ジャーナル: Nat Commun / 年: 2020 タイトル: Structural basis for tuning activity and membrane specificity of bacterial cytolysins. 著者: Nita R Shah / Tomas B Voisin / Edward S Parsons / Courtney M Boyd / Bart W Hoogenboom / Doryen Bubeck / 要旨: Cholesterol-dependent cytolysins (CDCs) are pore-forming proteins that serve as major virulence factors for pathogenic bacteria. They target eukaryotic cells using different mechanisms, but all ...Cholesterol-dependent cytolysins (CDCs) are pore-forming proteins that serve as major virulence factors for pathogenic bacteria. They target eukaryotic cells using different mechanisms, but all require the presence of cholesterol to pierce lipid bilayers. How CDCs use cholesterol to selectively lyse cells is essential for understanding virulence strategies of several pathogenic bacteria, and for repurposing CDCs to kill new cellular targets. Here we address that question by trapping an early state of pore formation for the CDC intermedilysin, bound to the human immune receptor CD59 in a nanodisc model membrane. Our cryo electron microscopy map reveals structural transitions required for oligomerization, which include the lateral movement of a key amphipathic helix. We demonstrate that the charge of this helix is crucial for tuning lytic activity of CDCs. Furthermore, we discover modifications that overcome the requirement of cholesterol for membrane rupture, which may facilitate engineering the target-cell specificity of pore-forming proteins.
モデル: Quantifoil R1.2/1.3 / 材質: COPPER / メッシュ: 400 / 支持フィルム - 材質: GRAPHENE OXIDE / 支持フィルム - トポロジー: CONTINUOUS / 前処理 - タイプ: GLOW DISCHARGE / 前処理 - 時間: 60 sec. / 前処理 - 雰囲気: AIR 詳細: Grids were glow discharged before application of graphene oxide, then left to dry for 1 hour before use.
凍結
凍結剤: ETHANE / チャンバー内湿度: 95 % / チャンバー内温度: 294 K / 装置: FEI VITROBOT MARK III / 詳細: Wait time of 60 s, blot time 2.5 s, blot force 3.
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電子顕微鏡法
顕微鏡
FEI TITAN KRIOS
詳細
Pixel size 1.4 A
撮影
フィルム・検出器のモデル: FEI FALCON III (4k x 4k) 検出モード: INTEGRATING / 平均露光時間: 1.0 sec. / 平均電子線量: 66.0 e/Å2 詳細: Some images were collected at a 30 degree tilt. Images were collected in movie mode at 39 frames per second.
Chain - Source name: PDB / Chain - Initial model type: experimental model
詳細
Model of ILY-CD59 was fit and refined into the central subunit density. A combination of rigid body fitting and global minimization with secondary structure restraints was used to fit and refine the central subunit model. Then the central subunit model was rigid body fit as one body into the neighbouring subunits to generate a 3 subunit oligomer model.
精密化
空間: REAL / プロトコル: RIGID BODY FIT
得られたモデル
PDB-6zd0: Disulfide-locked early prepore intermedilysin-CD59