Nucleosome positioning: bringing order to the eukaryotic genome.

Nucleosomes are an essential component of eukaryotic chromosomes. The impact of nucleosomes is seen not just on processes that directly access the genome, such as transcription, but also on an evolutionary timescale. Recent studies in various organisms have provided high-resolution maps of nucleosomes throughout the genome. Computational analysis, in conjunction with many other kinds of data, has shed light on several aspects of nucleosome biology. Nucleosomes are positioned by several means, including intrinsic sequence biases, by stacking against a fixed barrier, by DNA-binding proteins and by chromatin remodelers. These studies underscore the important organizational role of nucleosomes in all eukaryotic genomes. This paper reviews recent genomic studies that have shed light on the determinants of nucleosome positioning and their impact on the genome.