通过控制鞭毛蛋白的分泌，TonB系统是嗜水气单胞菌运动所必需的。

TonB systems are required for Aeromonas hydrophila motility by controlling the secretion of flagellin.

作者信息

Dong Yuhao, Xu Meng, Wan Xihe, Zhao Dan, Geng Jinzhu, Huang Hao, Jiang Mingguo, Lu Chengping, Liu Yongjie

机构信息

Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China.

Institute of Oceanology and Marine Fisheries, Nantong, 226007, Jiangsu, China.

出版信息

Microbes Infect. 2023 Jan-Feb;25(1-2):105038. doi: 10.1016/j.micinf.2022.105038. Epub 2022 Aug 10.

DOI:10.1016/j.micinf.2022.105038

Abstract

The TonB system is required for the active transport of iron compounds across the outer membrane in Gram-negative bacteria. Our previous data indicated that three TonB systems act coordinately to contribute to the motility of Aeromonas hydrophila NJ-35. In this study, we found that flagellum biogenesis was defective in the ΔtonB123 mutant. Subcellular localization indicated that the flagellin subunits FlaA and FlaB were trapped in the cytoplasm of ΔtonB123 mutant with reduced molecular mass. Overexpression of FlaA or FlaB in the ΔtonB123 mutant was unable to restore the secretion of flagellin subunits. Further investigation demonstrated that flagellins in the ΔtonB123 mutant showed a weak affinity for the flagellin-specific chaperone FliS, which is necessary for the export of flagellins. Deglycosylation analysis indicated that flagellins in the cytoplasm of the ΔtonB123 mutant were almost nonglycosylated. Our data suggested that disruption of tonB123 impairs the formation of flagella by inhibiting flagellin glycosylation and decreasing the binding affinity of flagellin for the chaperone FliS. Taken together, our findings indicate a new role of the TonB system in flagellar biogenesis in A. hydrophila.

摘要

TonB系统是革兰氏阴性菌中铁化合物跨外膜主动运输所必需的。我们之前的数据表明，三个TonB系统协同作用，有助于嗜水气单胞菌NJ-35的运动性。在本研究中，我们发现ΔtonB123突变体的鞭毛生物合成存在缺陷。亚细胞定位表明，鞭毛蛋白亚基FlaA和FlaB被困在ΔtonB123突变体的细胞质中，分子量降低。在ΔtonB123突变体中过表达FlaA或FlaB无法恢复鞭毛蛋白亚基的分泌。进一步研究表明，ΔtonB123突变体中的鞭毛蛋白对鞭毛蛋白特异性伴侣蛋白FliS的亲和力较弱，而FliS是鞭毛蛋白输出所必需的。去糖基化分析表明，ΔtonB123突变体细胞质中的鞭毛蛋白几乎没有糖基化。我们的数据表明，tonB123的破坏通过抑制鞭毛蛋白糖基化和降低鞭毛蛋白与伴侣蛋白FliS的结合亲和力，损害了鞭毛的形成。综上所述，我们的研究结果表明TonB系统在嗜水气单胞菌鞭毛生物合成中具有新的作用。