Chemical and structural analysis of an antibody folding intermediate trapped during glycan biosynthesis

Journal article

Human IgG Fc glycosylation modulates immunological effector functions such as antibody-dependent cellular cytotoxicity and phagocytosis. Engineering of Fc glycans therefore enables fine-tuning of the therapeutic properties of monoclonal antibodies. The N-linked glycans of Fc are typically complex-type, forming a network of noncovalent interactions along the protein surface of the Cγ2 domain. Here, we manipulate the mammalian glycan-processing pathway to trap IgG1 Fc at sequential stages of maturation, from oligomannose- to hybrid- to complex-type glycans, and show that the Fc is structurally stabilized following the transition of glycans from their hybrid- to complex-type state. X-ray crystallographic analysis of this hybrid-type intermediate reveals that N-linked glycans undergo conformational changes upon maturation, including a flip within the trimannosyl core. Our crystal structure of this intermediate reveals a molecular basis for antibody biogenesis and provides a template for the structure-guided engineering of the protein-glycan interface of therapeutic antibodies.

Authors: Bowden, T; Baruah, K; Coles, C; Harvey, D; Yu, X

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Chemical Society
• Journal: Journal of the American Chemical Society
• Volume: 134
• Issue: 42
• Pages: 17554-17563
• Publication date: 2012-10-01
• DOI: 10.1021/ja306068g
• EISSN: 1520-5126
• ISSN: 0002-7863
• Language: English
• Keywords: Models, Molecular; Immunoglobulin Fc Fragments; Humans; Crystallography, X-Ray; Polysaccharides; Molecular Structure; Protein Folding