Selective transport control on molecular velcro made from intrinsically disordered proteins

Area of Science:

• Biophysics
• Materials Science
• Cell Biology

Background:

• Biological transport often utilizes 'reduction of dimensionality' to enhance speed and selectivity.
• This principle is desirable for engineered systems to accelerate diffusional search processes.
• Phenylalanine-glycine nucleoporins (FG Nups) are key proteins in nuclear pore complex transport.

Purpose of the Study:

• To reconstitute and study two-dimensional diffusion of colloidal particles on a FG Nup-based molecular brush surface.
• To investigate how FG Nups influence particle diffusivity and transport behavior.
• To explore the potential of FG Nups for biomimetic transport control in artificial systems.

Main Methods:

• Utilized optical trapping with a photonic force microscope for local measurements.
• Employed particle tracking via video microscopy for ensemble-level analysis.
• Reconstituted a 2D surface using FG Nups and colloidal particles functionalized with karyopherins.

Main Results:

• Observed that 1-µm colloidal particles exhibited variable diffusion, from localized to unhindered 2D diffusion.
• Demonstrated that particle diffusivity can be precisely controlled by modulating free karyopherins in solution.
• Showed that FG Nup density on the brush surface dictates the multivalency of binding sites, influencing particle behavior.

Conclusions:

• FG Nups act as stimuli-responsive molecular 'velcro', enabling 'reduction of dimensionality' for transport control.
• This FG Nup system provides a biomimetic approach for controlling diffusion in engineered environments.
• The findings highlight the potential of protein-based materials for advanced molecular transport applications.