A new dimension in structural biology: fully fledged high-pressure macromolecular crystallography

Abstract

The amount of accurate crystallographic data currently available on macromolecular structures at high pressure is extremely limited, mainly due to the lack of appropriate instrumentation and X-ray sources. A technical breakthrough has been achieved with a set-up at the ESRF ID30 beamline equipped with a diamond anvil cell and a large imaging plate, and taking advantage from undulators providing a quasi-plane wave of ultrashort wavelength X-rays. The accessible pressure range is increased by nearly one order of magnitude with respect to beryllium cells. A nearly perfect long-range order is preserved in protein and virus crystals compressed below the denaturation pressure. The quality of diffraction data collected at high pressure can meet usual standards, especially in the case of high symmetry space groups.

An overview of main results and ongoing studies is given, including the 7 kbar structure of hen egg-white lysozyme refined at 1.6 Å resolution and structural investigations of cowpea mosaic virus (CPMV), the first macromolecular assembly investigated at high pressure by single crystal X-ray diffraction. The ordering effect of high pressure on the molecular packing of disordered P23 crystals was highlighted. The 2.8 Å resolution structure of CPMV at 3.3 kbar was fully refined using high completeness data collected on pressure-ordered I23 crystals.

Keywords:

• High pressure
• Macromolecular crystallography
• Diamond anvil cell
• Lysozyme
• Virus

Acknowledgements

We thank one of the referees for suggesting the potential use of high pressure as a tool for phasing and phase improvement in macromolecular crystallography.