signaling pathways, most of which are still unknown. A toxin-antitoxin (TA) system is one of the candidates for controlling bacterial growth because the TA system could slow down growth by expressing a toxin component. The toxin protein can be neutralized by the antitoxin component, serving as a non-heritable phenotypic switch for growth rate. In this study, we investigated a type II toxin-antitoxin system from the intracellular bacterial pathogen Salmonella enterica serovar Typhimurium. We characterized residues required for toxin’s activity and a potential mechanism of the toxin by searching for its target via bacterial two-hybrid screening. Understanding the underlying mechanism of toxin-mediated persister formation and growth rate control within host cells will provide a new alternative to treat antibiotic resistant bacteria or intracellular bacteria surviving within host cells. Overall design: We used RNA-seq to determine if the profile of mono-phosphated-OH and mono-phosphated mRNA differed between the sehA mutant and a strain that overexpressed sehA by arabinose induction.

许多细菌常对抗生素与药物治疗产生耐药性：即便此类药物本身具备抗菌活性，细菌可通过降低自身生长速率，进而削弱药物的作用效果。类似的生长速率调控现象也存在于可感染并寄生于宿主的病原菌中。宿主细胞内的细菌生长速率可受多条信号通路调控，其中绝大多数通路的具体机制仍未明确。毒素-抗毒素（TA）系统是调控细菌生长的候选机制之一——该系统可通过表达毒素蛋白组分以降低细菌生长速率，而毒素蛋白可被抗毒素组分中和，以此作为调控生长速率的非遗传性表型开关。本研究针对胞内病原菌肠炎沙门氏菌鼠伤寒血清型（Salmonella enterica serovar Typhimurium）的II型毒素-抗毒素系统展开研究，通过细菌双杂交筛选寻找毒素的作用靶点，以此解析毒素活性所需的关键残基及其潜在作用机制。阐明宿主细胞内毒素介导的持留菌形成及生长速率调控的底层机制，将为治疗耐药菌或寄生于宿主细胞内的胞内病原菌提供全新策略。实验整体设计：本研究采用RNA测序（RNA-seq），对比sehA突变株与经阿拉伯糖诱导过表达sehA的菌株之间，单磷酸化-OH与单磷酸化mRNA的表达谱差异。