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Yeast As a Chassis for Developing Functional Assays to Study Human P53
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Yeast As a Chassis for Developing Functional Assays to Study Human P53

Published on: August 4, 2019

N-hydroxy-4-aminobiphenyl-DNA binding in human p53 gene: sequence preference and the effect of C5 cytosine

Zhaohui Feng1, Wenwei Hu, William N Rom

  • 1Department of Environmental Medicine, New York University Medical Center, Tuxedo, New York 10987, USA.

Biochemistry
|May 16, 2002
PubMed

Insights

4-Aminobiphenyl (4-ABP), a bladder cancer agent, binds to DNA, forming adducts. This study maps 4-ABP binding sites in the p53 gene, revealing methylation

Area of Science:

  • Molecular biology
  • Carcinogenesis research
  • Genetics

Background:

  • 4-Aminobiphenyl (4-ABP) is a known human bladder cancer agent.
  • Metabolic activation of 4-ABP leads to DNA adducts, initiating carcinogenesis.
  • The p53 tumor suppressor gene frequently harbors mutations in bladder cancer, with a unique mutational spectrum.

Purpose of the Study:

  • To determine the DNA binding spectrum of 4-ABP in the human p53 gene.
  • To investigate the influence of cytosine methylation on 4-ABP-DNA binding.
  • To elucidate the contribution of 4-ABP binding and methylation to the p53 mutational spectrum in bladder cancer.

Main Methods:

  • Utilized UvrABC nuclease from Escherichia coli for specific and quantitative incision of DNA fragments modified with N-hydroxy-4-aminobiphenyl (N-OH-4-ABP).
  • Mapped N-OH-4-ABP binding sites within exons 5, 7, and 8 of the human p53 gene.
  • Assessed the impact of C5 cytosine methylation on N-OH-4-ABP binding at specific DNA sites.

Main Results:

  • Identified codon 285, a non-CpG hotspot in bladder cancer, as a preferential N-OH-4-ABP binding site.
  • Demonstrated that C5 cytosine methylation significantly enhances N-OH-4-ABP binding at CpG sites.
  • Showed that mutational hotspots at CpG sites (codons 175 and 248) become preferential binding sites for N-OH-4-ABP only after methylation.

Conclusions:

  • The DNA binding specificity of 4-ABP contributes to the p53 mutational spectrum in bladder cancer.
  • Cytosine methylation plays a crucial role in directing 4-ABP binding to specific hotspots within the p53 gene.
  • Combined effects of 4-ABP binding and cytosine methylation explain unique p53 mutation patterns observed in human bladder cancer.

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