Topoisomerase I interacts with transcribed regions in Drosophila cells

David S. Gilmour, Gert Pflugfelder, James C. Wang, John T. Lis

Research output: Contribution to journalArticlepeer-review

157 Scopus citations


The in vivo distribution of topoisomerase I on specific DNA sequences is determined at high resolution in Drosophila cells using a photo-crosslinking method. Topoisomerase I-DNA adducts are generated by irradiation of intact cells with UV light and then purified by immunoprecipitation with antibody to topoisomerase I. Analyses of the DNA sequences crosslinked to topoisomerase I by blot-hybridization with appropriate DNA probes indicate that topoisomerase I is concentrated on transcribed regions and not on nontranscribed flanking sequences. Like RNA polymerase II, topoisomerase I is recruited to heat-shock genes during the heat-shock response. However, topoisomerase I and RNA polymerase II can interact independently with the transcribed region because different ratios of topoisomerase I and RNA polymerase II are crosslinked to the highly transcribed hsp70 gene and the moderately transcribed copia genes. We hypothesize that topoisomerase I allows topological changes in DNA that are required for transcription.

Original languageEnglish (US)
Pages (from-to)401-407
Number of pages7
Issue number3
StatePublished - Feb 14 1986

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)


Dive into the research topics of 'Topoisomerase I interacts with transcribed regions in Drosophila cells'. Together they form a unique fingerprint.

Cite this