p53 Basic C Terminus Regulates p53 Functions through DNA Binding Modulation of Subset of Target Genes

Abstract

Background:The role of the conserved basic C terminus of p53 remains elusive. Results: The C terminus of p53 controls target gene selectivity and is needed for cellular responses. Conclusion: The C terminus of p53 is required for full p53 function. Significance: This provides insight into the basis for target gene selectivity by p53 as well as determination of cell fate outcomes.

The p53 C Terminus Controls Site-Specific DNA Binding and Promotes Structural Changes within the Central DNA Binding Domain

“…In that study the relative ability of WT p53 and p53 in which the last 24 amino acids were deleted (creating Δ24 p53) were compared. It is highly likely that Δ30 p53 and Δ24 p53 are phenotypically equivalent since both lack the full set of C-terminal lysines and previous studies examining either Δ30 p53 (McKinney et al, 2004; Kim et al, 2012) or Δ24 p53 (Hamard et al, 2012) provided virtually identical results i.e. that lack of either 24 or 30 C-terminal amino acids significantly impairs p53 binding and transactivation ability.…”

“…To ask if the RE mutation may rescue binding by CTD-deleted p53 in vivo, we took advantage of constructs generated by Hamard et al (Hamard et al, 2012) where the relatively weaker Tp53 gene promoter drives the expression of p53 proteins. In that study the relative ability of WT p53 and p53 in which the last 24 amino acids were deleted (creating Δ24 p53) were compared.…”

“…The pDNAs expressing WT and Δ24 p53 under control of the endogenous p53 promoter were described (Hamard et al, 2012). The E180R/R181E ( RE ) double mutations were introduced into the corresponding cDNAs with a QuikChange II site-directed mutagenesis kit.…”

“…These features likely depend on low affinity electrostatic interactions between the multiple C-terminal lysines and the DNA phosphate backbone (Friedler et al, 2005). Two studies have presented evidence that implicates the CTD in site-specific binding of p53 although in depth mechanistic information is still lacking (Hamard et al, 2012; Kim et al, 2012). …”

The Tail That Wags the Dog: How the Disordered C-Terminal Domain Controls the Transcriptional Activities of the p53 Tumor-Suppressor Protein

“…Finally, using cell-based assays where full-length or CTD-deleted p53 proteins were expressed at near physiological levels, Hamard et al . reconfirmed the requirement of the CTD for p53 binding to and transactivation of the promoters of several bona fide p53 targets, such as p21 , Puma , and Mdm2 [48]. Importantly, they also showed that extremely high levels of CTD-deleted p53 transiently overexpressed under the strong human cytomegalovirus promoter may mask the detrimental effect of the CTD absence, emphasizing the need for more-physiological experimental conditions.…”