Transport receptor occupancy in nuclear pore complex mimics
Journal article, 2022

Nuclear pore complexes (NPCs) regulate all molecular transport between the nucleus and the cytoplasm in eukaryotic cells. Intrinsically disordered Phe-Gly nucleoporins (FG-Nups) line the central conduit of NPCs to impart a selective barrier where large proteins are excluded unless bound to a transport receptor (karyopherin; Kap). Here, we assess “Kap-centric” NPC models, which postulate that Kaps participate in establishing the selective barrier. We combine biomimetic nanopores, formed by tethering Nsp1 to the inner wall of a solid-state nanopore, with coarse-grained modeling to show that yeast Kap95 exhibits two populations in Nsp1-coated pores: one population that is transported across the pore in milliseconds, and a second population that is stably assembled within the FG mesh of the pore. Ionic current measurements show a conductance decrease for increasing Kap concentrations and noise data indicate an increase in rigidity of the FG-mesh. Modeling reveals an accumulation of Kap95 near the pore wall, yielding a conductance decrease. We find that Kaps only mildly affect the conformation of the Nsp1 mesh and that, even at high concentrations, Kaps only bind at most 8% of the FG-motifs in the nanopore, indicating that Kap95 occupancy is limited by steric constraints rather than by depletion of available FG-motifs. Our data provide an alternative explanation of the origin of bimodal NPC binding of Kaps, where a stable population of Kaps binds avidly to the NPC periphery, while fast transport proceeds via a central FG-rich channel through lower affinity interactions between Kaps and the cohesive domains of Nsp1. [Figure not available: see fulltext.]

nuclear transport receptors

nanopores

karyopherins

nuclear pore complex

intrinsically disordered proteins

coarse-grained modeling

molecular dynamics

biomimetics

Author

Alessio Fragasso

Delft University of Technology

Hendrik W. de Vries

University of Groningen

John Andersson

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Eli O. van der Sluis

Delft University of Technology

Erik van der Giessen

University of Groningen

Patrick R. Onck

University of Groningen

C. Dekker

Delft University of Technology

Nano Research

1998-0124 (ISSN) 1998-0000 (eISSN)

Vol. 15 11 9689-9703

Subject Categories

Pharmaceutical Sciences

Biophysics

Other Industrial Biotechnology

DOI

10.1007/s12274-022-4647-1

More information

Latest update

3/7/2024 9