title: A Point Mutation in the Exon Junction Complex Factor Y14 Disrupts Its Function in mRNA Cap Binding and Translation Enhancement.
abstract: Eukaryotic mRNA biogenesis involves a series of interconnected steps mediated by RNA-binding proteins. The exon junction complex core protein Y14 is required for nonsense-mediated mRNA decay (NMD) and promotes translation. Moreover, Y14 binds the cap structure of mRNAs and inhibits the activity of the decapping enzyme Dcp2. In this report, we show that an evolutionarily conserved tryptophan residue (Trp-73) of Y14 is critical for its binding to the mRNA cap structure. A Trp-73 mutant (W73V) bound weakly to mRNAs and failed to protect them from degradation. However, this mutant could still interact with the NMD and mRNA degradation factors and retained partial NMD activity. In addition, we found that the W73V mutant could not interact with translation initiation factors. Overexpression of W73V suppressed reporter mRNA translation in vitro and in vivo and reduced the level of a set of nascent proteins. These results reveal a residue of Y14 that confers cap-binding activity and is essential for Y14-mediated enhancement of translation. Finally, we demonstrated that Y14 may selectively and differentially modulate protein biosynthesis.
authors.affiliation: From the Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Tzu-Wei
authors.initials: TW
authors.lastname: Chuang
authors.affiliation: From the Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Kuo-Ming
authors.initials: KM
authors.lastname: Lee
authors.affiliation: From the Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Yuan-Chao
authors.initials: YC
authors.lastname: Lou
authors.affiliation: From the Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Chia-Chen
authors.initials: CC
authors.lastname: Lu
authors.affiliation: From the Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan wtarn@ibms.sinica.edu.tw.
authors.forename: Woan-Yuh
authors.initials: WY
authors.lastname: Tarn
mesh_terms: D019943:Amino Acid Substitution; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D017354:Point Mutation; D014176:Protein Biosynthesis / Q000502:physiology*; D012315:RNA Caps / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C406243:RBM8A protein, human; D012315:RNA Caps; D016601:RNA-Binding Proteins; D004722:Endoribonucleases; C467723:DCP2 protein, human
keywords: decapping; exon-junction complex; mRNA; mRNA cap; mRNA decay; mRNA stability; translation; translation control; translation regulation