Intrastrand crosslinks between G and T bases: Role of nitrosoperoxycarbonate in the formation of DNA lesions and their removal by nucleotide excision repair mechanisms


Conor Crean, cwc249@nyu.edu1, Byeong Hwa Yun, bhy1@nyu.edu2, Konstantin Kropachev, kk58@nyu.edu1, Marina Kolbanovskiy, mk124@nyu.edu2, Nicholas E. Geacintov, ng1@nyu.edu2, and Vladimir Shafirovich, vs5@nyu.edu1. (1) Department of Chemistry, New York University, 31 Washington Place, New York, NY 10003, (2) Chemistry Department, New York University, 31 Washington Pl, New York, NY 10003
Peroxynitrite produced by inflammatory cells rapidly combines with carbon dioxide to yield unstable nitrosoperoxycarbonate. Exposure of DNA containing 5'-GCT and 5'-GT sequences to the authentic peroxynitrite or peroxynitrite generator, 3-morpholinosydnonimine (SIN-1) in buffer solutions (pH 7.4) containing bicarbonate anions/carbon dioxide, which favors the formation of nitrosoperoxycarbonate, generates intrastrand cross-links, 5'-G*CT* and 5'-G*T*. In these cross-links, guanine and thymine are linked by covalent bonds between the C8 atom of G and N3 atom of T bases. The G*CT* lesions positioned in double-stranded DNA were medium to excellent substrates of Nucleotide Excision Repair (NER) in cell-free extracts from human HeLa cells, while the G*T* cross-linked product was only weakly incised. The presence of structural distortions rather than the presence of a bulky lesion appears to be sufficient for eliciting the efficient recognition and excision of such lesions by human NER factors. Supported by NIEHS Grant 5R01 ES011589-08.

General Papers
8:00 AM-12:00 PM, Sunday, August 16, 2009 Walter E. Washington Convention Center -- 207B, Oral

Division of Chemical Toxicology

The 238th ACS National Meeting, Washington, DC, August 16-20, 2009