ジャーナル: Science / 年: 2018 タイトル: Structures of C1-IgG1 provide insights into how danger pattern recognition activates complement. 著者: Deniz Ugurlar / Stuart C Howes / Bart-Jan de Kreuk / Roman I Koning / Rob N de Jong / Frank J Beurskens / Janine Schuurman / Abraham J Koster / Thomas H Sharp / Paul W H I Parren / Piet Gros / 要旨: Danger patterns on microbes or damaged host cells bind and activate C1, inducing innate immune responses and clearance through the complement cascade. How these patterns trigger complement initiation ...Danger patterns on microbes or damaged host cells bind and activate C1, inducing innate immune responses and clearance through the complement cascade. How these patterns trigger complement initiation remains elusive. Here, we present cryo-electron microscopy analyses of C1 bound to monoclonal antibodies in which we observed heterogeneous structures of single and clustered C1-immunoglobulin G1 (IgG1) hexamer complexes. Distinct C1q binding sites are observed on the two Fc-CH2 domains of each IgG molecule. These are consistent with known interactions and also reveal additional interactions, which are supported by functional IgG1-mutant analysis. Upon antibody binding, the C1q arms condense, inducing rearrangements of the C1rs proteases and tilting C1q's cone-shaped stalk. The data suggest that C1r may activate C1s within single, strained C1 complexes or between neighboring C1 complexes on surfaces.
凍結剤: ETHANE / チャンバー内湿度: 96 % / チャンバー内温度: 294 K / 装置: LEICA EM GP 詳細: 3 microlitres applied and incubated for 30 seconds, blot for 1 second before plunging.
詳細
Extruded liposomes were incubated with IgG1 and C1. Gold fiducials were added just before applying to grids.
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