Bacterial flagella disrupt host cell membranes and interact with cytoskeletal components

Abstract

AbstractBacterial flagella have many established roles beyond swimming motility. Despite clear evidence of flagella-dependent adherence, the specificity of ligands and mechanisms of binding are still debated. In this study, the molecular basis ofE. coliO157:H7 andS. 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. SEM revealed flagella disappearing into cellular surfaces and TEM ofS. Typhiumurium indicated host membrane deformation and disruption in proximity to flagella. Motor mutants ofE. coliO157:H7 andS. Typhimurium caused reduced haemolysis compared to wild-type, indicating that membrane disruption was in part due to flagella rotation. Flagella fromE. coliO157 (H7), EPEC O127 (H6), andS. Typhimurium (P1 & P2 flagella) were shown to bind to purified intracellular components of the actin cytoskeleton and directly increase in vitro actin polymerisation rates.