In eukaryotes, histone proteins help package DNA into chromatin. Marks or covalent modifications on histones play an important role in the epigenetic regulation of gene expression, as well as DNA replication and repair. It has been assumed that the histones within chromatin will be fairly stable. Mito et al. and Dion et al. instead show that for certain regions of the genome in yeast and in Drosophila, there is a dramatic variation in histone H3 turnover rates. Coding regions in the genome were unexpectedly "quiet," and protein binding sites in promoters--and especially boundary elements--showed a very high level of turnover. In regions of high turnover, epigenetic marks must be in a state of constant flux, which provides the potential for their rapid and dynamic regulation.
- Changing the Histone Landscape
Regions of chromatin that are epigenetically silenced and highly regulated are coated with histones that rapidly bind and release the DNA.Permalink: