High-resolution cryo-EM using a common LaB 6 120-keV electron microscope equipped with a sub–200-keV direct electron detector

• DOI: 10.1126/sciadv.adr0438
• Publication Date: 2025-01-03T18:58:47Z
• Authors: Hariprasad Venugopal; Jesse Mobbs; Cyntia Taveneau; Daniel R. Fox; Ziva Vuckovic; Sahil Gulati; Gavin Knott; Rhys Grinter; David Thal; Stephen Mick; Cory Czarnik; Georg Ramm
• Keywords: Cryo-Electron Microscopy; Thermionic emission

High-resolution cryo–electron microscopy (cryo-EM) requires costly 200- to 300-keV cryo–transmission electron microscopes (cryo-TEMs) with field emission gun (FEG) sources, stable columns, constant-powered lenses, autoloader, and direct detectors (DED). Recent advances in 100-keV imaging the emergence of sub–200-keV optimized DED technology promises development more affordable cryo-TEMs. So far, has required FEG sources. We here explored whether a standard 120-keV TEMs thermionic lanthanum hexaboride (LaB 6 ) source can be upgraded for high-resolution cryo-EM. Using this configuration, we successfully obtained 2.65 Å reconstruction apoferritin, 4.33 64-kDa hemoglobin, 4.4 an asymmetric 153kDa membrane protein GPCR. All results were achieved using automated data collection SerialEM, demonstrating feasibility collect large cryo-EM datasets side-entry cryo-holder. These showcase widely accessible solution obtaining interpretable structures at low cost contribute “democratization”