Topography of the ISW2-nucleosome complex: insights into nucleosome spacing and chromatin remodeling

EMBO J. 2004 May 19;23(10):2092-104. doi: 10.1038/sj.emboj.7600220. Epub 2004 May 6.


Linker DNA was found to be critical for the specific docking of ISW2 with nucleosomes as shown by mapping the physical contacts of ISW2 with nucleosomes at base-pair resolution. Hydroxyl radical footprinting revealed that ISW2 not only extensively interacts with the linker DNA, but also approaches the nucleosome from the side perpendicular to the axis of the DNA superhelix and contacts two disparate sites on the nucleosomal DNA from opposite sides of the superhelix. The topography of the ISW2-nucleosome was further delineated by finding which of the ISW2 subunits are proximal to specific sites within the linker and nucleosomal DNA regions by site-directed DNA photoaffinity labeling. Although ISW2 was shown to contact approximately 63 bp of linker DNA, a minimum of 20 bp of linker DNA was required for stable binding of ISW2 to nucleosomes. The remaining approximately 43 bp of flanking linker DNA promoted more efficient binding under competitive binding conditions and was functionally important for enhanced sliding of nucleosomes when ISW2 was significantly limiting.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphatases / chemistry
  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism*
  • Binding Sites
  • Chromatin / metabolism*
  • DNA / chemistry
  • DNA / metabolism
  • DNA Footprinting
  • Humans
  • Macromolecular Substances
  • Models, Molecular
  • Nucleosomes / chemistry
  • Nucleosomes / genetics
  • Nucleosomes / metabolism*
  • Protein Binding
  • Protein Conformation
  • Protein Subunits / genetics
  • Protein Subunits / metabolism*
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*


  • Chromatin
  • ISWI protein
  • Macromolecular Substances
  • Nucleosomes
  • Protein Subunits
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • DNA
  • Adenosine Triphosphatases