Department of Plant Physiology, Warsaw University of Life Sciences - SGGW, 02-776 Warsaw, Poland.
Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University, 12800 Prague, Czech Republic.
Structure. 2021 Nov 4;29(11):1279-1285.e3. doi: 10.1016/j.str.2021.06.014. Epub 2021 Jul 14.
Bacterial surface layers are paracrystalline assemblies of proteins that provide the first line of defense against environmental shocks. Here, we report the 3D structure, in situ localization, and orientation of the S-layer deinoxanthin-binding complex (SDBC), a hetero-oligomeric assembly of proteins that in Deinococcus radiodurans represents the main S-layer unit. The SDBC is resolved at 11-Å resolution by single-particle analysis, while its in situ localization is determined by cryo-electron crystallography on intact cell-wall fragments leading to a projection map at 4.5-Å resolution. The SDBC exhibits a triangular base with three comma-shaped pores, and a stalk departing orthogonally from the center of the base and oriented toward the intracellular space. Combining state-of-the-art techniques, results show the organization of this S-layer and its connection within the underlying membranes, demonstrating the potential for applications from nanotechnologies to medicine.
细菌表面层是蛋白质的准晶组装，为抵御环境冲击提供了第一道防线。在这里，我们报告了 3D 结构、原位定位和取向的 S-层脱氮黄嘌呤结合复合物（SDBC），这是一种异源寡聚体蛋白组装，在 Deinococcus radiodurans 中代表主要的 S-层单元。通过单颗粒分析解析了 SDBC 的分辨率为 11-Å，而其原位定位则通过对完整细胞壁片段进行低温电子晶体学确定，得到分辨率为 4.5-Å 的投影图。SDBC 呈现三角形基底，有三个逗号形孔，一个从基底中心垂直伸出并朝向细胞内空间的柄。结合最先进的技术，结果表明了这种 S-层的组织及其与底层膜的连接，展示了从纳米技术到医学的潜在应用。
