Electron Energy Filtering System for Cryo-EM Imaging

PROJECT SUMMARY Cryogenic electron microscopy (cryo-EM) is indispensable for structural biology studies. Arizona State University (ASU) has a long history of leadership in the electron microscopy field. ASU has been expanding and promoting cryo-EM research for biomedicine and fundamental biology since establishing its cryo-EM facility in 2017. ASU

has a large pool of researchers utilizing cryo-EM to study biomolecular structures and their action mechanisms and to develop new medical applications, such as rational drug design and nanomedicine. However, the hardware for cryo-EM imaging has dramatically advanced in recent years, and the ASU cryo-EM instrument has

been outdated, presenting challenges in imaging thick specimens for electron tomography or achieving high- quality data of membrane or small proteins. This limits the productivity of scientific studies and prohibits the advancement of knowledge in this field at ASU. To this end, ASU requests an energy filter to upgrade the cryo-EM capability, aiming to improve cryo-EM data

quality and research productivity in structural biology. An energy filter can filter the inelastically scattered electrons and reduce the background noise, thereby boosting the data quality and improving the resolution of the target structure. This energy filter is equipped with a new-generation direct electron detect (DED) camera,

which enhances the image signal-to-noise ratio (SNR) and records the data at full temporal resolution. The proposed energy filter system is fully compatible with the current cryo-EM setup at ASU and will be operated by the natively supported software. The new cryo-EM workflow with the proposed instrument is expected to improve

the resolutions of crystallographic reconstruction of micro-crystals and image reconstruction of single particles.

It will also allow imaging of thick samples for cell biology studies, enabling in situ structural investigation of protein complexes. ASU has a complete and existing management system for multiple electron microscope instruments. The cryo-EM instruments are managed and maintained by the ASU Eyring Materials Center (EMC), which has

extensive long-term experience and a thorough framework in managing electron microscopes and related instruments. ASU also contains a pool of electron microscopy experts who can provide expertise and suggestions in research and administration of these instruments. Overall, the addition of the proposed cryo-EM

upgrade will significantly benefit NIH-funded biomedical research at ASU and the broader community in the Southwestern region.