title: Phosphorylation of Y14 modulates its interaction with proteins involved in mRNA metabolism and influences its methylation.
abstract: The multicomponent exon junction complex (EJC) is deposited on the spliced mRNA during pre-mRNA splicing and is implicated in several post-splicing events, including mRNA export, nonsense-mediated mRNA decay (NMD), and translation control. This report is the first to identify potential post-translational modifications of the EJC core component Y14. We demonstrate that Y14 is phosphorylated at its repeated arginine/serine (RS) dipeptides, likely by SR protein-specific kinases. Phosphorylation of Y14 abolished its interaction with EJC components as well as factors that function downstream of the EJC. A non-phosphorylatable Y14 mutant was equivalent to the wild-type protein with respect to its association with spliced mRNA and its ability in NMD activation, but the mutant sequestered EJC and NMD factors on ribosome-containing mRNA ribonucleoproteins (mRNPs). We therefore hypothesize that phosphorylation of Y14 occurs upon completion of mRNA surveillance, leading to dissociation of Y14 from ribosome-containing mRNPs. Moreover, we found that Y14 is possibly methylated at multiple arginine residues in the carboxyl-terminal domain and that methylation of Y14 was antagonized by phosphorylation of RS dipeptides. This study reveals antagonistic post-translational modifications of Y14 that may be involved in the remodeling of Y14-containing mRNPs.
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Ia-Wen
authors.initials: IaW
authors.lastname: Hsu
authors.forename: Min
authors.initials: M
authors.lastname: Hsu
authors.forename: Chin
authors.initials: C
authors.lastname: Li
authors.forename: Tzu-Wei
authors.initials: TW
authors.lastname: Chuang
authors.forename: Ru-Inn
authors.initials: RI
authors.lastname: Lin
authors.forename: Woan-Yuh
authors.initials: WY
authors.lastname: Tarn
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000737:chemistry; D005091:Exons; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D008745:Methylation; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry; D012326:RNA Splicing; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D014162:Transfection; D014982:Xenopus laevis
chemical_list: D010455:Peptides; C406243:RBM8A protein, human; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D012313:RNA; D001120:Arginine; D005982:Glutathione Transferase