ジャーナル: Structure / 年: 2024 タイトル: Structural basis for the inhibition of βFXIIa by garadacimab. 著者: Ieva Drulyte / Rajesh Ghai / Saw Yen Ow / Eugene A Kapp / Adam J Quek / Con Panousis / Michael J Wilson / Andrew D Nash / Matthias Pelzing / 要旨: Activated FXII (FXIIa) is the principal initiator of the plasma contact system and can activate both procoagulant and proinflammatory pathways. Its activity is important in the pathophysiology of ...Activated FXII (FXIIa) is the principal initiator of the plasma contact system and can activate both procoagulant and proinflammatory pathways. Its activity is important in the pathophysiology of hereditary angioedema (HAE). Here, we describe a high-resolution cryoelectron microscopy (cryo-EM) structure of the beta-chain from FXIIa (βFXIIa) complexed with the Fab fragment of garadacimab. Garadacimab binds to βFXIIa through an unusually long CDR-H3 that inserts into the S1 pocket in a non-canonical way. This structural mechanism is likely the primary contributor to the inhibition of activated FXIIa proteolytic activity in HAE. Garadacimab Fab-βFXIIa structure also reveals critical determinants of high-affinity binding of garadacimab to activated FXIIa. Structural analysis with other bona fide FXIIa inhibitors, such as benzamidine and C1-INH, reveals a surprisingly similar mechanism of βFXIIa inhibition by garadacimab. In summary, the garadacimab Fab-βFXIIa structure provides crucial insights into its mechanism of action and delineates primary and auxiliary paratopes/epitopes.
pH: 5.5 / 詳細: 10 mM Na Acetate, 100 mM NaCl pH 5.5
グリッド
モデル: UltrAuFoil R1.2/1.3 / 材質: GOLD / メッシュ: 300 / 前処理 - タイプ: GLOW DISCHARGE / 前処理 - 時間: 30 sec. / 前処理 - 雰囲気: AIR / 詳細: plasma current 20 mA
凍結
凍結剤: ETHANE / チャンバー内湿度: 90 % / チャンバー内温度: 277 K / 装置: FEI VITROBOT MARK IV
詳細
Immediately before blotting and plunge freezing, fluorinated octyl maltoside (FOM) was added to the sample to the final concentration of 0.005%-0.01% (w/v)
-
電子顕微鏡法
顕微鏡
FEI TITAN KRIOS
特殊光学系
エネルギーフィルター - 名称: TFS Selectris / エネルギーフィルター - スリット幅: 10 eV 詳細: Electron source E-CFEG (cold-FEG), energy filter Selectris X
撮影
フィルム・検出器のモデル: FEI FALCON IV (4k x 4k) 撮影したグリッド数: 2 / 実像数: 4000 / 平均電子線量: 50.0 e/Å2 / 詳細: 2000 with 0.005% FOM and 2000 with 0.01% FOM
選択した数: 271636 詳細: Particles were picked from each of the datasets independently using a blob picker using 50-170 A diameter. 124767 particles were picked from the 0.005% FOM dataset and 146869 particles from the 0.01% FOM dataset.
初期モデル
モデルのタイプ: INSILICO MODEL / In silico モデル: Ab Initio / 詳細: Ab Initio reconstruction was performed in cryoSPARC