ジャーナル: Proc Natl Acad Sci U S A / 年: 2013 タイトル: Inward-facing conformation of the zinc transporter YiiP revealed by cryoelectron microscopy. 著者: Nicolas Coudray / Salvatore Valvo / Minghui Hu / Ralph Lasala / Changki Kim / Martin Vink / Ming Zhou / Davide Provasi / Marta Filizola / Juoehi Tao / Jia Fang / Pawel A Penczek / Iban ...著者: Nicolas Coudray / Salvatore Valvo / Minghui Hu / Ralph Lasala / Changki Kim / Martin Vink / Ming Zhou / Davide Provasi / Marta Filizola / Juoehi Tao / Jia Fang / Pawel A Penczek / Iban Ubarretxena-Belandia / David L Stokes / 要旨: YiiP is a dimeric Zn(2+)/H(+) antiporter from Escherichia coli belonging to the cation diffusion facilitator family. We used cryoelectron microscopy to determine a 13-Å resolution structure of a ...YiiP is a dimeric Zn(2+)/H(+) antiporter from Escherichia coli belonging to the cation diffusion facilitator family. We used cryoelectron microscopy to determine a 13-Å resolution structure of a YiiP homolog from Shewanella oneidensis within a lipid bilayer in the absence of Zn(2+). Starting from the X-ray structure in the presence of Zn(2+), we used molecular dynamics flexible fitting to build a model consistent with our map. Comparison of the structures suggests a conformational change that involves pivoting of a transmembrane, four-helix bundle (M1, M2, M4, and M5) relative to the M3-M6 helix pair. Although accessibility of transport sites in the X-ray model indicates that it represents an outward-facing state, our model is consistent with an inward-facing state, suggesting that the conformational change is relevant to the alternating access mechanism for transport. Molecular dynamics simulation of YiiP in a lipid environment was used to address the feasibility of this conformational change. Association of the C-terminal domains is the same in both states, and we speculate that this association is responsible for stabilizing the dimer that, in turn, may coordinate the rearrangement of the transmembrane helices.
凍結剤: ETHANE / チャンバー内温度: 100 K / 装置: GATAN CRYOPLUNGE 3 / 手法: Blot for 2-5 seconds before plunging.
詳細
Proteins solubilized in DM were mixed with 18:1 dioleoylphosphatidyl glycerol lipids solubilized in DDM at a lipid-to-protein mass ratio of 1. This solution was dialyzed at room temperature for two weeks. Crystal cell parameters were a=57.5, b=34.0, c=100.0, alpha=90, beta=90, gamma=85.3.
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電子顕微鏡法
顕微鏡
FEI TECNAI F20
温度
平均: 100 K
アライメント法
Legacy - 非点収差: Objective astigmatism corrected at 200,000 times magnification
Indexing of the helical symmetry was done by comparing the positions of individual layer lines in Fourier space with the outer radius of the tube in real space. IHRSR method used to calculate the 3D structure.
Chain - #0 - Chain ID: A / Chain - #1 - Chain ID: C
詳細
Protocol: MDFF. An initial homology model of YiiP from S. oneidensis was built with MODELLER 9v7 using the X-ray crystal structure of YiiP from E. coli (PDB entry 3H90) as a template. This model included 9 residues at the N-terminus and 4 residues at the C-terminus that were not present in the X-ray structure.
精密化
空間: REAL / プロトコル: FLEXIBLE FIT
得られたモデル
PDB-3j1z: Inward-Facing Conformation of the Zinc Transporter YiiP revealed by Cryo-electron Microscopy