Figure 3
Disulfatide binding to wtGLTP and the D48V mutant. (a) 3,6-O-Disulfo-Gal headgroup in the wtGLTP recognition centre. Dashed lines indicate hydrogen bonds. Disulfatide atoms are coloured red, blue, green and magenta for oxygen, nitrogen, sulfur and carbon, respectively. Protein C[alpha] backbone and side-chain C atoms are coloured silver and gold, respectively. The grey circle labelled W1 or W indicates the conserved water molecule. S1 and S2 (pink rectangles) are 3-O- and 6-O-sulfo groups, respectively. (b) Chemical structure of N-lauroyl-3,6-O-disulfo-galactosylceramide. (c) 3,6-O-Disulfo-Gal headgroup in the recognition centre of the D48V mutant. Colour codes and designations are as in (a), except for ligand C atoms, which are coloured cyan. The mutated residue 48 is shown in a red circle; the black arrow points out the different conformation of S2 compared with that in wtGLTP (a). (de) Electrostatic surface view (blue, positive; red, negative; grey, neutral) of the GLTP recognition centre in the wild-type protein (d) and the D48V mutant (e) occupied by a disulfatide molecule shown in stick representation within a space-filled semitransparent shape with green-coloured sulfo groups. Colour codes are as in (a) and (b). The mutated residue is shown in a red circle; arrows point out the `empty' space (filled by water molecules) resulting from the D48V mutation and the conformational change of the S2 group promoting the movement of the C-end. (f, h) Dimeric arrangements of 12:0-diSF in wtGLTP (f) and D48V (h), with the ligand in ball-and-stick representation. Colour codes are as in Figs. 2[link](d) and (e). (g) Superimposed disulfatide molecules as bound to D48V (cyan) versus wtGLTP (magenta).  [article HTML]