8RPB image
Entry Detail
PDB ID:
8RPB
Keywords:
Title:
Structure of S79 Fab in complex with IgV domain of human PD-L1
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2024-01-15
Release Date:
2024-06-19
Method Details:
Experimental Method:
Resolution:
2.79 Å
R-Value Free:
0.25
R-Value Work:
0.22
R-Value Observed:
0.23
Space Group:
P 62 2 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:heavy chain of S79 fab
Chain IDs:A (auth: H)
Chain Length:223
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:light chain of S79 fab
Chain IDs:B (auth: L)
Chain Length:217
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Programmed cell death 1 ligand 1
Chain IDs:C (auth: P)
Chain Length:125
Number of Molecules:1
Biological Source:Homo sapiens
Primary Citation
Structural analysis of light chain-driven bispecific antibodies targeting CD47 and PD-L1.
Mabs 16 2362432 2362432 (2024)
PMID: 38849989 DOI: 10.1080/19420862.2024.2362432

Abstact

In contrast to natural antibodies that rely mainly on the heavy chain to establish contacts with their cognate antigen, we have developed a bispecific antibody format in which the light chain (LC) drives antigen binding and specificity. To better understand epitope-paratope interactions in this context, we determined the X-ray crystallographic structures of an antigen binding fragment (Fab) in complex with human CD47 and another Fab in complex with human PD-L1. These Fabs contain a κ-LC and a λ-LC, respectively, which are paired with an identical heavy chain (HC). The structural analysis of these complexes revealed the dominant contribution of the LCs to antigen binding, but also that the common HC provides some contacts in both CD47 and PD-L1 Fab complexes. The anti-CD47 Fab was affinity optimized by diversifying complementary-determining regions of the LC followed by phage display selections. Using homology modeling, the contributions of the amino acid modification to the affinity increase were analyzed. Our results demonstrate that, despite a less prominent role in natural antibodies, the LC can mediate high affinity binding to different antigens and neutralize their biological function. Importantly, Fabs containing a common variable heavy (VH) domain enable the generation of bispecific antibodies retaining a truly native structure, maximizing their therapeutic potential.

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