Temperature-dependent solvation modulates the dimensions of disordered proteins

Area of Science:

• Biophysics
• Protein Science
• Chemical Physics

Background:

• Disordered proteins lack a fixed 3D structure, making their chain dimensions crucial.
• Chain dimensions are sensitive to environmental factors like temperature.
• Understanding these interactions is key to protein function.

Purpose of the Study:

• To investigate the temperature-induced chain collapse of five intrinsically disordered proteins.
• To probe the physical interactions governing disordered protein dimensions.

Main Methods:

• Single-molecule Förster resonance energy transfer (smFRET) was employed.
• Theoretical modeling and simulations were used in conjunction with experimental data.

Main Results:

• All five proteins exhibited temperature-induced chain collapse.
• The most hydrophilic proteins showed the largest collapse.
• The most hydrophobic protein (λ-repressor) re-expanded at high temperatures.

Conclusions:

• The observed collapse is driven by temperature-dependent solvation free energies of amino acids.
• Hydrophilic residue solvation significantly influences disordered protein dimensions.
• Classical hydrophobic effect alone does not explain the observed collapse behavior.