Department of Chemistry, University of California, Davis, California, USA.
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Protein Sci. 2024 Oct;33(10):e5168. doi: 10.1002/pro.5168.
The tropomyosin 1 isoform I/C C-terminal domain (Tm1-LC) fibril structure is studied jointly with cryogenic electron microscopy (cryo-EM) and solid state nuclear magnetic resonance (NMR). This study demonstrates the complementary nature of these two structural biology techniques. Chemical shift assignments from solid state NMR are used to determine the secondary structure at the level of individual amino acids, which is faithfully seen in cryo-EM reconstructions. Additionally, solid state NMR demonstrates that the region not observed in the reconstructed cryo-EM density is primarily in a highly mobile random coil conformation rather than adopting multiple rigid conformations. Overall, this study illustrates the benefit of investigations combining cryo-EM and solid state NMR to investigate protein fibril structure.
肌球蛋白轻链 1 同工型 I/C C 末端结构域（Tm1-LC）纤维结构通过低温电子显微镜（cryo-EM）和固态核磁共振（NMR）联合研究。本研究证明了这两种结构生物学技术的互补性。固态 NMR 的化学位移赋值用于确定单个氨基酸水平的二级结构，这在 cryo-EM 重建中得到了忠实的体现。此外，固态 NMR 表明，在重建的 cryo-EM 密度中未观察到的区域主要处于高度运动的无规卷曲构象，而不是采用多种刚性构象。总体而言，这项研究说明了结合 cryo-EM 和固态 NMR 研究蛋白质纤维结构的研究的益处。
