Winkler Andreas, Barends Thomas R M, Udvarhelyi Anikó, Lenherr-Frey Daniel, Lomb Lukas, Menzel Andreas, Schlichting Ilme
Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research , Jahnstrasse 29, 69120 Heidelberg, Germany.
ACS Chem Biol. 2015 Feb 20;10(2):502-9. doi: 10.1021/cb500744m. Epub 2014 Nov 17.
Optical control of cellular processes is an emerging approach for studying biological systems, affording control with high spatial and temporal resolution. Specifically designed artificial photoswitches add an interesting extension to naturally occurring light-regulated functionalities. However, despite a great deal of structural information, the generation of new tools cannot be based fully on rational design yet; in many cases design is limited by our understanding of molecular details of light activation and signal transduction. Our biochemical and biophysical studies on the established optogenetic tool PA-Rac1, the photoactivatable small GTPase Rac1, reveal how unexpected details of the sensor-effector interface, such as metal coordination, significantly affect functionally important structural elements of this photoswitch. Together with solution scattering experiments, our results favor differences in the population of pre-existing conformations as the underlying allosteric activation mechanism of PA-Rac1, rather than the assumed release of the Rac1 domain from the caging photoreceptor domain. These results have implications for the design of new optogenetic tools and highlight the importance of including molecular details of the sensor-effector interface, which is however difficult to assess during the initial design of novel artificial photoswitches.
细胞过程的光学控制是一种新兴的研究生物系统的方法，能够提供高空间和时间分辨率的控制。专门设计的人工光开关为自然发生的光调节功能增添了有趣的扩展。然而，尽管有大量的结构信息，但新工具的生成目前还不能完全基于合理设计；在许多情况下，设计受到我们对光激活和信号转导分子细节理解的限制。我们对已建立的光遗传学工具PA-Rac1（光激活的小GTP酶Rac1）进行的生化和生物物理研究揭示了传感器-效应器界面的意外细节，如金属配位，是如何显著影响这种光开关的功能重要结构元件的。结合溶液散射实验，我们的结果支持预先存在的构象群体差异作为PA-Rac1潜在的变构激活机制，而不是假定的Rac1结构域从笼形光感受器结构域释放。这些结果对新光遗传学工具的设计有影响，并突出了纳入传感器-效应器界面分子细节的重要性，然而在新型人工光开关的初始设计过程中很难评估这些细节。
