title: Visualization of membrane protein crystals in lipid cubic phase using X-ray imaging.
abstract: The focus in macromolecular crystallography is moving towards even more challenging target proteins that often crystallize on much smaller scales and are frequently mounted in opaque or highly refractive materials. It is therefore essential that X-ray beamline technology develops in parallel to accommodate such difficult samples. In this paper, the use of X-ray microradiography and microtomography is reported as a tool for crystal visualization, location and characterization on the macromolecular crystallography beamlines at the Diamond Light Source. The technique is particularly useful for microcrystals and for crystals mounted in opaque materials such as lipid cubic phase. X-ray diffraction raster scanning can be used in combination with radiography to allow informed decision-making at the beamline prior to diffraction data collection. It is demonstrated that the X-ray dose required for a full tomography measurement is similar to that for a diffraction grid-scan, but for sample location and shape estimation alone just a few radiographic projections may be required.
authors.affiliation: Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England.
authors.forename: Anna J
authors.initials: AJ
authors.lastname: Warren
authors.forename: Wes
authors.initials: W
authors.lastname: Armour
authors.forename: Danny
authors.initials: D
authors.lastname: Axford
authors.forename: Mark
authors.initials: M
authors.lastname: Basham
authors.forename: Thomas
authors.initials: T
authors.lastname: Connolley
authors.forename: David R
authors.initials: DR
authors.lastname: Hall
authors.forename: Sam
authors.initials: S
authors.lastname: Horrell
authors.forename: Katherine E
authors.initials: KE
authors.lastname: McAuley
authors.forename: Vitaliy
authors.initials: V
authors.lastname: Mykhaylyk
authors.forename: Armin
authors.initials: A
authors.lastname: Wagner
authors.forename: Gwyndaf
authors.initials: G
authors.lastname: Evans
mesh_terms: D000465:Algorithms; D001436:Bacteriorhodopsins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D003627:Data Interpretation, Statistical; D001330:Electronic Data Processing; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008055:Lipids / Q000737:chemistry*; D008852:Microradiography; D009572:Nitrite Reductases / Q000737:chemistry*; D043705:Receptor, Adenosine A2A / Q000737:chemistry*; D012984:Software; D014057:Tomography, X-Ray Computed
chemical_list: D008055:Lipids; D043705:Receptor, Adenosine A2A; D001436:Bacteriorhodopsins; D009572:Nitrite Reductases; C052695:nitrite reductase, copper-containing
keywords: lipid cubic phase; membrane proteins; microradiography; microtomography