- EMDB-24002: Cryo-EM map of the FLP cargo within the T. maritima encapsulin -
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基本情報
登録情報
データベース: EMDB / ID: EMD-24002
タイトル
Cryo-EM map of the FLP cargo within the T. maritima encapsulin
マップデータ
Symmetry expansion and local classification of one FLP cargo protein within the T. maritima encapsulin
試料
細胞器官・細胞要素: Cryo-EM map of FLP cargo protein within the T. maritima encapsulin
機能・相同性
機能・相同性情報
encapsulin nanocompartment / 加水分解酵素; プロテアーゼ; ペプチド結合加水分解酵素 / iron ion transport / peptidase activity / intracellular iron ion homeostasis / proteolysis 類似検索 - 分子機能
Type 1 encapsulin shell protein / Encapsulating protein for peroxidase / : 類似検索 - ドメイン・相同性
ジャーナル: Sci Rep / 年: 2021 タイトル: The encapsulin from Thermotoga maritima is a flavoprotein with a symmetry matched ferritin-like cargo protein. 著者: Benjamin J LaFrance / Caleb Cassidy-Amstutz / Robert J Nichols / Luke M Oltrogge / Eva Nogales / David F Savage / 要旨: Bacterial nanocompartments, also known as encapsulins, are an emerging class of protein-based 'organelles' found in bacteria and archaea. Encapsulins are virus-like icosahedral particles comprising a ...Bacterial nanocompartments, also known as encapsulins, are an emerging class of protein-based 'organelles' found in bacteria and archaea. Encapsulins are virus-like icosahedral particles comprising a ~ 25-50 nm shell surrounding a specific cargo enzyme. Compartmentalization is thought to create a unique chemical environment to facilitate catalysis and isolate toxic intermediates. Many questions regarding nanocompartment structure-function remain unanswered, including how shell symmetry dictates cargo loading and to what extent the shell facilitates enzymatic activity. Here, we explore these questions using the model Thermotoga maritima nanocompartment known to encapsulate a redox-active ferritin-like protein. Biochemical analysis revealed the encapsulin shell to possess a flavin binding site located at the interface between capsomere subunits, suggesting the shell may play a direct and active role in the function of the encapsulated cargo. Furthermore, we used cryo-EM to show that cargo proteins use a form of symmetry-matching to facilitate encapsulation and define stoichiometry. In the case of the Thermotoga maritima encapsulin, the decameric cargo protein with fivefold symmetry preferentially binds to the pentameric-axis of the icosahedral shell. Taken together, these observations suggest the shell is not simply a passive barrier-it also plays a significant role in the structure and function of the cargo enzyme.
照射モード: FLOOD BEAM / 撮影モード: BRIGHT FIELD / Cs: 2.7 mm 最大 デフォーカス(公称値): 2.8000000000000003 µm 最小 デフォーカス(公称値): 1.5 µm
試料ステージ
試料ホルダーモデル: GATAN 626 SINGLE TILT LIQUID NITROGEN CRYO TRANSFER HOLDER ホルダー冷却材: NITROGEN
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画像解析
詳細
Images were saved in counting mode using leginon software, and subsequently processed in RELION.
粒子像選択
選択した数: 86124 詳細: 1000 particles were manually selected from random micrographs. 2D classification was performed on these 1000 particles, and 2D classes were used for relion auto picking
CTF補正
ソフトウェア - 名称: CTFFIND (ver. 4) 詳細: CTFFind4 implemented within RELION/3.0, CTFRefine was also performed after initial reconstruction was achieved.
詳細: Original T. maritima crystal structure from Sutter et al 'molmap' function in Chimera was used to generate surface model. Initial model was lowpass filtered to 30A for initial reconstruction, ...詳細: Original T. maritima crystal structure from Sutter et al 'molmap' function in Chimera was used to generate surface model. Initial model was lowpass filtered to 30A for initial reconstruction, and once high-resolution was achieved, a 5A model was used to assure the correct handedness.
最終 再構成
使用したクラス数: 1 / 想定した対称性 - 点群: C1 (非対称) / 解像度のタイプ: BY AUTHOR / 解像度: 4.0 Å / 解像度の算出法: FSC 0.143 CUT-OFF / ソフトウェア - 名称: RELION (ver. 3.1) 詳細: It should be noted that this number of particles is not 'true' single particles, but the result of symmetry expansion. Thus, some of these particles are unique orientations of the same ...詳細: It should be noted that this number of particles is not 'true' single particles, but the result of symmetry expansion. Thus, some of these particles are unique orientations of the same encapsulin. Also, the resolution of 4A is for the entire shell with cargo, however, the cargo is estimated to be 7-8A. 使用した粒子像数: 249296
初期 角度割当
タイプ: MAXIMUM LIKELIHOOD / ソフトウェア - 名称: RELION (ver. 3.1)
最終 角度割当
タイプ: MAXIMUM LIKELIHOOD / ソフトウェア - 名称: RELION (ver. 3.1)
最終 3次元分類
ソフトウェア - 名称: RELION (ver. 3.1) 詳細: The icosahedral particles were symmetry expanded and a localized alignment free classification was performed at one 5-fold vertex to better classify a single FLP cargo protein. 3 iterations ...詳細: The icosahedral particles were symmetry expanded and a localized alignment free classification was performed at one 5-fold vertex to better classify a single FLP cargo protein. 3 iterations of this were performed resulting in the final reconstruction deposited herein.
The homology model for the encapsulated FLP was created using Biozentrum's SWISS-MODEL, with 5DA5 as the reference structure. This was then rigid body docked into the FLP map using ChimeraX followed by PHENIX. The final model can be found in the supplementary materials of this manuscript at 'FLP-pentamer_model.py'