Résumé:
Magnetotactic bacteria (MTBs) are microaerophilic aquatic bacteria that can swim (using their flagella) toward their optimal development zone, the oxic-anoxic transition zone (OATZ). For that, they are helped by magnetotaxis (detection of the Earth's magnetic field) and chemotaxis (detection of the oxygen gradient). These three components (magnetotaxis, chemotaxis, and swimming) define an unique property of MTBs: the magneto-aerotaxis. We demonstrated that the flagellin (the protein that forms the flagellar filament) of MTBs is glycosylated, and that this glycosylation is crucial for the set-up of the filament and therefore for the motility. The synergy of our respective expertise in bacterial genetics, protein crystallography, and glycobiology bioinformatics has allowed us to identify three new types of bacterial glycosyltransferases found in MTBs, as well as in many other bacterial species, and to demonstrate their essential roles in the mechanism of forming a functional flagellum.
Mots clés:
Magnetotactic bacteria, motility, flagella structure, glycosylation, glycosyltransferases