title: The Dbp5 cycle at the nuclear pore complex during mRNA export II: nucleotide cycling and mRNP remodeling by Dbp5 are controlled by Nup159 and Gle1.
abstract: Essential messenger RNA (mRNA) export factors execute critical steps to mediate directional transport through nuclear pore complexes (NPCs). At cytoplasmic NPC filaments, the ATPase activity of DEAD-box protein Dbp5 is activated by inositol hexakisphosphate (IP(6))-bound Gle1 to mediate remodeling of mRNA-protein (mRNP) complexes. Whether a single Dbp5 executes multiple remodeling events and how Dbp5 is recycled are unknown. Evidence suggests that Dbp5 binding to Nup159 is required for controlling interactions with Gle1 and the mRNP. Using in vitro reconstitution assays, we found here that Nup159 is specifically required for ADP release from Dbp5. Moreover, Gle1-IP(6) stimulates ATP binding, thus priming Dbp5 for RNA loading. In vivo, a dbp5-R256D/R259D mutant with reduced ADP binding bypasses the need for Nup159 interaction. However, NPC spatial control is important, as a dbp5-R256D/R259D nup42Δ double mutant is temperature-sensitive for mRNA export. Further analysis reveals that remodeling requires a conformational shift to the Dbp5-ADP form. ADP release factors for DEAD-box proteins have not been reported previously and reflect a new paradigm for regulation. We propose a model wherein Nup159 and Gle1-IP(6) regulate Dbp5 cycles by controlling its nucleotide-bound state, allowing multiple cycles of mRNP remodeling by a single Dbp5 at the NPC.
authors.affiliation: Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
authors.forename: Kristen N
authors.initials: KN
authors.lastname: Noble
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Tran
authors.forename: Abel R
authors.initials: AR
authors.lastname: Alcázar-Román
authors.forename: Christine A
authors.initials: CA
authors.lastname: Hodge
authors.forename: Charles N
authors.initials: CN
authors.lastname: Cole
authors.forename: Susan R
authors.initials: SR
authors.lastname: Wente
mesh_terms: D021581:Active Transport, Cell Nucleus; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D022022:Nuclear Pore / Q000378:metabolism*; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism*; D029543:Nucleocytoplasmic Transport Proteins / Q000235:genetics / Q000378:metabolism; D009711:Nucleotides / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D012333:RNA, Messenger / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C101408:GLE1 protein, S cerevisiae; C093510:NUP159 protein, S cerevisiae; D028861:Nuclear Pore Complex Proteins; D029543:Nucleocytoplasmic Transport Proteins; D009711:Nucleotides; D012333:RNA, Messenger; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; C026452:messenger ribonucleoprotein; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; C492382:DBP5 protein, S cerevisiae; D053487:DEAD-box RNA Helicases