Fig. 4.

Negative stain reconstruction of partially-deglycosylated soluble 664G Env trimer in complex with PGT 128 Fab. Soluble (664G) Env trimer was complexed with Fab PGT 128 and treated with Endo H to remove non-protected glycans. (A) Coordinates of the 128/eODmV3 complex structure fitted into the reconstruction density (blue). Overhead (top) and side (bottom) views show the fit of the crystal structure to the EM density (see SOM). Fab 128, depicted as blue (heavy) and white (light), and eODmV3 (red) are depicted in schematic backbone representation with glycans shown as yellow sticks. (B) Reconstruction density overlayed with cryo-electron tomographic reconstruction of native, unliganded trimer (yellow) (30). The putative location of V1/V2 is indicated. V3, N301, and N332 are exposed on the surface of the outer domain and slightly below the trimer apex, which corresponds to location of the V1/V2 loops. The PGT 128 epitope is located approximately on the opposite side of gp120 from the CD4bs (fig. S13C).