TY  - JOUR
A1  - Nettels, Daniel
A1  - Müller-Späth, Sonja
A1  - Küster, Frank
A1  - Hofmann, Hagen
A1  - Haenni, Domminik
A1  - Rüegger, Stefan
A1  - Reymond, Luc
A1  - Hoffmann, Armin S.
A1  - Kubelka, Jan
A1  - Heinz, Benjamin
A1  - Gast, Klaus
A1  - Best, Robert B.
A1  - Schuler, Benjamin
T1  - Single-molecule spectroscopy of the temperature-induced collapse of unfolded proteins
N2  - We used single-molecule FRET in combination with other biophysical methods and molecular simulations to investigate the effect of temperature on the dimensions of unfolded proteins. With singlemolecule FRET, this question can be addressed even under nearnative conditions, where most molecules are folded, allowing us to probe a wide range of denaturant concentrations and temperatures. We find a compaction of the unfolded state of a small cold shock protein with increasing temperature in both the presence and the absence of denaturant, with good agreement between the results from single-molecule FRET and dynamic light scattering. Although dissociation of denaturant from the polypeptide chain with increasing temperature accounts for part of the compaction, the results indicate an important role for additional temperaturedependent interactions within the unfolded chain. The observation of a collapse of a similar extent in the extremely hydrophilic, intrinsically disordered protein prothymosin suggests that the hydrophobic effect is not the sole source of the underlying interactions. Circular dichroism spectroscopy and replica exchange molecular dynamics simulations in explicit water show changes in secondary structure content with increasing temperature and suggest a contribution of intramolecular hydrogen bonding to unfolded state collapse.
Y1  - 2009
UR  - http://www.pnas.org/content/106/49/20740.full.pdf+html
SN  - 0027-8424
ER  -