Cambridge researcher receives Nobel Prize for the development of cryo-EM
The Nobel Prize is an international award administered by the Nobel Foundation in Stockholm, Sweden, and is bestowed in recognition of academic, cultural or scientific advances. It is categorised into physics, chemistry, physiology or medicine, literature, economic sciences and peace, with each Nobel Prize consisting of a medal, a personal diploma, and a substantial cash award.
In terms of the sciences, this year’s award for physics was shared by three researchers, Rainer Weiss, Kip Thorne and Barry Barish of the LIGO-Virgo collaboration, for the detection of gravitational waves, while the award for physiology or medicine honoured three US scientists, Jeffrey Hall, Michael Rosbash and Michael Young, for their discoveries of molecular mechanisms controlling the circadian rhythm. For chemistry, Jacques Dubochet, Joachim Frank and Richard Henderson received a Nobel Prize on 4th October 2017 for their work in developing cryo-electron microscopy (cryo-EM); while Jacques Dubochet was born in Switzerland and Joachim Frank is German, Richard Henderson originates from Edinburgh, and is the 15th Nobel laureate to work at the Medical Research Council (MRC) Laboratory of Molecular Biology in Cambridge.
For decades, biomolecular structures have been imaged using X-ray crystallography, a process which involves the scattering of X-rays as they pass through a crystallised protein, however not all proteins are amenable to being crystallised. Cryo-EM instead relies on a cryogenically frozen protein sample, allowing researchers to deduce high resolution protein structures of virtually any biological specimen close to its native state.
The research carried out by Dubochet, Frank and Henderson was performed during the 1970s and 1980s, yet laid essential groundwork for subsequent improvements in the sensitivity of electron microscopes and their associated software. In 1975, Henderson and his colleague Nigel Unwin used electron microscopy to successfully produce a 3D model of bacteriorhodopsin, a molecule which is unsuited to X-ray crystallography, publishing their findings in Nature. During the same decade Frank, now based at Columbia University in New York City, and colleagues developed image-processing software to generate 3D molecular structures from the output of the electron microscope. In the early 1980s Dubochet, now an honorary professor at the University of Lausanne in Switzerland, and colleagues established a method of flash-freezing protein solutions using liquid ethane, preventing water soluble biomolecules from drying out in the vacuum of an electron microscope, and allowing them to retain their shape during imaging.
Cryo-EM over X-ray crystallography
Many laboratories now favour cryo-EM over X-ray crystallography, and it is rapidly becoming an essential tool for structural biology. For example, during the 2015 Zika virus outbreak researchers turned to cryo-EM to visualise the virus and accelerate the search for potential drug targets. Sirohi et al identified a sequence of amino acids surrounding the Asn154 glycosylation site of the envelope glycoproteins which showed significant variability between Zika strains, suggesting a role in virus transmission and disease, while Prasad et al observed differences in pre-epidemic and epidemic Zika strains which could modulate the sensitivity of the virus to antibodies, and impact the potency of viral infection.
Not only is the Nobel Prize one of the highest accolades that a researcher can receive, it can also bring well-needed funding to a field that is notoriously competitive. This year’s awards for scientific advancement cover a diversity of research areas, further raising the profile of the entire scientific community.