Cryo-EM for understanding molecular processes in health and disease

Knowledge of the molecular structure of proteins and nucleic acids that are the building blocks of life has had unparalleled impact on our understanding of human health and disease. Almost 90% of the structures determined to date have been solved by crystallography, using diffraction of X-rays. Electrons are, however, 1000 times less damaging to biological molecules than X-rays, in terms of energy deposited per useful scattering event. This makes it possible to use electron cryomicroscopy (cryoEM) to record images of single macromolecules embedded in a layer of vitreous ice at cryogenic temperatures. It is expected that this technique, for which Jacques Dubochet, Joachim Frank and Richard Henderson were awarded the 2017 Nobel Prize, will be used to determine an ever-increasing proportion of structures of macromolecules in the future.

The project will employ cutting-edge cryoEM approaches, including the use of electron diffraction from sub-micron sized crystals (nanocrystals) for structure determination. Recent studies showed that electron diffraction can be successfully applied to determine structures of test proteins (such as lysozyme) from nanocrystals and to determine novel structures from 'invisible' crystals of short peptides. Nanocrystals are millions of times smaller than the crystals required for x-ray diffraction. The aim of this project is to apply this novel technique to systems available in Prof Fred Antson lab (nucleic acid-processing machines involved in virus biogenesis). In particular, the research will question whether protein crystals that diffract x-rays poorly can be used to generate nanocrystals for electron diffraction to enable structural discoveries that are important for human health. Moreover, as nanocrystals suitable for electron diffraction are too small to be observed using a light microscope one exciting possibility this project will address is whether apparently 'failed' crystallisation trials in fact contain nanocrystals suitable for collection of electron diffraction data.

The project is at the interface of biochemistry, physics and structural biology; it will involve both the development of novel methods and structure determination by cryoEM, in particular by electron diffraction.