Revisiting the role of glycosylation in the structure of human IgG Fc.
Revisiting the role of glycosylation in the structure of human IgG Fc.
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DOI：
10.1021/cb300130k
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发表时间：
2012-09-21
影响因子：
4
通讯作者：
Georgiou, George
中科院分区：
文献类型：
--
作者：
Borrok, M. Jack;Jung, Sang Taek;Kang, Tae Hyun;Monzingo, Arthur F.;Georgiou, George
免疫球蛋白G（IgG）的Fc结构域与白细胞上的Fcγ受体结合可引发一系列信号传导事件，导致抗体依赖性细胞介导的细胞毒性（ADCC）和其他重要的免疫应答。在N297处缺乏糖基化的Fc结构域大大降低了Fcγ受体结合，并且缺乏启动稳健ADCC应答的能力。对具有全长或截短N297聚糖的Fc结构域的早期结构研究提出，这些聚糖可以稳定Fcγ受体识别的“开放”Fc构象。我们确定了一个E.在3.1 nm分辨率下表达了去糖基化的人Fc结构域，并观察到C′E环（Fcγ受体结合的关键区域）的显著紊乱，以及相对于糖基化的Fc结构，CH 2结构域之间的距离减少。然而，无糖基化的人Fc结构与酶促去糖基化的Fc结构的比较揭示了CH 2结构域之间的相对取向和距离的巨大差异。为了更好地了解溶液中Fc结构域的生理学相关构象，我们通过小角X射线散射（SAXS）确定了回转半径（Rg），并发现非糖基化Fc显示出比糖基化Fc更大的Rg，表明在这些条件下更开放的CH 2取向。此外，无糖基化Fc的Rg通过CH 2-CH 3界面处的突变（E382 V/M428 I）而降低，这赋予了与FcγRI的高度选择性结合和新的生物学活性。
Binding of the Fc domain of Immunoglobulin G (IgG) to Fcγ receptors on leukocytes can initiate a series of signaling events resulting in antibody-dependent cell-mediated cytotoxicity (ADCC) and other important immune responses. Fc domains lacking glycosylation at N297 have greatly diminished Fcγ receptor binding and lack the ability to initiate a robust ADCC response. Earlier structural studies of Fc domains with either full length or truncated N297 glycans led to the proposal that these glycans can stabilize an “open” Fc conformation recognized by Fcγ receptors. We determined the structure of an E. coli expressed, aglycosylated human Fc domain at 3.1 Å resolution and observed significant disorder in the C′E loop, a region critical for Fcγ receptor binding, as well as a decrease in distance between the CH2 domains relative to glycosylated Fc structures. However, comparison of the aglycosylated human Fc structure with enzymatically deglycosylated Fc structures revealed large differences in the relative orientations and distances between CH2 domains. To provide a better appreciation of the physiologically relevant conformation of the Fc domain in solution, we determined Radii of Gyration (Rg) by small angle X-ray scattering (SAXS) and found that the aglycosylated Fc displays a larger Rg than glycosylated Fc, suggesting a more open CH2 orientation under these conditions. Moreover, the Rg of aglycosylated Fc was reduced by mutations at the CH2-CH3 interface (E382V/M428I), which confer highly selective binding to FcγRI and novel biological activities.
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影响因子：
4.8
作者：
Mimura, Y;Sondermann, P;Jefferis, R
通讯作者：
Jefferis, R
影响因子：
6.1
作者：
Konarev, PV;Volkov, VV;Svergun, DI
通讯作者：
Svergun, DI
影响因子：
4
作者：
Borrok, M. Jack;Zhu, Yimin;Forest, Katrina T.;Kiessling, Laura L.
通讯作者：
Kiessling, Laura L.
影响因子：
11.5
作者：
Niwa, R;Sakurada, M;Shitara, K
通讯作者：
Shitara, K
DOI：
10.1107/s0907444995016477
发表时间：
1996-07-01
期刊：
ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY
影响因子：
--
作者：
Kleywegt, GJ
通讯作者：
Kleywegt, GJ