4BM7

Crystal Structure of IgG Fc F241A mutant with native glycosylation

4BM7 の概要

• エントリーDOI: 10.2210/pdb4bm7/pdb
• 分子名称: IG GAMMA-1 CHAIN C REGION, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-2)-alpha-D-mannopyranose-(1-6)-[alpha-D-mannopyranose-(1-3)]beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-[beta-L-fucopyranose-(1-6)]2-acetamido-2-deoxy-beta-D-glucopyranose, CHLORIDE ION, ... (4 entities in total)
• 機能のキーワード: immune system, glycan
• 由来する生物種: HOMO SAPIENS (HUMAN)
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 53854.99

構造登録者

Yu, X.,Baruah, K.,Harvey, D.J.,Vasiljevic, S.,Alonzi, D.S.,Song, B.,Higgins, M.K.,Bowden, T.A.,Crispin, M.,Scanlan, C.N. (登録日: 2013-05-07, 公開日: 2013-07-03, 最終更新日: 2024-10-16)

主引用文献

Yu, X.,Baruah, K.,Harvey, D.J.,Vasiljevic, S.,Alonzi, D.S.,Song, B.,Higgins, M.K.,Bowden, T.A.,Scanlan, C.N.,Crispin, M.
Engineering Hydrophobic Protein-Carbohydrate Interactions to Fine-Tune Monoclonal Antibodies.
J.Am.Chem.Soc., 135:9723-, 2013

PubMed Abstract: Biologically active conformations of the IgG1 Fc homodimer are maintained by multiple hydrophobic interactions between the protein surface and the N-glycan. The Fc glycan modulates biological effector functions, including antibody-dependent cellular cytotoxicity (ADCC) which is mediated in part through the activatory Fc receptor, FcγRIIIA. Consistent with previous reports, we found that site-directed mutations disrupting the protein-carbohydrate interface (F241A, F243A, V262E, and V264E) increased galactosylation and sialylation of the Fc and, concomitantly, reduced the affinity for FcγRIIIA. We rationalized this effect by crystallographic analysis of the IgG1 Fc F241A mutant, determined here to a resolution of 1.9 Å, which revealed localized destabilization of this glycan-protein interface. Given that sialylation of Fc glycans decreases ADCC, one explanation for the effect of these mutants on FcγRIIIA binding is their increased sialylation. However, a glycan-engineered IgG1 with hypergalactosylated and hypersialylated glycans exhibited unchanged binding affinity to FcγRIIIA. Moreover, when we expressed these mutants as a chemically uniform (Man5GlcNAc2) glycoform, the individual effect of each mutation on FcγRIIIA affinity was preserved. This effect was broadly recapitulated for other Fc receptors (FcγRI, FcγRIIA, FcγRIIB, and FcγRIIIB). These data indicate that destabilization of the glycan-protein interactions, rather than increased galactosylation and sialylation, modifies the Fc conformation(s) relevant for FcγR binding. Engineering of the protein-carbohydrate interface thus provides an independent parameter in the engineering of Fc effector functions and a route to the synthesis of new classes of Fc domain with novel combinations of affinities for activatory and inhibitory Fc receptors.

PubMed: 23745692
DOI: 10.1021/JA4014375

実験手法

X-RAY DIFFRACTION (1.95 Å)