Bliska J B, Falkow S
Department of Microbiology and Immunology, Stanford University School of Medicine, CA 94305.
Proc Natl Acad Sci U S A. 1992 Apr 15;89(8):3561-5. doi: 10.1073/pnas.89.8.3561.
Ail is a 17-kDa outer membrane Yersinia protein that mediates bacterial attachment to, and invasion of, cultured epithelial cells. We report here an alternative role for Ail in the pathogenesis of Yersinia infection. We found that Escherichia coli HB101 harboring the 4-kilobase recombinant ail clone pVM102 were highly resistant to killing in up to 50% normal human serum. A 674-base-pair fragment of DNA from pVM102, which encodes the ail gene, was inserted into pUC18 and shown to promote full resistance to complement killing in E. coli HB101. Cellular attachment and resistance to complement killing in a plasmid-cured inv- strain of Yersinia enterocolitica (0:8) was correlated with the thermoinduced expression of Ail at 37 degrees C. Insertional inactivation of ail in Y. enterocolitica resulted in loss of both thermoinduced bacterial properties. Cellular attachment and serum resistance were restored by complementation of the defect by plasmid-encoded ail. Complementation of cell attachment activity required bacterial growth at 37 degrees C, indicating that an additional thermoinduced factor is required for this Ail function. In addition, these studies reveal that functional homology exists between Ail and the structurally related protein Rck, which promotes resistance to complement killing in Salmonella typhimurium.
Ail是一种17千道尔顿的耶尔森氏菌外膜蛋白，它介导细菌与培养的上皮细胞的附着和侵入。我们在此报告Ail在耶尔森氏菌感染发病机制中的另一种作用。我们发现，携带4千碱基重组ail克隆pVM102的大肠杆菌HB101在高达50%的正常人血清中具有高度抗杀伤能力。将来自pVM102的编码ail基因的674碱基对DNA片段插入pUC18，结果显示可促进大肠杆菌HB101对补体杀伤的完全抗性。小肠结肠炎耶尔森氏菌（0:8）的质粒消除inv-菌株中的细胞附着和对补体杀伤的抗性与37℃时Ail的热诱导表达相关。小肠结肠炎耶尔森氏菌中ail的插入失活导致这两种热诱导细菌特性丧失。通过质粒编码的ail对缺陷进行互补可恢复细胞附着和血清抗性。细胞附着活性的互补需要细菌在37℃生长，这表明这种Ail功能还需要另一种热诱导因子。此外，这些研究表明Ail与结构相关蛋白Rck之间存在功能同源性，Rck可促进鼠伤寒沙门氏菌对补体杀伤的抗性。
