title: The DEAD-box helicase Ded1 from yeast is an mRNP cap-associated protein that shuttles between the cytoplasm and nucleus.
abstract: The DEAD-box helicase Ded1 is an essential yeast protein that is closely related to mammalian DDX3 and to other DEAD-box proteins involved in developmental and cell cycle regulation. Ded1 is considered to be a translation-initiation factor that helps the 40S ribosome scan the mRNA from the 5' 7-methylguanosine cap to the AUG start codon. We used IgG pull-down experiments, mass spectrometry analyses, genetic experiments, sucrose gradients, in situ localizations and enzymatic assays to show that Ded1 is a cap-associated protein that actively shuttles between the cytoplasm and the nucleus. NanoLC-MS/MS analyses of purified complexes show that Ded1 is present in both nuclear and cytoplasmic mRNPs. Ded1 physically interacts with purified components of the nuclear CBC and the cytoplasmic eIF4F complexes, and its enzymatic activity is stimulated by these factors. In addition, we show that Ded1 is genetically linked to these factors. Ded1 comigrates with these proteins on sucrose gradients, but treatment with rapamycin does not appreciably alter the distribution of Ded1; thus, most of the Ded1 is in stable mRNP complexes. We conclude that Ded1 is an mRNP cofactor of the cap complex that may function to remodel the different mRNPs and thereby regulate the expression of the mRNAs.
authors.affiliation: Expression Génétique Microbienne, CNRS FRE3630 (UPR9073), in association with Université Paris Diderot, Sorbonne Paris Cité, Paris 75005, France Université Paris-Sud, Ecole Doctorale 426 GGC, Orsay, France.
authors.forename: Meriem
authors.initials: M
authors.lastname: Senissar
authors.affiliation: Expression Génétique Microbienne, CNRS FRE3630 (UPR9073), in association with Université Paris Diderot, Sorbonne Paris Cité, Paris 75005, France.
authors.forename: Agnès
authors.initials: A
authors.lastname: Le Saux
authors.affiliation: Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, CNRS UMR8226 (FRE3354), UPMC, Paris 75005, France.
authors.forename: Naïma
authors.initials: N
authors.lastname: Belgareh-Touzé
authors.affiliation: Expression Génétique Microbienne, CNRS FRE3630 (UPR9073), in association with Université Paris Diderot, Sorbonne Paris Cité, Paris 75005, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Adam
authors.affiliation: Expression Génétique Microbienne, CNRS FRE3630 (UPR9073), in association with Université Paris Diderot, Sorbonne Paris Cité, Paris 75005, France kyle.tanner@ibpc.fr.
authors.forename: Josette
authors.initials: J
authors.lastname: Banroques
authors.affiliation: Expression Génétique Microbienne, CNRS FRE3630 (UPR9073), in association with Université Paris Diderot, Sorbonne Paris Cité, Paris 75005, France kyle.tanner@ibpc.fr.
authors.forename: N Kyle
authors.initials: NK
authors.lastname: Tanner
mesh_terms: D021581:Active Transport, Cell Nucleus; D000251:Adenosine Triphosphatases / Q000378:metabolism; D002467:Cell Nucleus / Q000201:enzymology*; D003593:Cytoplasm / Q000201:enzymology*; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D006151:Guanosine / Q000031:analogs & derivatives / Q000378:metabolism; D014176:Protein Biosynthesis; D012315:RNA Caps / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D012315:RNA Caps; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; C026452:messenger ribonucleoprotein; D006151:Guanosine; C016578:7-methylguanosine; D000251:Adenosine Triphosphatases; C059787:D1Pas1 protein, mouse; C119332:DDX3X protein, human; C492152:DED1 protein, S cerevisiae; D053487:DEAD-box RNA Helicases