Three-Dimensional Electron Microscopy of Macromolecules
From BTRR
Overview
Technology and research development efforts are focused on extending the resolution, speed, and flexibility of electron cryomicroscopy for three-dimensional structure determination of biological macromolecular assemblies. The resource tackles structural problems that are too complex or too difficult for X-ray crystallography and nuclear magnetic resonance spectroscopy. In the center, researchers have demonstrated the feasibility of visualizing secondary structure elements such as alpha helices and beta sheets of protein components in several large assemblies. They are developing technology for routine structure determinations at subnanometer resolution, approaching a resolution sufficient for tracing a polypeptide backbone. Generally they focus on macromolecular assemblies ranging from 300 kDa to 30 MDa and can produce structures from very small quantities of purified specimens.
Experimentally, researchers are involved in evaluation of new instruments for single particle imaging, development of automation techniques for high-throughput data collection, and improvements to cryopreparation techniques. Computationally, they are developing algorithms and improving computational efficiency for the three-dimensional reconstruction of single particles toward atomic resolution. This software is embodied in EMAN and SAVR, which offer complete solutions for low symmetry and icosahedral single particles. In addition, they have produced SAIL, a set of specialized modules for producing professional-quality scientific animations. All three suites and several other tools are distributed free of charge.
Most efforts are focused on collaborative and service projects with a variety of groups around the world. Current biological projects include cytoskeletal filaments and bundles, ion channels, membrane transporters, chaperones, icosahedral viruses, and large oligomeric proteins. In addition, the resource sponsors workshops and symposia regularly to disseminate its imaging technology to a broader community.
