德国海因里希海涅大学Carsten Sachse和赛默飞世尔科技公司Ivan Lazi共同合作近期取得重要工作进展，他们研究利用iDPC-STEM法获得近原子分辨率的单粒子冷冻电镜结构。该研究成果2022年9月5日在线发表于《自然—方法学》杂志上。

研究人员使用集成微分相差模式（也称为 iDPC-STEM）的扫描透射电子显微镜（STEM）应用于两个冷冻电镜测试样本，孔雀石绿素（KLH）和烟草花叶病毒（TMV）。显微照片显示完全对比度转移到高分辨率，并能够使用单粒子重建方法在6.5 Å分辨率下确定KLH和3.5 Å分辨率下的TMV的冷冻电镜结构，这些方法与先前获得的相同大小TMV数据集的CTEM图具有相同的特征。

这些数据表明，一般而言，STEM成像，特别是iDPC-STEM方法，可以应用于玻璃化的单粒子标本，以确定生物大分子的近原子分辨率冷冻电镜结构。

据了解，在冷冻电镜（cryo-EM）中，玻璃化生物样品的分子图像是通过大底焦的传统透射显微镜（CTEM）获得的，然后通过计算组合成高分辨率的三维结构。

附：英文原文

Title: Single-particle cryo-EM structures from iDPC–STEM at near-atomic resolution

Author: Lazi, Ivan, Wirix, Maarten, Leidl, Max Leo, de Haas, Felix, Mann, Daniel, Beckers, Maximilian, Pechnikova, Evgeniya V., Mller-Caspary, Knut, Egoavil, Ricardo, Bosch, Eric G. T., Sachse, Carsten

Issue&Volume: 2022-09-05

Abstract: In electron cryomicroscopy (cryo-EM), molecular images of vitrified biological samples are obtained by conventional transmission microscopy (CTEM) using large underfocuses and subsequently computationally combined into a high-resolution three-dimensional structure. Here, we apply scanning transmission electron microscopy (STEM) using the integrated differential phase contrast mode also known as iDPC–STEM to two cryo-EM test specimens, keyhole limpet hemocyanin (KLH) and tobacco mosaic virus (TMV). The micrographs show complete contrast transfer to high resolution and enable the cryo-EM structure determination for KLH at 6.5 resolution, as well as for TMV at 3.5 resolution using single-particle reconstruction methods, which share identical features with maps obtained by CTEM of a previously acquired same-sized TMV data set. These data show that STEM imaging in general, and in particular the iDPC–STEM approach, can be applied to vitrified single-particle specimens to determine near-atomic resolution cryo-EM structures of biological macromolecules.

DOI: 10.1038/s41592-022-01586-0

Source: https://www.nature.com/articles/s41592-022-01586-0