First de novo structure at Diamond

Scientists from Newcastle University have solved the first de novo crystal structure of a protein using diffraction data from Diamond Light Source. The researchers successfully crystallised a protein called RsbS from the bacterium Moorella thermoacetica, and solved the crystal structure to 2.5 Å resolution.

M. thermoacetica is a thermophile, a bacterium that likes to grow in high temperature environments. It has the ability to form heat-resistant spores that can resist temperatures as high as 121 ^oC. RsbS is a component of assemblies of proteins known as ‘stressosomes’ in another bacterium, called Bacillus subtilis. These stressosomes regulate stress resistance by transmitting signals via a protein called RsbT when in a stressful environment.

However, the equivalent structure in M. thermoacetica, which includes RsbS proteins, does not regulate stress resistance. Instead, it regulates the production of a very common signalling molecule called cyclic diguanosine monophosphate. Nonetheless, because the sequences of RsbS proteins in both species of bacterium are similar, the new crystal structure will allow comparisons to be made to investigate how the stressosome binds and releases the signalling protein RsbT.

Section of the 3.5 A ° experimentally phased electron-density map produced by the program RESOLVE.

Solution of the crystal structure of RsbS used a technique known as SAD phasing. This is one method of recovering important information lost during the measurement of diffraction data, and can be advantageous when using delicate protein samples as it requires less time in the synchrotron radiation beam. In addition, less beamtime is needed, saving resources. This research therefore shows Diamond has a promising future producing high-quality protein structures on the Macromolecular Crystallography beam-lines.

This research was funded by the BBSRC and Newcastle University.

Maureen Quin, Joseph Newman, Susan Firbank, Richard J. Lewis and Jon Marles-Wright Crystallization and preliminary X-ray analysis of RsbS from Moorella thermoacetica at 2.5A° resolution, 2008 Acta Crystallographica Section F, Structural Biology and Crystallization Communications