ジャーナル: Nat Struct Mol Biol / 年: 2016 タイトル: Molecular basis of caspase-1 polymerization and its inhibition by a new capping mechanism. 著者: Alvin Lu / Yang Li / Florian I Schmidt / Qian Yin / Shuobing Chen / Tian-Min Fu / Alexander B Tong / Hidde L Ploegh / Youdong Mao / Hao Wu / 要旨: Inflammasomes are cytosolic caspase-1-activation complexes that sense intrinsic and extrinsic danger signals, and trigger inflammatory responses and pyroptotic cell death. Homotypic interactions ...Inflammasomes are cytosolic caspase-1-activation complexes that sense intrinsic and extrinsic danger signals, and trigger inflammatory responses and pyroptotic cell death. Homotypic interactions among Pyrin domains and caspase recruitment domains (CARDs) in inflammasome-complex components mediate oligomerization into filamentous assemblies. Several cytosolic proteins consisting of only interaction domains exert inhibitory effects on inflammasome assembly. In this study, we determined the structure of the human caspase-1 CARD domain (caspase-1(CARD)) filament by cryo-electron microscopy and investigated the biophysical properties of two caspase-1-like CARD-only proteins: human inhibitor of CARD (INCA or CARD17) and ICEBERG (CARD18). Our results reveal that INCA caps caspase-1 filaments, thereby exerting potent inhibition with low-nanomolar Ki on caspase-1(CARD) polymerization in vitro and inflammasome activation in cells. Whereas caspase-1(CARD) uses six complementary surfaces of three types for filament assembly, INCA is defective in two of the six interfaces and thus terminates the caspase-1 filament.
モード: BRIGHT FIELD / 倍率(補正後): 28736 X / 最大 デフォーカス(公称値): 6000 nm / 最小 デフォーカス(公称値): 1000 nm / Cs: 2.7 mm
撮影
電子線照射量: 20 e/Å2 フィルム・検出器のモデル: DIRECT ELECTRON DE-16 (4k x 4k)
画像スキャン
デジタル画像の数: 200
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解析
EMソフトウェア
ID
名称
カテゴリ
1
IHRSR
3次元再構成
2
SPIDER
3次元再構成
CTF補正
詳細: EACH MICROGRAPH
3次元再構成
手法: IHRSR / 解像度: 4.8 Å / 粒子像の数: 69222 / ピクセルサイズ(実測値): 0.87 Å 詳細: SUBMISSION BASED ON EXPERIMENTAL DATA FROM EMDB EMD-3241. (DEPOSITION ID: 14034). 対称性のタイプ: HELICAL
原子モデル構築
プロトコル: OTHER / 空間: REAL / 詳細: REFINEMENT PROTOCOL--EM