title: Disruption of an intermonomer salt bridge in the p53 tetramerization domain results in an increased propensity to form amyloid fibrils.
abstract: We describe in molecular detail how disruption of an intermonomer salt bridge (Arg337-Asp352) leads to partial destabilization of the p53 tetramerization domain and a dramatically increased propensity to form amyloid fibrils. At pH 4.0 and 37 degrees C, a p53 tetramerization domain mutant (p53tet-R337H), associated with adrenocortical carcinoma in children, readily formed amyloid fibrils, while the wild-type (p53tet-wt) did not. We characterized these proteins by equilibrium denaturation, 13C(alpha) secondary chemical shifts, (1H)-15N heteronuclear NOEs, and H/D exchange. Although p53tet-R337H was thermodynamically less stable, NMR data indicated that the two proteins had similar secondary structure and molecular dynamics. NMR derived pK(a) values indicated that at low pH the R337H mutation partially disrupted an intermonomer salt bridge. Backbone H/D exchange results showed that for at least a small population of p53tet-R337H molecules disruption of this salt bridge resulted in partial destabilization of the protein. It is proposed that this decrease in p53tet-R337H stability resulted in an increased propensity to form amyloid fibrils.
authors.affiliation: Department of Structural Biology, St. Jude Children's Research Hospital, 332 North Lauderdale Street, Memphis, TN 38105, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Galea
authors.forename: Prentice
authors.initials: P
authors.lastname: Bowman
authors.forename: Richard W
authors.initials: RW
authors.lastname: Kriwacki
mesh_terms: D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism*; D001120:Arginine / Q000235:genetics / Q000378:metabolism; D006859:Hydrogen / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D011489:Protein Denaturation; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D012492:Salts / Q000737:chemistry*; D013696:Temperature; D017186:Titrimetry; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D000682:Amyloid; D012492:Salts; D016159:Tumor Suppressor Protein p53; D006859:Hydrogen; D001120:Arginine