First Release of Science paper by J. Heberle (B3), I. Schapiro (C6) and colleagues from the ETH Zurich and PSI Villingen
A brand-new publication by SFB 1078 PIs and colleagues from Switzerland proposes the ion transfer pathway in bacterial halorhodopsin and discusses the interplay between the driving force created by the protein dipole moment and the control of transport by molecular gates. Furthermore, the authors provide details of how light energy is converted into kinetic energy for chloride translocation. The resulting charge separation represents a fundamental feature for light energy conversion in nature as well as in technology:
Mous et al. 2022. Dynamics and mechanism of a light-driven chloride pump. Science (3 Feb 2022), DOI: 10.1126/science.abj6663
News from Feb 04, 2022
Chloride transport by microbial rhodopsins is an essential process for which molecular details—such as the mechanisms that convert light energy to drive ion pumping and ensure the unidirectionality of the transport—have remained elusive. We combined time-resolved serial crystallography with time-resolved spectroscopy and multiscale simulations to elucidate the molecular mechanism of a chloride pumping rhodopsin and the structural dynamics throughout the transport cycle. We traced transient anion binding sites, obtained evidence for how light energy is used in the pumping mechanism, and identified steric and electrostatic molecular gates ensuring unidirectional transport. An interaction with the π-electron system of the retinal supports transient chloride ion binding across a major bottleneck in the transport pathway. These results allow us to propose key mechanistic features enabling finely controlled chloride transport across the cell membrane in this light powered chloride ion pump.