Cryo-electron microscopy, or Cryo-EM, enables us to build a 3D image of complex proteins at incredible resolution.
This technique enables us to directly image single molecules using electron beams. By imaging an object in many orientations to computationally construct a 3D model, you can reveal what the molecule looks like and can see the biological mechanism of how it works. It means that we can study complex proteins at a tenth of a millionth of a millimetre in scale.
A protein sample is flash-frozen in a thin, single-molecule thick, layer of vitreous ice. Advances in camera technology give us clear and high resolution images of individual molecules. By taking the averages of approximately 100,000 images, we can create a representation of the shape of the molecule.
This technology is being used by our structural biologists to uncover ground-breaking insights into potential therapeutic targets in cancer and in metabolic disease.
The Cryo-EMs we use are manufactured by FEI, the world leader in developing these microscopes.
Dramatically improves image quality and resolution of molecules
We can study molecules of a complexity it has not been possible to see before
Easy for scientists to use and high throughput relative to previous techniques
Real-time imaging readouts - at a speed of 400HZ
Automatically corrects for instability of image - multiple conflations of the protein image are created simultaneously
Perspectives from our scientists
Chris Phillips Associate Director, Discovery Sciences
Jenny Sandmark Associate Principal Scientist, Discovery Sciences
What is the key function of this equipment?
Chris: Cryo-EM allows us to determine near atomic resolution models of complex protein molecules. You can directly image individual molecules, using a focused electron beam, and from the 2D projections obtained you can construct a 3D image. You then know what the molecule looks like and can understand how it functions, casting light on important biological mechanisms. Images from approximately 100,000 individual molecules are used to computationally build a 3D model.
Why has AstraZeneca invested in Cryo-EM?
Jenny: We believe cryo-EM is important for the discovery of novel drug targets and the design of candidate molecules, as it enables us to image larger protein complexes. By investing in this technology, we can accelerate the development of new chemical and biological entities to bring potential new medicines to patients.
Where do you use Cryo-EM?
Chris: Cryo-EM is used by the Discovery Sciences structural biology teams at AstraZeneca. For example, we have invested in Cryo-EM as part of a Cambridge area consortium of five pharma companies, the Laboratory of Molecular Biology/Medical Research Council, the University of Cambridge and FEI to enable access to this technology. This shared cost model allows us to access the very highest-level technology in a pre-competitive manner.
Jenny: We have also collaborated with SciLifeLab at Stockholm University and the Karolinska Institutet to access this state-of-the-art technology in Sweden.
How does the use of Cryo-EM help AstraZeneca achieve scientific leadership?
Chris: Cryo-EM is revolutionising structural biology, allowing us to resolve the structures of complex macromolecular machines for the first time. High resolution structures of our target proteins have previously only been available through crystallography but many molecules of interest to the pharma industry, such as integral membrane protein, can’t be crystallised. Cryo-EM allows us to investigate the biological mechanisms underlying disease states and design potential new drugs based on this knowledge.
What have we achieved that we could we not have done without it?
Jenny: Single molecule Cryo-EM is changing the structural world. The last few years have seen technical advances that have enabled a step change in the capability of electron microscopy and there are now an impressive number of high-resolution protein structures that have been determined by this technique. For the structural biologist this is transformational, as many target proteins important to drug discovery, such as integral membrane proteins or large multicomponent macromolecular machines, now become accessible for study for the first time.
This technology has allowed our scientists, in collaboration with academic institutions, to uncover and publish world-first protein structures in the fields of cancer, neurodegenerative disorders and diabetes.
Has this kit been used in any notable discoveries or activities in AstraZeneca?
Chris: In collaboration with the MRC Laboratory of Molecular Biology we have applied this technology to define the world’s first protein structures for human ataxia telangiectasia mutated (ATM). ATM is a key trigger protein in the DNA damage response and a prime therapeutic target in cancer.
Jenny: In collaboration with SciLifeLab at Stockholm University and the Karolinska Institutet, we have applied this technology to determine the structure of a protein complex including the extracellular region of the receptor tyrosine kinase RET. The mechanisms of RET activation have proved elusive. Through Cryo-EM we have been able to propose a model for RET activation and also provide a framework for potential targeting of this mechanism, which is relevant in neurodegenerative disease and diabetes.
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