Visualizing the disordered nuclear transport machinery in situ

Area of Science:

• Cell Biology
• Biophysics
• Structural Biology

Background:

• The nuclear pore complex (NPC) regulates transport between the nucleus and cytoplasm.
• Intrinsically disordered proteins (IDPs), specifically FG-nucleoporins (FG-NUPs), form the NPC's central transport channel.
• The precise structure and dynamics of FG-NUPs within the NPC remain poorly understood.

Purpose of the Study:

• To directly probe the conformations of FG-NUP98 within the NPC in live and permeabilized cells.
• To map the molecular environment inside the NPC's transport channel.
• To understand how FG-NUP conformations influence nuclear transport.

Main Methods:

• Synthetic biology-enabled site-specific small-molecule labeling.
• Highly time-resolved fluorescence microscopy.
• Coarse-grained molecular simulations of the NPC.

Main Results:

• FG-NUP98 conformations were directly measured within the NPC.
• The NPC channel was characterized as a 'good solvent' environment.
• This environment promotes expanded FG-NUP conformations, controlling nuclear transport.

Conclusions:

• The NPC channel's 'good solvent' nature is crucial for FG-NUP function.
• Understanding IDP disorder-function relationships in situ is vital for cellular processes.
• This work provides insights into IDP roles in signaling, aging, and viral entry.