Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Microbiology and Immunology, University of British Columbia, BC V6T 1Z3, Canada.
Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
Cell Rep. 2022 Apr 26;39(4):110731. doi: 10.1016/j.celrep.2022.110731.
The type VI secretion system (T6SS) is a contractile nanomachine widely distributed among pathogenic and commensal Gram-negative bacteria. The T6SS is used for inter-bacterial competition to directly kill competing species; however, its importance during bacterial infection in vivo remains poorly understood. We report that the murine pathogen Citrobacter rodentium, used as a model for human pathogenic Escherichia coli, harbors two functional T6SSs. C. rodentium employs its T6SS-1 to colonize the murine gastrointestinal tract by targeting commensal Enterobacteriaceae. We identify VgrG1 as a C. rodentium T6SS antibacterial effector, which exhibits toxicity in E. coli. Conversely, commensal prey species E. coli Mt1B1 employs two T6SSs of its own to counter C. rodentium colonization. Collectively, these data demonstrate that the T6SS is a potent weapon during bacterial competition and is used by both invading pathogens and resident microbiota to fight for a niche in the hostile gut environment.
VI 型分泌系统（T6SS）是一种广泛分布于致病性和共生革兰氏阴性菌中的可收缩纳米机器。T6SS 用于细菌间的竞争，以直接杀死竞争物种；然而，其在体内细菌感染过程中的重要性仍知之甚少。我们报告称，作为人类致病性大肠杆菌模型的鼠病原体柠檬酸杆菌携带两个功能 T6SS。C. rodentium 通过靶向共生肠杆菌科来利用其 T6SS-1 定植于小鼠胃肠道。我们鉴定出 VgrG1 是 C. rodentium T6SS 的一种抗菌效应物，它在大肠杆菌中表现出毒性。相反，共生猎物大肠杆菌 Mt1B1 利用自身的两个 T6SS 来对抗 C. rodentium 的定植。总的来说，这些数据表明 T6SS 是细菌竞争过程中的一种强大武器，入侵病原体和常驻微生物群都利用它在恶劣的肠道环境中争夺生态位。
