The unidirectional translocation of messenger RNA (mRNA) through the aqueous channel of the nuclear pore complex (NPC) is mediated by interactions between soluble mRNA export factors and distinct binding sites on the NPC. At the cytoplasmic side of the NPC, the conserved mRNA export factors Gle1 and inositol hexakisphosphate (IP6) play an essential role in mRNA export by activating the ATPase activity of the DEAD-box protein Dbp5, promoting localized mRNP remodeling and ensuring the directionality of the export process. In addition, Dbp5, Gle1, and IP6 are also required for proper translation termination. However, the specificity of the IP6-Gle1 interaction in vivo is unknown. Here, we characterize the biochemical interaction between Gle1 and IP6 and the relationship to Dbp5 binding and stimulation. We identify Gle1 residues required for IP6 binding and show that these residues are needed for IP6-dependent Dbp5 stimulation in vitro. Furthermore, we demonstrate that Gle1 is the primary target of IP6 for both mRNA export and translation termination in vivo. In S. cerevisiae cells, the IP6-binding mutants recapitulate all the mRNA export and translation termination defects found in mutants depleted of IP6. We conclude that Gle1 specifically binds IP6, and that this interaction is required for the full potentiation of Dbp5 ATPase activity during both mRNA export and translation termination.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|