Extensive histone post-translational modification in honey bees.

Histone post-translational modifications (PTMs) play a key role in regulating a variety of cellular processes including the establishment, maintenance and reversal of transcriptional programmes in eukaryotes. However, little is known about such modifications in the economically and ecologically important insect pollinator, the honey bee (Apis mellifera). Using mass spectrometry approaches, we show that histone H3.1, H3.3 and H4 of the honey bee are extensively modified by lysine acetylation and lysine methylation. We analysed histones isolated from queen ovaries and 96 hr-old larvae, in toto we quantified 23 specific modification states on 23 distinct peptides. In addition, we have identified and characterised patterns of histone PTMs that reside on the same peptide, generating detailed combinatorial information. Overall, we observed similar profiles of histone PTMs in both samples, with combinatorial patterns of lysine methylations on H3K27 and H3K36 more frequently identified in histones extracted from queen ovaries than from larvae. To our knowledge, this comprehensive dataset represents the first identification and quantitation of histone PTMs in this eusocial insect and emerging epigenetic model.