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Hot-spot mutants of p53 core domain evince characteristic local structural changes
K B Wong1, B S DeDecker, S M Freund
1Cambridge University Chemical Laboratory and Cambridge Centre for Protein Engineering, Medical Research Council Centre, Lensfield Road, Cambridge, CB2 1EW, United Kingdom.
Abstract:
Most of the oncogenic mutations in the tumor suppressor p53 map to its DNA-binding (core) domain. It is thus a potential target in cancer therapy for rescue by drugs. To begin to understand how mutation inactivates p53 and hence to provide a structural basis for drug design, we have compared structures of wild-type and mutant p53 core domains in solution by NMR spectroscopy. Structural changes introduced by five hot-spot mutations (V143A, G245S, R248Q, R249S, and R273H) were monitored by chemical-shift changes. Only localized changes are observed for G245S, R248Q, R249S, and R273H, suggesting that the overall tertiary folds of these mutant proteins are similar to that of wild type. Structural changes in R273H are found mainly in the loop-sheet-helix motif and the loop L3 of the core domain. Mutations in L3 (G245S, R248Q, and R249S) introduce structural changes in the loop L2 and L3 as well as terminal residues of strands 4, 9, and 10. It is noteworthy that R248Q, which is often regarded as a contact mutant that affects only interactions with DNA, introduces structural changes as extensive as the other loop L3 mutations (G245S and R249S). These changes suggest that R248Q is also a structural mutant that perturbs the structure of loop L2-L3 regions of the p53 core domain. In contrast to other mutants, replacement of the core residue valine 143 to alanine causes chemical-shift changes in almost all residues in the beta-sandwich and the DNA-binding surface. Long-range effects of V143A mutation may affect the specificity of DNA binding.
Insights
Most cancer-linked mutations in the p53 tumor suppressor occur in its DNA-binding core domain. This study used NMR to reveal how mutations like V143A and R248Q structurally alter p53, aiding drug design for cancer therapy.
Area of Science:
- Biochemistry
- Structural Biology
- Cancer Research
Background:
- The p53 tumor suppressor protein is frequently mutated in cancer, with most oncogenic mutations located in its DNA-binding core domain.
- Understanding the structural consequences of these mutations is crucial for developing targeted cancer therapies aimed at restoring p53 function.
Purpose of the Study:
- To investigate the structural impact of key p53 core domain mutations using NMR spectroscopy.
- To provide a structural basis for the design of drugs that could potentially rescue p53 function in cancer.
Main Methods:
- Solution Nuclear Magnetic Resonance (NMR) spectroscopy was employed to compare the structures of wild-type and mutant p53 core domains.
- Chemical shift changes were monitored to identify and quantify structural alterations induced by specific mutations.
Main Results:
- Five hot-spot mutations (V143A, G245S, R248Q, R249S, R273H) were analyzed.
- Most mutations (G245S, R248Q, R249S, R273H) caused localized structural changes, preserving the overall tertiary fold.
- The R248Q mutation, often considered a DNA contact mutant, induced significant structural perturbations in loop L2-L3 regions, similar to other loop L3 mutations.
- The V143A mutation resulted in widespread chemical shift changes across the protein, indicating long-range structural effects that may impact DNA binding specificity.
Conclusions:
- p53 mutations can have diverse structural consequences, ranging from localized changes to extensive perturbations affecting the entire core domain.
- The R248Q mutation's structural impact challenges its classification solely as a DNA contact mutant.
- The V143A mutation's long-range effects highlight its potential to broadly disrupt p53 structure and function, offering insights for structure-based drug design.