Retinal isomerization in bacteriorhodopsin captured by a femtosecond x-ray laser

• Published in: Science (American Association for the Advancement of Science) 2018-07, Vol.361 (6398)
• Main Authors: Nogly, Przemyslaw, Weinert, Tobias, James, Daniel, Carbajo, Sergio, Ozerov, Dmitry, Furrer, Antonia, Gashi, Dardan, Borin, Veniamin, Skopintsev, Petr, Jaeger, Kathrin, Nass, Karol, Båth, Petra, Bosman, Robert, Koglin, Jason, Seaberg, Matthew, Lane, Thomas, Kekilli, Demet, Brünle, Steffen, Tanaka, Tomoyuki, Wu, Wenting, Milne, Christopher, White, Thomas, Barty, Anton, Weierstall, Uwe, Panneels, Valerie, Nango, Eriko, Iwata, So, Hunter, Mark, Schapiro, Igor, Schertler, Gebhard, Neutze, Richard, Standfuss, Jörg
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Analytisk kemi; Aspartic acid; Aspartic Acid - chemistry; Atomic properties; Atomic structure; Bacteriorhodopsin; Bacteriorhodopsins - chemistry; Bacteriorhodopsins - radiation effects; BASIC BIOLOGICAL SCIENCES; Biological activity; Charge distribution; Charge transfer; Chemical reactions; Chromophores; Circadian rhythms; Coherent light; Crystal structure; Crystallography; Dynamic structural analysis; Electrochemistry; Evolution; excited-state dynamics; free-electron lasers; Imines; Information processing; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Integral membrane proteins; Intermediates; Ion Transport; Isomerism; Isomerization; Lasers; Light; Light sources; Mechanics (Physics); Membranes; Microcrystals; Molecular chains; photoactive yellow protein; Photochemical reactions; Photochemicals; photoisomerization; primary photochemical event; Protein Conformation; Proteins; Protons; Proximity; Quantum mechanics; Radiation; Residues; resolved serial crystallography; Retina; Retinal-binding protein; Retinaldehyde - chemistry; Retinaldehyde - radiation effects; Schiff Bases - chemistry; schiff-base; Science & Technology - Other Topics; source; Spatial resolution; spectroscopy; Stereoselectivity; structural-changes; Time Factors; Timing; Water; Water - chemistry; X-ray diffraction; X-Rays
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.aat0094

Ultrafast isomerization of retinal is the primary step in photoresponsive biological functions including vision in humans and ion transport across bacterial membranes. We used an x-ray laser to study the subpicosecond structural dynamics of retinal isomerization in the light-driven proton pump bacteriorhodopsin. A series of structural snapshots with near-atomic spatial resolution and temporal resolution in the femtosecond regime show how the excited all-trans retinal samples conformational states within the protein binding pocket before 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 facet of this stereoselective and efficient photochemical reaction.