title: Gemin5 promotes IRES interaction and translation control through its C-terminal region.
abstract: Gene expression control largely depends on ribonucleoprotein complexes regulating mRNA translation. Initiation of translation in mRNAs that overcome cap-dependent translation inhibition is often driven by internal ribosome entry site (IRES) elements, whose activity is regulated by multifunctional RNA-binding factors. Here we show that Gemin5 interacts preferentially with a specific domain of a viral IRES consisting of a hairpin flanked by A/U/C-rich sequences. RNA-binding assays using purified proteins revealed that Gemin5-IRES interaction depends on the C-terminal region of the protein. Consistent with this novel finding, the C-terminal region of Gemin5, but not the N-terminal region, impaired translation. Furthermore, RNA selective 2'hydroxyl acylation analysed by primer extension (SHAPE) reactivity demonstrated that addition of purified Gemin5 to IRES mRNA induced the specific protection of residues around the hairpin of the IRES element. We further demonstrate that Gemin5 out-competed SHAPE reactivity variations induced by the IRES-binding factor PTB, leading to a local conformational change in the IRES structure. Together, our data unveil the inhibitory mechanism of Gemin5 on IRES-mediated translation.
authors.affiliation: Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas-Universidad Autonoma de Madrid, Cantoblanco 28049 Madrid, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Piñeiro
authors.forename: Noemi
authors.initials: N
authors.lastname: Fernández
authors.forename: Jorge
authors.initials: J
authors.lastname: Ramajo
authors.forename: Encarnación
authors.initials: E
authors.lastname: Martínez-Salas
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D015536:Down-Regulation; D029544:Foot-and-Mouth Disease Virus / Q000235:genetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D038941:Polypyrimidine Tract-Binding Protein / Q000378:metabolism; D014176:Protein Biosynthesis; D012367:RNA, Viral / Q000737:chemistry / Q000378:metabolism; D038621:Regulatory Sequences, Ribonucleic Acid; D055532:SMN Complex Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D012367:RNA, Viral; D038621:Regulatory Sequences, Ribonucleic Acid; D055532:SMN Complex Proteins; D038941:Polypyrimidine Tract-Binding Protein