MS01-P02 Retinal isomerization in bacteriorhodopsin captured by a femtosecond X-ray laser Przemyslaw Nogly (Department of Biology, ETH Zurich, Zurich, Switzerland) Tobias Weinert (Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland) Daniel James (Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland) Sergio Carbajo (Linac Coherent Light Source, Stanford Linear Accelerator Center National Accelerator Laboratory, Menlo Park, United States of America) Dmitry Ozerov (Science IT, Paul Scherrer Institute, Villigen, Switzerland) Igor Schapiro (Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel) Gebhard Schertler (Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland) Richard Neutze (Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden) Jörg Standfuss (Division of Biology and Chemistry, Paul Scherrer Institute, Villigen, Switzerland)email: przemyslaw.nogly@biol.ethz.chUltrafast isomerization of retinal is the primary step in photoresponsive biological functions including vision in humans and ion-transport across bacterial membranes. We studied the sub-picosecond structural dynamics of retinal isomerization in the light-driven proton pump bacteriorhodopsin using an X-ray laser. A series of structural snapshots with near-atomic spatial and temporal resolution in the femtosecond regime show how the excited all-trans retinal samples conformational states within the protein binding pocket prior to passing through a twisted geometry and emerging in the 13-cis conformation. Our findings suggest ultrafast collective motions of aspartic acid residues and functional water molecules in the proximity of the retinal Schiff base as a key ingredient for this stereo-selective and effcient photochemical reaction.References:

Nogly, P. et al. Retinal isomerization in bacteriorhodopsin captured by a femtosecond X-ray laser, under revision.

Nango, E. et al. (2016). Science, 354, 1552-1557.

Nogly, P. et al. (2016). Nat. Commun, 7, 12314.
Keywords: time-resolved crystallography, X-ray free electron laser, ultra-fast dynamics