Identification of A-to-I RNA Editing Sites in Honey Bee (Apis mellifera) Using RNAseq Data

RNA editing is a post-transcriptional process that leads to addition, substitution and deletion of certain bases in RNA molecules, and accordingly alters their biological properties. A-to-I RNA editing refers to the conversion of adenosine (A) to inosine (I) through deamination catalyzed by adenosine deaminase acting on RNA (ADAR).

We performed computational identification of potential A-to-I RNA editing sites in the honey bee brain using the latest genome assembly and Illumina-generated RNAseq data from ten honey bee brains (five nurses and five foragers, two to three replicates per individual). A total of 63 editing sites were identified, with 38 in coding exons, 20 in 3’ UTRs, 4 in introns and 1 in 5’ UTR. Guanosine was depleted as the 5’ most adjacent base and favored as the 3’ most adjacent base of editing sites, consistent with base context previously shown as being recognized by ADAR. The editing sites in coding exons did not show preference for codon position, but 29 resulted in non-synonymous changes. We found two conserved A-to-I editing sites in the gene orthologous to quiver (qvr) in Drosophila melanogaster. The first conserved A-to-I editing site recodes serine (AGU) to glycine (GGU), and the second conserved site recodes histidine (CAC) to arginine (CGC). Conservation of these specific amino acid conversions across 300 million years of evolutionary divergence suggests important biological functions. This is the first systematic investigation of A-to-I editing in the honey bee brain, and experimental validation is underway to verify the candidate A-to-I editing sites.