Time-resolved cryo-EM using a combination of droplet microfluidics with on-demand jetting.
Torino, S., Dhurandhar, M., Stroobants, A., Claessens, R., Efremov, R.G.(2023) Nat Methods 20: 1400-1408
- PubMed: 37592181 
- DOI: https://doi.org/10.1038/s41592-023-01967-z
- Primary Citation of Related Structures:  
8BK7, 8BK8, 8BK9, 8BKA, 8BKB, 8BKG, 8BKZ, 8BL2, 8BL7, 8BLC, 8BLD, 8BLE, 8BLF, 8BLY, 8BM0, 8BM1, 8BMD, 8BMO, 8BMT - PubMed Abstract: 
Single-particle cryogenic electron microscopy (cryo-EM) allows reconstruction of high-resolution structures of proteins in different conformations. Protein function often involves transient functional conformations, which can be resolved using time-resolved cryo-EM (trEM). In trEM, reactions are arrested after a defined delay time by rapid vitrification of protein solution on the EM grid. Despite the increasing interest in trEM among the cryo-EM community, making trEM samples with a time resolution below 100 ms remains challenging. Here we report the design and the realization of a time-resolved cryo-plunger that combines a droplet-based microfluidic mixer with a laser-induced generator of microjets that allows rapid reaction initiation and plunge-freezing of cryo-EM grids. Using this approach, a time resolution of 5 ms was achieved and the protein density map was reconstructed to a resolution of 2.1 Å. trEM experiments on GroEL:GroES chaperonin complex resolved the kinetics of the complex formation and visualized putative short-lived conformations of GroEL-ATP complex.
Organizational Affiliation: 
Center for Structural Biology, Vlaams Instituut voor Biotechnologie, Brussels, Belgium.