ジャーナル: Nature / 年: 2010 タイトル: The structural basis for membrane binding and pore formation by lymphocyte perforin. 著者: Ruby H P Law / Natalya Lukoyanova / Ilia Voskoboinik / Tom T Caradoc-Davies / Katherine Baran / Michelle A Dunstone / Michael E D'Angelo / Elena V Orlova / Fasséli Coulibaly / Sandra ...著者: Ruby H P Law / Natalya Lukoyanova / Ilia Voskoboinik / Tom T Caradoc-Davies / Katherine Baran / Michelle A Dunstone / Michael E D'Angelo / Elena V Orlova / Fasséli Coulibaly / Sandra Verschoor / Kylie A Browne / Annette Ciccone / Michael J Kuiper / Phillip I Bird / Joseph A Trapani / Helen R Saibil / James C Whisstock / 要旨: Natural killer cells and cytotoxic T lymphocytes accomplish the critically important function of killing virus-infected and neoplastic cells. They do this by releasing the pore-forming protein ...Natural killer cells and cytotoxic T lymphocytes accomplish the critically important function of killing virus-infected and neoplastic cells. They do this by releasing the pore-forming protein perforin and granzyme proteases from cytoplasmic granules into the cleft formed between the abutting killer and target cell membranes. Perforin, a 67-kilodalton multidomain protein, oligomerizes to form pores that deliver the pro-apoptopic granzymes into the cytosol of the target cell. The importance of perforin is highlighted by the fatal consequences of congenital perforin deficiency, with more than 50 different perforin mutations linked to familial haemophagocytic lymphohistiocytosis (type 2 FHL). Here we elucidate the mechanism of perforin pore formation by determining the X-ray crystal structure of monomeric murine perforin, together with a cryo-electron microscopy reconstruction of the entire perforin pore. Perforin is a thin 'key-shaped' molecule, comprising an amino-terminal membrane attack complex perforin-like (MACPF)/cholesterol dependent cytolysin (CDC) domain followed by an epidermal growth factor (EGF) domain that, together with the extreme carboxy-terminal sequence, forms a central shelf-like structure. A C-terminal C2 domain mediates initial, Ca(2+)-dependent membrane binding. Most unexpectedly, however, electron microscopy reveals that the orientation of the perforin MACPF domain in the pore is inside-out relative to the subunit arrangement in CDCs. These data reveal remarkable flexibility in the mechanism of action of the conserved MACPF/CDC fold and provide new insights into how related immune defence molecules such as complement proteins assemble into pores.
凍結剤: ETHANE / チャンバー内湿度: 100 % / 装置: OTHER / 詳細: Vitrification instrument: Vitrobot 手法: liposomes were applied to neg. glow discharged grids first, then protein solution was added. Grids were left inside Vitrobot equilibrated at 37C for 1-2 min for pore formaition. Blot for 2 seconds before plunging
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電子顕微鏡法
顕微鏡
FEI TECNAI F20
アライメント法
Legacy - 非点収差: Objective lens astigmatism was corrected at 150,000x magnification
試料ホルダー: Side entry LN2 cooled, single tilt / 試料ホルダーモデル: GATAN LIQUID NITROGEN
実験機器
モデル: Tecnai F20 / 画像提供: FEI Company
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画像解析
詳細
Image regions containing the pores with small surrounding areas of membrane were selected manually using EMAN-Boxer software
CTF補正
詳細: Estimated with CTFFIND3, then phases flipped for each particle
最終 再構成
想定した対称性 - 点群: C20 (20回回転対称) / アルゴリズム: OTHER / 解像度のタイプ: BY AUTHOR / 解像度: 28.5 Å / 解像度の算出法: FSC 0.5 CUT-OFF / ソフトウェア - 名称: Imagic, Spider 詳細: 20-fold symmetrised reconstruction. Hand of the map has not been determined 使用した粒子像数: 59