title: Evaluation of a symmetry-based strategy for assembling protein complexes.
abstract: We evaluate a strategy for assembling proteins into large cage-like structures, based on the symmetry associated with the native protein's quaternary structure. Using a trimeric protein, KDPG aldolase, as a building block, two fusion proteins were designed that could assemble together upon mixing. The fusion proteins, designated A-(+) and A-(-), comprise the aldolase domain, a short, flexible spacer sequence, and a sequence designed to form a heterodimeric antiparallel coiled-coil between A-(+) and A-(-). The flexible spacer is included to minimize constraints on the ability of the fusion proteins to assemble into larger structures. On incubating together, A-(+) and A-(-) assembled into a mixture of complexes that were analyzed by size exclusion chromatography coupled to multi-angle laser light scattering, analytical ultracentrifugation, transmission electron microscopy and atomic force microscopy. Our analysis indicates that, despite the inherent flexibility of the assembly strategy, the proteins assemble into a limited number of globular structures. Dimeric and tetrameric complexes of A-(+) and A-(-) predominate, with some evidence for the formation of larger assemblies; e.g. octameric A-(+): A-(-) complexes.
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Dustin P
authors.initials: DP
authors.lastname: Patterson
authors.forename: Ankur M
authors.initials: AM
authors.lastname: Desai
authors.forename: Mark M Banaszak
authors.initials: MM
authors.lastname: Holl
authors.forename: E Neil G
authors.initials: EN
authors.lastname: Marsh