1. The Therapeutic Antibody LM609 Selectively Inhibits Ligand Binding to Human α V β 3 Integrin via Steric Hindrance.
- Author
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Borst AJ, James ZM, Zagotta WN, Ginsberg M, Rey FA, DiMaio F, Backovic M, and Veesler D
- Subjects
- Amino Acid Motifs, Angiogenesis Inhibitors chemistry, Angiogenesis Inhibitors immunology, Angiogenesis Inhibitors metabolism, Antibodies, Monoclonal genetics, Antibodies, Monoclonal immunology, Antigens genetics, Antigens immunology, Antiviral Agents chemistry, Antiviral Agents immunology, Antiviral Agents metabolism, Binding Sites, Bone Density Conservation Agents chemistry, Bone Density Conservation Agents immunology, Bone Density Conservation Agents metabolism, Cloning, Molecular, Crystallography, X-Ray, Escherichia coli genetics, Escherichia coli metabolism, Gene Expression, Genetic Vectors chemistry, Genetic Vectors metabolism, Humans, Immunoglobulin Fab Fragments genetics, Immunoglobulin Fab Fragments immunology, Integrin alphaVbeta3 genetics, Integrin alphaVbeta3 immunology, Ligands, Models, Molecular, Oligopeptides genetics, Oligopeptides immunology, Protein Binding, Protein Conformation, beta-Strand, Protein Interaction Domains and Motifs, Recombinant Proteins chemistry, Recombinant Proteins genetics, Recombinant Proteins immunology, Antibodies, Monoclonal chemistry, Antigens chemistry, Immunoglobulin Fab Fragments chemistry, Integrin alphaVbeta3 chemistry, Oligopeptides chemistry
- Abstract
The LM609 antibody specifically recognizes α
V β3 integrin and inhibits angiogenesis, bone resorption, and viral infections in an arginine-glycine-aspartate-independent manner. LM609 entered phase II clinical trials for the treatment of several cancers and was also used for αV β3 -targeted radioimmunotherapy. To elucidate the mechanisms of recognition and inhibition of αV β3 integrin, we solved the structure of the LM609 antigen-binding fragment by X-ray crystallography and determined its binding affinity for αV β3 . Using single-particle electron microscopy, we show that LM609 binds at the interface between the β-propeller domain of the αV chain and the βI domain of the β3 chain, near the RGD-binding site, of all observed integrin conformational states. Integrating these data with fluorescence size-exclusion chromatography, we demonstrate that LM609 sterically hinders access of large ligands to the RGD-binding pocket, without obstructing it. This work provides a structural framework to expedite future efforts utilizing LM609 as a diagnostic or therapeutic tool., (Copyright © 2017 Elsevier Ltd. All rights reserved.)- Published
- 2017
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