ジャーナル: Proc Natl Acad Sci U S A / 年: 2010 タイトル: Three-dimensional structure of tropism-switching Bordetella bacteriophage. 著者: Wei Dai / Asher Hodes / Wong H Hui / Mari Gingery / Jeff F Miller / Z Hong Zhou / 要旨: Bacteriophage BPP-1, which infects Bordetella species, can switch its specificity by mutations to the ligand-binding surface of its major tropism-determinant protein, Mtd. This targeted mutagenesis ...Bacteriophage BPP-1, which infects Bordetella species, can switch its specificity by mutations to the ligand-binding surface of its major tropism-determinant protein, Mtd. This targeted mutagenesis results from the activity of a phage-encoded diversity-generating retroelement. Purified Mtd binds its receptor with low affinity, yet BPP-1 binding and infection of Bordettella cells are efficient because of high-avidity binding between phage-associated Mtd and its receptor. Here, using an integrative approach of three-dimensional (3D) structural analyses of the entire phage by cryo-electron tomography and single-prticle cryo-electron microscopy, we provide direct localization of Mtd in the phage and the structural basis of the high-avidity binding of the BPP-1 phage. Our structure shows that each BPP-1 particle has a T = 7 icosahedral head and an unusual tail apparatus consisting of a short central tail "hub," six short tail spikes, and six extended tail fibers. Subtomographic averaging of the tail fiber maps revealed a two-lobed globular structure at the distal end of each long tail fiber. Tomographic reconstructions of immuno-gold-labeled BPP-1 directly localized Mtd to these globular structures. Finally, our icosahedral reconstruction of the BPP-1 head at 7A resolution reveals an HK97-like major capsid protein stabilized by a smaller cementing protein. Our structure represents a unique bacteriophage reconstruction with its tail fibers and ligand-binding domains shown in relation to its tail apparatus. The localization of Mtd at the distal ends of the six tail fibers explains the high avidity binding of Mtd molecules to cell surfaces for initiation of infection.
凍結剤: ETHANE / チャンバー内温度: 100 K / 装置: HOMEMADE PLUNGER 詳細: Vitrification instrument: lab-made plunger. Vitrification was carried out at room temperature. CPV were embedded in a thin layer of vitreous ice suspended across the holes of holey carbon ...詳細: Vitrification instrument: lab-made plunger. Vitrification was carried out at room temperature. CPV were embedded in a thin layer of vitreous ice suspended across the holes of holey carbon films for cryoEM imaging. 手法: blot for 3 seconds with filter paper before plunging
想定した対称性 - 点群: I (正20面体型対称) / アルゴリズム: OTHER / 解像度のタイプ: BY AUTHOR / 解像度: 7.0 Å / 解像度の算出法: FSC 0.5 CUT-OFF / ソフトウェア - 名称: IMIRS 詳細: Determination of particle orientation and center parameters and subsequent 3D reconstruction were carried out using programs in the IMIRS software package, which are based on Fourier common ...詳細: Determination of particle orientation and center parameters and subsequent 3D reconstruction were carried out using programs in the IMIRS software package, which are based on Fourier common lines and Fourier-Bessel synthesis methods. 使用した粒子像数: 9000