Journal Article

The mRNA export protein DBP5 binds RNA and the cytoplasmic nucleoporin NUP214 in a mutually exclusive manner

Basquin, Claire, von Moeller, Holger, Conti, Elena

2009

Overview

The DEAD-box protein DBP5 is involved in yeast mRNA export, though the mechanism by which it helps to remodel and release transcripts on the cytoplasmic face of the nuclear pore complex has been unclear. The structures of DBP5 in complex with the mRNA and AMPPNP, as well as with the nucleoporin NUP214, indicate that the transcript and nucleoporin compete for the same binding site, suggesting a model for the sequence of events occurring at the last step of export. The DEAD-box protein DBP5 is essential for mRNA export in both yeast and humans. It binds RNA and is concentrated and locally activated at the cytoplasmic side of the nuclear pore complex. We have determined the crystal structures of human DBP5 bound to RNA and AMPPNP, and bound to the cytoplasmic nucleoporin NUP214. The structures reveal that binding of DBP5 to nucleic acid and to NUP214 is mutually exclusive. Using in vitro assays, we demonstrate that NUP214 decreases both the RNA binding and ATPase activities of DBP5. The interactions are mediated by conserved residues, implying a conserved recognition mechanism. These results suggest a framework for the consecutive steps leading to the release of mRNA at the final stages of nuclear export. More generally, they provide a paradigm for how binding of regulators can specifically inhibit DEAD-box proteins.

• Publisher: Nature Publishing Group US,Nature Publishing Group
• Subject: Adenylyl Imidodiphosphate - chemistry / Adenylyl Imidodiphosphate - metabolism / Binding sites / Biochemistry / Biological Microscopy / Biological transport / Biomedical and Life Sciences / Crystal structure / Crystallography, X-Ray / DEAD-box RNA Helicases - chemistry / DEAD-box RNA Helicases - metabolism / DNA binding proteins / Genetic aspects / Health aspects / Humans / Life Sciences / Membrane Biology / Messenger RNA / Models, Molecular / Molecular biology / Nuclear Pore Complex Proteins - chemistry / Nuclear Pore Complex Proteins - metabolism / Nucleic acids / Nucleocytoplasmic Transport Proteins - chemistry / Nucleocytoplasmic Transport Proteins - metabolism / Physiological aspects / Protein Binding / Protein Structure / Protein Structure, Quaternary / Proteins / RNA, Messenger - metabolism / Yeast / Yeasts