DNA interstrand crosslinks arising from DAN strand breaks at true abasic sites in duplex DNA

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Abasic sites (apurinic/apyrimidinic sites, Ap sites) are one of the most common forms of lesions found in genomic DNA. For the past decade, Gates group has endeavored to identify DNA interstrand crosslinks arising from Ap sites, that are sources of endogenous interstrand crosslinks which relate to aging, cancer and neurodegenerative diseases. This thesis describes my work in this area, starting from studying the DNA strand cleavage at abasic sites via [beta]-elimination reaction, that can generate a family of structurally diverse sugar remnants at the 3' terminus of the nicked strand under physiological conditions. Using an in vitro system, I have characterized a series of DNA interstrand crosslinks arising from these single strand breaks, which structures are dependent on changing DNA sequence contexts and varied assay conditions that are all bio-relevant. These structures are novel and haven't been reported to the best of our knowledge. In the meantime, this work has highlighted amine catalysis in Michael addition, and brought to attention the role of GSH in the formation of complex DNA lesions.