ジャーナル: J Struct Biol / 年: 2018 タイトル: Flexibility of the Sec13/31 cage is influenced by the Sec31 C-terminal disordered domain. 著者: Mohammadreza Paraan / Nilakshee Bhattacharya / Vladimir N Uversky / Scott M Stagg / 要旨: In COPII mediated vesicle formation, Sec13/Sec31 heterotetramers play a role in organizing the membranes into a spherical vesicle. There they oligomerize into a cage that interacts with the other ...In COPII mediated vesicle formation, Sec13/Sec31 heterotetramers play a role in organizing the membranes into a spherical vesicle. There they oligomerize into a cage that interacts with the other COPII proteins to direct vesicle formation and concentrate cargo into a bud. In this role they must be flexible to accommodate different sizes and shapes of cargo, but also have elements that provide rigidity to help deform the membrane. Here we characterize the influence the C-terminal disordered region of Sec31 has on cage flexibility and rigidity. After deleting this region (residues 820-1220), we characterized Sec13/Sec31ΔC heterotetramers biophysically and structurally through cryo-EM. Our results show that Sec13/31ΔC self-assembles into canonical cuboctahedral cages in vitro at buffer conditions similar to wild type. The distribution of cage sizes indicated that unlike the wild type, Sec13/31ΔC cages have a more homogeneous geometry. However, the structure of cuboctahedrons exhibited more conformational heterogeneity than wild type. Through localized reconstruction of cage vertices and molecular dynamics flexible fitting we found a new hinge for the flexing of Sec31 β-propeller domain and more flexibility of the previously known hinge. Together, these results show that the C-terminal region of Sec31 regulates the flexing of other domains such that flexibility and rigidity are not compromised during transport of large and/or asymmetric cargo.
全体 : Assembly of 24 SEC13/SEC31deltaC heterotetramers into a cuboctahe...
全体
名称: Assembly of 24 SEC13/SEC31deltaC heterotetramers into a cuboctahedron for which localized reconstruction reveals vertices (4 heterotetramers).
要素
複合体: Assembly of 24 SEC13/SEC31deltaC heterotetramers into a cuboctahedron for which localized reconstruction reveals vertices (4 heterotetramers).
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超分子 #1: Assembly of 24 SEC13/SEC31deltaC heterotetramers into a cuboctahe...
超分子
名称: Assembly of 24 SEC13/SEC31deltaC heterotetramers into a cuboctahedron for which localized reconstruction reveals vertices (4 heterotetramers). タイプ: complex / ID: 1 / 親要素: 0
由来(天然)
生物種: Homo sapiens (ヒト)
組換発現
生物種: Spodoptera frugiperda (ツマジロクサヨトウ)
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実験情報
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構造解析
手法
クライオ電子顕微鏡法
解析
単粒子再構成法
試料の集合状態
particle
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試料調製
緩衝液
pH: 7.5
凍結
凍結剤: ETHANE
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電子顕微鏡法
顕微鏡
FEI TITAN KRIOS
撮影
フィルム・検出器のモデル: DIRECT ELECTRON DE-20 (5k x 3k) 検出モード: INTEGRATING / 実像数: 2528 / 平均露光時間: 1.08 sec. / 平均電子線量: 60.8 e/Å2
電子線
加速電圧: 300 kV / 電子線源: FIELD EMISSION GUN
電子光学系
照射モード: FLOOD BEAM / 撮影モード: BRIGHT FIELD
実験機器
モデル: Titan Krios / 画像提供: FEI Company
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画像解析
粒子像選択
選択した数: 16000 詳細: This is the number of cage (cuboctahedron) particles initially picked from the micrographs. For the localized reconstruction method, 12 subparticles (vertices) were extracted per cage particle.
初期モデル
モデルのタイプ: EMDB MAP 詳細: For classification and refinement of cages, a low-pass filtered initial model of cages was used. For classification and alignment of vertices, one vertex was extracted from the symmetrized ...詳細: For classification and refinement of cages, a low-pass filtered initial model of cages was used. For classification and alignment of vertices, one vertex was extracted from the symmetrized cage map generated in the previous step.
最終 再構成
解像度のタイプ: BY AUTHOR / 解像度: 20.0 Å / 解像度の算出法: FSC 0.5 CUT-OFF / ソフトウェア - 名称: RELION 詳細: This is the number of particles used to generate the Class 1 map in this deposition. 使用した粒子像数: 21650
初期 角度割当
タイプ: PROJECTION MATCHING / 詳細: RELION
最終 角度割当
タイプ: PROJECTION MATCHING / 詳細: RELION
最終 3次元分類
クラス数: 5 / ソフトウェア - 名称: RELION 詳細: For each of cage classification and vertex classification, 5 classes were generated.