- EMDB-2023: Three-dimensional reconstruction of a targeted individual 17nm na... -
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基本情報
登録情報
データベース: EMDB / ID: EMD-2023
タイトル
Three-dimensional reconstruction of a targeted individual 17nm nascent high-density lipoprotein (HDL) particle by individual-particle electron tomography (IPET). The reconstruction displayed a ring-shaped structure of containing three protein - apoipoprotein A-Is (28 kDa each).
ジャーナル: PLoS One / 年: 2012 タイトル: IPET and FETR: experimental approach for studying molecular structure dynamics by cryo-electron tomography of a single-molecule structure. 著者: Lei Zhang / Gang Ren / 要旨: The dynamic personalities and structural heterogeneity of proteins are essential for proper functioning. Structural determination of dynamic/heterogeneous proteins is limited by conventional ...The dynamic personalities and structural heterogeneity of proteins are essential for proper functioning. Structural determination of dynamic/heterogeneous proteins is limited by conventional approaches of X-ray and electron microscopy (EM) of single-particle reconstruction that require an average from thousands to millions different molecules. Cryo-electron tomography (cryoET) is an approach to determine three-dimensional (3D) reconstruction of a single and unique biological object such as bacteria and cells, by imaging the object from a series of tilting angles. However, cconventional reconstruction methods use large-size whole-micrographs that are limited by reconstruction resolution (lower than 20 Å), especially for small and low-symmetric molecule (<400 kDa). In this study, we demonstrated the adverse effects from image distortion and the measuring tilt-errors (including tilt-axis and tilt-angle errors) both play a major role in limiting the reconstruction resolution. Therefore, we developed a "focused electron tomography reconstruction" (FETR) algorithm to improve the resolution by decreasing the reconstructing image size so that it contains only a single-instance protein. FETR can tolerate certain levels of image-distortion and measuring tilt-errors, and can also precisely determine the translational parameters via an iterative refinement process that contains a series of automatically generated dynamic filters and masks. To describe this method, a set of simulated cryoET images was employed; to validate this approach, the real experimental images from negative-staining and cryoET were used. Since this approach can obtain the structure of a single-instance molecule/particle, we named it individual-particle electron tomography (IPET) as a new robust strategy/approach that does not require a pre-given initial model, class averaging of multiple molecules or an extended ordered lattice, but can tolerate small tilt-errors for high-resolution single "snapshot" molecule structure determination. Thus, FETR/IPET provides a completely new opportunity for a single-molecule structure determination, and could be used to study the dynamic character and equilibrium fluctuation of macromolecules.
試料ホルダー: Gatan / 試料ホルダーモデル: GATAN LIQUID NITROGEN / Tilt series - Axis1 - Min angle: -60 ° / Tilt series - Axis1 - Max angle: 60 °
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画像解析
詳細
Single targeted particle"s images were reconstructed by focus ET reconstruction (FETR) algorithm of individual particle electron tomography (IPET) method. Average number of tilts used in the 3D reconstructions: 81. Average tomographic tilt angle increment: 1.5.
最終 再構成
アルゴリズム: OTHER / 解像度のタイプ: BY AUTHOR / 解像度: 42.0 Å / 解像度の算出法: OTHER / ソフトウェア - 名称: IPET, and, FETR 詳細: Map was reconstructed by individual-particle electron tomography (IPET)and Focus ET Reconstruction Algorithm.
CTF補正
詳細: TOMOCTF
最終 角度割当
詳細: Tomography tilt angle from -60 to 60 in step of 1.5