Burkholderia cenocepacia is an opportunistic pathogen threatening patients with
cystic fibrosis. Flagella are required for biofilm formation, as well as adhesion to and invasion of epithelial cells. Recognition of
flagellin via the
Toll-like receptor 5 (TLR5) contributes to exacerbate B. cenocepacia-induced lung epithelial inflammatory responses. In this study, we report that B. cenocepacia
flagellin is glycosylated on at least 10 different sites with a single
sugar, 4,6-dideoxy-4-(3-hydroxybutanoylamino)-D-glucose. We have identified key genes that are required for
flagellin glycosylation, including a predicted
glycosyltransferase gene that is linked to the
flagellin biosynthesis cluster and a putative
acetyltransferase gene located within the
O-antigen lipopolysaccharide cluster. Another
O-antigen cluster gene, rmlB, which is required for
flagellin glycan and
O-antigen biosynthesis, was essential for bacterial viability, uncovering a novel target against
Burkholderia infections. Using glycosylated and nonglycosylated purified
flagellin and a cell reporter system to assess TLR5-mediated responses, we also show that the presence of
glycan in
flagellin significantly impairs the inflammatory response of epithelial cells. We therefore suggest that
flagellin glycosylation reduces recognition of
flagellin by host TLR5, providing an evasive strategy to infecting bacteria.