Pt. Lowary et J. Widom, NUCLEOSOME PACKAGING AND NUCLEOSOME POSITIONING OF GENOMIC DNA, Proceedings of the National Academy of Sciences of the United Statesof America, 94(4), 1997, pp. 1183-1188
The goals of this study were to assess the extent to which bulk genomi
c DNA sequences contribute to their own packaging in nucleosomes and t
o reveal the relationship between nucleosome packaging and positioning
, Using a competitive nucleosome reconstitution assay, we found that a
t least 95% of bulk DNA sequences have an affinity for histone octamer
in nucleosomes that is similar to that of randomly synthesized DNA; t
hey contribute little to their own packaging at the level of individua
l nucleosomes. An equation was developed that relates the measured fre
e energy to the fractional occupancy of specific nucleosome positions,
Evidently, the bulk of eukaryotic genomic DNA is also not evolved or
constrained for significant sequence-directed nucleosome positioning a
t the level of individual nucleosomes. Implications for gene regulatio
n in vivo are discussed.