Structure and mechanics of the human Nuclear Pore Complex basket

Abstract

Nuclear pore complexes (NPCs) are the only gateways between the nucleus and cytoplasm in eukaryotic cells. They restrict free diffusion to molecules below 5 nm while facilitating the active transport of selected cargoes, sometimes as large as the pore itself. This versatility implies an important pore plasticity. Recently, cryo-EM and AI-based protein modeling revealed with acute precision how most NPC constituents are arranged. But the basket, a fish trap-like structure capping the nucleoplasmic side of the pore, remains the missing piece in this puzzle. Here by Atomic Force Microscopy (AFM) coupled to Single Molecule Localization Microscopy (SMLM) we revealed that the basket is very soft and explores a large conformational landscape: apart from its canonical shape, it dives into the central pore channel or opens, with filaments reaching to the pore sides. Our observations enlighten how this structure can adapt and let morphologically diverse cargoes shuttling through NPCs