Figure 5

Binding properties of selected gL-reverted mAbs is HCDR3-dependent Residues in the HCDR3 region of two selected igL binders were mutated in specific sites within their respective HCDR3s to asses binding to soluble YU2 gp140-F trimers.

These mutations were guided by previous modeling information of mature GE136 and GE148 and their interactions with gp120. (A) Fv regions of GEBT391 and GEBT404 were generated by the Protein Homology/Analogy Recognition Engine (Phyre) and the model was used in the computational protein docking program, ClusPro2 to generate models of GEBT391 (left) and GEBT404 (right) binding to gp120. The gp120 core is modeled inside the structure of BG505 SOSIP (PDB ID: 4TVP) to depict orientation in the context of the trimer. Both antibodies approach the gp120 CD4bs “from the side”, creating clash with the adjacent protomer in the trimer context. This clash is shown by the partial burial of the Hc within the protomer colored light blue (middle). The residues involved in recognition are depicted with a white dashed box (A) and are shown magnified (B). GEBT 391 residue Y107 and GEBT 404 residue V107 interact with D368 of gp120. (C) Mutating residues 106 and 107 in both mAbs eliminated recognition but changing the residue 109, which is relatively distal to the CD4 binding loop of gp120, resulted in only a partial reduction in binding.