Department of Chemistry, School of Science, The University of Tokyo , Tokyo, Japan.
J Phys Chem B. 2013 Oct 24;117(42):13212-8. doi: 10.1021/jp4032817. Epub 2013 May 28.
Split green fluorescent protein (GFP) is a powerful tool for imaging of protein-protein interactions in living cells, but molecular mechanisms of the folding and the assembly of split GFPs are poorly understood. Here, using a simple Go model that is based on the energy landscape theory, we performed comprehensive folding simulations of six split GFPs with different split points. Of the six, the fluorescence recovery was reported in four but not in the other two. In the simulations, we found that when the complete folding and assembly were observed, the N-terminal fragment always folded earlier than the C-terminal fragment. The in silico folding rates of the split GFPs were larger for the four split GFPs that the fluorescence recovery was reported in literature. The stability of standalone N-terminal fragments were well-correlated with the folding rates of split GFPs. These suggest that the efficient folding and assembly of split GFPs are realized when the N-terminal fragment folds spontaneously with the central α-helix as a nucleation core and that the C-terminal fragment folding is coupled to the assembly to the preformed N-terminal fragment.
分裂绿色荧光蛋白（GFP）是一种用于在活细胞中成像蛋白质-蛋白质相互作用的强大工具，但分裂 GFP 的折叠和组装的分子机制尚不清楚。在这里，我们使用基于能量景观理论的简单 Go 模型，对六个具有不同分裂点的分裂 GFP 进行了全面的折叠模拟。在这六个中，有四个的荧光恢复有报道，但另外两个没有。在模拟中，我们发现当观察到完整的折叠和组装时，N 端片段总是比 C 端片段更早折叠。文献中报道有荧光恢复的四个分裂 GFP 的折叠速率在计算机模拟中更大。独立的 N 端片段的稳定性与分裂 GFP 的折叠速率密切相关。这表明，当 N 端片段自发折叠并以中央α-螺旋作为核时，分裂 GFP 可以实现有效的折叠和组装，并且 C 端片段的折叠与预形成的 N 端片段的组装相耦合。
