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bioRxiv · 10.1101/2022.10.14.512266

Barrier-properties of Nup98 FG phases ruled by FG motif identity and inter-FG spacer length

Ng, S. C.·Biswas, A.·Huyton, T.·Schunemann, J.·Reber, S.·Gorlich, D.
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Abstract

Nup98 FG repeat domains comprise hydrophobic FG motifs linked through uncharged spacers. FG motifs capture nuclear transport receptors (NTRs) during nuclear pore complex (NPC) passage, confer inter-repeat cohesion, and condense the domains into a selective phase with NPC-typical barrier properties. We found that shortening inter-FG spacers enhances cohesion, increases phase density, and tightens such barrier, all consistent with a sieve-like phase. Phase separation tolerated mutating the Nup98-typical GLFG motifs, provided domain-hydrophobicity remained preserved. NTR-entry, however, was sensitive to (certain) deviations from canonical FG motifs, suggesting co-evolutionary adaptation. Unexpectedly, we found arginines to promote FG-phase-entry apparently also by hydrophobic interactions/ H-bonding and not just through cation-{pi} interactions. Although incompatible with NTR{middle dot}cargo complexes, a YG phase displayed remarkable transport selectivity, particularly for engineered GFPNTR-variants. GLFG to FSFG mutations made the FG phase hypercohesive, precluding NTR-entry. Extending spacers relaxed this hypercohesion. Thus, antagonism between cohesion and NTR{middle dot}FG interactions is key to transport selectivity.

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Ng, S. C., Biswas, A., Huyton, T., Schunemann, J., Reber, S., Gorlich, D.. 2022-10-14. Barrier-properties of Nup98 FG phases ruled by FG motif identity and inter-FG spacer length. https://doi.org/10.1101/2022.10.14.512266

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