Determinants for mRNP remodeling at the cytoplasmic face of the nuclear pore complex

Abstract

Transcript export from the nucleus to the cytoplasm through the nuclear pore complex (NPC) is an essential step for gene expression in eukaryotes. Messenger RNAs coated in proteins (mRNPs) are able to cross the NPC due to export factor interaction with a class of proteins in the NPC known as FG Nups. Central to this process is the removal of export factors by the DEAD-box ATPase Dbp5 once the transcript reaches the cytoplasmic face of the NPC. This is termed mRNP remodeling, and it confers mRNP transport directionality. The ATPase activity of Dbp5 is stimulated by cofactors Gle1-IP6, and both of these proteins are localized to the NPC by FG Nups assembled at the cytoplasmic face of the NPC. Using the model Saccharomyces cerevisiae, we find a link between mRNP export and mRNP remodeling by uncovering a function for FG domains during the mRNP remodeling process. Furthermore, the proximal positioning between an FG domain and Gle1 is sufficient for this function, suggesting that FG domains on the cytoplasmic face of the NPC direct exporting mRNPs for remodeling.