Recent Advances and Future Prospects of Serial Crystallography using XFEL and synchrotron X-ray sources

Abstract

Protein structure determination at the atomic level is an essential step for understanding protein functions and developing new drugs. However, growing crystals of sufficient quality and size necessary to obtain good diffraction patterns is a significant bottleneck. The advent of X-ray free electron lasers (XFELs) has made it possible to collect high quality X-ray diffraction patterns from nano- or micro-sized crystals because a typical XFEL pulse is intense enough to provide a diffraction pattern from such small sized crystals and is temporally short (less than 50 femtoseconds) enough to collect the diffraction pattern prior to crystal destruction or significant radiation damage. A combination of this idea and a continuous sample delivery system supplying a fresh crystal for every X-ray pulse provides a nascent field of serial femtosecond crystallography (SFX). The concept of serial crystallography (SX) is also being adapted in conventional micro- and nanofocused synchrotron beamlines, resulting in serial synchrotron crystallography (SSX). In this review, we survey and examine a variety of currently available sample delivery systems in SFX and SSX and discuss their advantages and drawbacks. We also review the protein systems studied by SFX and SSX and various protein crystallization techniques that are particularly useful for membrane proteins in the application with SFX and SSX. Finally, we highlight the applicability of the SFX and SSX methods for time-resolved studies, which offer notable new possibilities for tracking both the reversible and irreversible structural dynamics of proteins at the atomic level in real time. SSX and SFX may revolutionize the field of structural biology. © 2015 Bio Design