Polymer scaling laws of unfolded and intrinsically disordered proteins quantified with single-molecule spectroscopy
- The dimensions of unfolded and intrinsically disordered proteins are highly dependent on their amino acid composition and solution conditions, especially salt and denaturant concentration. However, the quantitative implications of this behavior have remained unclear, largely because the effective theta-state, the central reference point for the underlying polymer collapse transition, has eluded experimental determination. Here, we used single-molecule fluorescence spectroscopy and two-focus correlation spectroscopy to determine the theta points for six different proteins. While the scaling exponents of all proteins converge to 0.62 +/- 0.03 at high denaturant concentrations, as expected for a polymer in good solvent, the scaling regime in water strongly depends on sequence composition. The resulting average scaling exponent of 0.46 +/- 0.05 for the four foldable protein sequences in our study suggests that the aqueous cellular milieu is close to effective theta conditions for unfolded proteins. In contrast, two intrinsicallyThe dimensions of unfolded and intrinsically disordered proteins are highly dependent on their amino acid composition and solution conditions, especially salt and denaturant concentration. However, the quantitative implications of this behavior have remained unclear, largely because the effective theta-state, the central reference point for the underlying polymer collapse transition, has eluded experimental determination. Here, we used single-molecule fluorescence spectroscopy and two-focus correlation spectroscopy to determine the theta points for six different proteins. While the scaling exponents of all proteins converge to 0.62 +/- 0.03 at high denaturant concentrations, as expected for a polymer in good solvent, the scaling regime in water strongly depends on sequence composition. The resulting average scaling exponent of 0.46 +/- 0.05 for the four foldable protein sequences in our study suggests that the aqueous cellular milieu is close to effective theta conditions for unfolded proteins. In contrast, two intrinsically disordered proteins do not reach the T-point under any of our solvent conditions, which may reflect the optimization of their expanded state for the interactions with cellular partners. Sequence analyses based on our results imply that foldable sequences with more compact unfolded states are a more recent result of protein evolution.…
Verfasserangaben: | Hagen Hofmann, Andrea Soranno, Alessandro Borgia, Klaus Gast, Daniel Nettels, Benjamin Schuler |
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DOI: | https://doi.org/10.1073/pnas.1207719109 |
ISSN: | 0027-8424 |
Titel des übergeordneten Werks (Englisch): | Proceedings of the National Academy of Sciences of the United States of America |
Verlag: | National Acad. of Sciences |
Verlagsort: | Washington |
Publikationstyp: | Wissenschaftlicher Artikel |
Sprache: | Englisch |
Jahr der Erstveröffentlichung: | 2012 |
Erscheinungsjahr: | 2012 |
Datum der Freischaltung: | 26.03.2017 |
Freies Schlagwort / Tag: | coil-globule transition; polymer theory; protein folding; single-molecule FRET |
Band: | 109 |
Ausgabe: | 40 |
Seitenanzahl: | 6 |
Erste Seite: | 16155 |
Letzte Seite: | 16160 |
Fördernde Institution: | Swiss National Science Foundation; Swiss National Center of Competence in Research for Structural Biology; Starting Investigator Grant of the European Research Council |
Organisationseinheiten: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Biochemie und Biologie |
Peer Review: | Referiert |