2025-02-26 アルゴンヌ国立研究所(ANL)
EFX技術は、結晶化したタンパク質に電場を適用し、その動的変化を連続的にX線で撮影することで、タンパク質の動きを「動画」として記録します。研究チームは、この方法をカリウムイオンチャネルに適用し、イオンがチャネルを通過する様子をナノ秒単位で観察することに成功しました。この成果は、過去25年間にわたる生化学的研究の知見を一度に確認するものであり、EFXがタンパク質ダイナミクスの迅速な可視化と理解に強力なツールであることを示しています。
<関連情報>
- https://pme.uchicago.edu/news/new-x-ray-technology-captures-proteins-motion
- https://biologicalsciences.uchicago.edu/news/new-x-ray-technology-captures-proteins-motion
- https://www.sciencedirect.com/science/article/abs/pii/S0092867424014193
カリウムチャネルにおける電界刺激イオン伝導の直接可視化 Direct visualization of electric-field-stimulated ion conduction in a potassium channel
BoRam Lee, K. Ian White, Michael Socolich, Margaret A. Klureza, Robert Henning, Vukica Srajer, Rama Ranganathan, Doeke R. Hekstra
Cell Available online: 9 January 2025
DOI:https://doi.org/10.1016/j.cell.2024.12.006
Graphical abstract
Highlights
- Observation of ion permeation in an ion channel by time-resolved X-ray crystallography
- Inward and outward conduction events display different intermediate states
- Dynamics of the selectivity filter suggest a mechanism for tuning rectification
- The data suggest deep conservation of dynamics in the K+ channel family
Summary
Understanding protein function would be facilitated by direct, real-time observation of chemical kinetics in the atomic structure. The selectivity filter (SF) of the K+ channel provides an ideal model, catalyzing the dehydration and transport of K+ ions across the cell membrane through a narrow pore. We used a “pump-probe” method called electric-field-stimulated time-resolved X-ray crystallography (EFX) to initiate and observe K+ conduction in the NaK2K channel in both directions on the timescale of the transport process. We observe both known and potentially new features in the high-energy conformations visited along the conduction pathway, including the associated dynamics of protein residues that control selectivity and conduction rate. A single time series of one channel in action shows the orderly appearance of features observed in diverse homologs with diverse methods, arguing for deep conservation of the dynamics underlying the reaction coordinate in this protein family.
