Batch crystallization of rhodopsin for structural dynamics using an X-ray free-electron laser.

Wenting Wu, Przemyslaw Nogly, Jan Rheinberger, Leonhard M Kick, Cornelius Gati, Garrett Nelson, Xavier Deupi, Jörg Standfuss, Gebhard Schertler, Valérie Panneels

Index: Acta Crystallogr. F. Struct. Biol. Commun. 71 , 856-60, (2015)

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Abstract

Rhodopsin is a membrane protein from the G protein-coupled receptor family. Together with its ligand retinal, it forms the visual pigment responsible for night vision. In order to perform ultrafast dynamics studies, a time-resolved serial femtosecond crystallography method is required owing to the nonreversible activation of rhodopsin. In such an approach, microcrystals in suspension are delivered into the X-ray pulses of an X-ray free-electron laser (XFEL) after a precise photoactivation delay. Here, a millilitre batch production of high-density microcrystals was developed by four methodical conversion steps starting from known vapour-diffusion crystallization protocols: (i) screening the low-salt crystallization conditions preferred for serial crystallography by vapour diffusion, (ii) optimization of batch crystallization, (iii) testing the crystal size and quality using second-harmonic generation (SHG) imaging and X-ray powder diffraction and (iv) production of millilitres of rhodopsin crystal suspension in batches for serial crystallography tests; these crystals diffracted at an XFEL at the Linac Coherent Light Source using a liquid-jet setup.