Specific interactions of LPyV VP1 and 3SL.

A and B. LPyV VP1 is shown in cartoon and surface representation, with side chains interacting with 3SL shown in stick representation. The 3SL oligosaccharide is shown in stick representation and colored by element, with carbons in orange, nitrogens in blue and oxygens in red. Waters are represented with spheres. Selected carbon atoms of 3SL are numbered in italics. Residues engaging in hydrophobic interactions with 3SL are colored bright green and residues forming polar van der Waals contacts or water-mediated hydrogen bonds are colored dark green. Direct hydrogen bonds between LPyV VP1 and the oligosaccharide are shown as red dashed lines, water-mediated hydrogen bonds are colored black. The views depicted in A and B differ by a 70° rotation around a vertical axis. C. Location of LPyV VP1 mutations influencing cell tropism. An entire LPyV VP1 pentamer is shown in surface representation. The N-terminal arms were omitted for clarity. One monomer is colored dark green, and the residues forming the oligosaccharide binding site are highlighted in light green. Residues whose mutation was shown to influence cell tropism of LPyV VP1 are colored magenta. The 3SL and 3SLN oligosaccharides are shown in stick representation and colored orange and yellow, respectively.