Structure and functional relationships of archaeal and eukaryal histones and nucleosomes

A decade after the discovery of histones in Archaea, there is now also a bi ochemical description of the archaeal nucleosome. A tetrameric core of arch aeal histones is encircled by similar to 80 bp of DNA, and nuclease digesti ons indicate that adjacent archaeal nucleosomes exist in vivo compacting ar chaeal genomic DNA. Most Eukarya employ a similar structure: to organize th eir chromosomal DNA, the eukaryal nucleosome, with a histone octamer and 14 6 bp of DNA. Here we compare the properties of both nucleosomes in terms of DNA packaging and the accessibility of the packaged DNA for transcription.