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Updated: Aug 8, 2026

Proofreading and DNA Repair Assay Using Single Nucleotide Extension and MALDI-TOF Mass Spectrometry Analysis
Published on: June 19, 2018
Down modulation of topoisomerase I affects DNA repair efficiency
1Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA.
Abstract:
Topoisomerase I (topo I) relaxes supercoiled DNA through a breakage/rejoining reaction which involves a transient covalent bond between topo I and the 3' end of the cleaved DNA strand. Topo I activity is now shown to be involved in DNA damage/repair pathway in vivo. Down regulating topo I levels using anti-sense RNA approach inhibits repair of UV-induced DNA lesions, negatively affects clonogenic survival following UV-irradiation, and reduces the formation of repair patches at the cytological level. Finally, topo I is actively recruited onto genomic DNA following DNA damage by UV light without inducing ubiquitin-dependent degradation of topo I. Thus, topo I activity is important, possibly required, for pre- or post-DNA damage processing in nucleotide excision repair (NER).
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