Kim Hanseong, Zou Taisong, Modi Chintan, Dörner Katerina, Grunkemeyer Timothy J, Chen Liqing, Fromme Raimund, Matz Mikhail V, Ozkan S Banu, Wachter Rebekka M
Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA.
Center for Biological Physics, Department of Physics, Arizona State University, Tempe, AZ 85287, USA.
Structure. 2015 Jan 6;23(1):34-43. doi: 10.1016/j.str.2014.11.011.
In proteins, functional divergence involves mutations that modify structure and dynamics. Here we provide experimental evidence for an evolutionary mechanism driven solely by long-range dynamic motions without significant backbone adjustments, catalytic group rearrangements, or changes in subunit assembly. Crystallographic structures were determined for several reconstructed ancestral proteins belonging to a GFP class frequently employed in superresolution microscopy. Their chain flexibility was analyzed using molecular dynamics and perturbation response scanning. The green-to-red photoconvertible phenotype appears to have arisen from a common green ancestor by migration of a knob-like anchoring region away from the active site diagonally across the β barrel fold. The allosterically coupled mutational sites provide active site conformational mobility via epistasis. We propose that light-induced chromophore twisting is enhanced in a reverse-protonated subpopulation, activating internal acid-base chemistry and backbone cleavage to enlarge the chromophore. Dynamics-driven hinge migration may represent a more general platform for the evolution of novel enzyme activities.
在蛋白质中，功能分化涉及改变结构和动力学的突变。在此，我们提供了一种进化机制的实验证据，该机制仅由长程动态运动驱动，而无显著的主链调整、催化基团重排或亚基组装变化。测定了几种属于超分辨率显微镜中常用的绿色荧光蛋白（GFP）类别的重建祖先蛋白的晶体结构。使用分子动力学和扰动响应扫描分析了它们的链柔性。绿到红的光转换表型似乎起源于一个常见的绿色祖先，通过一个旋钮状锚定区域对角地从活性位点移开，穿过β桶折叠。变构偶联的突变位点通过上位性提供活性位点构象流动性。我们提出，在反向质子化亚群中，光诱导的发色团扭曲增强，激活内部酸碱化学和主链裂解以扩大发色团。动力学驱动的铰链迁移可能代表了新酶活性进化的一个更通用的平台。
