Global chromatin domain organization of the Drosophila genome

In eukaryotes, neighboring genes can be packaged together in specific chromatin structures that ensure their coordinated expression. Examples of such multi-gene chromatin domains are well-documented, but a global view of the chromatin organization of eukaryotic genomes is lacking. To systematically identify multi-gene chromatin domains, we constructed a compendium of genome-scale binding maps for a broad panel of chromatin-associated proteins in Drosophila melanogaster. Next, we computationally analyzed this compendium for evidence of multi-gene chromatin domains using a novel statistical segmentation algorithm. We find that at least 34% of the fly genome is organized into chromatin domains, which often consist of dozens of genes. The domains are characterized by various known and novel combinations of chromatin proteins. The genes in many of the domains are coregulated during development and share biological functions. Furthermore, fewer chromosomal rearrangements occur inside chromatin domains than outside domains during evolution. Our results indicate that a substantial portion of the Drosophila genome is packaged into functionally coherent, multi-gene chromatin domains. This has broad mechanistic implications for gene regulation and genome evolution. Keywords: DamID DamID experiments for multiple chromatin proteins was performed in Drosophila cell cultures. Samples were hybridized to spotted cDNA arrays. Every experiment was repeated at least 2 times, with one sample in the reverse dye orientation. When hybridization was performed 4 times, two samples were hybridized in the reverse dye orientation.