New insight into the recognition of branched DNA structure by junction-resolving enzymes

Curr Opin Struct Biol. 2008 Feb;18(1):86-95. doi: 10.1016/ Epub 2007 Dec 21.


Junction-resolving enzymes are nucleases that exhibit structural selectivity for the four-way (Holliday) junction in DNA. In general, these enzymes both recognize and distort the structure of the junction. New insight into the molecular recognition processes has been provided by two recent co-crystal structures of resolving enzymes bound to four-way DNA junctions in highly contrasting ways. T4 endonuclease VII binds the junction in an open conformation to an approximately flat binding surface whereas T7 endonuclease I envelops the junction, which retains a much more three-dimensional structure. Both proteins make contacts with the DNA backbone over an extensive area in order to generate structural specificity. The comparison highlights the versatility of Holliday junction resolution, and extracts some general principles of recognition.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Binding Sites
  • DNA Restriction Enzymes / chemistry
  • DNA Restriction Enzymes / metabolism
  • DNA, Cruciform / chemistry*
  • DNA, Cruciform / metabolism
  • Deoxyribonuclease I / chemistry
  • Deoxyribonuclease I / metabolism
  • Endodeoxyribonucleases / chemistry
  • Endodeoxyribonucleases / metabolism
  • Holliday Junction Resolvases / chemistry*
  • Holliday Junction Resolvases / metabolism*
  • Humans
  • Models, Molecular
  • Nucleic Acid Conformation
  • Protein Conformation


  • DNA, Cruciform
  • Endodeoxyribonucleases
  • DNA Restriction Enzymes
  • Holliday Junction Resolvases
  • Deoxyribonuclease I
  • endodeoxyribonuclease VII