Temperature effects on the hydrodynamic radius of the intrinsically disordered N‐terminal region of the p53 protein

Abstract

Intrinsically disordered proteins (IDPs) are often characterized in terms of the hydrodynamic radius, Rh . The Rh 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 Rh . Though sequence and charge effects on the Rh of IDPs have been studied, the temperature sensitivity has been noted only briefly. Reported here are Rh 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 Rh 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 Rh observed for a model folded protein. The simulations demonstrated that heat caused Rh 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 Rh of p53(1-93), which was confirmed by measuring Rh for a substitution variant that had all 22 proline residues changed for glycine.

Temperature-dependent solvation modulates the dimensions of disordered proteins

“…The results were in good agreement with dynamic light-scattering experiments on unlabeled protein, demonstrating that the effect is independent of the presence of the fluorophores (22). This result is in line with previous laser temperature jump experiments on acid-denatured BBL protein (24) and recent light-and small-angle X-ray-scattering results on the disordered N-terminal part of p53 (25) and several other IDPs (26). All of these observations are in contrast to the behavior expected for a polymer chain with a temperatureindependent monomer-monomer interaction energy, which will expand with increasing temperature owing to the increasing entropic contribution to the free energy (27,28).…”

The Proline/Glycine-Rich Region of the Biofilm Adhesion Protein Aap Forms an Extended Stalk that Resists Compaction

“…In parallel to the sedimentation velocity analysis, we determined the radius of hydration ( R h ) of PGR by size exclusion chromatography (SEC) [51]. A series of well-characterized globular proteins were run over a G-100 Sephadex column to determine the linear relationship between the thermodynamic retention factor ( K D ) and R h for control proteins with known crystal structures [51, 52] (Fig.…”

“…A series of well-characterized globular proteins were run over a G-100 Sephadex column to determine the linear relationship between the thermodynamic retention factor ( K D ) and R h for control proteins with known crystal structures [51, 52] (Fig. 2a).…”

The Rheology behind Stress-Induced Solidification in Native Silk Feedstocks

“…Although it may provide a plausible explanation for globular proteins with hydrophilic and hydrophobic regions within well-defined tertiary structures in their native states, it appears inappropriate for B. mori fibroin, which appears to exhibit a random coil structure, as already discussed. Instead, the thermal gelation of fibroin may be more related to the gradual decrease in coil dimensions shown by IDPs during heating, which contrasts with the sudden expansion over a narrow temperature range shown by “conventional” proteins [58,79]. Although less well studied, silk feedstocks can also be gelled through freezing [80], which occurs presumably without any melting of the tertiary structure.…”