title: Uridylation prevents 3' trimming of oligoadenylated mRNAs.
abstract: 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' to 3' degradation by XRN proteins, or alternatively 3' to 5' 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' 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' ribonucleolytic attacks. This conclusion is further supported by an increase in 3' truncated transcripts detected in urt1 mutants. We propose that preventing 3' trimming of oligo(A)-tailed mRNAs by uridylation participates in establishing the 5' to 3' directionality of mRNA degradation. Importantly, uridylation prevents 3' shortening of mRNAs associated with polysomes, suggesting that a key biological function of uridylation is to confer 5' to 3' polarity in case of co-translational mRNA decay.
authors.affiliation: Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg, 12 rue du général Zimmer, 67084 Strasbourg Cedex, France.
authors.forename: François Michaël
authors.initials: FM
authors.lastname: Sement
authors.forename: Emilie
authors.initials: E
authors.lastname: Ferrier
authors.forename: Hélène
authors.initials: H
authors.lastname: Zuber
authors.forename: Rémy
authors.initials: R
authors.lastname: Merret
authors.forename: Malek
authors.initials: M
authors.lastname: Alioua
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Deragon
authors.forename: Cécile
authors.initials: C
authors.lastname: Bousquet-Antonelli
authors.forename: Heike
authors.initials: H
authors.lastname: Lange
authors.forename: Dominique
authors.initials: D
authors.lastname: Gagliardi
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009843:Oligoribonucleotides / Q000378:metabolism*; D011132:Polyribosomes / Q000378:metabolism; D026721:RNA 3' End Processing; D012316:RNA Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism*; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism*; D014529:Uridine / Q000378:metabolism; D014542:Uridine Monophosphate / Q000378:metabolism*
chemical_list: D000227:Adenine Nucleotides; D029681:Arabidopsis Proteins; C556248:LOM1 protein, Arabidopsis; D009843:Oligoribonucleotides; D012333:RNA, Messenger; C023505:2',5'-oligoadenylate; D014542:Uridine Monophosphate; D012316:RNA Nucleotidyltransferases; C584074:URT1 protein, Arabidopsis; C031687:UTP-RNA uridylyltransferase; D014529:Uridine