Sgs1: a eukaryotic homolog of E. coli RecQ that interacts with topoisomerase II in vivo and is required for faithful chromosome segregation

Cell. 1995 Apr 21;81(2):253-60. doi: 10.1016/0092-8674(95)90335-6.


Topoisomerase II (topo II) catalyzes the decatenation of interlinked DNA molecules and is essential for chromosome segregation. To test the hypothesis that the noncatalytic C-terminal domain of topo II is necessary for mediating interactions with other proteins required for chromosome segregation, we used a two-hybrid cloning strategy to identify proteins that interact with S. cerevisiae topo II in vivo. One protein identified (Sgs1p) is structurally related to E. coli RecQ protein and contains helicase signature motifs. Strains lacking Sgs1p exhibit elevated levels of chromosome misseggregation during both mitotic and meiotic division. We propose a model to account for the interaction of a topoisomerase and a helicase in the faithful segregation of newly replicated eukaryotic chromosomes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / genetics
  • Amino Acid Sequence
  • Base Sequence
  • Chromosomes, Fungal
  • Cloning, Molecular
  • DNA Helicases / genetics*
  • DNA Helicases / metabolism
  • DNA Topoisomerases, Type II / metabolism*
  • Escherichia coli / enzymology
  • Escherichia coli / genetics
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Gene Deletion
  • Genes, Fungal / genetics
  • Leucine Zippers
  • Meiosis / genetics*
  • Mitosis / genetics*
  • Models, Genetic
  • Molecular Sequence Data
  • Nondisjunction, Genetic
  • RecQ Helicases
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae Proteins
  • Sequence Homology, Amino Acid
  • Spores, Fungal / growth & development


  • Fungal Proteins
  • Saccharomyces cerevisiae Proteins
  • Adenosine Triphosphatases
  • RecQ protein, E coli
  • SGS1 protein, S cerevisiae
  • DNA Helicases
  • RecQ Helicases
  • DNA Topoisomerases, Type II