Adventures through wonderland: the wild world of histone gene organization, evolution, and regulation in over 250 species.
Histone proteins are critical for the compaction and organization of DNA. In eukaryotes, these proteins are typically encoded by a multigene family. Replication-dependent histones are highly conserved, both in their amino acid sequence and in their S-phase linked expression. Despite striking protein and regulatory similarities, histone genes often reside in wildly different organizations within genomes, even those of closely related species. At the same time, distantly-related species sometimes share organizational themes. How each species similarly regulates histone genes despite organizational differences remains unclear, and a multi-species approach is necessary to address this gap in knowledge. Here, we distill, categorize, and describe the histone gene organizations of over 250 species spanning 11 phyla. Our comprehensive curation of histone gene organizations provides new insights into the divergence and evolutionary changes of this ancient, conserved gene family. Additionally, we suggest that histone gene organization may contribute to subsequent regulation, as well as misregulation in disease.