Li Quan, Li Zheng, Fei Xia, Tian Yichen, Zhou Guodong, Hu Yuhan, Wang Shifeng, Shi Huoying
College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China.
Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, Jiangsu, China.
AMB Express. 2022 Jan 25;12(1):5. doi: 10.1186/s13568-022-01347-4.
The Tol-Pal system of Gram-negative bacteria is necessary for maintaining outer membrane integrity. It is a multiprotein complex of five envelope proteins, TolQ, TolR, TolA, TolB, and Pal. These proteins were first investigated in E. coli, and subsequently been identified in many other bacterial genera. However, the function of the Tol-Pal system in Salmonella Choleraesuis pathogenesis is still unclear. Here, we reported the role of three of these proteins in the phenotype and biology of S. Choleraesuis. We found that mutations in tolA, tolB, and tolR caused severe damage to the cell wall, which was supported by observing the microstructure of spherical forms, long chains, flagella defects, and membrane blebbing. We confirmed that all the mutants significantly decreased S. Choleraesuis survival when exposed to sodium deoxycholate and exhibited a high sensitivity to vancomycin, which may be explained by the disruption of envelope integrity. In addition, tolA, tolB, and tolR mutants displayed attenuated virulence in a mouse infection model. This could be interpreted as a series of defective phenotypes in the mutants, such as severe defects in envelope integrity, growth, and motility. Further investigation showed that all the genes participate in outer membrane vesicles (OMVs) biogenesis. Interestingly, immunization with OMVs from ΔtolB efficiently enhanced murine viability in contrast to OMVs from the wild-type S. Choleraesuis, suggesting its potential use in vaccination strategies. Collectively, this study provides an insight into the biological role of the S. Choleraesuis Tol-Pal system.
革兰氏阴性菌的Tol-Pal系统对于维持外膜完整性是必需的。它是由五种包膜蛋白TolQ、TolR、TolA、TolB和Pal组成的多蛋白复合物。这些蛋白最初在大肠杆菌中被研究，随后在许多其他细菌属中也被鉴定出来。然而，Tol-Pal系统在猪霍乱沙门氏菌致病机制中的作用仍不清楚。在此，我们报道了其中三种蛋白在猪霍乱沙门氏菌表型和生物学中的作用。我们发现tolA、tolB和tolR的突变对细胞壁造成了严重损伤，这通过观察球形形态、长链、鞭毛缺陷和膜泡化的微观结构得到了证实。我们证实，当暴露于脱氧胆酸钠时，所有突变体均显著降低了猪霍乱沙门氏菌的存活率，并对万古霉素表现出高度敏感性，这可能是由于包膜完整性的破坏所致。此外，tolA、tolB和tolR突变体在小鼠感染模型中表现出毒力减弱。这可以解释为突变体中出现了一系列缺陷表型，如包膜完整性、生长和运动性方面的严重缺陷。进一步研究表明，所有这些基因都参与外膜囊泡（OMV）的生物合成。有趣的是，与野生型猪霍乱沙门氏菌的OMV相比，用ΔtolB的OMV进行免疫能有效提高小鼠的存活率，这表明其在疫苗接种策略中有潜在用途。总的来说，这项研究深入了解了猪霍乱沙门氏菌Tol-Pal系统的生物学作用。
