National Institutes of Health/National Heart, Lung, and Blood Institute (NIH/NHLBI)
R01HL115153
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
R01GM104427
米国
National Institutes of Health/National Institute of Mental Health (NIH/NIMH)
R01MH077303
米国
National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Disease (NIH/NIDDK)
R01DK042667
米国
引用
ジャーナル: bioRxiv / 年: 2023 タイトル: Tertiary structure of single-instant RNA molecule reveals folding landscape. 著者: Jianfang Liu / Ewan K S McRae / Meng Zhang / Cody Geary / Ebbe Sloth Andersen / Gang Ren 要旨: The folding of RNA and protein molecules during their synthesis is a crucial self-assembly process that nature employs to convert genetic information into the complex molecular machinery that ...The folding of RNA and protein molecules during their synthesis is a crucial self-assembly process that nature employs to convert genetic information into the complex molecular machinery that supports life. Misfolding events are the cause of several diseases, and the folding pathway of central biomolecules, such as the ribosome, is strictly regulated by programmed maturation processes and folding chaperones. However, the dynamic folding processes are challenging to study because current structure determination methods heavily rely on averaging, and existing computational methods do not efficiently simulate non-equilibrium dynamics. Here we utilize individual-particle cryo-electron tomography (IPET) to investigate the folding landscape of a rationally designed RNA origami 6-helix bundle that undergoes slow maturation from a "young" to "mature" conformation. By optimizing the IPET imaging and electron dose conditions, we obtain 3D reconstructions of 120 individual particles at resolutions ranging from 23-35 Å, enabling us first-time to observe individual RNA helices and tertiary structures without averaging. Statistical analysis of 120 tertiary structures confirms the two main conformations and suggests a possible folding pathway driven by helix-helix compaction. Studies of the full conformational landscape reveal both trapped states, misfolded states, intermediate states, and fully compacted states. The study provides novel insight into RNA folding pathways and paves the way for future studies of the energy landscape of molecular machines and self-assembly processes.
超分子 #1: RNA Origami 6 Helix Bundle with Clasp (6HBC)
超分子
名称: RNA Origami 6 Helix Bundle with Clasp (6HBC) / タイプ: complex / ID: 1 / 親要素: 0 / 含まれる分子: all 詳細: The RNA was transcribed from linearized DNA template using T7 RNA polymerase purified in house.
凍結剤: ETHANE / チャンバー内湿度: 90 % / チャンバー内温度: 277 K / 装置: LEICA EM GP
詳細
In vitro transcribed RNA was purified by size exclusion chromatography and spin concentrated in amicon spin columns.
切片作成
その他: NO SECTIONING
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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: GATAN K3 BIOQUANTUM (6k x 4k) 撮影したグリッド数: 1 / 実像数: 21 / 平均露光時間: 0.88 sec. / 平均電子線量: 8.0 e/Å2
電子線
加速電圧: 300 kV / 電子線源: FIELD EMISSION GUN
電子光学系
C2レンズ絞り径: 50.0 µm / 照射モード: FLOOD BEAM / 撮影モード: BRIGHT FIELD / Cs: 2.7 mm / 倍率(公称値): 81000
試料ステージ
試料ホルダーモデル: FEI TITAN KRIOS AUTOGRID HOLDER
実験機器
モデル: Titan Krios / 画像提供: FEI Company
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画像解析
詳細
Motion correction of the multi-frame movie was conducted by MotionCor2. The tilt series of whole micrographs were initial aligned by IMOD. Additionally, to reduce the image noise, tilt series were further conducted by a machine learning, a median-filter process and a contrast enhancement method.
最終 再構成
アルゴリズム: FOURIER SPACE / 解像度のタイプ: BY AUTHOR / 解像度: 28.0 Å / 解像度の算出法: FSC 0.5 CUT-OFF 詳細: The targeted images of individual particle were reconstructed by Individual-Particle Electron Tomography (IPET). To reduce the missing-wedge artifact caused by the limited tilt angle range, ...詳細: The targeted images of individual particle were reconstructed by Individual-Particle Electron Tomography (IPET). To reduce the missing-wedge artifact caused by the limited tilt angle range, the final 3D map was submitted to a low-tilt tomographic 3D reconstruction method (LoTToR). IPET 3D map was low-pass filtered to 0.8 nm following by Gaussian filtering (standard deviation is 3.0) and median filter (3x3x3) using EMAN and UCSF Chimera, and displayed by Chimera with applied the hidden dust function. 使用した粒子像数: 21