The cryo-EM lab at the U-M Life Sciences Institute serves as a collaborative resource for answering structural biology questions posed by investigators across the institution.
The LSI's highly-trained faculty and staff provide expertise, guidance and training to researchers and students — operating as a collaborative partner rather than a traditional fee-for-service core lab.
Cryo-electron microscopy — cryo-EM for short — is an imaging technology that is revolutionizing biology by allowing scientists to obtain pictures of biological “machines.” With it, researchers can turn snapshots of purified proteins into movie-like scenes that show how the components of these machines interact and provide clues for which regions of these complexes are dynamic.
To obtain an image using cryo-EM, researchers must instantaneously freeze many copies of a single protein or a protein complex in a thin layer of vitrified ice. The freezing is done so fast that the proteins retain their natural shape and organization.
Once the sample has been vitrified, a focused beam of electrons is to take images of the sample. Specialized computer analysis is then conducted to combine hundreds of thousands of individual two-dimensional snapshots into a composite that can be viewed in 3D.
In comparing it with other scientific techniques, LSI faculty member Melanie Ohi likens it to the difference between having a parts list for an engine versus being able to see the engine put together and running.
The LSI’s cryo-EM facility supports structural biology projects across U-M that are advancing understanding of these machines, and their impact on human health and disease.
For example, in collaboration with researchers from the U-M Department of Microbiology and Immunology, Melanie Ohi’s lab used single particle cryo-EM to determine the 3D structure of the Legionella Type IV Secretion System. This complex molecular machine enables Legionella pneumophila to spread the potentially fatal pneumonia Legionnaires’ disease.
Researchers in Michael Cianfrocco’s lab at the LSI used cryo-EM to determine structures of dynamic cell signaling complexes to understand how cells control migration, helping to understand how it goes wrong in metastatic cancer.
New technological gains have expanded the reach of cryo-EM to determine the structures of complexes in their native cellular environment. Cryo-electron tomography (cryo-ET) offers access to protein complexes that cannot be isolated for single-particle analysis or that lose their district forms and functions outside of the cell.
LSI faculty member Shyamal Mosalaganti, for example, is applying his cryo-ET expertise to investigate a type of organelle called lysosomes, examining they communicate with other organelles in the cell — and how their functions affect human health and disease. Researchers in his lab capitalize on cryo-ET to analyze the organelles within the unperturbed cellular environment.
Developing Cryo-EM Tools
LSI researchers are also focused on developing new tools that expand the horizons of electron microscopy, as well as making them more readily accessible to researchers across the globe.
For example, faculty member Michael Cianfrocco is helping to develop a pipelines for automated cryoEM data processing, levering advanced in deep-learning with his cryo-EM expertise.