ジャーナル: Nat Struct Mol Biol / 年: 2016 タイトル: Membrane insertion of a Tc toxin in near-atomic detail. 著者: Christos Gatsogiannis / Felipe Merino / Daniel Prumbaum / Daniel Roderer / Franziska Leidreiter / Dominic Meusch / Stefan Raunser / 要旨: Tc toxins from pathogenic bacteria use a special syringe-like mechanism to perforate the host cell membrane and inject a deadly enzyme into the host cytosol. The molecular mechanism of this unusual ...Tc toxins from pathogenic bacteria use a special syringe-like mechanism to perforate the host cell membrane and inject a deadly enzyme into the host cytosol. The molecular mechanism of this unusual injection system is poorly understood. Using electron cryomicroscopy, we determined the structure of TcdA1 from Photorhabdus luminescens embedded in lipid nanodiscs. In our structure, compared with the previous structure of TcdA1 in the prepore state, the transmembrane helices rearrange in the membrane and open the initially closed pore. However, the helices do not span the complete membrane; instead, the loops connecting the helices form the rim of the funnel. Lipid head groups reach into the space between the loops and consequently stabilize the pore conformation. The linker domain is folded and packed into a pocket formed by the other domains of the toxin, thereby considerably contributing to stabilization of the pore state.
電子線源: FIELD EMISSION GUN / 加速電圧: 300 kV / 照射モード: OTHER
電子レンズ
モード: BRIGHT FIELD / 倍率(公称値): 59000 X / アライメント法: COMA FREE
試料ホルダ
凍結剤: NITROGEN
撮影
電子線照射量: 15.4 e/Å2 フィルム・検出器のモデル: FEI FALCON II (4k x 4k) 実像数: 1957
画像スキャン
動画フレーム数/画像: 7
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解析
ソフトウェア
名称: PHENIX / バージョン: 1.10_2152: / 分類: 精密化
EMソフトウェア
ID
名称
バージョン
カテゴリ
2
EPU
画像取得
4
CTFFIND
4
CTF補正
7
Coot
モデルフィッティング
9
RELION
初期オイラー角割当
10
RELION
最終オイラー角割当
12
RELION
3次元再構成
13
PHENIX
モデル精密化
14
REFMAC
モデル精密化
CTF補正
タイプ: PHASE FLIPPING AND AMPLITUDE CORRECTION
粒子像の選択
選択した粒子像数: 30061 / 詳細: particles were picked manually
対称性
点対称性: C5 (5回回転対称)
3次元再構成
解像度: 3.46 Å / 解像度の算出法: FSC 0.143 CUT-OFF / 粒子像の数: 13000 詳細: The density was filtered to its local resolution, using localfilt (SPARX) and RESMAP 対称性のタイプ: POINT