The Structural Role of Antibody N-Glycosylation in Receptor Interactions.
The Structural Role of Antibody N-Glycosylation in Receptor Interactions.
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DOI：
10.1016/j.str.2015.06.015
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发表时间：
2015-09-01
期刊：
影响因子：
--
通讯作者：
Barb AW
中科院分区：
文献类型：
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作者：
Subedi GP;Barb AW
IgG Fc的天冬酰胺(N)297链糖基化是与Fcγ riia、IIb和IIIa结合所必需的，但其作用机制尚不清楚。我们发现糖基化Fc的四级结构与糖基化Fc难以区分，这表明n -糖基化不保持Fc c - γ2/ c - γ3结构域的相对取向。然而，含有N297的C e环的构象在糖基化的Fc变体中明显受到干扰。用一系列Fc变体测量的C e环构象显示了与Fcγ riiia亲和力的强相关性。这些结果表明，IgG1 Fc n -聚糖的主要作用是通过碳水化合物和氨基酸残基之间的分子内相互作用来稳定C - e环，并预先组织Fcγ riiia界面以获得最佳的结合亲和力。有助于IgG1 Fc n -聚糖限制蛋白质构象和调节结合亲和力的功能在其他抗体中保守，包括IgG2-4、IgD、IgE和IgM。
Asparagine(N)297-linked glycosylation of IgG Fc is required for binding to FcγRIIa, IIb and IIIa though it is unclear how it contributes. We found the quaternary structure of glycosylated Fc was indistinguishable from aglycosylated Fc indicating N-glycosylation does not maintain relative Fc Cγ2/Cγ3 domain orientation. However, the conformation of the C'E loop, which contains N297, was significantly perturbed in the aglycosylated Fc variant. The conformation of the C'E loop as measured with a range of Fc variants shows a strong correlation with FcγRIIIa affinity. These results indicate the primary role of the IgG1 Fc N-glycan is to stabilize the C'E loop through intramolecular interactions between carbohydrate and amino acid residues and preorganize the FcγRIIIa interface for optimal binding affinity. The features that contribute to the capacity of the IgG1 Fc N-glycan to restrict protein conformation and tune binding affinity are conserved in other antibodies including IgG2-4, IgD, IgE and IgM.