Uridylation of microRNA-directed 5' cleavage products by TUTases /

Many studies have shown that uridylation, a post- transcriptional modification that results in the addition of non-templated uridines to the 3' ends of various RNAs, effect the stability of these transcripts. Belonging to the same family as canonical nucleotidyl transferases such as the well characterized poly(A) polymerase, non- canonical nucleotidyl-transferases (nc-rNTrs) are template -independent polymerases capapble of catalyzing the transfer of single or multiple nucleotide residues to the 3' ends of various RNAs. Here we identified the in vitro activities of six of the seven human nc-rNTrs. We found that TUTases 4 and 7 are prefer to add uridines, while TUTases 2, 3 and 5 prefer to add adenines. Furthermore, we studied uridylation of microRNA-directed 5' cleavage products in vivo. Our preliminary results identified TUTase 2 and 7 as the enzymes that may be responsible for the uridylation of the 5' cleavage fragment. Knockdown of these enzymes in combination led to a decrease in uridylated transcripts. Here, we laid the groundwork for future experiments that will help elucidate the effects of uridylation on mRNA stabilit