Abstract

Single particle cryo-electron microscopy (cryo-EM) is an emerging powerful tool for structural studies of macromolecular assemblies. Although less concentrated and smaller amounts of samples are required for single particle cryo-EM compared to X-ray crystallography, it remains challenging to study specimens that are low-abundance, low-yield, or short-lived. The recent development of affinity grid techniques holds great promise to tackle these challenging samples by combining the sample purification and freezing on TEM grids steps in cryo-EM grid preparation into a single step, revolutionize the grid preparation of cryo-EM, and extend single particle cryo-EM to a routine structural biology tool to characterize structures of a broad spectrum of macromolecules.

In my PhD study, I have established a new design of the affinity cryo-EM approach, cryo-SPIEM that applies a traditional pathogen diagnosis tool Solid Phase Immune Electron Microscopy (SPIEM) to the single particle cryo-EM method, and also systematically explored the applications of affinity EM approaches and the potentials of affinity cryo-EM approaches for near-atomic single particle 3-D reconstruction. The cryo-SPIEM approach provides an alternative, largely simplified and easier to use affinity grid that directly works with most native macromolecular complexes with established antibodies, and enables cryo-EM studies of native samples directly from cell cultures. The application of the affinity cryo-EM approach for high-resolution cryo-EM has been demonstrated successfully by solving a 6.3 Å structure of Tulane virus using the polylysine-based affinity grid, and a 2.6 Å structure of Tulane virus using the antibody-based affinity grid with a sample of low concentrations that defies standard cryo-EM study. Moreover, we have applied the affinity grid technique to investigate the interaction between Tulane virus and its cellular receptor Histo-blood group antigens, which revealed the potential roles of HBGA receptors in mediating genome release.

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Science

Committee Chair

Wen Jiang

Date of Award

5-2016

First Advisor

Wen Jiang

Committee Member 1

Richard J. Kuhn

Committee Member 2

Jason Lanman

Committee Member 3

Chiwook Park

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