A comparative analysis of histone methyltransferases and demethylases in insect genome: A meta-analysis

Background The epigenetic regulation through post-translational modification of histones, especially methylation is well conserved, while DNA methylation is variable, being very low or absent in Drosophila melanogaster . Though there are several insect genomes sequenced, an analysis with a focus on their epigenetic repertoire is limited. We have compared the histone methyltransferases and the demethylases in the genome of Drosophila melanogaster, Aedes aegypti (Diptera), the pea aphid Acyrthosiphon pisum , the triatomid bug Rhodnius prolixus (Hemiptera), the honeybee Apis mellifera (Hymenoptera), the silkworm Bombyx mori (Lepidoptera) and the red flour beetle Tribolium castaneum (Coleoptera). Results We identified 38 clusters consisting of arginine, lysine methyltransferases and demethylases using OrthoFinder. To eliminate false positives, we designed a method based on identifying highly conserved domain within each class designated as the high priority domain. Out of the 9 arginine methyltransferases, Art2, Art6 and Art9 are identified in D . melanogaster only. We observe copy number variation between the genomes; A . pisum has nine copies of eggless gene (H3K9me3 methyltransferase), which can be correlated with the switch between parthenogenesis and sexual reproduction. Other than the high-priority domains, these proteins contain shared and unique domains that can mediate protein-protein interaction. Phylogenetic analysis indicates that the there is a broad conservation within the members of a class while duplication and divergence is observed in LSD1. Conclusion This meta-analysis provides a method for reliable identification of epigenetic modifiers of histones in newly sequenced insect genomes. Similar approach can be taken for other classes of genes.