The Nuclear Pore Complex consists of two independent scaffolds

Abstract

Macromolecular transport between the nucleus and cytoplasm is mediated through Nuclear Pore Complexes (NPCs), which are built from multiple copies of roughly 34 distinct proteins, called nucleoporins1–3. Models of the NPC depict it as a composite of several sub-domains that have been named the outer rings, inner ring, cytoplasmic fibrils and nuclear basket. While the NPC has been extensively studied, the roles of individual nucleoporins within NPCs and their functional interactions remain poorly understood. Here, we applied a rapid degron system to systematically investigate how individual nucleoporins contribute toward NPC architecture. We find that acute depletion of outer ring components (NUP96 or NUP107) disperses the outer ring and cytoplasmic fibrils without disassembly of inner ring members. Conversely, rapid degradation of the inner ring complex component NUP188 disrupts the inner ring without dislodging outer ring members. We also found that depletion of NUP93 destabilized all NPC domains, indicating that it has a unique role as a lynchpin of NPC structure. Our data highlight the modular nature of NPC organization, suggesting that the outer and inner ring complexes do not extensively rely on each other for structural stability after NPC assembly is complete. This dynamic assessment provides new insights regarding the remarkable structural independence of domains within the NPC.