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Folding and misfolding mechanisms of the p53 DNA binding domain at physiological temperature
Author(s) -
Butler James S.,
Loh Stewart N.
Publication year - 2006
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.062324206
Subject(s) - biophysics , chemistry , folding (dsp implementation) , protein folding , kinetics , dna , mutant , native state , function (biology) , crystallography , microbiology and biotechnology , biochemistry , biology , gene , physics , quantum mechanics , electrical engineering , engineering
Abstract p53 modulates a large number of cellular response pathways and is critical for the prevention of cancer. Wild‐type p53, as well as tumorigenic mutants, exhibits the singular property of spontaneously losing DNA binding activity at 37°C. To understand the molecular basis for this effect, we examine the folding mechanism of the p53 DNA binding domain (DBD) at elevated temperatures. Folding kinetics do not change appreciably from 5°C to 35°C. DBD therefore folds by the same two‐channel mechanism at physiological temperature as it does at 10°C. Unfolding rates, however, accelerate by 10,000‐fold. Elevated temperatures thus dramatically increase the frequency of cycling between folded and unfolded states. The results suggest that function is lost because a fraction of molecules become trapped in misfolded conformations with each folding‐unfolding cycle. In addition, at 37°C, the equilibrium stabilities of the off‐pathway species are predicted to rival that of the native state, particularly in the case of destabilized mutants. We propose that it is the presence of these misfolded species, which can aggregate in vitro and may be degraded in the cell, that leads to p53 inactivation.