title: Molecular mechanisms of functional rescue mediated by P53 tumor suppressor mutations.
abstract: We have utilized both molecular dynamics simulations and solution biophysical measurements to investigate the rescue mechanism of mutation N235K, which plays a key role in the recently identified global suppressor motif of K235/Y239/R240 in the human p53 DNA-binding domain (DBD). Previous genetic analysis indicates that N235K alone rescues five out of six destabilized cancer mutants. However, the solution biophysical measurement shows that N235K generates only a slight increase to the stability of DBD, implying a rescue mechanism that is not a simple additive contribution to thermodynamic stability. Our molecular simulations show that the N235K substitution generates two non-native salt bridges with residues D186 and E198. We find that the nonnative salt bridges, D186-K235 and E198-K235, and a native salt bridge, E171-R249, are mutually exclusive, thus resulting in only a marginal increase in stability as compared to the wild type protein. When a destabilized V157F is paired with N235K, the native salt bridge E171-R249 is retained. In this context, the non-native salt bridges, D186-K235 and E198-K235, produce a net increase in stability as compared to V157F alone. A similar rescue mechanism may explain how N235K stabilize other highly unstable beta-sandwich cancer mutants.
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, California, 92697, USA.
authors.forename: Yu-Hong
authors.initials: YH
authors.lastname: Tan
authors.forename: Y Morris
authors.initials: YM
authors.lastname: Chen
authors.forename: Xiang
authors.initials: X
authors.lastname: Ye
authors.forename: Qiang
authors.initials: Q
authors.lastname: Lu
authors.forename: Vira
authors.initials: V
authors.lastname: Tretyachenko-Ladokhina
authors.forename: Wei
authors.initials: W
authors.lastname: Yang
authors.forename: Donald F
authors.initials: DF
authors.lastname: Senear
authors.forename: Ray
authors.initials: R
authors.lastname: Luo
mesh_terms: D019943:Amino Acid Substitution; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D011485:Protein Binding / Q000235:genetics*; D011487:Protein Conformation; D017510:Protein Folding; D055503:Protein Multimerization / Q000235:genetics*; D017434:Protein Structure, Tertiary / Q000235:genetics; D055672:Static Electricity; D013696:Temperature; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry* / Q000235:genetics / Q000502:physiology
chemical_list: D016159:Tumor Suppressor Protein p53