Credit: Francesca Mattiroli
Archea wrap their DNA (yellow) around proteins called histones (blue), shown above in a 3-D representation. The wrapped structure bears an uncanny resemblance to the eukaryotic nucleosome, a bundle of eight histone proteins with DNA spooled around it. But unlike eukaryotes, archaea wind their DNA around just one histone protein, and form a long, twisting structure called a superhelix.