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Mutant p53 proteins bind hsp 72/73 cellular heat shock-related proteins in SV40-transformed monkey cells
H W Stürzbecher1, P Chumakov, W J Welch
1Marie Curie Research Institute, The Chart, Oxted, Surrey, UK.
Abstract:
We have examined the expression of a series of mouse mutant, as well as wild-type, p53 proteins in SV40-transformed monkey COS cells. Wild-type mouse p53 binds predominantly to SV40 large T antigen in these cells. However, several of the mutants co-precipitate exclusively with proteins of approximately 68 Kd relative molecular mass. We show by immunological and proteolytic mapping techniques that these proteins are identical to the hsp 72/73 heat shock proteins. p53 mutants in complex with hsp 72/73 have an altered subcellular location compared to the wild-type protein and the hsp 72/73 binding p53 mutants fail to exhibit an epitope recognized by monoclonal antibody PAb 246. The existence of at least two antigenically distinct subclasses of hsp 72/73 complexed to mutant p53 is shown.
Insights
Mutant mouse p53 proteins bind to heat shock proteins (hsp 72/73) in monkey cells, altering their location and antibody recognition. Wild-type p53 binds differently, highlighting distinct protein interactions and functions.
Area of Science:
- Molecular biology
- Cell biology
- Protein interactions
Background:
- The p53 protein is a crucial tumor suppressor.
- Mutations in p53 are common in human cancers.
- Understanding p53 protein interactions is vital for cancer research.
Purpose of the Study:
- To investigate the interactions of wild-type and mutant mouse p53 proteins in SV40-transformed monkey COS cells.
- To characterize the proteins that co-precipitate with mutant p53.
- To determine the functional and antigenic differences between wild-type and mutant p53 complexes.
Main Methods:
- Expression of wild-type and mutant mouse p53 in COS cells.
- Co-precipitation assays to identify binding partners.
- Immunological and proteolytic mapping to characterize proteins.
- Subcellular localization studies.
- Monoclonal antibody epitope mapping.
Main Results:
- Wild-type mouse p53 predominantly binds to SV40 large T antigen.
- Several mouse p53 mutants exclusively co-precipitate with heat shock proteins (hsp 72/73).
- p53 mutants complexed with hsp 72/73 exhibit altered subcellular localization compared to wild-type p53.
- hsp 72/73 binding p53 mutants lack recognition by monoclonal antibody PAb 246.
- At least two antigenically distinct subclasses of hsp 72/73 complexed with mutant p53 were identified.
Conclusions:
- Mouse p53 mutants exhibit distinct protein-protein interaction profiles compared to wild-type p53.
- Interactions with heat shock proteins (hsp 72/73) are specific to certain p53 mutants and affect their cellular localization and antigenic properties.
- These findings suggest that p53 mutations can lead to altered protein complexes with functional consequences.