Structural Evidence for Common Ancestry of the Nuclear Pore Complex and Vesicle Coats

Nuclear pore complexes (NPCs) facilitate nucleocytoplasmic transport. These massive assemblies comprise an eight-fold symmetric scaffold of architectural proteins and central-channel phenylalanine-glycine-repeat proteins forming the transport barrier. We determined the Nup85*Seh1 structure, a module in the heptameric Nup84 complex, at 3.5 A resolution. Structural, biochemical, and genetic analyses position the Nup84 complex in two peripheral NPC rings. We establish a conserved tripartite element, the ancestral coatomer element ACE1, that reoccurs in several nucleoporins and vesicle coat proteins, providing structural evidence of coevolution from a common ancestor. We identify interactions that define the organization of the Nup84 complex based on comparison with vesicle coats and confirmed the sites by mutagenesis. We propose the NPC scaffold, like vesicle coats, is composed of polygons with vertices and edges forming a membrane-proximal lattice providing docking sites for additional nucleoporins. 10.1126/science.1165886