Uridylation prevents 3%26apos; trimming of oligoadenylated mRNAs

作者：Sement Francois Michael; Ferrier Emilie; Zuber Helene; Merret Remy; Alioua Malek; Deragon Jean Marc; Bousquet Antonelli Cecile; Lange Heike; Gagliardi Dominique^*

来源：Nucleic Acids Research, 2013, 41(14): 7115-7127.

DOI：10.1093/nar/gkt465

Degradation of mRNAs is usually initiated by deadenylation, the shortening of long poly(A) tails to oligo(A) tails of 12-15 As. Deadenylation leads to decapping and to subsequent 5%26apos; to 3%26apos; degradation by XRN proteins, or alternatively 3%26apos; to 5%26apos; degradation by the exosome. Decapping can also be induced by uridylation as shown for the non-polyadenylated histone mRNAs in humans and for several mRNAs in Schizosaccharomyces pombe and Aspergillus nidulans. Here we report a novel role for uridylation in preventing 3%26apos; trimming of oligoadenylated mRNAs in Arabidopsis. We show that oligo(A)-tailed mRNAs are uridylated by the cytosolic UTP:RNA uridylyltransferase URT1 and that URT1 has no major impact on mRNA degradation rates. However, in absence of uridylation, oligo(A) tails are trimmed, indicating that uridylation protects oligoadenylated mRNAs from 3%26apos; ribonucleolytic attacks. This conclusion is further supported by an increase in 3%26apos; truncated transcripts detected in urt1 mutants. We propose that preventing 3%26apos; trimming of oligo(A)-tailed mRNAs by uridylation participates in establishing the 5%26apos; to 3%26apos; directionality of mRNA degradation. Importantly, uridylation prevents 3%26apos; shortening of mRNAs associated with polysomes, suggesting that a key biological function of uridylation is to confer 5%26apos; to 3%26apos; polarity in case of co-translational mRNA decay.

• 出版日期2013-8