Fig. 5

Comparisons of the V1V2 domain when bound by V2p, V2q and V2i mAbs. a A cartoon representation of CAP228-16H (V2p, left), PG9 (V2q, middle) and 830 A (V2i, right) bound to 1FD6 scaffolded V1V2. Only the Fab variable domains are shown for clarity, with the heavy and light chains coloured dark and light washed-out grey, respectively. All three structures are oriented with respect to the 1FD6 scaffold (metallic blue). Residues 167–179 that make up the V1V2 C-strand, or the IGHV5-51 bound α-helix, are shown in bright red, with the remaining V1V2 regions coloured as in Fig. 4. The V1V2 internal disulphide bonds are shown with yellow sticks, and α4β7 binding determinants are labelled with gold and silver spheres. A dashed line was used to indicate the approximate location for the rest of gp160 relative to full length V1V2. b Schematic of the V1V2 domain, showing the relative refolding of B- and C-strands, and repositioning of the A- and D-strands between the α-helical and β-stranded conformations of V1V2. The α4β7 binding determinants and disulphide bonds are labelled as in a. c Cartoon views and schematic representations of V1V2 in the CD4-bound or monomeric gp160 state (left panel), the V2p-bound α-helical state (middle panel), and the prefusion, entry-competent gp160 trimer (right panel). The β20 and β21 strands that make up one half of the bridging sheet are coloured orange and pink, respectively. The β2 strand of gp120 (or overlapping prefusion associated α-helical structure), and subsequent V1V2 A-strand region is coloured dark blue, while the V1V2 D-strand and subsequent β3 strand of gp120 is coloured green. The remaining V1V2 region is coloured as in b