Fig. 5
Comparison of GDIR recognition by BG18 and 10-1074. a Cartoon and stick representation of BG18 CDRH3 (dark blue), BG18 CDL2 (light blue), and gp120 (gray; residues 318-330). Electron density contoured at 1σ from 2Fobs−Fcalc final refined electron density map with −100 Å2 B-sharpening is shown (gray mesh). b BG18 interactions with the gp120 GDIR motif (G324gp120-D325gp120-I326gp120-R327gp120) at the base of the V3-loop. In common with the PGT121-like bNAbs, CDRH3 E111HC forms a potential salt bridge with R327gp120, while CDRH3 Y104HC stacks against D325gp120. In addition, CDRL2 residues S53LC and Q54LC engage D325gp120 forming potential H-bond interactions. c Comparison of BG18 (light blue) and 10-1074 (pink; PDB 5T3Z (http://dx.doi.org10.2210/pdb5T3Z/pdb)) interactions with D325gp120 in the GDIR motif. Engagement of the carboxylate group of D325gp120 is achieved by residues in CDRL2 (BG18) or serine residues in CDRs L1 and L3 (10-1074). Potential H-bonds represented as dashed lines. d Alignment of sequences of inferred germline and mature light chains of BG18 and 10-1074. The LV3-21*02 germline V gene segment is used for both 10-1074 and PGT121-like antibodies40. Red asterisks indicate residues involved in D325gp120 recognition in the GDIR motif as shown in c
