Sjors Scheres

Methods development for cryo-EM structure determination
Group Leader page

Structure determination by electron cryomicroscopy (cryo-EM) single-particle analysis has been undergoing a revolution during the past few years (see some of the contributions from our group in the references below). Nowadays, near-atomic resolution structures can be obtained for a wide range of samples. However, the applicability of the method is still limited for very flexible and for small complexes. In addition, many fragile complexes fall apart during the preparation of the required thin layer of ice, and despite 10-100-fold improvements in required material compared to X-ray crystallography, many complexes still cannot be purified in high enough quantities to allow cryo-EM structure determination.

Our group aims to develop novel sample preparation and image processing methods that will further broaden the applicability of cryo-EM structure determination, and we often apply these methods to exciting biological projects in collaborations with other groups. Our image processing developments are focussed on statistical methods (Bayesian approaches, see our RELION program) that make optimal use of the little signal in the images. Our sample preparation developments are aimed towards the design of molecular scaffolds, and the development of affinity-based purification methods directly on cryo-EM support films. Combined, these developments will allow structure determination of many more proteins, including important drug targets like G-protein coupled receptors (GPCRs) and ion channels.

This PhD project offer a unique opportunity to become an expert in this rapidly expanding technique. Depending on your strengths and preferences, it could have an emphasis on the computational and/or the experimental sides of our work.


References:

Bai, X.-C., Yan, C., Yang, G., Lu, P., Ma, D., Sun, L., Zhou, R., Scheres, S.H.W. and Shi, Y. (2015)
An atomic structure of human gamma-secretase
Nature, 525, 212-217.

Nguyen, T.H., Galey, W.P., Bai, X.-C., Savva, C.G., Newman, A.J., Scheres, S.H.W. and Nagai,  K.(2015)
The architecture of the spliceosomal U4/U6.U5 tri-snRNP
Nature, 253, 47-52.

Amunts, A., Brown, A., Bai, X.-C., Llacer, J.L., Hussain, T., Emsley, P., Long, F., Murshudov, G., Scheres, S.H.W. and Ramakrishnan, V. (2014)
Structure of the Yeast Mitochondrial Large Ribosomal Subunit
Science, 343, 1485-1489.

Fernandez, I.S., Bai, X.-C., Hussain, T., Kelley, A.C., Lorsch, J.R., Ramakrishnan, V. and Scheres, S.H.W. (2013)
Molecular architecture of a eukaryotic translational initiation complex
Science, 342, 6160.

Bai, X.-C., Fernandez, I.S., McMullan, G. and Scheres, S.H.W. (2013)
Ribosome structures to near-atomic resolution from thirty thousand cryo-EM particles
eLife, 2:e00461.

Scheres, S.H.W. (2012)
A Bayesian view on cryo-EM structure determination
J. Mol. Biol., 415, 406-418