ジャーナル: J Mol Biol / 年: 2006 タイトル: The structure of a filamentous bacteriophage. 著者: Ying A Wang / Xiong Yu / Stacy Overman / Masamichi Tsuboi / George J Thomas / Edward H Egelman / 要旨: Many thin helical polymers, including bacterial pili and filamentous bacteriophage, have been seen as refractory to high-resolution studies by electron microscopy. Studies of the quaternary structure ...Many thin helical polymers, including bacterial pili and filamentous bacteriophage, have been seen as refractory to high-resolution studies by electron microscopy. Studies of the quaternary structure of such filaments have depended upon techniques such as modeling or X-ray fiber diffraction, given that direct visualization of the subunit organization has not been possible. We report the first image reconstruction of a filamentous virus, bacteriophage fd, by cryoelectron microscopy. Although these thin ( approximately 70 A in diameter) rather featureless filaments scatter weakly, we have been able to achieve a nominal resolution of approximately 8 A using an iterative helical reconstruction procedure. We show that two different conformations of the virus exist, and that in both states the subunits are packed differently than in conflicting models previously proposed on the basis of X-ray fiber diffraction or solid-state NMR studies. A significant fraction of the population of wild-type fd is either disordered or in multiple conformational states, while in the presence of the Y21M mutation, this heterogeneity is greatly reduced, consistent with previous observations. These results show that new computational approaches to helical reconstruction can greatly extend the ability to visualize heterogeneous protein polymers at a reasonably high resolution.
モード: BRIGHT FIELD / 倍率(公称値): 50000 X / 最大 デフォーカス(公称値): 3800 nm / 最小 デフォーカス(公称値): 1400 nm
試料ホルダ
資料ホルダタイプ: Gatan
撮影
フィルム・検出器のモデル: KODAK SO-163 FILM
放射
プロトコル: SINGLE WAVELENGTH / 単色(M)・ラウエ(L): M
放射波長
相対比: 1
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解析
EMソフトウェア
名称: IHRSR / カテゴリ: 3次元再構成
CTF補正
詳細: phase flipping of entire images
3次元再構成
手法: IHRSR / 解像度: 8 Å / 解像度の算出法: FSC 0.5 CUT-OFF / 粒子像の数: 16367 / ピクセルサイズ(公称値): 2.4 Å / ピクセルサイズ(実測値): 2.4 Å / 倍率補正: TMV 詳細: The C-N bond distance is 0.09 A between GLN15 and ALA16, 0.12 A between ALA35 and THR36 and 0.44 A between ALA25 and TRP26 対称性のタイプ: HELICAL