当前位置: X-MOL 学术Nature › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
A mechanism of ferritin crystallization revealed by cryo-STEM tomography
Nature ( IF 64.8 ) Pub Date : 2020-03-25 , DOI: 10.1038/s41586-020-2104-4
Lothar Houben 1 , Haim Weissman 2 , Sharon G Wolf 1 , Boris Rybtchinski 2
Affiliation  

Protein crystallization is important in structural biology, disease research and pharmaceuticals. It has recently been recognized that nonclassical crystallization—involving initial formation of an amorphous precursor phase—occurs often in protein, organic and inorganic crystallization processes1,2,3,4,5. A two-step nucleation theory has thus been proposed, in which initial low-density, solvated amorphous aggregates subsequently densify, leading to nucleation4,6,7. This view differs from classical nucleation theory, which implies that crystalline nuclei forming in solution have the same density and structure as does the final crystalline state1. A protein crystallization mechanism involving this classical pathway has recently been observed directly8. However, a molecular mechanism of nonclassical protein crystallization9,10,11,12,13,14,15 has not been established9,11,14. To determine the nature of the amorphous precursors and whether crystallization takes place within them (and if so, how order develops at the molecular level), three-dimensional (3D) molecular-level imaging of a crystallization process is required. Here we report cryogenic scanning transmission microscopy tomography of ferritin aggregates at various stages of crystallization, followed by 3D reconstruction using simultaneous iterative reconstruction techniques to provide a 3D picture of crystallization with molecular resolution. As crystalline order gradually increased in the studied aggregates, they exhibited an increase in both order and density from their surface towards their interior. We observed no highly ordered small structures typical of a classical nucleation process, and occasionally we observed several ordered domains emerging within one amorphous aggregate, a phenomenon not predicted by either classical or two-step nucleation theories. Our molecular-level analysis hints at desolvation as the driver of the continuous order-evolution mechanism, a view that goes beyond current nucleation models, yet is consistent with a broad spectrum of protein crystallization mechanisms.



中文翻译:

冷冻 STEM 断层扫描揭示的铁蛋白结晶机制

蛋白质结晶在结构生物学、疾病研究和药物学中很重要。最近人们认识到,非经典结晶(包括初始形成无定形前体相)通常发生在蛋白质、有机和无机结晶过程中1,2,3,4,5。因此提出了一个两步成核理论,其中最初的低密度溶剂化无定形聚集体随后致密化,导致成核4,6,7。这种观点不同于经典的成核理论,后者意味着在溶液中形成的晶核具有与最终晶态1相同的密度和结构。最近直接观察到涉及这种经典途径的蛋白质结晶机制8 . 然而,非经典蛋白质结晶的分子机制9,10,11,12,13,14,15尚未建立9,11,14. 为了确定无定形前体的性质以及是否在其中发生结晶(如果是,那么在分子水平上如何形成有序),需要对结晶过程进行三维 (3D) 分子水平成像。在这里,我们报告了在结晶的各个阶段对铁蛋白聚集体进行低温扫描透射显微镜断层扫描,然后使用同步迭代重建技术进行 3D 重建,以提供具有分子分辨率的结晶 3D 图片。随着所研究的聚集体的结晶有序度逐渐增加,它们的有序度和密度从表面到内部都呈现出增加的趋势。我们没有观察到典型的经典成核过程的高度有序的小结构,偶尔我们观察到在一个无定形聚集体中出现了几个有序域,这是经典或两步成核理论都没有预测到的现象。我们的分子水平分析暗示去溶剂化是连续有序演化机制的驱动因素,这一观点超越了当前的成核模型,但与广泛的蛋白质结晶机制相一致。

更新日期:2020-03-25
down
wechat
bug