Establishing micro electron diffraction as new tool for structural biology
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Date
2017-12-03
Journal Title
Journal ISSN
Volume Title
Publisher
Society of Crystallographers in Australia and New Zealand
Abstract
X-ray crystallography has been the dominant method for protein structure determination since the first structure of myoglobin was solved in the 1950s. The requirement for large, well-formed, micron-sized crystals can be a limiting factor in obtaining these structures. Consequently, projects that fail to meet these requirements often rely on X-ray Free Electron Lasers (XFELs), a method that require copious amounts of small crystals which is something that cannot be readily achieved for many proteins. In addition, access to free-electron lasers is prohibitive with only a handful currently operating. Given these challenges, an alternative method is required to determine high-resolution protein structures from small crystals. Recent advances in cryo electron microscopy have allowed for the development of a technique called micro electron diffraction (MED) where an electron microscope is used to collect electron diffraction patterns from cryogenically frozen sub-micron (< 500 nm) sized crystals. This technique is becoming increasingly popular with several structures solved including the core peptide of Tau filaments to a resolution of 1.1Å, the first novel structure solved by MED. Additionally, numerous crystallisation conditions that are typically overlooked for use by conventional methods have been shown to contain nano-crystals when analysed by electron microscopy, presenting new opportunities for MED.
In collaboration with Thermo Fisher (formerly FEI), we are working to establish MED as a viable alternative to both X-ray crystallography and XFELs for protein structure determination here at Monash University. Preliminary data collection techniques have been developed, along with preprocessing software to help streamline indexing, merging, and analysis of electron diffraction data. More recently, we have successfully collected test datasets of lysozyme that have yielded structures with a resolution of 2.8Å. Together, we have demonstrated the feasibility of this technique and now look toward applying it to novel protein samples.
Description
Keywords
Crystallography, X-ray diffraction, Free electron lasers, Electron microscopy, Data acquisition, Feasibility studies
Citation
Lupton, C., Buijsse, B., Yu, L., Law, R., Radjainia, M., Ramm, G., Caradoc-Davies, T., & Whisstock, J. (2017). Establishing micro electron diffraction as new tool for structural biology. Paper presented at CRYSTAL 31, the 31st Biennial Conference of the Society of Crystallographers in Australia and New Zealand, Pullman Bunker Bay, Western Australia, 3 – 7 December 2017. Retrieved from: https://crystal31.com/wp-content/uploads/2017/11/SCANZ-Crystal-31-2017-Book-of-Abstracts-FINAL.pdf#page=56