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.
Then, in 2006, Eran Segal at the Weizmann Institute of Science, and Jonathan Widom at Northwestern University, and their colleagues, revealed they could predict nucleosome position based on DNA sequence alone with roughly 50% accuracy—significantly better than the 35% predicted by chance.1 To do so, they first mapped out and compared DNA sequences that were incorporated into about 200 yeast nucleosomes to figure out what sequences nucleosomes ...
