Fig. 2: N-glycosylation of archaellins in the Hbt. salinarum archaellum.

a Cartoon presentation of an archaellin, showing the positions of the three N-glycosylation sites and neighboring residues in different colors. b For each colored region highlighted in (a), the alignment of the five archaellin sequences (top right), the cryo-EM map (displayed as a mesh), and our consensus model (in stick presentation) of the archaellin and N-linked tetrasaccharide (N80 and N93) are presented. N80, N93, and N123 are colored cyan, red, and orange, respectively, as are other residues in the surroundings of each asparagine residue. Tetrasaccharide sugar carbons are colored black. c Surface presentation of the archaellum filament model with the tetrasaccharides linked to N80 and N93 colored cyan and red, respectively. Arrowheads indicate tetrasaccharides, which in this view, clearly protrude from the protein surface, instead of forming interactions with neighboring archaellins. The box on the right provides a closer view of one archaellin colored white with its tetrasaccharides linked to N80 and N93 colored cyan and red, respectively. In addition, the position of N123 is indicated in orange (the N-linked tetrasaccharide was not modeled at this position because only residual density was observed in the cryo-EM map), showing it is not found at the interface with neighboring archaellins, which are colored gray.