Briggs Group
Enveloped viruses and coated vesicles – cryo-electron microscopy and tomography
Figure 1: 3D reconstruction of HIV-1 virions using cryo-electron microscopy.
Figure 2: Correlative fluorescence and electron microscopy can be used to locate an individual fluorescent virus particle at the surface of a cell (Kukulski et al. 2011)
Previous and current research
We are interested in the mechanisms of assembly and budding of enveloped viruses and coated vesicles. We aim to understand how proteins collect together the cargo of the virus or vesicle, and define and manipulate the shape of the membrane to cause budding. To explore these questions we are studying a range of different cellular and viral specimens using cryo-electron microscopy and tomography.
Cryo-electron microscopy techniques are particularly appropriate for studying vesicles and viruses because they allow membrane topology to be observed in the native state, while maintaining information about the structure and arrangement of associated proteins. Computational image processing and three-dimensional reconstructions are used to extract and interpret this information.
A particular emphasis of our research is the structure and life-cycle of asymmetric membrane viruses such as HIV and Marburg virus. The structure and assembly of the virus particles offers insights into general features of membrane budding.
We take a step-by-step approach to understanding the native structure of budding events. Correlative fluorescence and electron microscopy methods can be used to locate and characterise features of interest. Three-dimensional reconstructions of these features can be obtained using electron tomography of the biological system in its native state. These reconstructions can be better interpreted by comparison with data collected from in vitro reconstituted systems. A detailed view is obtained by fitting these reconstructions with higher resolution structures obtained using cryo-electron microscopy and single particle reconstruction of purified complexes.
Future projects and goals
Our goal is to understand the interplay between protein assemblies and membrane shape. How do proteins induce the distortion of cellular membranes into vesicles of different dimensions? What are the similarities and differences between the variety of cellular budding events? How do viruses hijack cellular systems for their own use? What is the role and arrangement of the cytoskeleton during membrane distortions? How does the curvature of a membrane influence its interaction with particular proteins? We are developing and applying novel microscopy and image processing approaches to address these questions.
Podcast on Cryo-electron microscopy
Sarah Stanley talks to EMBL scientists about cryo-EM. Click on the image to play.
Duration: 7 mins.
Download script