Flagella methylation promotes bacterial adhesion and host cell invasion

Abstract

AbstractThe flagellum is the motility device of many bacteria and the long external filament is made of several thousand copies of a single protein, flagellin. While posttranslational modifications of flagellin are common among bacterial pathogens, the role of lysine methylation remained unknown. Here, we show that both flagellins ofSalmonella enterica, FliC and FljB, are methylated at surface-exposed lysine residues. ASalmonellamutant deficient in flagellin methylation was outcompeted for gut colonization in a gastroenteritis mouse model. In support, methylation of flagellin promoted invasion of epithelial cellsin vitro. Lysine methylation increased the surface hydrophobicity of flagellin and enhanced flagella-dependent adhesion ofSalmonellato phosphatidylcholine vesicles and epithelial cells. In summary, posttranslational flagellin methylation constitutes a novel mechanism how flagellated bacteria facilitate adhesion to hydrophobic host cell surfaces and thereby contributes to efficient gut colonization and successful infection of the host.