DNA Repair Synthesis and Ligation Affect the Processing of Excised Oligonucleotides Generated by Human Nucleotide Excision Repair [DNA and Chromosomes]

August 8th, 2014 by Kemp, M. G., Gaddameedhi, S., Choi, J.-H., Hu, J., Sancar, A.

Ultraviolet (UV) photoproducts are removed from genomic DNA by dual incisions in humans in the form of 24- to 32-nucleotide-long oligomers (canonical 30-mers) by the nucleotide excision repair system. How the small, excised, damage-containing DNA oligonucleotides (sedDNAs) are processed in cells following the dual incision event is not known. Here we demonstrate that sedDNAs are localized to the nucleus in two biochemically distinct forms, which include chromatin-associated, TFIIH-bound complexes and more readily-solubilized, RPA-bound complexes. Because the nuclear mobility and repair functions of TFIIH and RPA are influenced by post-incision gap filling events, we examined how DNA repair synthesis and DNA ligation affect sedDNA processing. We found that though these gap filling activities are not essential for the dual incision/sedDNA generation event per se, the inhibition of DNA repair synthesis and ligation is associated with a decrease in UV photoproduct removal rate and an accumulation of RPA-sedDNA complexes in the cell. These findings indicate that sedDNA processing and association with repair proteins following the dual incisions may be tightly coordinated with gap filling during nucleotide excision repair in vivo.
  • Posted in Journal of Biological Chemistry, Publications
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