The determination of cellular organization and protein structures is most significant in both understanding cellular function and developing targeted therapies, an approach termed molecular medicine. Cryo-electron microscopy (cryoEM) is currently leading a revolution in structural biology providing nanometer and often near atomic resolution of cellular machines and macromolecular complexes. The Department of Pathology and Laboratory Medicine is equipped with a state-of-the-art cryo-EM facility including a 300kV cryo-electron microscope (Technai F30 Polara) and a new generation direct electron detector (GATAN K2 Summit). Funded by the National Institutes of Health, a high-throughput imaging process pipeline has been developed to allow remote data collection and structural determination of macromolecular complexes at high resolution by cryoEM. Our system is particularly powered by high-speed computing resources, which facilitate offsite data processing ideal for residents interested in computational biology. This arrangement is well tailored to accommodate the demanding clinical requirements of residents in their efforts to establish a significant research component during their clinical training. Interested medical residents, postdocs, and graduate students should contact Drs. Jun Liu, Xiangan Liu or Dr. Amanda Tchakarov.
The structure-function relationships of bacterial pathogenesis.
Understanding the pathogenesis of Shigella, a leading cause of dysentery worldwide, is crucial to combat developing antibiotic resistance. Cryo-ET has been employed to resolve the 3D structure of the Shigella injectisome within Shigella minicells (Hu, Morado et al. 2015).
Molecular Basis of viral infection and genome translocation.
Cryo-ET studies are now increasing our understanding of bacteriophage structure, cellular adsorption and genome ejection, aspects that are fundamental to phage life cycle and are crucial steps in the development of bacteriophage treatments for bacterial infections, which are increasingly antibiotic resistance. As shown below, Cryo-ET has been employed to capture T4 virions at successive stages of infection.
3DEM of macromolecules of biological interest.
Atomic resolution X-ray structures of the component enzymes are docked in the EM map of the pyruvate dehydrogenase multienzyme complex consequently rendering high resolution insight into the functional organization of the largest enzyme complex known (10 megadaltons) (24). PDC is the crucial enzyme linking glycolysis and the tricarboxylic acid cycle. The core functional unit of the enzyme is shown in B) in which the x-ray structure has been docked into the EM map. The E1 tetramers are shown in yellow and the E2 trimer is in green. Structural determination of the PDC complex has provided a better understanding of disorders like PDC deficiency and may lead to development of targeted therapies in the future.