Poly(dA:dT) tracts: major determinants of nucleosome organization

Curr Opin Struct Biol. 2009 Feb;19(1):65-71. doi: 10.1016/j.sbi.2009.01.004. Epub 2009 Feb 7.


Homopolymeric stretches of deoxyadenosine nucleotides (A's) on one strand of double-stranded DNA, referred to as poly(dA:dT) tracts or A-tracts, are overabundant in eukaryotic genomes. They have unusual structural, dynamic, and mechanical properties, and may resist sharp bending. Such unusual material properties, together with their overabundance in eukaryotes, raised the possibility that poly(dA:dT) tracts might function in eukaryotes to influence the organization of nucleosomes at many genomic regions. Recent genome-wide studies strongly confirm these ideas and suggest that these tracts play major roles in chromatin organization and genome function. Here we review what is known about poly(dA:dT) tracts and how they work.

Publication types

  • Review

MeSH terms

  • Animals
  • Base Sequence
  • DNA / chemistry
  • DNA / genetics
  • Humans
  • Models, Biological
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Nucleosomes / chemistry*
  • Nucleosomes / metabolism
  • Poly dA-dT / chemistry*
  • Poly dA-dT / genetics


  • Nucleosomes
  • Poly dA-dT
  • DNA