34 ESRF

To quote a famous Scottish poet, 2020 was a year when the best-laid schemes o Mice an Men / Gang aft agley (Robert Burns, 1785), and the COVID-19 pandemic turned everybody s world upside down, with upheaval to the global economy and tragic loss of life. Inevitably, COVID-19 restrictions meant that our plans for the post-Extremely Brilliant Source (EBS) recommissioning of our beamlines were thrown into disarray. It also meant that the restart of user operation in August 2020 was not straightforward, with remote control/mail-in experiments becoming the order of the day and contact with users being mostly virtual.

Nevertheless, all the ESRF Structural Biology beamlines are now back online, facilitating the collection of high-quality X-ray diffraction (MX), solution scattering (BioSAXS) and cryo-electron (cryo-EM) data for structural biology research. That this is the case is down to the hard work and dedication of all those associated with the Structural Biology group including staff from the EMBL Grenoble outstation (with whom we make up the Grenoble Joint Structural Biology Group), the Institut de Biologie Structurale (IBS), the Commissariat à l Energie Atomique et aux énergies alternatives (CEA) and the Institut Laue Langevin (ILL) and that of the members of the many ESRF support groups and services who have helped us implement a raft of hardware and software upgrades, which will help our external user community to take best advantage of the new X-ray beams the ESRF-EBS now provides.

In addition to incremental upgrades on nearly all our facilities, two areas are particularly worth highlighting. The first is the almost complete refurbishment of the BioSAXS beamline BM29. The end-station s optical elements required significant realignment to the beamline s new X-ray source and its sample environment has also been renewed. This has included the installation of a new liquid handling sample-changing robot, new sample exposure units (SEUs), a new flight tube and a new, larger detector, which operates in vacuo. These upgrades will improve signal-to- noise ratios in BioSAXS experiments, allowing analysis of smaller sample volumes, including those contained in microfluidics devices, on much faster time scales, thus paving the way for time-resolved BioSAXS studies.

In collaboration with EMBL Grenoble, our beamline for completely automated MX data collection (MASSIF-1) is also being refurbished. The replacement of the RoboDiff device with

a standard microdiffractometer / FlexHCD combination is already complete with the device now available for mail-in MX experiments, while the installation and integration of a CrystalDirect® robot should be completed in the first half of 2021. Together with upgrades to the end-station s optical configuration, this refurbishment will significantly increase functionality and throughput, making MASSIF-1 even more attractive for studies including the fragment screening campaigns, which are very important in the design of new therapeutic agents.

Major post-EBS upgrades of the ESRF s beamlines and end-stations will not stop there. The brand- new facility for time-resolved synchrotron serial crystallography (EBSL8) is now under construction on the ID29 port. During 2020, the construction of optical, experimental hutches was completed and the beamline is on track to welcome its first friendly users in 2021. In parallel, the in-crystallo optical spectroscopy laboratory (icOS) is commissioning a new terahertz laser setup to allow time-resolved spectroscopy measurements. In other plans, the energy-tuneable end-station ID23-1 will receive a new large detector (with CdTe sensor) and a microdiffractometer by spring/summer 2021. Discussions are also underway regarding upgrading the CM01 cryo-EM facility with a latest-generation detector that will both improve throughput and, in favourable cases, allow single particle reconstructions of biological macromolecules at truly atomic resolution.

As demonstrated in this chapter, high-quality user research facilitated by access to the ESRF s facilities for structural biology continues to feed through to publication in high-impact journals. Much of the data on which these articles are based were collected before the EBS shutdown. However, icOS and CM01 continued operation during this period. This chapter reflects this, containing a number of articles illustrating the increasing significance of cryo-EM in structural biology. These include the reconstruction of the structure of Potato virus X at a resolution of 2.2 Å (page 44), a description as to how connections between molecular machines manage the synchronisation of transcription and translation rates and regulate gene expression (page 45), and the elucidation of the architecture of the orphan glutamate delta receptor-1 (GluD1) that plays crucial roles in brain function. Dysfunction of GluD1 is associated with neuronal disorders (page 56). This latter article is representative of a long-term expansion of neuroscience research,

STRUCTURAL BIOLOGY