Identification of a DNA supercoiling activity in Saccharomyces cerevisiae

Hyeon Sook Koo, Kawai Lau, Hai Young Wu, Leroy-Fong Liu

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


A relaxed plasmid DNA is shown to become positively supercoiled in cell extracts from top1 strains of Saccharomyces cerevisiae. This positive supercoiling activity is dependent on the presence of bacterial DNA topoisomerase I and ATP (or dATP), and the positive supercoils generated in this reaction are not constrained by protein(s). Non-hydrolyzable ATP analogs cannot substitute for ATP in this supercoiling reaction, and the supercoiling activity is not due to RNA synthesis. The presence of an ARS sequence in the DNA does not alter the activity. Furthermore, this activity is equally active against UV irradiated or intact DNA. Extracts prepared from rad50 and rad52 mutant cells exhibited the same activity. Partial purification of this activity suggests that a protein factor with a native molecular weight of approximately 150 KDa is primarily responsible for the activity. The possibility that this supercoiling activity may be due to tracking of a protein along the intact duplex DNA is discussed.

Original languageEnglish
Pages (from-to)5067-5072
Number of pages6
JournalNucleic Acids Research
Issue number19
Publication statusPublished - Oct 11 1992
Externally publishedYes

ASJC Scopus subject areas

  • Genetics
  • Statistics, Probability and Uncertainty
  • Applied Mathematics
  • Health, Toxicology and Mutagenesis
  • Toxicology
  • Genetics(clinical)


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