Recognition of m6A RNA by the non-canonical reader IMP1

m6A methylation is the prevalent post-transcriptional modification in eukaryotic mRNAs and provides an essential layer of regulation in organismal development and in disease. The information encoded by m6A methylation is integrated into existing RNA regulatory networks by the binding of an expanding list of m6A readers. An important question is how protein readers that do not contain a canonical m6A-specific YTH domain recognize methylated RNA. Here, we show that the non-canonical reader IMP1 directly recognises the m6A group using a dedicated hydrophobic platform in the KH4 domain, creating a stable and high affinity interaction with the methylated RNA targets. Notably, the recognition of the m6A group is independent from the underlying sequence context, but is layered upon IMP1 strong sequence specificity for GGAC RNA. Together, our data indicate that, contrarily to the well-characterised YTH readers, IMP1 recognises and binds both m6A-methylated and non-methylated RNA targets with high affinity. This suggests that m6A methylation does not provide a general layer of control of IMP1 function, but rather plays a directed role in specific regulatory pathways. iCLIP in HeLa for IMP1