Navigating the Nucleosome

The eukaryotic genome can be up to 130 billion base pairs long, but required to fit inside each cell nucleus. To do this, DNA is tightly wrapped around histone proteins in bead-like clusters. Each cluster is called a nucleosome. For years, mapping experiments had revealed that nucleosomes favored particular DNA sequences, reflecting the ability of certain DNA sequences to bend more sharply and wrap around histones. Still, whether such preferences actually meant DNA coded for the positions of nucleosomes in vivo was unclear.