Adenine methylation is very scarce in the <i>Drosophila</i> genome and not erased by the ten-eleven translocation dioxygenase.

Abstract

N6-methyladenine (6mA) DNA modification has recently been described in metazoans, including in <i>Drosophila</i>, for which the erasure of this epigenetic mark has been ascribed to the ten-eleven translocation (TET) enzyme. Here, we re-evaluated 6mA presence and TET impact on the <i>Drosophila</i> genome. Using axenic or conventional breeding conditions, we found traces of 6mA by LC-MS/MS and no significant increase in 6mA levels in the absence of TET, suggesting that this modification is present at very low levels in the <i>Drosophila</i> genome but not regulated by TET. Consistent with this latter hypothesis, further molecular and genetic analyses showed that TET does not demethylate 6mA but acts essentially in an enzymatic-independent manner. Our results call for further caution concerning the role and regulation of 6mA DNA modification in metazoans and underline the importance of TET non-enzymatic activity for fly development.