Towards the structural analysis of protein nanocrystals with X-ray free-electron laser sources — ASN Events
  1. Schedule
  2. Session Ten - Poster Session C including Refreshments
  3. Towards the structural analysis of protein nanocrystals with X-ray free-electron laser sources

Towards the structural analysis of protein nanocrystals with X-ray free-electron laser sources (#370)

Sophie R. Williams 1 2 , Ruben A. Dilanian 1 2 , Victor A. Streltsov 3 , Andrew V. Martin 1 2 , Harry M. Quiney 1 2
  1. ARC Centre of Excellence in Advanced Molecular Imaging, University of Melbourne, VIC, Australia
  2. School of Physics, University of Melbourne, Parkville, VIC, Australia
  3. CSIRO, Parkville, VIC, Australia
Significant limitations are imposed upon protein crystal samples for conventional synchrotron-based protein crystallography by radiation damage. The intensity and femtosecond time-scale of X-ray free-electron laser (XFEL) sources present new opportunities for the study of protein crystal structures by reducing the size and quality requirements for crystal samples. Serial femtosecond X-ray crystallography experiments with XFEL sources (Chapman 2011) have produced several recent successes in structural biology (e.g. Redecke 2103, Johansson 2013, Liu 2013). Fresh consideration of the analysis of data from SFX experiments may be required, however, due to extended intensity distributions arising around Bragg reflections (Yefanov 2014).

A new approach towards the analysis of SFX diffraction data is presented here. This builds upon an analysis technique established in powder diffraction, the Le Bail method (LeBail 1988), with the observation that similarities are held between powder diffraction patterns and merged SFX data-sets. In both cases, peak-shape distributions are formed by the shape, size and disorder characteristics of a large set of independent scatterers. The presented work utilises a whole-pattern fitting approach for the modelling of SFX data and the extraction of structure-factor amplitudes to be used in subsequent stages of the structure determination process. This follows the work of Dilanian et al. (2013) in the use of a continuous description of the diffractive field from a protein nanocrystal sample, rather than considering discrete Bragg reflections (Kirian 2010). 

Findings from a simulation study on the sugar binding domain of Langerin protein with F241L mutation (PDB:4AK8) are presented with structure factor amplitudes extracted and tested against 
calculated values from the published structure of the test protein. These results indicate the feasibility of this approach for the analysis of high-resolution experimental SFX data from large collections of nanocrystals in which crystal size-effects and structural imperfections can be incorporated. This analysis approach also holds potential for application to synchrotron-based serial protein crystallography at hard X-ray microfocussed beamlines.
  1. H. N. Chapman, P. Fromme, A. Barty, et al., Nature, 470, 73 (2011)
  2. L. Redecke, K. Nass, D. P. DePonte, et al., Science, 339, 227 (2013).
  3. L. C. Johansson, D. Arnlund, G. Katona, et al., Nat. Commun., 4, 2911 (2013).
  4. W. Liu, D. Wacker, C. Gati, et al., Science, 342, 1521 (2013).
  5. O. Yefanov, C. Gati, G. Bourenkov, et al., Phil. Trans. R. Soc. B, 369, 20130333 (2014).
  6. A. Le Bail, H. Duroy, J.L. Fourquet, Mat. Res. Bull., 23, 447 (1988).
  7. R. A. Dilanian, V. A. Streltsov, H. M. Quiney, K. A. Nugent, Acta Cryst., A69, 108 ( 2013).
  8. R. A. Kirian, X. Wang, U. Weierstall, et al., Opt. Exp., 18, 5713 (2010).
  9. PDB ID: 4AK8, E. Chabrol, M. Thepaut, C. Dezutter-Dambuyant, et al. DOI:10.2210/pdb4ak8/pdb.