Effect of charge, hydrophobicity, and sequence of nucleoporins on the translocation of model particles through the nuclear pore complex

Tagliazucchi, Mario; Peleg, Orit; Kröger, Martin; Rabin, Yitzhak; Szleifer, Igal

doi:10.1073/pnas.1212909110

Cited by 149 publications

(227 citation statements)

References 45 publications

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“…We found that when expressed as MBP-fusion peptides, substitution of the acidic residues for alanine reduced binding of the N(1-132) sequence to Nup153-FG repeats by ~50% (Fig. 7 A,B), consistent with a reduced electrostatic interaction (42). Interestingly, this was not sufficient to impede the rate of transport.…”

Section: The N-and C-tails Bind Directly To Fg-rich Nucleoporins Of Tsupporting

confidence: 51%

WITHDRAWN: The hydrophobic rich N- and C-terminal tails of beta-catenin facilitate nuclear import of beta-catenin

et al. 2014

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Section: The N-and C-tails Bind Directly To Fg-rich Nucleoporins Of Tsupporting

confidence: 51%

WITHDRAWN: The hydrophobic rich N- and C-terminal tails of beta-catenin facilitate nuclear import of beta-catenin

et al. 2014

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“…The spacer regions may form nonspecific and transient interactions with NTF2, both providing anchors for rapid recontacting of loose FG motifs, and resulting in a weak multivalency effect. As already suggested (70), electrostatic interactions between the disordered regions and TFs may also play a role similar to the well-characterized effect of electrostatic steering on the kinetics of protein-protein interactions (71). We also observed electrostatic steering due to long-range interaction between the multiple lysine residues in the FG motifs and the acidic patch on NTF2 (residues 91-93), which we shall further investigate in future work.…”

Section: Discussionmentioning

confidence: 71%

Slide-and-exchange mechanism for rapid and selective transport through the nuclear pore complex

Raveh

Karp

Sparks

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

131

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Nucleocytoplasmic transport is mediated by the interaction of transport factors (TFs) with disordered phenylalanine-glycine (FG) repeats that fill the central channel of the nuclear pore complex (NPC). However, the mechanism by which TFs rapidly diffuse through multiple FG repeats without compromising NPC selectivity is not yet fully understood. In this study, we build on our recent NMR investigations showing that FG repeats are highly dynamic, flexible, and rapidly exchanging among TF interaction sites. We use unbiased long timescale all-atom simulations on the Anton supercomputer, combined with extensive enhanced sampling simulations and NMR experiments, to characterize the thermodynamic and kinetic properties of FG repeats and their interaction with a model transport factor. Both the simulations and experimental data indicate that FG repeats are highly dynamic random coils, lack intrachain interactions, and exhibit significant entropically driven resistance to spatial confinement. We show that the FG motifs reversibly slide in and out of multiple TF interaction sites, transitioning rapidly between a strongly interacting state and a weakly interacting state, rather than undergoing a much slower transition between strongly interacting and completely noninteracting (unbound) states. In the weakly interacting state, FG motifs can be more easily displaced by other competing FG motifs, providing a simple mechanism for rapid exchange of TF/FG motif contacts during transport. This slide-and-exchange mechanism highlights the direct role of the disorder within FG repeats in nucleocytoplasmic transport, and resolves the apparent conflict between the selectivity and speed of transport.nuclear pore | molecular dynamics | nucleoporins | transport factors | NMR T he nuclear pore complex (NPC) regulates macromolecular transport between the nucleus and the cytoplasm in all eukaryotic cells (1, 2). The NPC allows for passive diffusion of small molecules including sugars, ions, and water, while simultaneously imposing size-dependent exclusion of macromolecules without nuclear transport factor (TF) binding sites, generating unique nuclear and cytoplasmic compartments (3, 4). Larger macromolecules can bypass the selectivity barrier of the NPC by interacting with TFs that shuttle cargo through the central channel of the pore. In pathological conditions, including many cancers and viral infections, the NPC is hijacked and used to transport undesired particles, or it is modified to attenuate the cellular responses to disease onset (5, 6).TFs traverse the NPC by selective and reversible association with disordered phenylalanine-glycine (FG) repeat domains of the FG nucleoporin proteins (FG Nups), which line the surface of the NPC (7-14). Each FG repeat domain consists of 5-50 FG repeats. In turn, each FG repeat consists of a single FG motif of various sequence flavors, such as the FSFG and GLFG motifs, and 10-30 spacer residues that separate consecutive FG motifs (15, 16). The spacer residues are strongly hydrophilic (17) and rich ...

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“…Cargo lacking NLS may cross the NPC autonomously at a rate dominated by size, but also affected by charge and hydrophobicity (16)(17)(18). At steady state, its concentration will reach a uniform distribution:…”

Section: Passive-only Transportmentioning

confidence: 99%

A Simple Kinetic Model with Explicit Predictions for Nuclear Transport

Kim

Elbaum

2013

Biophysical Journal

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Molecular exchange between the cell nucleus and cytoplasm is one of the most fundamental features of eukaryotic cell biology. The nuclear pores act as a conduit of this transport, both for cargo that crosses the pore autonomously as well as that whose translocation requires an intermediary receptor. The major class of such receptors is regulated by the small GTPase Ran, via whose interaction the nucleo-cytoplasmic transport system functions as a selective molecular pump. We propose a simple analytical model for transport that includes both translocation and receptor binding kinetics. The model is suitable for steady-state kinetics such as fluorescence recovery after photobleaching. Time constants appear as a combination of parameters whose effects on measured kinetics are not separable. Competitive cargo binding to receptors and large cytoplasmic volume buffer the transport properties of any particular cargo. Specific limits to the solutions provide a qualitative insight and interpretation of nuclear transport in the cellular context. Most significantly, we find that under realistic conditions receptor binding, rather than permeability of the nuclear pores, may be rate-limiting for nucleo-cytoplasmic exchange.

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Effect of charge, hydrophobicity, and sequence of nucleoporins on the translocation of model particles through the nuclear pore complex

Cited by 149 publications

References 45 publications

WITHDRAWN: The hydrophobic rich N- and C-terminal tails of beta-catenin facilitate nuclear import of beta-catenin

WITHDRAWN: The hydrophobic rich N- and C-terminal tails of beta-catenin facilitate nuclear import of beta-catenin

Slide-and-exchange mechanism for rapid and selective transport through the nuclear pore complex

A Simple Kinetic Model with Explicit Predictions for Nuclear Transport

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