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Differential sensitivity of transcription factors to mustard-damaged DNA

X M Chen1, P J Gray, C Cullinane

  • 1Department of Biochemistry, La Trobe University, Bundoora, Victoria, Australia.

Chemico-Biological Interactions
|May 5, 1999
PubMed

Insights

Nitrogen mustard (HN2) and other alkylating agents damage DNA, inhibiting transcription factor binding. Differences in DNA lesion stereochemistry explain varying sensitivities of factors like Sp1, AP2, and TBP to this damage.

Area of Science:

  • Molecular Biology
  • Toxicology
  • Biochemistry

Background:

  • Nitrogen mustards are alkylating agents that can damage DNA.
  • Transcription factors bind to specific DNA sequences to regulate gene expression.
  • DNA damage can interfere with transcription factor binding and gene regulation.

Purpose of the Study:

  • To investigate the effects of nitrogen mustard (HN2) and related compounds on the binding of transcription factors to DNA.
  • To determine if DNA damage caused by different mustards differentially affects transcription factor binding.
  • To explore the role of DNA lesion stereochemistry in the sensitivity of transcription factors to alkylating agents.

Main Methods:

  • Inhibition of Sp1 and AP2 binding to consensus sequences by HN2.
  • Assessment of TATA binding protein (TBP) binding to the TATA element.
  • Quantification of DNA alkylation levels by HN2, sulfur mustard, and 2-chloroethyl ethyl sulfide (CEES).
  • Correlation of DNA alkylation with inhibition of TBP-DNA complex formation.

Main Results:

  • HN2 inhibited Sp1 and AP2 complex formation at specific concentrations.
  • HN2, sulfur mustard, and CEES showed varying levels of DNA alkylation on TBP oligonucleotides.
  • Despite similar alkylation levels for HN2 and sulfur mustard, both significantly inhibited TBP-DNA complex formation compared to CEES.
  • Differential sensitivity of transcription factors to mustard-induced DNA damage was observed.

Conclusions:

  • The binding of transcription factors Sp1, AP2, and TBP is inhibited by nitrogen mustard (HN2).
  • The extent of inhibition is not always proportional to the level of DNA alkylation, suggesting other factors are involved.
  • Stereochemical differences in DNA lesions induced by various mustards play a dominant role in the differential sensitivity of transcription factors.

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