Sub-nanometer resolution imaging of individual biological molecules by electron cryomicroscopy
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Many fundamental problems in biology relate to how proteins interact with DNA and RNA. The difficulty in addressing these questions arises from the limitations of current microscopes and the complex and fragile nature of biomolecules. Recent advances in electron cryomicroscopy (cryo-EM) imaging technology have improved the quality of biological electron microscopy to the point that near-atomic resolution 3D structures are almost routine.
This project will involve improving the resolving power of the electron microscope to allow direct imaging of individual biomolecules with sufficient resolution to understand how they work. The signal in the micrographs, which is used to determine these structures, has not reached the physical limits imposed by radiation damage and electron detector quantum efficiency. This is because the individual molecules move during electron irradiation. This movement blurs the images of the molecules, thus reducing the structural information available in each micrograph. We have recently developed new specimen supports that that nearly eliminate substrate motion during irradiation. This increases the sub-nanometer image contrast such that the helices of individual proteins are resolved in single images. The project will extend this work to reengineer how specimens are made and imaged, to prevent them from moving before they are damaged by the electrons. This will enable direct observation of the detailed features of biomolecules as they function.
The ideal candidate will have a strong background in physics or engineering and be interested in applying theses skills to important biological problems. This will involve the development of new instruments and methods to improve our ability to image DNA, RNA and their interactions with complex macromolecular machines. A knowledge of optics and experience with vacuum systems will be particularly useful.
Russo, C.J. and Passmore, L.A. (2014).
Controlling protein adsorption on graphene for cryo-EM using low-energy hydrogen plasmas.
Nature Methods 11 649–652
Russo, C.J. and Passmore, L.A. (2014)
Ultrastable gold substrates for electron cryomicroscopy.
Science 346 1377–1380
Russo, C.J. and Passmore, L.A. (2016)
Progress towards an optimal specimen support for electron cryomicroscopy.
Curr. Opin. Struct. Biol. 37, 81-89
Passmore, L.A. and Russo, C.J. (2016)
Specimen Preparation for High-Resolution Cryo-EM
Methods in Enzymology, in press http://dx.doi.org/10.1016/bs.mie.2016.04.011 .