title: 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.
authors.affiliation: Department of Chemistry and Biochemistry, Texas State University, San Marcos, Texas, 78666.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Langridge
authors.forename: Micheal J
authors.initials: MJ
authors.lastname: Tarver
authors.forename: Steven T
authors.initials: ST
authors.lastname: Whitten
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D002942:Circular Dichroism; D003198:Computer Simulation; D004591:Electrophoresis, Polyacrylamide Gel; D005998:Glycine / Q000737:chemistry; D057446:Hydrodynamics; D057927:Hydrophobic and Hydrophilic Interactions; D064267:Intrinsically Disordered Proteins / Q000737:chemistry* / Q000648:ultrastructure; D008958:Models, Molecular; D011392:Proline / Q000737:chemistry; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D013696:Temperature; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry* / Q000648:ultrastructure*
chemical_list: D064267:Intrinsically Disordered Proteins; D016159:Tumor Suppressor Protein p53; D011392:Proline; D005998:Glycine
keywords: acidic activation domain; heat; hydrodynamic radius; intrinsically disordered protein; net charge; polyproline