Elucidating the Chemistry and Targets of Cross-linking by Endogenous DNA Damage

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DESCRIPTION (provided by applicant): Reactive oxygen species (ROS) produced from cellular metabolism and exposure to environmental agents pose a significant threat to genomic stability. Direct DNA oxidation by ROS or modification by products of lipid peroxidation result in the formation of mutagenic DNA adducts that are implicated in carcinogenesis. A variety of DNA adducts are produced following DNA oxidation including 3-(2!-deoxy- "-D-erythro-pentofuranosyl)- pyrimido[1,2-a]purin-10(3H)-one (M1dG) and N6-oxopropenyl-dA (OPdA). M1dG and OPdA possess the unique characteristic of electrophilic reactivity, which enables them to react with a variety of nucleophiles. OPdA is the more reactive adduct and forms covalent cross-links with N#-acetyl lysine. This raises the possibility that OPdA forms cross-links with DNA-binding proteins. The chemistry of this DNA-protein cross-link formation is not well understood and presents an exciting and novel area for discovery. I propose to use EcoRI as a model DNA-binding protein to elucidate the chemistry of cross-link formation and to optimize the methods for detection and identification of adducted proteins. I will then identify the proteins cross-linked to OPdA adducts in nuclear extracts of mammalian cells. The formation of covalent cross-links between DNA damage and protein has not been extensively investigated despite the detrimental cellular effects these conjugates can induce. The studies outlined in this proposal will increase our understanding of how cross-links are formed as well as what proteins are able to form cross-links with OPdA. This investigation represents the first study to elucidate the interaction of OPdA with DNA-binding proteins.