A model for topoisomerase I-mediated insertions and deletions with duplex DNA substrates containing branches, nicks, and gaps.
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.
Henningfeld
K A
KA
Department of Chemistry, University of Virginia, Charlottesville 22901, USA.
Hecht
S M
SM
D001483:Base Sequence; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004251:DNA Transposable Elements; D017353:Gene Deletion; D008969:Molecular Sequence Data; D011995:Recombination, Genetic; D017421:Sequence Analysis; D013379:Substrate Specificity
D004251:DNA Transposable Elements; D004247:DNA; D004264:DNA Topoisomerases, Type I