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|3g6d, resolution 3.20Å ()|
|Gene:||IL13, NC30 (Homo sapiens)|
Crystal structure of the complex between CNTO607 Fab and IL-13
CNTO607 is a neutralizing anti-interleukin-13 (IL-13) human monoclonal antibody obtained from a phage display library. To determine how this antibody inhibits the biological effect of IL-13, we determined the binding epitope by X-ray crystallography. The crystal structure of the complex between CNTO607 Fab and IL-13 reveals the antibody epitope at the surface formed by helices A and D of IL-13. This epitope overlaps with the IL-4Ralpha/IL-13Ralpha1 receptor-binding site, which explains the neutralizing effect of CNTO607. The extensive antibody interface covers an area of 1000 A(2), which is consistent with the high binding affinity. The key features of the interface are the charge and shape complementarity of the molecules that include two hydrophobic pockets on IL-13 that accommodate Phe32 [complementarity-determining region (CDR) L2] and Trp100a (CDR H3) and a number of salt bridges between basic residues of IL-13 and acidic residues of the antibody. Comparison with the structure of the free Fab shows that the CDR residues do not change their conformation upon complex formation, with the exception of two residues in CDR H3, Trp100a and Asp100b, which change rotamer conformations. To evaluate the relative contribution of the epitope residues to CNTO607 binding, we performed alanine-scanning mutagenesis of the A-D region of IL-13. This study confirmed the primary role of electrostatic interactions for antigen recognition.
Epitope mapping of anti-interleukin-13 neutralizing antibody CNTO607., Teplyakov A, Obmolova G, Wu SJ, Luo J, Kang J, O'Neil K, Gilliland GL, J Mol Biol. 2009 May 29;389(1):115-23. Epub 2009 Apr 8. PMID:19361524
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
[IL13_HUMAN] Defects in IL13 may be a cause of susceptibility to allergic rhinitis (ALRH) [MIM:607154]. Allergic rhinitis is a common disease of complex inheritance and is characterized by mucosal inflammation caused by allergen exposure.
[IL13_HUMAN] Cytokine. Inhibits inflammatory cytokine production. Synergizes with IL2 in regulating interferon-gamma synthesis. May be critical in regulating inflammatory and immune responses.