The ultimate carcinogen of 4-nitroquinoline 1-oxide does not react with Z-DNA and hyperreacts with B-Z junctions

C. Rodolfo, A. Lanza, S. Tornaletti, G. Fronza, A. M. Pedrini

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Abstract

DNA secondary and tertiary structures are known to affect the reaction between the double helix and several damaging agents. We have previously shown that the tertiary structure of DNA influences the reactivity of 4-acetoxyaminoquinoline 1-oxide (Ac-4-HAQO), the ultimate carcinogen of 4-nitroquinoline 1-oxide (4-NQO), being more reactive with naturally supercoiled DNA than with relaxed DNA. The relative proportion of the three main stable adducts and of an unstable adduct, that resulted in strand scission and/or AP sites, was also affected by the degree of supercoiling of plasmid DNA. In this study we examined the influence of Z-DNA structure on the reactivity of Ac-4-HAQO by mapping the distribution of the two main Ac-4-HAQO adducts, C8-guanine and N2-guanine, along a (dC-dG) 16 sequence inserted at the BamHI site of pBR322 plasmid DNA. This insert adopted the left-handed Z and right-handed B structure depending on the superhelical density of the plasmid. Sites of C8-guanine adduct formation were determined by hot piperidine cleavage of Ac-4-HAQO modified DNA, while N2-guanine adducts were mapped by the arrest of the 3'-5' exonuclease activity of T4 DNA polymerase. The results showed that Ac-4-HAQO did not react with guanine residues when the (dC-dG) 16 sequence was in Z conformation, while hyperreactivity at the B-Z junction was observed. These results indicate that Ac-4-HAQO can probe the polymorphism of DNA at the nucleotide level.

Original languageEnglish
Pages (from-to)314-320
Number of pages7
JournalNucleic Acids Research
Volume22
Issue number3
Publication statusPublished - Feb 11 1994

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Z-Form DNA
4-Nitroquinoline-1-oxide
Carcinogens
Guanine
DNA
Plasmids
Superhelical DNA
Exonucleases
DNA Probes
DNA-Directed DNA Polymerase
Nucleotides

ASJC Scopus subject areas

  • Genetics

Cite this

The ultimate carcinogen of 4-nitroquinoline 1-oxide does not react with Z-DNA and hyperreacts with B-Z junctions. / Rodolfo, C.; Lanza, A.; Tornaletti, S.; Fronza, G.; Pedrini, A. M.

In: Nucleic Acids Research, Vol. 22, No. 3, 11.02.1994, p. 314-320.

Research output: Contribution to journalArticle

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