ジャーナル: Nat Commun / 年: 2015 タイトル: Cryo-EM structure of the bacteriophage T4 portal protein assembly at near-atomic resolution. 著者: Lei Sun / Xinzheng Zhang / Song Gao / Prashant A Rao / Victor Padilla-Sanchez / Zhenguo Chen / Siyang Sun / Ye Xiang / Sriram Subramaniam / Venigalla B Rao / Michael G Rossmann / 要旨: The structure and assembly of bacteriophage T4 has been extensively studied. However, the detailed structure of the portal protein remained unknown. Here we report the structure of the bacteriophage ...The structure and assembly of bacteriophage T4 has been extensively studied. However, the detailed structure of the portal protein remained unknown. Here we report the structure of the bacteriophage T4 portal assembly, gene product 20 (gp20), determined by cryo-electron microscopy (cryo-EM) to 3.6 Å resolution. In addition, analysis of a 10 Å resolution cryo-EM map of an empty prolate T4 head shows how the dodecameric portal assembly interacts with the capsid protein gp23 at the special pentameric vertex. The gp20 structure also verifies that the portal assembly is required for initiating head assembly, for attachment of the packaging motor, and for participation in DNA packaging. Comparison of the Myoviridae T4 portal structure with the known portal structures of φ29, SPP1 and P22, representing Podo- and Siphoviridae, shows that the portal structure probably dates back to a time when self-replicating microorganisms were being established on Earth.
A: Portal protein gp20 B: Portal protein gp20 C: Portal protein gp20 D: Portal protein gp20 E: Portal protein gp20 F: Portal protein gp20 G: Portal protein gp20 H: Portal protein gp20 I: Portal protein gp20 J: Portal protein gp20 K: Portal protein gp20 L: Portal protein gp20
名称: 20 mM Tris-HCl, 400 mM NaCl, 5 mM EDTA / pH: 7.8 / 詳細: 20 mM Tris-HCl, 400 mM NaCl, 5 mM EDTA
試料
濃度: 1 mg/ml / 包埋: NO / シャドウイング: NO / 染色: NO / 凍結: YES
試料支持
詳細: Quantifoil R1.2/1.3 holey carbon on 200 mesh copper
急速凍結
装置: GATAN CRYOPLUNGE 3 / 凍結剤: ETHANE / Temp: 120 K / 湿度: 90 % 詳細: Blot for 7 seconds before plunging into liquid ethane (GATAN CRYOPLUNGE 3). 手法: Blot for 7 seconds before plunging
モード: BRIGHT FIELD / 倍率(公称値): 29000 X / 倍率(補正後): 50000 X / 最大 デフォーカス(公称値): 2500 nm / 最小 デフォーカス(公称値): 1500 nm / Cs: 2.7 mm
試料ホルダ
試料ホルダーモデル: FEI TITAN KRIOS AUTOGRID HOLDER 資料ホルダタイプ: Liquid nitrogen-cooled / 温度: 100 K / 最高温度: 105 K / 最低温度: 80 K
撮影
電子線照射量: 2 e/Å2 / フィルム・検出器のモデル: GATAN K2 (4k x 4k)
電子光学装置
エネルギーフィルター名称: GIF / エネルギーフィルター 上限: 25 eV / エネルギーフィルター 下限: 0 eV
画像スキャン
デジタル画像の数: 839
放射
プロトコル: SINGLE WAVELENGTH / 単色(M)・ラウエ(L): M / 散乱光タイプ: x-ray
放射波長
相対比: 1
-
解析
EMソフトウェア
名称: RELION / カテゴリ: 3次元再構成
CTF補正
詳細: each particle
対称性
点対称性: C12 (12回回転対称)
3次元再構成
手法: Cross-common lines / 解像度: 3.6 Å / 解像度の算出法: FSC 0.143 CUT-OFF / 粒子像の数: 98000 / ピクセルサイズ(公称値): 1 Å / ピクセルサイズ(実測値): 1 Å 詳細: FSC was calculated from two independent reconstructions. Particles were selected using an automatic selection program. (Single particle--Applied symmetry: C12) クラス平均像の数: 15 / 対称性のタイプ: POINT
精密化
解像度: 3.6→3.6 Å / SU ML: 0.48 / σ(F): 0 / 位相誤差: 28.36 / 立体化学のターゲット値: ML
Rfactor
反射数
%反射
Rfree
0.2719
2016
0.23 %
Rwork
0.2644
878498
-
obs
0.2644
880514
99.93 %
溶媒の処理
減衰半径: 0.9 Å / VDWプローブ半径: 1.11 Å / 溶媒モデル: FLAT BULK SOLVENT MODEL