Unfolding, Aggregation, and Amyloid Formation by the Tetramerization Domain from Mutant p53 Associated with Lung Cancer

Abstract

The p53 tumor suppressor is a tetrameric transcriptional enhancer, and its activity is compromised by mutations that cause amino acid substitutions in its tetramerization domain. Here we analyze the biochemical and biophysical properties of peptides corresponding to amino acids 319 to 358 of wildtype human p53, which includes the tetramerization domain, and that of a cancer-derived mutant with valine substituted for glycine 334. Unlike the wild-type peptide, the G334V peptide forms amyloid fibrils by a two step process under physiological conditions of temperature and pH. Nevertheless, the G334V peptide is capable of forming hetero-oligomers with a wild-type peptide. Computational modeling of the G334V peptide structure suggests that substitution of valine for glycine 334 causes a local distortion that contributes to a β-dominated structural transition leading to amyloid formation. Since the distortion is mostly on the surface, the mutant peptide is still able to form a pseudo-native tetramer complex at higher concentrations and/or lower temperatures. Our † KS was supported in

Stability and structural recovery of the tetramerization domain of p53-R337H mutant induced by a designed templating ligand

“…Indeed, p53TD-G334V, another natural mutant associated to cancer (31, 32) of weak tetrameric integrity (33), was also structurally and thermally stabilized by the calixarene (Fig. S4 and Fig.…”

The aggregation of mutant p53 produces prion-like properties in cancer

“…85,86 Previous studies have described the formation of amyloidlike aggregates during oligomerization. The formation of these aggregates is driven by the transactivation domains of p53, 61,70,87 which could affect the subcellular localization of the protein. Several cancers are characterized by an abnormal accumulation of wild-type or mutant p53 in the cytoplasm or in the nucleus of the cell.…”

Structure–function–rescue: the diverse nature of common p53 cancer mutants

“…Similarly, other cancer-associated mutations also destabilize the tetramerization domain, for example by introducing a helix breaking proline (L344P) or weakening the hydrophobic core of the primary dimers (F341L), which either completely abrogates oligomerization or shifts the tetramerization equilibrium, thus preventing tetramer formation at normal cellular levels (Ishioka et al, 1997;Mateu and Fersht, 1999;Che`ne, 2001;Kawaguchi et al, 2005). The G334V mutant of the tetramerization domain, which is associated with lung cancer, was found to form amyloid fibrils under physiological conditions, although it was still able to form a tetrameric complex at high concentrations at lower temperatures (Higashimoto et al, 2006). In the wildtype tetramerization domain, Gly-334 facilitates the formation of a sharp turn connecting the b-strand with the a-helix and adopts a backbone conformation that would be energetically unfavorable for a non-glycine residue, indicating that structural distortions are to be expected upon mutation.…”