Proteins provide the machinery of life. As nanoscale machines that carry out tasks, they are inherently dynamic systems. Yet, observing them in action is not generally possible, since this requires not only near-atomic spatial resolution, but also a time resolution of at least microseconds. This is the timescale on which the large-amplitude domain motions of proteins occur that are typically associated with their activity. If we cannot observe proteins at work, our understanding of protein function must remain fundamentally incomplete.
Our group has recently developed a novel technique that enables such observations by improving the time resolution of cryo-EM by three orders of magnitude. It involves flash melting a cryo sample with a laser beam and inducing dynamics of the embedded particles as soon as the sample is liquid. Once the laser is switched off, the sample revitrifies in just a few microseconds, trapping particles in their transient configurations, which can subsequently be characterized with existing cryo-EM imaging techniques. Most recently, we have demonstrated our approach by observing the microsecond motions of the capsid of CCMV, an icosahedral plant virus.
Related publications:
Microsecond Time-Resolved Cryo-Electron Microscopy
U.J. Lorenz. Curr. Opin. Struct. Biol. 98, 102840 (2024)
Fast Viral Dynamics Revealed by Microsecond Time-Resolved Cryo-EM
O.F. Harder, S.V. Barrass, M. Drabbels, U.J. Lorenz. Nat. Commun. 14, 5649 (2023)
Near-atomic resolution reconstructions from in situ revitrified cryo sample
Microsecond melting and revitrification of cryo samples with a correlative light-electron microscopy approach
G. Bongiovanni, O.F. Harder, M. Drabbels, U.J. Lorenz. Front. Mol. Biosci. 9, 1044509 (2022)
Microsecond Melting and Revitrification of Cryo Samples: Protein Structure and Beam-Induced Motion.
O.F. Harder, J.M. Voss, P.K. Olshin, M. Drabbels, U.J. Lorenz. Acta Cryst. D. 78, 883–889 (2022)
Microsecond Melting and Revitrification of Cryo Samples.
J.M. Voss, O.F. Harder, P.K. Olshin, M. Drabbels, U.J. Lorenz. Struct. Dyn. 8, 054302 (2021)
Rapid Melting and Revitrification as an Approach to Microsecond Time-Resolved Cryo-Electron Microscopy.
J.M. Voss, O.F. Harder, P.K. Olshin, M. Drabbels, U.J. Lorenz. Chem. Phys. Lett. 778, 138812 (2021)