Fully-fledged macromolecular crystallography under high pressure and lessons: plea for ultra-short wavelength beamlines

R. Kahn (1) , R. Fourme (2), E. Girard (2), I. Ascone (3), M. Mezouar (4), T. Lin (5) & J. E. Johnson (5)

(1) IBS, 41 Rue Jules Horowitz, 38027 Grenoble Cedex, France
(2) Synchrotron-SOLEIL, BP48 Saint Aubin, 91192 Gif sur Yvette, France
(3) LURE, B209D, Université Paris-Sud, 91898, Orsay cedex, France
(4) ESRF, BP220, 38027, Grenoble Cedex, France
(5) The Scripps Research Institute, 10550N, Torrey Pines Road, La Jolla, CA 92037, USA

The 2.8 Å structure of the capsid of an icosahedral virus, Cowpea Mosaic Virus (CPMV) compressed at 330 MPa, has been refined to R- and R-free values equal resp. to 0.161 and 0.167. The completeness of the data set (space group I23) collected with a MAR 345 imaging plate detector was 91.2 %. Main changes from atmospheric pressure to high pressure will be described, including temperature factors, cavity volumes, buried surfaces and hydrogen-bond lengths. This is the first structural study of a complex macromolecular structure under high pressure.

Data collection was performed on the ID30 beamline at the ESRF, using ultrashort wavelength (0.331 Å) and special diamond anvil cells. Instrumentation and procedures by which accurate and high completeness data were collected under high pressure will be described.

Results obtained for protein crystals demonstrate that such studies are possible even in the case of low symmetry space groups, thus demonstrating that high pressure macromolecular crystallography is now a fully-fledged technique.

Lessons from these measurements suggest that quasi-parallel beams of ultrashort wavelength may be of considerable interest also for conventional macromolecular crystallography, in particular because, in the case of CPMV studies, the diffraction information per unit volume of sample was increased with respect to 1 Å data collection.

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