| Autor: |
Pinto M; Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario N1G 2W1, Canada. vladizha@uoguelph.ca., Saliminasab M; Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario N1G 2W1, Canada. vladizha@uoguelph.ca., Harris A; Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario N1G 2W1, Canada. vladizha@uoguelph.ca., Lazaratos M; Freie Universität Berlin, Physics Department, Theoretical Molecular Biophysics Group, D-14195 Berlin, Germany., Bondar AN; University of Bucharest, Faculty of Physics, Măgurele 077125, Romania.; Forschungszentrum Jülich, Institute for Computational Biomedicine (IAS-5/INM-9), 52428 Jülich, Germany., Ladizhansky V; Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario N1G 2W1, Canada. vladizha@uoguelph.ca., Brown LS; Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario N1G 2W1, Canada. vladizha@uoguelph.ca. |
| Abstrakt: |
Inward proton pumping is a relatively new function for microbial rhodopsins, retinal-binding light-driven membrane proteins. So far, it has been demonstrated for two unrelated subgroups of microbial rhodopsins, xenorhodopsins and schizorhodopsins. A number of recent studies suggest unique retinal-protein interactions as being responsible for the reversed direction of proton transport in the latter group. Here, we use solid-state NMR to analyze the retinal chromophore environment and configuration in an inward proton-pumping Antarctic schizorhodopsin. Using fully 13 C-labeled retinal, we have assigned chemical shifts for every carbon atom and, assisted by structure modelling and molecular dynamics simulations, made a comparison with well-studied outward proton pumps, identifying locations of the unique protein-chromophore interactions for this functional subclass of microbial rhodopsins. Both the NMR results and molecular dynamics simulations point to the distinctive polar environment in the proximal part of the retinal, which may result in a hydration pattern dramatically different from that of the outward proton pumps, causing the reversed proton transport. |
