Department of Biological Sciences, Birkbeck College
Our lab is interested in understanding how assembly of coat proteins remodels membranes to form transport carriers. In particular we study the COPII protein complex, which is responsible for shuttling thousands of diverse proteins from the endoplasmic reticulum to the Golgi apparatus. This is a fundamental aspect of eukaryotic cell biology, and the molecular mechanisms that govern COPI-mediated membrane budding still remain to be investigated.
To gain insights into how COPII assembles to induce membrane deformation, we wanted to look at the high-resolution structure of the membrane-bound coat. To do this, we decided to employ cryo-electron tomography and subtomogram averaging: techniques that were pioneered in the Briggs group at EMBL, and for which state-of-the-art data collection routines were developed by EMBL Senior Engineer Wim Hagen.
The experience was fantastic. Wim Hagen was very efficient in setting up optimal data collection, while at the same time always involving us in decision-making. Wim collected a dataset for us that we used to obtain a 4.9 Å structure of the assembled COPII coat, now published in Nature Communications. This is the highest-resolution structure of a membrane-assembled coat, and one of the highest-resolution subtomogram averages obtained so far.
We obtained data that allowed us to make significant discoveries in the field of COPII-mediated membrane budding. The resolution we achieved allowed us to identify molecular interfaces between coat subunits and also to visualise the membrane-interacting region of the coat, leading us in turn to propose a model for how coat assembly might regulate membrane remodelling.
We also learned a lot from our visit, thanks to open discussion of protocols. We are now implementing the same protocols on our own microscope at Birkbeck, University of London, so the impact of our visit will extend to other projects as well.
Definitely the expertise of the team running the microscopes, and their ability to combine research and development of new methodologies with provision of the service.
I’d say they’re in for a very good session of data collection. I’d also recommend that they make sure they bring thoroughly screened grids, so as not to waste very precious data collection time.