The capture of a DNA double helix by an ATP-dependent protein clamp: a key step in DNA transport by type II DNA topoisomerases

Cell. 1992 Nov 27;71(5):833-40. doi: 10.1016/0092-8674(92)90558-t.


The binding of linear and circular forms of DNA to yeast DNA topoisomerase II or its complex with AMPPNP, the nonhydrolyzable beta,gamma-imido analog of ATP, was carried out to probe the ATP analog-induced conformational change of the enzyme. Binding of the ATP analog is shown to convert the enzyme to a circular clamp with an annulet, through which only a linear DNA can pass; subsequent circularization of the bound linear DNA forms a salt-stable catenane between the protein circular clamp and the DNA ring. Analysis of catenane formation between a small DNA ring originally bound to the topoisomerase and a large DNA ring subsequently added, under conditions such that the two do not exchange, supports a model in which a second DNA double-helix can enter the open jaws of a DNA-bound protein clamp, and the closure of the jaws upon ATP-binding traps the second duplex and transports it through an enzyme-operated gate in the first DNA duplex.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphatases / metabolism*
  • Adenylyl Imidodiphosphate / metabolism
  • DNA / metabolism*
  • DNA Topoisomerases, Type II / metabolism*
  • DNA-Binding Proteins / metabolism*
  • Motion
  • Protein Conformation
  • Saccharomyces cerevisiae / enzymology


  • DNA-Binding Proteins
  • Adenylyl Imidodiphosphate
  • DNA
  • Adenosine Triphosphatases
  • DNA Topoisomerases, Type II