Watching DNA being read with cryo-EM
7 Feb 2018 by Evoluted New Media
Scientists have unveiled images of the DNA code being read and interpreted – revealing new detail about one of the fundamental processes of life.
Scientists at The Institute of Cancer Research captured images of RNA Polymerase III in the act of transcribing a gene in exquisite and unprecedented detail. The team used an advanced form of Cryo-electron microscopy – for which the Nobel Prize in Chemistry was awarded in 2017 – to zoom in and capture images of the reading mechanism in unprecedented detail.
Dr Alessandro Vannini, Team Leader in Structural Biology at The Institute of Cancer Research, said: “We were able to freeze and catch the RNA polymerase III complex in the act of attaching to, separating and reading the DNA code. We obtained almost a million of independent snapshots and, using powerful computers we grouped similar snapshots together, enhancing their detail to obtain a vivid reconstruction of this machinery at work.
“Now we know how the components of this crucial molecular mechanism fit together, we may be able to design drugs that turn the system on or off – and these could offer a whole new way of treating cancer.”
RNA polymerase III is crucial to life for all eukaryotic cells and in cancer, it is more active, causing cells to produce larger numbers of the building blocks they need to grow and multiply. Using cryo-EM the team could take pictures of tiny molecules – approximately 5 nanometers or 20000th of the width of a human hair – at almost an atomic level.
Cryo-EM involves freezing and imaging samples at -180°C to preserve minute details of protein structure. Professor Paul Workman, Chief Executive of The Institute of Cancer Research, London, said: “Cryo-EM is revolutionising molecular and cellular biology, allowing us to look in minute detail at molecular machines within cells and how they work. The technique is helping scientists to discover weaknesses in cancer cells that could be targeted by the next generation of drugs.”
The work is published in Nature.
