Division of Immunity and Infection, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK.
Departments of Biochemistry, Biomedical Sciences Building, The University of Bristol, Bristol, BS8 1TD, UK.
Microbiology (Reading). 2020 Oct;166(10):947-965. doi: 10.1099/mic.0.000959.
Bacterial flagella have many established roles beyond swimming motility. Despite clear evidence of flagella-dependent adherence, the specificity of the ligands and mechanisms of binding are still debated. In this study, the molecular basis of O157:H7 and serovar Typhimurium flagella binding to epithelial cell cultures was investigated. Flagella interactions with host cell surfaces were intimate and crossed cellular boundaries as demarcated by actin and membrane labelling. Scanning electron microscopy revealed flagella disappearing into cellular surfaces and transmission electron microscopy of . Typhiumurium indicated host membrane deformation and disruption in proximity to flagella. Motor mutants of O157:H7 and . Typhimurium caused reduced haemolysis compared to wild-type, indicating that membrane disruption was in part due to flagella rotation. Flagella from O157 (H7), EPEC O127 (H6) and . Typhimurium (P1 and P2 flagella) were shown to bind to purified intracellular components of the actin cytoskeleton and directly increase actin polymerization rates. We propose that flagella interactions with host cell membranes and cytoskeletal components may help prime intimate attachment and invasion for O157:H7 and . Typhimurium, respectively.
细菌鞭毛除了在游泳运动中具有许多既定的作用外。尽管有明确的证据表明鞭毛依赖性附着，但配体的特异性和结合机制仍存在争议。在这项研究中，研究了 O157:H7 和 鼠伤寒沙门氏菌鞭毛与上皮细胞培养物结合的分子基础。鞭毛与宿主细胞表面的相互作用非常密切，并穿过了由肌动蛋白和膜标记物划定的细胞边界。扫描电子显微镜显示鞭毛消失在细胞表面，透射电子显微镜观察到 鼠伤寒沙门氏菌 表明在靠近鞭毛的地方宿主膜发生变形和破裂。与野生型相比，O157:H7 和 鼠伤寒沙门氏菌 的运动突变体引起的溶血减少，表明膜的破坏部分是由于鞭毛的旋转。O157（H7）、EPEC O127（H6）和 鼠伤寒沙门氏菌（P1 和 P2 鞭毛）的鞭毛被证明可以与肌动蛋白细胞骨架的纯化细胞内成分结合，并直接增加 肌动蛋白聚合率。我们提出，鞭毛与宿主细胞膜和细胞骨架成分的相互作用可能有助于分别为 O157:H7 和 鼠伤寒沙门氏菌 进行紧密附着和入侵做好准备。
