DNA adduct-induced stabilization of slipped frameshift intermediates within repetitive sequences: implications for mutagenesis.
- 1 July 1993
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 90 (13), 5989-5993
- https://doi.org/10.1073/pnas.90.13.5989
Abstract
Chemical carcinogens such as the aromatic amide 2-acetylaminofluorene (AAF) are known to induce -1 frameshift mutation hotspots at repetitive sequences. This mutagenesis pathway was suggested to involve slipped intermediates formed during replication. To investigate the stability and structure of such intermediates we have constructed DNA duplexes containing single AAF adducts within a run of three guanine residues. The strand complementary to that bearing the AAF adducts contained either the wild-type sequence (homoduplexes) or lacked one cytosine directly opposite the run of guanines containing the AAF adduct and thus modeled the putative slipped mutagenic intermediates (SMIs). The melting temperature of AAF-modified homoduplexes or the unmodified SMI was reduced by approximately 10 degrees C relative to the unmodified homoduplex. Surprisingly, AAF adducts stabilized the SMIs as evidenced by an increase in melting temperature to a level approaching that of the unmodified homoduplex. The chemical probes hydroxylamine and bromoacetaldehyde were strongly reactive toward cytosine residues opposite the adduct in AAF-modified homoduplexes, indicating adduct-induced denaturation. In contrast, no cytosine reactivities were observed in the AAF-modified SMIs, suggesting that the two cytosines were paired with unmodified guanines. Use of diethyl pyrocarbonate to probe the guanine residues showed that all three guanines in the unmodified SMI adopted a transient single-stranded state which was delocalized along the repetitive sequence. However, when an AAF adduct was present, reduced diethyl pyrocarbonate reactivity at guanines adjacent to the adduct in AAF-modified SMIs reflected localization of the bulge to the adducted base. Our results suggest that AAF exerts a local denaturing and destabilizing effect within the homoduplex which is alleviated by the formation of a bulge. The stabilization by the AAF adduct of the SMIs may contribute to the dramatic increase in -1 frameshift mutation frequency induced by AAF adducts in repetitive sequences.Keywords
This publication has 20 references indexed in Scilit:
- NMR and computational characterization of the N-(deoxyguanosin-8-yl)aminofluorene adduct [(AF)G] opposite adenosine in DNA: (AF)G[syn].cntdot.A[anti] pair formation and its pH dependenceBiochemistry, 1989
- Reaction conditions affect the specificity of bromoacetaidehyde as a probe for DNA cruciforms and B—Z junctionsNucleic Acids Research, 1987
- Mechanisms of frameshift mutagenesis by aflatoxin B1-2,3-dichlorideJournal of Molecular Biology, 1987
- Proton nuclear magnetic resonance studies on bulge-containing DNA oligonucleotides from a mutational hot-spot sequenceBiochemistry, 1987
- Diethyl pyrocarbonate: a chemical probe for secondary structure in negatively supercoiled DNA.Proceedings of the National Academy of Sciences, 1985
- Chemical probes of DNA conformation: detection of Z-DNA at nucleotide resolutionCell, 1985
- DNA binding and mutation spectra of the carcinogen N-2-aminofluorene in Escherichia coliJournal of Molecular Biology, 1985
- Carcinogen-induced mutation spectrum in wild-type, uvrA and umuC strains of Escherichia coliJournal of Molecular Biology, 1984
- [57] Sequencing end-labeled DNA with base-specific chemical cleavagesMethods in Enzymology, 1980
- Physical studies on deoxyribonucleic acid after covalent binding of a carcinogenBiochemistry, 1972