4Z8K : Phycocyanin structure from T. elongatus at 2.5-A from XFEL using a viscous delivery medium for serial femtosecond crystallography

Experimental Technique/Method:X-RAY DIFFRACTION Resolution:2.5 Classification:PHOTOSYNTHESIS Release Date:2015-08-12 Deposition Date:2015-04-09 Revision Date:2018-02-14 Molecular Weight:37453.39 Macromolecule Type:Protein Residue Count:334 Atom Site Count:2627 DOI:10.2210/pdb4z8k/pdb Abstract: Serial femtosecond crystallography (SFX) has opened a new era in crystallo-graphy by permitting nearly damage-free, room-temperature structure determination of challenging proteins such as membrane proteins. In SFX, femtosecond X-ray free-electron laser pulses produce diffraction snapshots from nanocrystals and microcrystals delivered in a liquid jet, which leads to high protein consumption. A slow-moving stream of agarose has been developed as a new crystal delivery medium for SFX. It has low background scattering, is compatible with both soluble and membrane proteins, and can deliver the protein crystals at a wide range of temperatures down to 4°C. Using this crystal-laden agarose stream, the structure of a multi-subunit complex, phycocyanin, was solved to 2.5 Å resolution using 300 µg of microcrystals embedded into the agarose medium post-crystallization. The agarose delivery method reduces protein consumption by at least 100-fold and has the potential to be used for a diverse population of proteins, including membrane protein complexes.