Pervasive mRNA uridylation in fission yeast catalysed by both Cid1 and Cid16 terminal uridyltransferases

Abstract

Messenger RNA uridylation is pervasive and conserved among eukaryotes, but the consequences of this modification for mRNA fate are still under debate. Utilising a simple model organism to study uridylation may facilitate efforts to understand the cellular function of this process. Here we demonstrate that uridylation can be detected using simple bioinformatics approach. We utilise it to unravel widespread transcript uridylation in fission yeast and demonstrate the contribution of both Cid1 and Cid16, the only two annotated terminal uridyltransferases (TUT-ases) in this yeast. To detect uridylation in transcriptome data, we used a RNA-sequencing (RNA-seq) library preparation protocol involving initial linker ligation to fragmented RNA. We next explored the data to detect uridylation marks. Our analysis shows that uridylation in yeast is pervasive, similarly to the ones in multicellular organisms. Importantly, our results confirm the role of the cytoplasmic uridyltransferase Cid1 as the primary uridylation catalyst. However, we also observed an auxiliary role of the second uridyltransferase, Cid16. Thus both fission yeast uridyltransferases are involved in mRNA uridylation. Intriguingly, we found no physiological phenotype of the single and double deletion mutants of cid1 and cid16 and only limited impact of uridylation on steady-state mRNA levels. Our work establishes fission yeast as a potent model to study uridylation in a simple eukaryote, and we demonstrate that it is possible to detect uridylation marks in RNA-seq data without the need for specific methodologies.

Uridylation regulates mRNA decay directionality in fission yeast.

“…This suggests that Cid16 can take over some of the Cid1 function in poly(A) tails uridylation at least in the background of cid1 gene deletion. This redundancy in poly(A) uridylation between both TUTases is supported by our earlier observations [25].…”

“…There are two annotated terminal uridyltransferase genes encoded in the ssion yeast genome: cid1 and cid16 [16]. Cid1 was shown to be responsible for the majority of poly(A) tail uridylation [10], while Cid16 was proposed to be involved in both mRNA uridylation [17] and the turnover of small RNAs [18].…”