Improved 3D Reconstruction of Virus Structures through Parallel Processing

Three-dimensional (3D) reconstruction from transmission electron cryomicroscopy images is a technique for 3D structure determination of macromolecular complexes such as spherical viruses with icosahedral symmetry. To calculate virus structures to higher resolution, it is necessary to combine information from hundreds (perhaps thousands) of high resolution but extremely noisy images. The most intensive step is an optimization calculation in which the parameters determining particle center and orientation are refined. The complexity increases quadratically as the number of particle images increases, making it impractical to refine hundreds of particles on conventional workstations. We discuss a parallel implementation of the refinement algorithm on shared-memory platforms. The speed-up obtained thus far has made it possible for us to reconstruct an improved resolution structure of herpes simplex virus-1 (HSV-1) capsid. 1 Introduction Three-dimensional structural determinatio..