A Model for Topoisomerase I-Mediated Insertions And Deletions with Duplex DNA Substrates Containing Branches, Nicks, and Gaps

Kristine A. Henningfeld, Sidney M. Hecht

Research output: Contribution to journalArticle

46 Scopus citations


The ability of DNA topoisomerase I to promote insertions and deletions in vitro has been studied at nucleotide resolution for structurally diverse DNA substrates that uncouple the cleavage and ligation reactions of the enzyme. Topoisomerase I-mediated ligations afforded DNA duplexes having deletions and insertions with “branched” substrates and deletions up to 18 nucleotides in length with substrates containing nicks or gaps. In addition, a number of the acceptor substrates altered the preferred site of DNA cleavage, thereby increasing the diversity of accessible ligation products. Also demonstrated by the production of two “recombinant” duplexes from a single set of reactants was the potential for amplification of such alterations. These findings illustrate plausible mechanisms by which topoisomerase I-mediated illegitimate recombination may obtain at a molecular level.

Original languageEnglish (US)
Pages (from-to)6120-6129
Number of pages10
Issue number18
StatePublished - May 1 1995


ASJC Scopus subject areas

  • Biochemistry

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