Figure 2: Effects of binding of CD4bs-targeting bNAbs.

Butterfly plots show the exchange profiles of SOSIP.664 trimers either unliganded (positive y axis) or as complexes with (a) VRC01 Fab or (b) b12 Fab (negative y axis). The per cent exchange for each observable peptide is plotted at the position of the centre of the peptide on the primary sequence for each time point (3 s to 20 h). The difference plots below each primary plot reveal regions undergoing slower exchange (more protected, above the zero) and faster exchange (less protected, below the zero). Individual plots for the peptides at V1/V2 and V3 are shown in Fig. 6, and plots for every peptide are in Supplementary Figs 1 and 2. (c,d) Differences are mapped onto the closed, pre-fusion trimer crystal structure (PDB accession code: 4NCO)¹⁰, with regions of faster (red) or slower exchange (blue) in the presence of each antibody highlighted. Segments unresolved in the crystal structure (V2, V4 and FPPR) are shown as dashed lines. As a reference, the binding surfaces of each bNAb on gp120 are shown in green (PDB: 3NGB, 2NY7)^21,22. Although b12 binds a more open conformation of the trimer^9,17,18, for the sake of comparison all data are illustrated on the closed, pre-fusion structure.