Polar flagellin glycan metaheterogeneity of Aeromonas hydrophila strain ATCC 7966T

Motile pathogens often rely upon flagellar motility as an essential virulence factor and in many species the structural flagellin protein is glycosylated. This post-translational modification has been shown to be necessary for proper folding of the flagellin structural proteins and proper function of the flagellar filament in a number of bacterial species. Aeromonas hydrophila is a ubiquitous aquatic pathogen with a constitutively expressed polar flagellum. Using a suite of mass spectrometry techniques, the flagellin FlaA and FlaB structural proteins of A. hydrophila strain ATCC 7966T were shown to be glycosylated with significant metaheterogeneity: heterologous glycans were observed with variable site occupancy. The penta- and hexa-saccharide glycan chains contained a previously unreported pseudaminic acid derivative with a mass of 422 Da as the linking sugar, followed in sequence by two hexoses, an N-acetylglucosamine derivative, a deoxy N-acetylglucosamine derivative, and sometimes an additional N-acetylglucosamine.