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Publication Detail

Title: On the formation and properties of interstrand DNA-DNA cross-links forged by reaction of an abasic site with the opposing guanine residue of 5'-CAp sequences in duplex DNA.

Authors: Johnson, Kevin M; Price, Nathan E; Wang, Jin; Fekry, Mostafa I; Dutta, Sanjay; Seiner, Derrick R; Wang, Yinsheng; Gates, Kent S

Published In J Am Chem Soc, (2013 Jan 23)

Abstract: We recently reported that the aldehyde residue of an abasic (Ap) site in duplex DNA can generate an interstrand cross-link via reaction with a guanine residue on the opposing strand. This finding is intriguing because the highly deleterious nature of interstrand cross-links suggests that even small amounts of Ap-derived cross-links could make a significant contribution to the biological consequences stemming from the generation of Ap sites in cellular DNA. Incubation of 21-bp duplexes containing a central 5'-CAp sequence under conditions of reductive amination (NaCNBH(3), pH 5.2) generated much higher yields of cross-linked DNA than reported previously. At pH 7, in the absence of reducing agents, these Ap-containing duplexes also produced cross-linked duplexes that were readily detected on denaturing polyacrylamide gels. Cross-link formation was not highly sensitive to reaction conditions, and the cross-link, once formed, was stable to a variety of workup conditions. Results of multiple experiments including MALDI-TOF mass spectrometry, gel mobility, methoxyamine capping of the Ap aldehyde, inosine-for-guanine replacement, hydroxyl radical footprinting, and LC-MS/MS were consistent with a cross-linking mechanism involving reversible reaction of the Ap aldehyde residue with the N(2)-amino group of the opposing guanine residue in 5'-CAp sequences to generate hemiaminal, imine, or cyclic hemiaminal cross-links (7-10) that were irreversibly converted under conditions of reductive amination (NaCNBH(3)/pH 5.2) to a stable amine linkage. Further support for the importance of the exocyclic N(2)-amino group in this reaction was provided by an experiment showing that installation of a 2-aminopurine-thymine base pair at the cross-linking site produced high yields (15-30%) of a cross-linked duplex at neutral pH, in the absence of NaCNBH(3).

PubMed ID: 23215239 Exiting the NIEHS site

MeSH Terms: 5' Untranslated Regions*; Aldehydes/chemistry; Chromatography, Liquid; Cross-Linking Reagents/chemistry*; DNA/chemistry*; Guanine/chemistry*; Models, Molecular; Molecular Structure; Tandem Mass Spectrometry

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