The relationship among p53 oligomer formation, structure and transcriptional activity using a comprehensive missense mutation library

Abstract

Tumor suppressor p53 forms a homo-tetramer through its COOH-terminal oligomerization domain and acts as a sequence-specific transcription factor. We have analysed the interrelation among the transcriptional activities, the structure and the cancer-related mutations in the oligomerization domain by using a comprehensive missense mutation library. Here, we examined the ability of 184 mutant p53s in the domain to form an oligomer by expressing these mutant p53s in yeast, and compared the data with the previous information. We showed that specific residues in the a-helix and the b-strand of the oligomerization domain were critical for both oligomer formation and sequence-specific transactivation, and the activities were closely related. In particular, the a-helix was more sensitive to amino-acid substitutions than the b-strand. We found identity in the interrelation between the two activities, that is, monomer mutants were transcriptionally inactive whereas dimer and tetramer mutants retained their transcriptional activities. In TP53 mutation databases, a small number of mutations have been reported in this domain. Surprisingly, most do not encode p53s defective in functional properties. These results indicate that, although oligomer formation is essential for p53 transactivation function, the inactivation of oligomer formation and therefore the inactivation of transactivation may not be essential for tumor suppression by p53 because they do not lead to oncogenic proteins.

Folding of Tetrameric p53: Oligomerization and Tumorigenic Mutations Induce Misfolding and Loss of Function

“…The tetrameric form is most effective for tumor-suppression activity. 23,24 Isolated DBDs are known to bind DNA in a cooperative manner, even in the absence of TD. 25 Accordingly, DBD-DBD interactions were observed in the X-ray structure of DBD bound to DNA 4 and further elucidated in the structure of a cross-linked DBD dimer/DNA complex.…”

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

“…In the case of the R337H mutation, the stability of the domain shows a strong pH-dependence in the physiologically relevant pH range, which correlates with the protonation state of the histidine side chain (DiGiammarino et al, 2002). 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).…”

Unique substitution ofCHEK2 andTP53 mutations implicated in primary prostate tumors and cancer cell lines

“…The Phe341Cys mutation is located in the c-terminal of TP53. Although it is not in the DNA binding domain, this mutation has been shown to be deficient in the ologmerization of TP53 (Kawaguchi, et al, 2005).…”