利用 2D template matching 改进 50 kDa 以下复合物的冷冻电镜重构
Improved cryo-EM reconstruction of sub-50 kDa complexes using 2D template matching
研究提出用高分辨率结构作为先验并结合 2D template matching，改进小分子量复合物的冷冻电镜比对与重构。作者用该方法重构了一个此前难以处理的约 43 kDa 蛋白激酶，并改善了其配体结合位点的密度。文章指出，传统单颗粒冷冻电镜近年已能解析越来越多小于 100 kDa 的结构，而该工作进一步把目标指向 50 kDa 以下的药物结合复合物。理论分析预测，这一方法有望把单颗粒冷冻电镜拓展到远低于 50 kDa 的重要药物结合复合物。
来源：eLife · doi.org
Visualizing the structures of small proteins and complexes has been a longstanding challenge in single-particle cryo-electron microscopy (cryo-EM). Some of these targets have been successfully resolved by binding to antibody fragments (Fabs) or fusing with external scaffolds to increase their size. Recent advances in conventional single-particle techniques have enabled the determination of an increasing number of structures smaller than 100 kDa, achieving resolutions relevant to drug research. Compared to X-ray crystallography, cryo-EM preserves the near-native states of biomolecules, can resolve structural heterogeneity, and has the potential to apply to a wide range of targets. In this work, we demonstrate that the alignment and reconstruction of small macromolecular complexes can be improved using high-resolution structures as priors, combined with 2D template matching. Using this method, we reconstructed a previously intractable ∼43 kDa protein kinase and improved the density of its ligand-binding site. Our theoretical analysis predicts that this method can further extend single-particle cryo-EM to important drug-binding complexes well below 50 kDa.