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Nucleic Acids Research







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Oxford University Press


Nucleotide excision repair (NER) is a major repair pathway that recognizes and corrects various lesions in cellular DNA. We hypothesize that damage recognition is an initial step in NER that senses conformational anomalies in the DNA caused by lesions. We prepared three DNA duplexes containing the carcinogen adduct N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-acetylaminofluorene (FAAF) at G(1), G(2) or G(3) of NarI sequence (5'-CCG(1)G(2)CG(3)CC-3'). Our (19)F-NMR/ICD results showed that FAAF at G(1) and G(3) prefer syn S- and W-conformers, whereas anti B-conformer was predominant for G(2). We found that the repair of FAAF occurs in a conformation-specific manner, i.e. the highly S/W-conformeric G(3) and -G(1) duplexes incised more efficiently than the B-type G(2) duplex (G(3)∼G(1)> G(2)). The melting and thermodynamic data indicate that the S- and W-conformers produce greater DNA distortion and thermodynamic destabilization. The N-deacetylated N-(2'-deoxyguanosin-8-yl)-7-fluoro-2-aminofluorene (FAF) adducts in the same NarI sequence are repaired 2- to 3-fold less than FAAF: however, the incision efficiency was in order of G(2)∼G(1)> G(3), a reverse trend of the FAAF case. We have envisioned the so-called N-acetyl factor as it could raise conformational barriers of FAAF versus FAF. The present results provide valuable conformational insight into the sequence-dependent UvrABC incisions of the bulky aminofluorene DNA adducts.


Author Posting. © Jain et al., 2012. This article is posted here by permission of the authors for personal use, not for redistribution. The article was published in Nucleic Acids Research, Volume 40, Issue 9, January 2012,

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Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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