Prof Neil Ranson
Electron microscopy, macromolecular assembly, structure, virus
I am interested in the structures of large macromolecular assemblies, and particularly in how conformational change in such structures drives biological function. We use cryo-electron microscopy, cryo-electron tomography and computational image processing methods to determine the structures of such complexes in 3-D. Current research interests are focussed around the assembly, structure and function of RNA viruses, and the structure of amyloid protein in vitro and in vivo.Current major projects include:
- Visualizing unique features of viruses by determining their structures
- Receptor-binding by ssRNA viruses and how binding leads to infection
- What can structure tell us about how viruses package their genomes?
- The structure of amyloid aggregates and the basis of cytotoxicity
Figure 1. Cryo-EM image of bacteriophage MS2 bound to its receptor, the bacterial F-pilus. The right-hand side of the image has been false-coloured to show the pilus (purple), with bound MS2 (red), together with the small fraction of MS2 that lack a viral maturation protein and therefore do not bind (green).
Single-stranded (ss)RNA viruses are major pathogens across all kingdoms of life, and new viruses of this type continue to emerge because of factors such as climate change, population growth and increased mobility. These viruses present society with huge public health and economic challenges, but few therapeutic options exist beyond vaccination, which is not always practical or effective. We need new therapies capable of tackling the diseases these viruses cause, and to develop them we need a deeper understanding of all aspects of the ssRNA virus lifecycle.
|Figure 2. Asymmetric structure of MS2 bound to its receptor. The fitted atomic coordinates are shown on the left hand side. The dashed lines illustrates that the virus binds at a slight (9°) angle on the pilus (Dent et al, 2013).|
We are interested in several aspects of virus lifecycles. Firstly we want to understand how viruses infect their host cells. This type of virus typically has an icosahedrally symmetric protein shell to protect its genome, but they also typically have asymmetric features as well, such as infectivity or maturation proteins, not to mention the genome itself. Such features are vital for the virus’ lifecycle, but we understand them poorly because they are lost when symmetry averaging is applied during structure determination. We are developing biochemical, methodological and computational approaches to allow asymmetric structure determination of this type of virus.
Figure 3. A section through the 9Å cryo-EM structure of MS2. The EM map has been masked away in the protein shell region. The remaining density corresponds to the encapsidated genomic RNA (Toropova et al, 2008).
One such approach is to look at the complex a virus makes with its receptor. This is especially important because it is the first step in establishing a new infection. It also leads directly to a large, highly charged RNA molecule crossing a membrane bilayer to get into the cytoplasm of a cell where it can be replicated and translated, and this process is very poorly understood. We are interested in all aspects of
receptor binding and in understanding the molecular details of how a genomic RNA enters the cell.
The assembly pathways of ssRNA viruses, and the structures of packaged RNAs that they lead to, are candidates for anti-viral therapy: if we understand how assembly is driven perhaps we can block it, if we know the structure a packaged RNA must adopt perhaps we can stop it.
We are also interested in protein misfolding and aggregation. The deposition of proteins as amyloid aggregates is linked to a wide range of diseases, such as Alzheimer’s and Parkinson’s diseases, and dialysis related amyloidosis. We want to understand the structure of the amyloid aggregates themselves, and the molecular mechanisms that underpin aggregation. We also want to understand how the process of aggregation into amyloid leads to the toxicity that can have such a devastating effects. To do this we are imaging the effects that amyloid aggregates have on cells and biological membranes.
Professor of Structural Molecular Biology
BSc (Bristol) PhD (Bristol)
PDRA, Birkbeck College London, 1997-2002
University Research Fellow, University of Leeds, 2002-2008
Lecturer, University of Leeds, 2008-2012
Astbury Building, Room 8.108
School of Molecular and Cellular Biology
0113 343 7065
Hurdiss, D.L., Thompson, R.F., Morgan, E.L., Prescott, E.L., Panou, M.M., Macdonald, A. & Ranson, N.A. (2016). New structural insights into the genome and minor capsid proteins of BK polyomavirus using cryo-electron microscopy. Structure, DOI:10.1016/j.str.2016.02.008
Hesketh, E.L., Meshcheriakova, Y., Dent, K.C., Saxena, P., Thompson, R.F., Cockburn, J.J.B, Lomonossoff, G.P. & Ranson, N.A. (2015). Mechanisms of assembly and genome packaging in an RNA virus revealed by high-resolution cryo-EM. Nature Comms., DOI:10.1038/ncomms10113
Bakker, S.E., Groppelli, E., Pearson, A.R., Stockley, S.G., Rowlands, D.J. & Ranson, N.A. (2014). Limits of Structural Plasticity in a Picornavirus Capsid Revealed by a Massively Expanded Equine Rhinitis A Virus Particle. J. Virol., 88, p6093
Dent, K.C., Thompson, R., Barker, A.M., Barr, J.N., Hiscox, J.A., Stockley, P.G. & Ranson, N.A. (2013). The asymmetric structure of an icosahedral virus bound to its receptor suggests a mechanism for genome release. Structure, 21, p1225-1234.