Detection of 3′-End RNA Uridylation with a Protein Nanopore

Post-transcriptional modifications of the 3'-ends of RNA molecules have a profound impact on their stability and processing in the cell. Uridylation, the addition of uridines to 3'-ends, has recently been found to be an important regulatory signal to stabilize the tagged molecules or to direct them toward degradation. Simple and cost-effective methods for the detection of this post-transcriptional modification are not yet available. Here, we demonstrate the selective and transient binding of 3'-uridylated ssRNAs inside the beta barrel of the staphylococcal a-hemolysin (aHL) nanopore and investigate the molecular basis of uridine recognition by the pore. We show the discrimination of 3'-oligouridine tails on the basis of their lengths and propose the aHL nanopore as a useful sensor for this biologically relevant RNA modification.