Current DateSeptember 19, 2021

Cryo-ME: they generate the most precise atom images ever observed

Thanks to electron cryo-microscopy (cryo-ME), German and British researchers have produced atomic images of unrivaled precision! What is this technology that has recently revolutionized the imaging of biomolecules?

A publication in the journal Nature on June 3, 2020 highlights research by teams from the Max Planck Institute for Biophysical Chemistry in Göttingen (Germany) and the Molecular Biology Laboratory at the Medical Research Council in Cambridge (UK). These microscopists and structural biologists claim to have produced images of atoms of unprecedented precision to date!

The microscope used to produce these images is none other than a transmission electron microscope. Recall that the traditional microscope allows the observation of a sample in the middle of a beam of light. On the other hand, the transmission electron microscope places this same sample in front of a ray where electrons circulate.

This technique called cryo-electron microscopy (cryo-ME) allows atomic resolution. Thanks to electromagnetic lenses, German and British researchers have observed atoms in a protein (apoferritin) with an incredible level of detail. There is talk of dimensions up to 1.2 worth 0.1 nanometer.

Besides the unique precision of the images, their sharpness is also a very interesting point. Indeed, the cryo-ME technique does not need any dye or chemical fixative. It turns out that the samples are quickly frozen in hydrated form. This therefore makes it possible to preserve their original state.

Both studies are available on the bioRxiv pre-publication platform, the German study, and the British study. Asked in the Nature article, the main author of the German study Holger Stark believes that this research represents “an important step” having overcome “the last resolution barrier”.

The cryo-ME technique is a very important advance in medicine. For their work which allowed its development, Jacques Dubochet (Switzerland), Joachim Frank (Germany) and Richard Henderson (Scotland) received the 2017 Nobel Prize in chemistry. In 2019, Finnish and Belgian researchers had highlighted a new characteristic of several viruses common to humans using the cryo-ME technique.

This technique was also used to better understand the Covid-19. This research has produced molecular-level images of a surface protein that allows the virus to cling to lung cells before infecting them. It was also about learning how this same protein diverts the primary functions of lung cells to allow the virus to multiply.

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