Structure and Function of the Nuclear Pore Complex Cytoplasmic mRNA Export Platform

Abstract

Summary The last steps in mRNA export and remodeling are performed by the Nup82 complex, a large conserved assembly at the cytoplasmic face of the nuclear pore complex (NPC). By integrating diverse structural data, we have determined the molecular architecture of the native Nup82 complex at subnanometer precision. The complex consists of two compositionally identical multiprotein subunits that adopt different configurations. The Nup82 complex fits into the NPC through the outer ring Nup84 complex. Our map shows that this entire 14 MDa Nup82-Nup84 complex assembly positions the cytoplasmic mRNA export factor docking sites and mRNP remodeling machinery right over the NPC's central channel, rather than on distal cytoplasmic filaments as previously supposed. We suggest that this configuration efficiently captures and remodels exporting mRNP particles immediately upon reaching the cytoplasmic side of the NPC.

Integrative structure and functional anatomy of a nuclear pore complex

“…These data were then used to solve the structure using an integrative modeling approach 8,9 (Extended Data Fig. 1; Methods; Supplementary Results and Discussion).…”

“…2–3C). To inform the proximities, orientations, and conformations of the Nups, isolated NPCs were subjected to cross-linking with MS readout 9,10 . This approach identified 3,077 unique cross-linked pairs of residues, providing distance restraints between them, both within and between Nups (Fig.…”

“…Individual Nups, their domains, and subcomplexes were represented based on published crystallographic structures, integrative structures, and comparative models 9,10,12 (Supplementary Table 2; Methods), validated by SAXS profiles for 18 Nups (147 constructs; Supplementary Table 6). An ensemble of structural solutions for the NPC that sufficiently satisfied all experimental data was calculated by extensive configurational sampling 8,9 (Supplementary Table 3; Methods). Variability among these solutions defines the structure’s precision, as quantified by the average root-mean-square deviation between solutions in the final ensemble 9 .…”

“…An ensemble of structural solutions for the NPC that sufficiently satisfied all experimental data was calculated by extensive configurational sampling 8,9 (Supplementary Table 3; Methods). Variability among these solutions defines the structure’s precision, as quantified by the average root-mean-square deviation between solutions in the final ensemble 9 . Our final structure defines the positions of 552 Nups (Fig.…”

“…The fitness defects of strains containing Nup truncations provide an estimate of the structural importance of the truncated regions 9,13 . Thus, we quantified the fitness defect of strains containing systematic truncations of every major symmetric Nup using ODELAY 14 (an automated phenotypic analysis platform; Extended Data Fig.…”