Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200241, China.
FEMS Microbiol Lett. 2018 Sep 1;365(17). doi: 10.1093/femsle/fny142.
Salmonella enterica serovar Typhimurium (S. Typhimurium) is an important food-borne zoonotic pathogen that causes increased morbidity and mortality worldwide. The autotransporter (AT) proteins are a large and diverse family of extracellular proteins, many of which contribute to the pathogenicity of Gram-negative bacteria. The S. Typhimurium AT protein MisL mediates intestinal colonization in mice. Bioinformatics analyses indicated that MisL clusters with ATs are involved in bacterial biofilm formation, aggregation and adherence. In this study, we found that the misL overexpression increased S. Typhimurium biofilm formation. In addition, the misL deletion reduced bacterial adherence and invasion abilities on HeLa cells, but did not affect the bacterial virulence. Similarly, MisL expression in Escherichia coli strain promoted bacterial biofilm formation as well as adhesion and invasion capacities. However, the misL overexpression had no influence on the bacterial aggregation except for AAEC189Δflu, a strain lacking type I fimbriae. Moreover, we demonstrated that immunization with recombinant MisL protein stimulated the production of high IgG antibody titers, which conferred modest protection against S. Typhimurium infection. This study illustrates the novel biological functions and immunoprotective effects of MisL in S. Typhimurium.
鼠伤寒沙门氏菌（S. Typhimurium）是一种重要的食源性病原体，可导致全球发病率和死亡率上升。自转运蛋白（AT）是一类庞大而多样的细胞外蛋白家族，其中许多蛋白与革兰氏阴性菌的致病性有关。S. Typhimurium 的 AT 蛋白 MisL 介导了在小鼠中的肠道定殖。生物信息学分析表明，MisL 与参与细菌生物膜形成、聚集和黏附的 AT 聚类。在本研究中，我们发现 MisL 的过表达增加了鼠伤寒沙门氏菌的生物膜形成。此外，misL 缺失降低了细菌对 HeLa 细胞的黏附和侵袭能力，但不影响细菌的毒力。同样，大肠杆菌菌株中 MisL 的表达也促进了细菌生物膜的形成以及黏附和侵袭能力。然而，除了缺乏 I 型菌毛的 AAEC189Δflu 菌株外，MisL 的过表达对细菌聚集没有影响。此外，我们证明了用重组 MisL 蛋白免疫可刺激产生高 IgG 抗体滴度，从而对鼠伤寒沙门氏菌感染提供适度的保护。本研究阐明了 MisL 在鼠伤寒沙门氏菌中的新生物学功能和免疫保护作用。
