Early-stage dynamics of chloride ion–pumping rhodopsin revealed by a femtosecond X-ray laser
Ji-Hye Yun, Xuanxuan Li, Jianing Yue, Jae-Hyun Park, Zeyu Jin, Chufeng Li, Hao Hu, Yingchen Shi, Suraj Pandey, Sergio Carbajo, Sébastien Boutet, Mark S. Hunter, Mengning Liang, Raymond G. Sierra, Thomas J. Lane, Liang Zhou, Uwe Weierstall, Nadia A. Zatsepin, Mio Ohki, Jeremy R. H. Tame, Sam‐Yong Park, John C. H. Spence, Wenkai Zhang, Marius Schmidt, Weontae Lee, Haiguang Liu
Abstract
into cells. How the ClR initiates the transport is elusive. Here, we show the dynamics of ion transport observed with time-resolved serial femtosecond (fs) crystallography using the Linac Coherent Light Source. X-ray pulses captured structural changes in ClR upon flash illumination with a 550 nm fs-pumping laser. High-resolution structures for five time points (dark to 100 ps after flashing) reveal complex and coordinated dynamics comprising retinal isomerization, water molecule rearrangement, and conformational changes of various residues. Combining data from time-resolved spectroscopy experiments and molecular dynamics simulations, this study reveals that the chloride ion close to the Schiff base undergoes a dissociation-diffusion process upon light-triggered retinal isomerization.