Temperature-dependent solvation modulates the dimensions of disordered proteins.
For disordered proteins, the dimensions of the chain are an important property that is sensitive to environmental conditions. We have used single-molecule Förster resonance energy transfer to probe the temperature-induced chain collapse of five unfolded or intrinsically disordered proteins. Because this behavior is sensitive to the details of intrachain and chain-solvent interactions, the collapse allows us to probe the physical interactions governing the dimensions of disordered proteins. We find that each of the proteins undergoes a collapse with increasing temperature, with the most hydrophobic one, λ-repressor, undergoing a reexpansion at the highest temperatures. Although such a collapse might be expected due to the temperature dependence of the classical "hydrophobic effect," remarkably we find that the largest collapse occurs for the most hydrophilic, charged sequences. Using a combination of theory and simulation, we show that this result can be rationalized in terms of the temperature-dependent solvation free energies of the constituent amino acids, with the solvation properties of the most hydrophilic residues playing a large part in determining the collapse.
Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland.
René
R
Wuttke
Hagen
H
Hofmann
Daniel
D
Nettels
Madeleine B
MB
Borgia
Jeetain
J
Mittal
Robert B
RB
Best
Benjamin
B
Schuler
D031541:Fluorescence Resonance Energy Transfer; D057927:Hydrophobic and Hydrophilic Interactions; D011487:Protein Conformation; D058767:Protein Unfolding; D012995:Solubility; D013696:Temperature; D013816:Thermodynamics
ABSINTH; HIV integrase; Sanchez theory; cold shock protein; prothymosin α