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Specific interaction of mutant p53 with regions of matrix attachment region DNA elements (MARs) with a high potential
K Will1, G Warnecke, L Wiesmüller
1Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie an der Universität Hamburg, Martinistrasse 52, D-20251 Hamburg, Germany.
Abstract:
Mutant, but not wild-type p53 binds with high affinity to a variety of MAR-DNA elements (MARs), suggesting that MAR-binding of mutant p53 relates to the dominant-oncogenic activities proposed for mutant p53. MARs recognized by mutant p53 share AT richness and contain variations of an AATATATTT "DNA-unwinding motif," which enhances the structural dynamics of chromatin and promotes regional DNA base-unpairing. Mutant p53 specifically interacted with MAR-derived oligonucleotides carrying such unwinding motifs, catalyzing DNA strand separation when this motif was located within a structurally labile sequence environment. Addition of GC-clamps to the respective MAR-oligonucleotides or introducing mutations into the unwinding motif strongly reduced DNA strand separation, but supported the formation of tight complexes between mutant p53 and such oligonucleotides. We conclude that the specific interaction of mutant p53 with regions of MAR-DNA with a high potential for base-unpairing provides the basis for the high-affinity binding of mutant p53 to MAR-DNA.
Insights
Mutant p53 binds to MAR-DNA by recognizing a specific DNA-unwinding motif. This interaction, crucial for dominant-oncogenic activities, involves mutant p53 catalyzing DNA strand separation within MAR regions.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Mutant p53 exhibits dominant-oncogenic activities not seen in wild-type p53.
- Mutant p53's high-affinity binding to MAR-DNA elements (MARs) suggests a link to its oncogenic functions.
Purpose of the Study:
- To investigate the molecular basis of mutant p53's high-affinity binding to MAR-DNA.
- To identify specific DNA sequence features within MARs that are recognized by mutant p53.
Main Methods:
- Analysis of MAR-DNA sequences recognized by mutant p53.
- Electrophoretic mobility shift assays to study protein-DNA interactions.
- Oligonucleotide-based assays to assess DNA strand separation and binding affinity.
Main Results:
- Mutant p53 preferentially binds to AT-rich MARs containing a conserved "DNA-unwinding motif" (AATATATTT).
- Mutant p53 catalyzes DNA strand separation within MARs containing this motif, particularly in labile sequence environments.
- Modifications to the motif or addition of GC-clamps reduced strand separation but still allowed tight complex formation.
Conclusions:
- The specific interaction of mutant p53 with MAR-DNA regions prone to base-unpairing underlies its high-affinity MAR-binding.
- This MAR-binding mechanism is proposed to be a key factor in the dominant-oncogenic activities of mutant p53.