Resolution extension by image summing in serial femtosecond crystallography of two-dimensional membrane-protein crystals.
Previous proof-of-concept measurements on single-layer two-dimensional membrane-protein crystals performed at X-ray free-electron lasers (FELs) have demonstrated that the collection of meaningful diffraction patterns, which is not possible at synchrotrons because of radiation-damage issues, is feasible. Here, the results obtained from the analysis of a thousand single-shot, room-temperature X-ray FEL diffraction images from two-dimensional crystals of a bacteriorhodopsin mutant are reported in detail. The high redundancy in the measurements boosts the intensity signal-to-noise ratio, so that the values of the diffracted intensities can be reliably determined down to the detector-edge resolution of 4 Å. The results show that two-dimensional serial crystallography at X-ray FELs is a suitable method to study membrane proteins to near-atomic length scales at ambient temperature. The method presented here can be extended to pump-probe studies of optically triggered structural changes on submillisecond timescales in two-dimensional crystals, which allow functionally relevant large-scale motions that may be quenched in three-dimensional crystals.
['Casadei|Cecilia M|CM|', 'Tsai|Ching-Ju|CJ|', 'Barty|Anton|A|', 'Hunter|Mark S|MS|', 'Zatsepin|Nadia A|NA|', 'Padeste|Celestino|C|https://orcid.org/0000-0001-7577-5781', 'Capitani|Guido|G|', 'Benner|W Henry|WH|', 'Boutet|Sébastien|S|https://orcid.org/0000-0003-3928-1244', 'Hau-Riege|Stefan P|SP|', 'Kupitz|Christopher|C|', 'Messerschmidt|Marc|M|https://orcid.org/0000-0002-8641-3302', 'Ogren|John I|JI|', 'Pardini|Tom|T|', 'Rothschild|Kenneth J|KJ|', 'Sala|Leonardo|L|', 'Segelke|Brent|B|', 'Williams|Garth J|GJ|', 'Evans|James E|JE|', 'Li|Xiao-Dan|XD|', 'Coleman|Matthew|M|', 'Pedrini|Bill|B|', 'Frank|Matthias|M|']
free-electron lasers two-dimensional crystals serial crystallography membrane proteins