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Mutations induced by aromatic amine DNA adducts in pBR322
W B Melchior1, M M Marques, F A Beland
1Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR 72079.
Carcinogenesis
|May 1, 1994
Summary
Aromatic amines like 2-acetylaminofluorene (AAF) and 1-aminopyrene (AP) cause mutations in DNA. Planar aromatic amines are more efficient at inducing frameshift mutations, increasing their overall mutagenic potential.
Area of Science:
- Molecular biology
- Genetics
- Toxicology
Background:
- Chemical modification of DNA can lead to mutations.
- Understanding the relationship between adduct structure and mutagenicity is crucial for risk assessment.
Purpose of the Study:
- To investigate how the structure of aromatic amine adducts affects mutation induction.
- To compare the mutagenic efficiencies of various aromatic amine adducts in a plasmid system.
Main Methods:
- Modification of the tetracycline resistance gene in pBR322 plasmid with aromatic amines.
- Characterization of adducts using 32P-postlabeling and chromatography.
- Introduction of modified plasmids into SOS-induced Escherichia coli to analyze mutations.
- Comparison of mutation frequencies and types (base substitutions, frameshifts) across different adducts.
Main Results:
- Aromatic amine adducts primarily formed at the C8 position of deoxyguanosine.
- Mutation types varied: AAF induced deletions/additions, AF induced -G deletions and G to T transversions, ABP/N'-acetylbenzidine induced G to T/G to C transversions, and AP induced both frameshifts and transversions.
- Mutagenic efficiency decreased in the order AP > AF > AAF ≈ ABP ≈ N'-acetylbenzidine.
- Planar aromatic amine derivatives predominantly induced frameshift mutations, enhancing mutagenic efficiency.
Conclusions:
- Structurally related aromatic amines induce both base substitution and frameshift mutations in pBR322.
- Frameshift mutations are predominantly induced by planar aromatic amine derivatives.
- The induction of frameshift mutations significantly increases the overall mutagenic efficiency of DNA adducts.