NEWS

7March 2021 ESRFnews

Santoni joins COVID-19 task force

Gianluca Santoni, an ESRF scientist, has joined 20 other researchers to form an independent task force to help the scientific community make the best use of the hundreds of published SARS-CoV-2 protein structures. Comprising members from France, Germany, the UK and the US, the recently set-up Coronavirus Structural Task Force aims to rapidly categorise, evaluate and review the structures, many of which could the members claim have errors due to the time constraints and immense pressure surrounding their determination. The task force has also been providing improved models for key structures, which have already been used by research projects such as Folding@ Home, OpenPandemics, and the EU Joint European Disruptive Initiative. I didn t expect it to have such a big impact on so many other international projects, says Santoni. More information at insidecorona.net.

A team led by the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg, Germany, has used ESRF X-rays to coherently control nuclear excitations, in a similar way to how electron behaviour can be controlled with lasers. The results open a door onto the control of nuclear dynamics, and could lead to more precise time standards. Modern experiments on quantum

dynamics can control, with attosecond (10 18 s) precision, the quantum processes of electrons in atoms to a large extent with lasers. The same cannot be said of atomic nuclei, the characteristic energy, time and length scales of which are so extreme that lasers leave them practically unaffected. Now Jörg Evers and colleagues at

the MPIK, together with colleagues at DESY in Hamburg, Germany, the Helmholtz Institute/Friedrich Schiller University in Jena, Germany, and the ESRF, have used the ESRF nuclear resonance beamline ID18 to achieve coherent control of nuclear excitations for the first time. First, the researchers sent a short X-ray pulse into a sample enriched with the iron isotope 57Fe, which became excited

X-rays probe nuclear excitations

before releasing its excess energy as a second X-ray pulse. In the very short time between this excitation and de-excitation, the researchers shifted the sample by about half the X-ray wavelength, corresponding to about an atom s radius, to change the time of flight and hence the relative phase of the second pulse to a second, identical sample. By adjusting this phase, the researchers were able to control the quantum-mechanical state of the nuclei in the second sample, with an unprecedented phase stability of a few zeptoseconds (10 21s) (Nature doi:10.1038/s41586-021-03276-x).

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The quality of X-rays at ID18 was crucial to the experiment s success.

Cryo-EM exposes viral installation into membranes The ESRF s CM01 cryo-EM facility has enabled scientists to see, for the first time, how the replication factors of a group of viruses including coronaviruses install themselves in cellular membranes inside the cell. The results show another way to look at viral replication, and could influence the search for antiviral drugs. Most of the current understanding

about the replication of viruses with RNA genomes such as SARS- CoV-2, the virus behind COVID-19 disease stems from the study of viral factors, such as polymerases and RNA-modifying enzymes. While these factors have become major targets for antiviral drugs, less attention has been paid to where the replication takes place, namely inside cells within membranous viral organelles. By studying this membrane installation at a resolution greater than 3Å in a structure of chikungunya, another virus with

RNA genomes, Juan Reguera of Aix- Marseille Université and the CNRS in France and colleagues have discovered how the membrane binding of the replication machinery triggers the bending of the membrane, enhances the viral enzymatic activity and results in the joining, or oligomerisation, of large viral replication platforms (Nature 589 615). This structure opens new avenues

for the understanding of viral replication within membranes, which will be determinant for the future generation of effective antiviral drugs for the treatment of a large number of SARS-CoV-2-like viral pathogens, says Reguera. In February, CM01 beamline scientist Eaazhisai Kandiah and her colleagues achieved a resolution of 1.63Å with the ESRF cryo-EM facility. Recorded on a test sample, the intestinal protein apoferritin, the resolution verges on the current world record of 1.25Å.

This structure opens new avenues for understanding viral replication within membranes

The five French collaborating research group (CRG) beamlines at the ESRF will benefit from the French government s Investments for the Future Programme thanks to the awarding of 9 m in funding to their managing agencies, the CNRS, the CEA and the UGA. The project Implementing the best new and global French infrastructures for studies with hard X-rays aims to boost the excellence and attractiveness of French scientific research by enabling the D2AM (BM02), FIP II (BM07), FAME-UHD (BM16), FAME (BM30) and IF (BM32) beamlines to take better advantage of the new, fourth-generation ESRF source, with state-of-the-art equipment. Operating 24 hours a day, six days a week, the F-CRG platform welcomes more than 500 researchers per year, from regional, national or international laboratories, and companies.

French CRGs get a boost

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ESRFMar21_News_v9.indd 7 26/02/2021 10:00