Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Frankfurt am Main, Germany.
Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
Biophys J. 2021 Feb 2;120(3):568-575. doi: 10.1016/j.bpj.2020.12.011. Epub 2020 Dec 19.
We investigated the temperature-dependent kinetics of the light-driven Na pump Krokinobacter rhodopsin 2 (KR2) at Na-pumping conditions. The recorded microsecond flash photolysis data were subjected to detailed global target analysis, employing Eyring constraints and spectral decomposition. The analysis resulted in the kinetic rates, the composition of the different photocycle equilibria, and the spectra of the involved photointermediates. Our results show that with the temperature increase (from 10 to 40°C), the overall photocycle duration is accelerated by a factor of 6, with the L-to-M transition exhibiting an impressive 40-fold increase. It follows from the analysis that in KR2 the chromophore and the protein scaffold are more kinetically decoupled than in other microbial rhodopsins. We link this effect to the rigidity of the retinal protein environment. This kinetic decoupling should be considered in future studies and could potentially be exploited for fine-tuning biotechnological applications.
我们研究了在钠泵条件下，光驱动 Na 泵嗜盐菌视紫红质 2（KR2）的温度依赖动力学。记录的微秒闪光光解数据经过详细的全局目标分析，采用 Eyring 约束和光谱分解。分析结果得到了动力学速率、不同光循环平衡的组成以及涉及的光中间产物的光谱。我们的结果表明，随着温度的升高（从 10°C 到 40°C），整个光循环时间加速了 6 倍，L 到 M 的转变令人印象深刻地增加了 40 倍。分析表明，在 KR2 中，发色团和蛋白质支架的动力学解耦程度比其他微生物视紫红质更高。我们将这种效应与视黄醛蛋白环境的刚性联系起来。在未来的研究中应该考虑这种动力学解耦，并且可能有潜力用于微调生物技术应用。
