Chemical and structural characterization of interstrand cross-links formed between abasic sites and adenine residues in duplex DNA.
Bottom Line: A synthetic standard was prepared for the putative nucleoside cross-link remnant 6 in which the anomeric carbon of the 2-deoxyribose residue was connected to the exocyclic N(6)-amino group of dA.These findings establish the chemical structure of the dA-Ap cross-link released from duplex DNA and may provide methods for the detection of this lesion in cellular DNA.Both the nucleoside cross-link remnant 6: and the cross-link in duplex DNA were quite stable at pH 7 and 37°C, suggesting that the dA-Ap cross-link could be a persistent lesion with the potential to block the action of various DNA processing enzymes.
Affiliation: Department of Chemistry, University of Missouri, 125 Chemistry Building, Columbia, MO 65211, USA.Show MeSH
Mentions: We recently reported a new type of interstrand DNA–DNA cross-link formed by reaction of a DNA abasic site (Ap site) with a 2′-deoxyadenosine (dA) residue on the opposing strand of the double helix (20). These interstrand cross-links form in high yields (15–70%) at 5′ApT/5′AA sequences in duplex DNA. In our earlier work, we proposed that formation of dA-Ap cross-links involved reaction of the exocyclic N6-amino group of 2′-deoxyadenosine with the aldehyde residue of the Ap site to generate a cyclic aminoglycoside (4, Scheme 1) (21–24). Digestion of double-stranded DNA containing the dA-Ap cross-link with a mixture of nuclease P1, alkaline phosphatase and phosphodiesterases I and II released a nucleoside cross-link ‘remnant’; however, the precise chemical connectivity of the dA-Ap cross-link was not rigorously established.
Affiliation: Department of Chemistry, University of Missouri, 125 Chemistry Building, Columbia, MO 65211, USA.