Yanaka Saeko, Sakae Yoshitake, Miyanoiri Yohei, Yamaguchi Takumi, Isono Yukiko, Kondo Sachiko, Iwasaki Miyuki, Onitsuka Masayoshi, Yagi Hirokazu, Kato Koichi
Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki 444-8787, Aichi, Japan.
Core for Spin Life Sciences, Okazaki Collaborative Platform, National Institutes of Natural Sciences, Myodaiji 444-8787, Okazaki, Japan.
Proc Natl Acad Sci U S A. 2025 Aug 12;122(32):e2505473122. doi: 10.1073/pnas.2505473122. Epub 2025 Aug 5.
We investigate the impact of glycoform alterations on the dynamic structure of the human immunoglobulin G1 (IgG1) Fc region using integrated computational and experimental approaches. Four distinct IgG1-Fc glycoforms, varying in core fucosylation and nonreducing terminal galactosylation, were generated through a combination of cell engineering and in vitro enzymatic reactions. Stable-isotope-assisted NMR spectroscopy, incorporating both glycan and protein signals, revealed that galactosylation induces chemical shift perturbations extending from the glycan-protein interface to the C2-C3 domain boundary. Molecular dynamics simulations demonstrated that the absence of galactose enhances the mobility of both the glycan and the C2 domain, broadening the conformational landscape of the Fc quaternary structure. This increased flexibility likely contributes to a greater entropic penalty upon binding to effector molecules, which constrain the Fc in an asymmetric conformation. Conversely, the effects of fucosylation are more localized, primarily influencing the dynamics of residues involved in Fcγ receptor IIIa binding. These findings provide atomic-level insights into the distinct yet synergistic mechanisms by which galactosylation and fucosylation modulate IgG1-Fc dynamics and effector functions, offering crucial information for the optimization of therapeutic antibodies.
我们采用综合计算和实验方法,研究了糖型改变对人免疫球蛋白G1(IgG1)Fc区域动态结构的影响。通过细胞工程和体外酶促反应相结合的方式,产生了四种不同的IgG1-Fc糖型,它们在核心岩藻糖基化和非还原末端半乳糖基化方面存在差异。结合聚糖和蛋白质信号的稳定同位素辅助核磁共振光谱显示,半乳糖基化会引起从聚糖-蛋白质界面延伸至C2-C3结构域边界的化学位移扰动。分子动力学模拟表明,缺乏半乳糖会增强聚糖和C2结构域的流动性,拓宽Fc四级结构的构象格局。这种增加的灵活性可能导致与效应分子结合时产生更大的熵罚,效应分子会将Fc限制在不对称构象中。相反,岩藻糖基化的影响更为局部,主要影响参与Fcγ受体IIIa结合的残基的动力学。这些发现为半乳糖基化和岩藻糖基化调节IgG1-Fc动力学和效应功能的独特但协同的机制提供了原子水平的见解,为治疗性抗体的优化提供了关键信息。
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