Atomic resolution dynamics of cohesive interactions in phase-separated Nup98 FG domains

Cohesive FG domains assemble into a condensed phase forming the selective permeability barrier of nuclear pore complexes. Nanoscopic insight into fundamental cohesive interactions has long been hampered by the sequence heterogeneity of native FG domains. We overcome this challenge by utilizing an engineered perfectly repetitive sequence and a combination of solution and magic angle spinning NMR spectroscopy. We map the dynamics of cohesive interactions in both phase-separated and soluble states at atomic resolution using TROSY for rotational correlation time (TRACT) measurements. We find that FG repeats exhibit nanosecond-range rotational correlation times and remain disordered in both states, although FRAP measurements show slow translation of phase-separated FG domains. NOESY measurements enable the direct detection of contacts involved in cohesive interactions. Finally, increasing salt concentration and temperature enhance phase separation and decrease local mobility of FG repeats. This lower critical solution temperature (LCST) behaviour indicates that cohesive interactions are driven by entropy.

Automated summary

The cohesive FG domains in nuclear pore complexes form a selective permeability barrier, with nanoscopic insight into their interactions hindered by sequence heterogeneity. By using an engineered repetitive sequence and NMR spectroscopy, researchers were able to overcome this challenge and map the dynamics of cohesive interactions. The study found that the FG repeats remained disordered in both phase-separated and soluble states, with slow translation observed in phase-separated domains.