Molecular and Cell Biology Department, Institute for Quantitative Biomedicine, University of California, Berkeley, CA, USA.
Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
Nature. 2024 Apr;628(8006):47-56. doi: 10.1038/s41586-024-07198-2. Epub 2024 Apr 3.
Most life scientists would agree that understanding how cellular processes work requires structural knowledge about the macromolecules involved. For example, deciphering the double-helical nature of DNA revealed essential aspects of how genetic information is stored, copied and repaired. Yet, being reductionist in nature, structural biology requires the purification of large amounts of macromolecules, often trimmed off larger functional units. The advent of cryogenic electron microscopy (cryo-EM) greatly facilitated the study of large, functional complexes and generally of samples that are hard to express, purify and/or crystallize. Nevertheless, cryo-EM still requires purification and thus visualization outside of the natural context in which macromolecules operate and coexist. Conversely, cell biologists have been imaging cells using a number of fast-evolving techniques that keep expanding their spatial and temporal reach, but always far from the resolution at which chemistry can be understood. Thus, structural and cell biology provide complementary, yet unconnected visions of the inner workings of cells. Here we discuss how the interplay between cryo-EM and cryo-electron tomography, as a connecting bridge to visualize macromolecules in situ, holds great promise to create comprehensive structural depictions of macromolecules as they interact in complex mixtures or, ultimately, inside the cell itself.
大多数生命科学家都认为,要了解细胞过程是如何运作的,就需要了解涉及的大分子的结构知识。例如,破解 DNA 的双螺旋性质揭示了遗传信息如何存储、复制和修复的基本方面。然而,结构生物学本质上是还原论的,需要大量大分子的纯化,通常是从更大的功能单元中修剪下来的。低温电子显微镜(cryo-EM)的出现极大地促进了对大型功能复合物的研究,通常也促进了难以表达、纯化和/或结晶的样品的研究。然而,cryo-EM 仍然需要在大分子运行和共存的自然环境之外进行纯化和可视化。相反,细胞生物学家一直在使用许多快速发展的技术来对细胞进行成像,这些技术不断扩展其空间和时间的范围,但始终远远低于可以理解化学的分辨率。因此,结构生物学和细胞生物学提供了细胞内部运作的互补但不相关的视角。在这里,我们讨论了 cryo-EM 和 cryo-electron tomography 之间的相互作用如何作为连接桥梁,以可视化原位的大分子,这为创建大分子在复杂混合物中相互作用的综合结构描述,或者最终在细胞内部的结构描述,带来了巨大的希望。