Structural basis for improved efficacy of therapeutic antibodies on defucosylation of their Fc glycans.

ABSTRACT: Removal of the fucose residue from the N-glycans of the Fc portion of immunoglobulin G (IgG) results in a dramatic enhancement of antibody-dependent cellular cytotoxicity (ADCC) through improved affinity for Fc? receptor IIIa (Fc?RIIIa). Here, we present the 2.2-Å structure of the complex formed between nonfucosylated IgG1-Fc and a soluble form of Fc?RIIIa (sFc?RIIIa) with two N-glycosylation sites. The crystal structure shows that one of the two N-glycans of sFc?RIIIa mediates the interaction with nonfucosylated Fc, thereby stabilizing the complex. However, fucosylation of the Fc N-glycans inhibits this interaction, because of steric hindrance, and furthermore, negatively affects the dynamics of the receptor binding site. Our results offer a structural basis for improvement in ADCC of therapeutic antibodies by defucosylation.

SUBMITTER: Mizushima T 

PROVIDER: S-EPMC3258418 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature