Journal Article

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

Reber, Simone, Schünemann, Jürgen, Görlich, Dirk, Ng, Sheung Chun, Biswas, Abin, Huyton, Trevor

2023

Overview

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 show that shortening inter-FG spacers enhances cohesion, increases phase density, and tightens such barrier - all consistent with a sieve-like phase. Phase separation tolerates mutating the Nup98-typical GLFG motifs, provided domain-hydrophobicity remains preserved. NTR-entry, however, is sensitive to (certain) deviations from canonical FG motifs, suggesting co-evolutionary adaptation. Unexpectedly, we observed that arginines promote FG-phase-entry apparently also by hydrophobic interactions/ hydrogen-bonding and not just through cation-π interactions. Although incompatible with NTR·cargo complexes, a YG phase displays remarkable transport selectivity, particularly for engineered GFP NTR -variants. GLFG to FSFG mutations make the FG phase hypercohesive, precluding NTR-entry. Extending spacers relaxes this hypercohesion. Thus, antagonism between cohesion and NTR·FG interactions is key to transport selectivity. The permeability barrier of the nuclear pore assembles from cohesive FG repeats. By systematic engineering and testing repeat variants, the authors pinpointed the sequence features that rule barrier assembly and transport selectivity.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 14/19 / 14/35 / 14/63 / 631/57/2269 / 631/57/2283 / 631/80/389/2023/2022 / 631/80/389/2029 / 82/83 / Active Transport, Cell Nucleus / Cohesion / Cytoplasm / Domains / Ecological adaptation / Humanities and Social Sciences / Hydrogen bonding / Hydrophobicity / Membrane permeability / multidisciplinary / Mutation / Nuclear capture / Nuclear Pore - metabolism / Nuclear Pore Complex Proteins - chemistry / Nuclear Pore Complex Proteins - genetics / Nuclear pores / Nuclear transport / Permeability / Phase separation / Science / Science (multidisciplinary) / Selectivity / Spacers