ジャーナル: Structure / 年: 2015 タイトル: Structural plasticity of helical nanotubes based on coiled-coil assemblies. 著者: E H Egelman / C Xu / F DiMaio / E Magnotti / C Modlin / X Yu / E Wright / D Baker / V P Conticello / 要旨: Numerous instances can be seen in evolution in which protein quaternary structures have diverged while the sequences of the building blocks have remained fairly conserved. However, the path through ...Numerous instances can be seen in evolution in which protein quaternary structures have diverged while the sequences of the building blocks have remained fairly conserved. However, the path through which such divergence has taken place is usually not known. We have designed two synthetic 29-residue α-helical peptides, based on the coiled-coil structural motif, that spontaneously self-assemble into helical nanotubes in vitro. Using electron cryomicroscopy with a newly available direct electron detection capability, we can achieve near-atomic resolution of these thin structures. We show how conservative changes of only one or two amino acids result in dramatic changes in quaternary structure, in which the assemblies can be switched between two very different forms. This system provides a framework for understanding how small sequence changes in evolution can translate into very large changes in supramolecular structure, a phenomenon that may have significant implications for the de novo design of synthetic peptide assemblies.
らせん対称: (回転対称性: 1 / Dyad axis: no / N subunits divisor: 1 / Num. of operations: 19 / Rise per n subunits: 2.2 Å / Rotation per n subunits: -87.1 °)
詳細
This peptide forms a helical nanotube of indeterminate length. The designation "nonadecameric" in REMARK 350 is an artifact of the PDB format and can be disregarded.
モード: BRIGHT FIELD / 最大 デフォーカス(公称値): 4400 nm / 最小 デフォーカス(公称値): 1400 nm / Cs: 2.7 mm
試料ホルダ
資料ホルダタイプ: FEI TITAN KRIOS AUTOGRID HOLDER
撮影
電子線照射量: 10 e/Å2 フィルム・検出器のモデル: FEI FALCON II (4k x 4k)
画像スキャン
デジタル画像の数: 260
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解析
EMソフトウェア
名称: SPIDER / カテゴリ: 3次元再構成
CTF補正
詳細: micrographs multiplied by CTF
らせん対称
回転角度/サブユニット: 87.1 ° / 軸方向距離/サブユニット: 2.2 Å / らせん対称軸の対称性: C1
3次元再構成
手法: IHRSR / 解像度: 3.6 Å / 解像度の算出法: OTHER / ピクセルサイズ(公称値): 1.02 Å / ピクセルサイズ(実測値): 1.02 Å 詳細: Both FSC and comparison with atomic model used for resolution determination. 対称性のタイプ: HELICAL