Albany 2013: Book of Abstracts
June 11-15 2013
©Adenine Press (2012)
Individual-Particle Electron Tomography: A method for studying macromolecule dynamics
In solution, macromolecules are naturally flexible and dynamic. Dynamic personalities and structural heterogeneities of macromolecules are essential to understanding their proper function (Karplus and Kuriyan 2005). However, structural determination of dynamic/heterogeneous macromolecules is limited by current technology such as: X-ray crystallography, Nuclear magnetic resonance (NMR) spectrum, small angle scattering and electron microscopy (EM) single-particle reconstruction because of a common requirement - averaged signal that were from thousands to millions of different macromolecules, and a common assumption - the structure of these thousands macromolecules are identically same. A fundamental solution for macromolecular structure determination should be back to determination of an individual macromolecule structure. Electron microscopic tomography provides a tool for high-resolution structural imaging an individual macromolecule from a series of tilted viewing angles. However, it is generally believed the signal from a single macromolecule is insufficient to be used to achieve an meaningful 3-dimensional (3D) structure. Our recently reported approach (Zhang and Ren 2012), individual-particle electron tomography (IPET), demonstrates first success 3D reconstruction of an individual IgG antibody at 14A resolution from negative-staining antibody images and an individual high-density lipoprotein at 36A resolution from vitreous ice embedded macromolecule images. IPET as a new robust strategy/approach does not require a pre-given initial model, averaging of multiple molecules or an extended ordered lattice, but can tolerate small tilt-errors for high-resolution single ‘‘snapshot’’ molecule structure determination (Zhang and Ren 2012). IPET can be used to study the dynamic character, equilibrium fluctuation, to track the intermediate-state of reaction of macromolecules and even to reveal macromolecular mechanism (Zhang, Cavigiolio et al. 2010; Zhang and Ren 2010).
This research has been supported by the Office of Science, Office of Basic Energy Sciences of the United States Department of Energy (contract no. DE-AC02-05CH11231) and the National Heart, Lung, and Blood Institute of the National Institutes of Health (no. R01HL115153).
Zhang, L., G. Cavigiolio, et al. (2010). "Structure of 9.6nm Discoidal High-Density Lipoprotein Revealed by Individual-Particle Electron Tomography." Biophysical Journal 98(3): 440a.
Zhang, L. and G. Ren (2010). "Determining the Dynamic Protein Structure by Individual-Particle Electron Tomography: An Individual Antibody Structure at a Nanometer Resolution " Biophysical Journal 98(3): 441a.
Zhang, L. and G. Ren (2012). "IPET and FETR: experimental approach for studying molecular structure dynamics by cryo-electron tomography of a single-molecule structure." PLoS ONE 7(1): e30249.