The Influence of Self-Repair on the Distribution of Cyclopyrimidine Dimers in DNA

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The link between DNA damage caused by ultraviolet (UV) light and genetic mutation is well established, but the determinants of hotspots of photochemical reactivity where UV damage is most likely to occur remain elusive. This project will address the origins and locations of these hotspots with a focus on how damage accumulates as a result of competition between its formation and spontaneous self-repair. The outcomes should inform future strategies for better protection of genomes from UV damage. The project will offer cross-disciplinary training opportunities for graduate and undergraduate students as they study molecular processes affecting the viability of life under UV exposure, and prepare them for diverse careers that serve the public interest.Curvature of duplex DNA was previously reported as a crucial variable in the formation and distribution of photochemical damage. Whether this property controls initial formation of the products or their steady state levels, established by competing formation and self-repair processes, has yet to be determined. Similarly, the sequences of DNA where damage is most sensitive to curvature have not been determined. Both of these unknowns will be addressed by probing a library of DNA sequences that can be switched between linear and bent conformations. The reversibility of UV damage will be assessed by the rate at which product profiles created by these two states of DNA interconvert, and sequences within the library most influenced by bending will be characterized by deep sequencing. The sequences most susceptible to UV damage will be reconstructed by statistical analysis and used to validate the correlation between sequence, conformation and hyperreactivity in vitro.This award was co-funded by the Division of Molecular and Cellular Biosciences and the Division of Chemistry.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.