Departments of Physics and Astronomy, Columbia, Missouri 65211.
Biochemistry, University of Missouri, Columbia, Missouri 65211.
J Biol Chem. 2013 Jun 7;288(23):16848-16854. doi: 10.1074/jbc.M113.471870. Epub 2013 Apr 22.
Purified SecYEG was reconstituted into liposomes and studied in near-native conditions using atomic force microscopy. These SecYEG proteoliposomes were active in translocation assays. Changes in the structure of SecYEG as a function of time were directly visualized. The dynamics observed were significant in magnitude (∼1-10 Å) and were attributed to the two large loops of SecY linking transmembrane helices 6-7 and 8-9. In addition, we identified a distribution between monomers and dimers of SecYEG as well as a smaller population of higher order oligomers. This work provides a new vista of the flexible and dynamic structure of SecYEG, an intricate and vital membrane protein.
纯化的 SecYEG 被重构成脂质体，并使用原子力显微镜在近乎天然的条件下进行研究。这些 SecYEG 磷脂囊泡在易位测定中是有活性的。可以直接观察到 SecYEG 结构随时间的变化。观察到的动力学变化幅度很大（约 1-10 Å），归因于连接跨膜螺旋 6-7 和 8-9 的 SecY 的两个大环。此外，我们还确定了 SecYEG 单体和二聚体之间的分布以及更小的高级寡聚体种群。这项工作为 SecYEG 的灵活和动态结构提供了一个新的视角，SecYEG 是一种复杂而重要的膜蛋白。
