Cryo-EM (cryo-electron microscopy) and drug discovery
Electron microscopy, invented almost a century ago, has historically been a powerful tool for visualizing the architecture of biologically relevant entities such as viruses, cells and tissue. Over the last two decades, rapid advances in imaging and computation technologies have expanded the usefulness of electron microscopy into exciting new realms. Electron microscopy at cryogenic temperatures, referred to as “cryo-EM” now enables 3D imaging of biological material at an unprecedented level of detail, at resolutions comparable to those achieved using X-ray crystallography. Related methods, using focused ion beams and scanning electron microscopy (FIB-SEM) are providing novel approaches to visualizing cells and tissue in 3D at a level of detail 10-100 times better than what is possible with optical confocal microscopy.
Our research program is focused on exploring these frontiers of cryo-EM, as they relate to imaging molecules, viruses and cells with the central goal of accelerating the development of effective therapeutic agents to treat cancer, disorders of the brain and infectious diseases such as HIV and influenza.
High resolution imaging of cells and tissue
Since our first demonstration in 2006 that Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) could be a powerful tool for imaging whole cells and tissue in 3D, we have continued to refine the method.
We have applied FIB-SEM methods to a variety of important problems in cell biology that have led to unprecedented insights into subcellular architecture and cellular mechanisms.
Our current interests in the use of this technology ranges include the study of cell-cell synapses involved in viral infection, cancer progression and age-related changes in mitochondrial architecture.
Enveloped virus vaccine design
Enveloped viruses gain entry to mammalian cells by interaction of trimeric envelope glycoproteins (“entry spikes”) with cellular receptors. Understanding the structure and structural changes of these “entry spike” complexes is important for understanding entry mechanisms and for the design of effective vaccines. We have developed powerful tools for determination of entry spike structures that enabled us to obtain the first 3D structures of HIV-1 envelope glycoproteins in their native states and in complex with a variety of neutralizing antibodies. Ongoing studies include work on structural biology of entry of HIV-1, influenza and Ebola viruses.
The success of our efforts to use electron microscopy to accelerate drug discovery and understand cellular mechanisms rely heavily on developing methods to obtain the most information from the use of electron imaging. Our active program to advance the frontier of electron microscopy has enabled us to achieve some of the highest resolutions possible using single particle cryo-EM as well as new advances in subcellular correlative imaging with focused ion beams and forays into chemical imaging of whole cells.