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Yeast As a Chassis for Developing Functional Assays to Study Human P53
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The potential of the cruciform structure formation as an important factor influencing p53 sequence-specific binding

Eva B Jagelská1, Hana Pivonková, Miroslav Fojta

  • 1Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic.

Biochemical and Biophysical Research Communications
|December 23, 2009
PubMed

Insights

The tumor suppressor p53 protein preferentially binds to DNA cruciform structures formed under superhelical stress. This DNA topology influences p53 binding to critical gene promoter regions.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • p53 is a crucial tumor suppressor protein that regulates genes involved in cell cycle arrest, apoptosis, and senescence in response to DNA damage.
  • DNA topology, particularly supercoiling, significantly impacts p53's ability to bind DNA and regulate gene transcription.
  • Understanding how DNA structure affects protein binding is vital for comprehending gene regulation and cancer development.

Purpose of the Study:

  • To investigate the formation of cruciform structures in p53-responsive sequences under negative superhelical stress.
  • To analyze how these DNA topology changes affect p53-DNA binding affinity and specificity.
  • To determine if cruciform structures enhance p53 binding to promoter regions of key genes like p21, RGC, mdm2, and GADD45.

Main Methods:

  • Investigated cruciform structure formation in p53-responsive sequences from p21, RGC, mdm2, and GADD45 promoters under negative superhelical stress.
  • Utilized gel retardation analyses, ELISA, and magnetic immunoprecipitation assays to assess p53-DNA binding.
  • Analyzed the impact of DNA topology and non-B DNA structures on p53 binding.

Main Results:

  • Demonstrated that p53 protein binds preferentially to negatively supercoiled plasmid DNAs containing p53-responsive sequences structured as cruciforms.
  • Observed that cruciform structure formation within supercoiled DNA enhances p53 binding.
  • Indicated that the potential for binding sites to adopt non-B DNA structures also contributes to favorable p53-DNA complex formation.

Conclusions:

  • p53 exhibits preferential binding to cruciform DNA structures, which are formed under negative superhelical stress.
  • DNA topology, specifically the formation of cruciforms and non-B DNA structures, plays a significant role in modulating p53-DNA interactions.
  • These findings provide insights into the mechanisms of p53-mediated gene regulation and its implications in cancer biology.

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