Binding symmetry and surface flexibility mediate antibody self-association.Schrag, J.D., Picard, M.E., Gaudreault, F., Gagnon, L.P., Baardsnes, J., Manenda, M.S., Sheff, J., Deprez, C., Baptista, C., Hogues, H., Kelly, J.F., Purisima, E.O., Shi, R., Sulea, T.
(2019) MAbs 11: 1300-1318
- PubMed: 31318308
- DOI: 10.1080/19420862.2019.1632114
- Structures With Same Primary Citation
- PubMed Abstract:
Solution stability is an important factor in the optimization of engineered biotherapeutic candidates such as monoclonal antibodies because of its possible effects on manufacturability, pharmacology, efficacy and safety. A detailed atomic understandi ...
Solution stability is an important factor in the optimization of engineered biotherapeutic candidates such as monoclonal antibodies because of its possible effects on manufacturability, pharmacology, efficacy and safety. A detailed atomic understanding of the mechanisms governing self-association of natively folded protein monomers is required to devise predictive tools to guide screening and re-engineering along the drug development pipeline. We investigated pairs of affinity-matured full-size antibodies and observed drastically different propensities to aggregate from variants differing by a single amino-acid. Biophysical testing showed that antigen-binding fragments (Fabs) from the aggregating antibodies also reversibly associated with equilibrium dissociation constants in the low-micromolar range. Crystal structures (PDB accession codes 6MXR, 6MXS, 6MY4, 6MY5) and bottom-up hydrogen-exchange mass spectrometry revealed that Fab self-association occurs in a symmetric mode that involves the antigen complementarity-determining regions. Subtle local conformational changes incurred upon point mutation of monomeric variants foster formation of complementary polar interactions and hydrophobic contacts to generate a dimeric Fab interface. Testing of popular in silico tools generally indicated low reliabilities for predicting the aggregation propensities observed. A structure-aggregation data set is provided here in order to stimulate further improvements of in silico tools for prediction of native aggregation. Incorporation of intermolecular docking, conformational flexibility, and short-range packing interactions may all be necessary features of the ideal algorithm.
Human Health Therapeutics Research Centre, National Research Council Canada , Montreal , QC H4P 2R2 , Canada.