Plasmid linking number change induced by topoisomerase I-mediated DNA damage

Pu Duann, Mei Sun, Chin Tai Lin, Hui Zhang, Leroy F. Liu

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


The state of cellular chromatin in response to DNA damage has been examined by monitoring the change in the linking number of circular episomes. COS cells transfected with an SV40-based vector were treated with camptothecin (CPT), a eukaryotic DNA topoisomerase I (TOP1) poison which induces TOP1-mediated DNA damage. Within minutes, a large increase in the linking number (over 10 linking number) of a small fraction (5-15%) of the episomal DNA was observed. A similar CPT-induced increase in plasmid DNA linking number was observed in Saccharomyces cerevisae expressing human DNA TOP1. In this case, the majority of the plasmid DNA can undergo rapid relaxation. The large increase in the plasmid linking number suggests major chromatin structural reorganization in response to TOP I-mediated DNA damage.

Original languageEnglish
Pages (from-to)2905-2911
Number of pages7
JournalNucleic Acids Research
Issue number14
Publication statusPublished - Jul 15 1999
Externally publishedYes

ASJC Scopus subject areas

  • Genetics


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