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Temperature effects on the hydrodynamic radius of the intrinsically disordered N‐terminal region of the p53 protein
Author(s) -
Langridge Timothy D.,
Tarver Micheal J.,
Whitten Steven T.
Publication year - 2014
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.24449
Subject(s) - proline , intrinsically disordered proteins , radius , hydrodynamic radius , chemistry , denaturation (fissile materials) , stokes radius , crystallography , random coil , glycine , amino acid , biochemistry , circular dichroism , size exclusion chromatography , enzyme , computer security , aqueous solution , computer science , micelle , nuclear chemistry
Intrinsically disordered proteins (IDPs) are often characterized in terms of the hydrodynamic radius, R h . The R h of IDPs are known to depend on fractional proline content and net charge, where increased numbers of proline residues and increased net charge cause larger R h . Though sequence and charge effects on the R h of IDPs have been studied, the temperature sensitivity has been noted only briefly. Reported here are R h measurements in the temperature range of 5–75°C for the intrinsically disordered N‐terminal region of the p53 protein, p53(1–93). Of note, the R h of this protein fragment was highly sensitive to temperature, decreasing from 35 Å at 5°C to 26 Å at 75°C. Computer generated simulations of conformationally dynamic and disordered polypeptide chains were performed to provide a hypothesis for the heat‐induced compaction of p53(1–93) structure, which was opposite to the heat‐induced increase in R h observed for a model folded protein. The simulations demonstrated that heat caused R h to trend toward statistical coil values for both proteins, indicating that the effects of heat on p53(1–93) structure could be interpreted as thermal denaturation. The simulation data also predicted that proline content contributed minimally to the native R h of p53(1–93), which was confirmed by measuring R h for a substitution variant that had all 22 proline residues changed for glycine. Proteins 2014; 82:668–678. © 2013 Wiley Periodicals, Inc.