8C67

Crystal structure of Ab25 Fab

Summary for 8C67

• Entry DOI: 10.2210/pdb8c67/pdb
• Descriptor: antibody 25 heavy chain, antibody 25 light chain (3 entities in total)
• Functional Keywords: antibody, fab-domain, igg, immune system
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 8
• Total formula weight: 192555.08

Authors

Nyblom, M.,Izadi, A.,Tang, D.,Bahnan, W.,Happonen, L.,Malmstroem, J.,Shannon, O.,Malmstroem, L.,Nordenfelt, P. (deposition date: 2023-01-11, release date: 2024-04-24, Last modification date: 2024-11-06)

Primary citation

Izadi, A.,Karami, Y.,Bratanis, E.,Wrighton, S.,Khakzad, H.,Nyblom, M.,Olofsson, B.,Happonen, L.,Tang, D.,Sundwall, M.,Godzwon, M.,Chao, Y.,Toledo, A.G.,Schmidt, T.,Ohlin, M.,Nilges, M.,Malmstrom, J.,Bahnan, W.,Shannon, O.,Malmstrom, L.,Nordenfelt, P.
The hinge-engineered IgG1-IgG3 hybrid subclass IgGh 47 potently enhances Fc-mediated function of anti-streptococcal and SARS-CoV-2 antibodies.
Nat Commun, 15:3600-3600, 2024

PubMed Abstract: Streptococcus pyogenes can cause invasive disease with high mortality despite adequate antibiotic treatments. To address this unmet need, we have previously generated an opsonic IgG1 monoclonal antibody, Ab25, targeting the bacterial M protein. Here, we engineer the IgG2-4 subclasses of Ab25. Despite having reduced binding, the IgG3 version promotes stronger phagocytosis of bacteria. Using atomic simulations, we show that IgG3's Fc tail has extensive movement in 3D space due to its extended hinge region, possibly facilitating interactions with immune cells. We replaced the hinge of IgG1 with four different IgG3-hinge segment subclasses, IgGh. Hinge-engineering does not diminish binding as with IgG3 but enhances opsonic function, where a 47 amino acid hinge is comparable to IgG3 in function. IgGh shows improved protection against S. pyogenes in a systemic infection mouse model, suggesting that IgGh has promise as a preclinical therapeutic candidate. Importantly, the enhanced opsonic function of IgGh is generalizable to diverse S. pyogenes strains from clinical isolates. We generated IgGh versions of anti-SARS-CoV-2 mAbs to broaden the biological applicability, and these also exhibit strongly enhanced opsonic function compared to the IgG1 subclass. The improved function of the IgGh subclass in two distant biological systems provides new insights into antibody function.

PubMed: 38678029
DOI: 10.1038/s41467-024-47928-8

Experimental method

X-RAY DIFFRACTION (1.88 Å)