Structural studies of small viruses using an X-ray Free Electron Laser

Abstract: X-ray crystallography has since its introduction been the most successful technique for solving protein structures. Viruses however, often possess structural components such as fibrils, tails and envelopes that make them difficult or impossible to crystallize. To explore virus structures and the structural changes they undergo during host entry and infection, instrumental developments are required. X-ray Free Electron Lasers posses some advantages compared to conventional synchrotron sources, which enable experiments that previously were impossible. The femtosecond pulses and peak brilliance that exceeds synchrotrons by 109 facilitate recording of diffraction from nano/microcrystals and single particles before radiation damage takes place. The challenges for XFELs to reach its true potential in structural biology are nevertheless still many. During the technical and computational developments, using well-characterized reference samples is advantageous. In this thesis, the Rice Dwarf virus and MS2 bacteriophage have been used for single particle imaging and crystallography experiments using XFELs. These viruses are two of the smallest biological samples so far studied as single particles using this technique and the crystallography data of MS2 presented might serve as basis for solving the first high-resolution genome structure.Nanodiamonds, having a similar elemental composition as biological samples, could potentially serve as reference samples in XFEL studies. However, the biomedical field also has an interest in nanodiamonds, for drug delivery and as implant coating for example. Toxicity and biocompatibility is therefore a legitimate concern. Here, results from toxicity experiments of nanodiamonds on bacterial and zebrafish model organisms are presented.