NMD factors UPF2 and UPF3 bridge UPF1 to the exon junction complex and stimulate its RNA helicase activity.
Nonsense-mediated mRNA decay (NMD) eliminates mRNAs containing a premature translation termination codon through the recruitment of the conserved NMD factors UPF1, UPF2 and UPF3. In humans, a dynamic assembly pathway allows UPF1 to join UPF2 and UPF3 recruited to the mRNA by the exon-junction complex (EJC). Here we show that the recombinant EJC core is sufficient to reconstitute, with the three UPF proteins, a stable heptameric complex on RNA. The EJC proteins MAGOH, Y14 and eIF4AIII provide a composite binding site for UPF3b that serves as a bridge to UPF2 and UPF1. In the UPF trimeric complex, UPF2 and UPF3b cooperatively stimulate both ATPase and RNA helicase activities of UPF1. This work demonstrates that the EJC core is sufficient to stably anchor the UPF proteins to mRNA and provides insights into the regulation of its central effector, UPF1.
Chamieh
Hala
H
Equipe Labélisée La Ligue, Centre de Génétique Moléculaire, CNRS UPR 2167, Associée aux Universités Paris 6 et Paris 11, Avenue de la terrasse, Gif-sur-Yvette, F-91198, France.
Ballut
Lionel
L
Bonneau
Fabien
F
Le Hir
Hervé
H
D001665:Binding Sites; D019281:Dimerization; D005091:Exons; D006801:Humans; D046911:Macromolecular Substances / Q000737:chemistry / Q000378:metabolism; D012313:RNA / Q000737:chemistry / Q000378:metabolism; D020365:RNA Helicases / Q000737:chemistry / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017384:Sequence Deletion; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D046911:Macromolecular Substances; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C468286:UPF2 protein, human; C435488:UPF3B protein, human; D012313:RNA; D020365:RNA Helicases; C101828:UPF1 protein, human