Promiscuous Binding of Karyopherinβ1 Modulates FG Nucleoporin Barrier Function and Expedites NTF2 Transport Kinetics

Wagner, Raphael S. and Kapinos, Larisa E. and Marshall, Neil J. and Stewart, Murray and Lim, Roderick Y. H.. (2015) Promiscuous Binding of Karyopherinβ1 Modulates FG Nucleoporin Barrier Function and Expedites NTF2 Transport Kinetics. Biophysical journal, 108 (4). pp. 918-927.

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Official URL: http://edoc.unibas.ch/dok/A6348306

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The transport channel of nuclear pore complexes (NPCs) contains a high density of intrinsically disordered proteins that are rich in phenylalanine-glycine (FG)-repeat motifs (FG Nups). The FG Nups interact promiscuously with various nuclear transport receptors (NTRs), such as karyopherins (Kaps), that mediate the trafficking of nucleocytoplasmic cargoes while also generating a selectively permeable barrier against other macromolecules. Although the binding of NTRs to FG Nups increases molecular crowding in the NPC transport channel, it is unclear how this impacts FG Nup barrier function or the movement of other molecules, such as the Ran importer NTF2. Here, we use surface plasmon resonance to evaluate FG Nup conformation, binding equilibria, and interaction kinetics associated with the multivalent binding of NTF2 and karyopherinβ1 (Kapβ1) to Nsp1p molecular brushes. NTF2 and Kapβ1 show different long- and short-lived binding characteristics that emerge from varying degrees of molecular retention and FG repeat binding avidity within the Nsp1p brush. Physiological concentrations of NTF2 produce a collapse of Nsp1p brushes, whereas Kapβ1 binding generates brush extension. However, the presence of prebound Kapβ1 inhibits Nsp1p brush collapse during NTF2 binding, which is dominated by weak, short-lived interactions that derive from steric hindrance and diminished avidity with Nsp1p. This suggests that binding promiscuity confers kinetic advantages to NTF2 by expediting its facilitated diffusion and reinforces the proposal that Kapβ1 contributes to the integral barrier function of the NPC.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Structural Biology & Biophysics > Nanobiology Argovia (Lim)
UniBasel Contributors:Lim, Roderick Y.H. and Wagner, Raphael and Kapinos Schneider, Larisa E. E
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Biophysical Society
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:18 Apr 2018 09:14
Deposited On:10 Apr 2015 09:12

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