Mechanisms of Neutralization of a Human Anti-alpha-toxin Antibody.
Oganesyan, V., Peng, L., Damschroder, M.M., Cheng, L., Sadowska, A., Tkaczyk, C., Sellman, B.R., Wu, H., Dall'Acqua, W.F.(2014) J Biol Chem 289: 29874-29880
- PubMed: 25210036 
- DOI: https://doi.org/10.1074/jbc.M114.601328
- Primary Citation of Related Structures:  
4U6V - PubMed Abstract: 
MEDI4893 is a neutralizing human monoclonal antibody that targets α-toxin (AT) and is currently undergoing evaluation in the field of Staphylococcus aureus-mediated diseases. We have solved the crystal structure of MEDI4893 Fab bound to monomeric AT at a resolution of 2.56 Å and further characterized its epitope using various engineered AT variants. We have found that MEDI4893 recognizes a novel epitope in the so-called "rim" domain of AT and exerts its neutralizing effect through a dual mechanism. In particular, MEDI4893 not only sterically blocks binding of AT to its cell receptor but also prevents it from adopting a lytic heptameric trans-membrane conformation.
Organizational Affiliation: 
From the Departments of Antibody Discovery and Protein Engineering and oganesyanv@medimmune.com.