title: Structural analysis of the DAP5 MIF4G domain and its interaction with eIF4A.
abstract: Death-associated protein 5 (DAP5/p97) is a homolog of the eukaryotic initiation factor 4G (eIF4G) that promotes the IRES-driven translation of multiple cellular mRNAs. Central to its function is the middle domain (MIF4G), which recruits the RNA helicase eIF4A. The middle domain of eIF4G consists of tandem HEAT repeats that coalesce to form a solenoid-type structure. Here, we report the crystal structure of the DAP5 MIF4G domain. Its overall fold is very similar to that of eIF4G; however, significant conformational variations impart distinct surface properties that could explain the observed differences in IRES binding between the two proteins. Interestingly, quantitative analysis of the DAP5-eIF4A interaction using isothermal titration calorimetry reveals a 10-fold lower affinity than with the eIF4G-eIF4A interaction that appears to affect their ability to stimulate eIF4A RNA unwinding activity in vitro. This difference in stability of the complex may have functional implications in selecting the mode of translation initiation.
authors.affiliation: Department of Biochemistry, McGill University, Montreal, QC H3G 0B1, Canada.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Virgili
authors.forename: Filipp
authors.initials: F
authors.lastname: Frank
authors.forename: Kateryna
authors.initials: K
authors.lastname: Feoktistova
authors.forename: Maxime
authors.initials: M
authors.lastname: Sawicki
authors.forename: Nahum
authors.initials: N
authors.lastname: Sonenberg
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Fraser
authors.forename: Bhushan
authors.initials: B
authors.lastname: Nagar
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D002850:Chromatography, Gel; D003001:Cloning, Molecular; D003460:Crystallization; D039601:Eukaryotic Initiation Factor-4A / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D039603:Eukaryotic Initiation Factor-4G / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D014176:Protein Biosynthesis / Q000235:genetics*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
chemical_list: C491300:EIF4G2 protein, human; D039603:Eukaryotic Initiation Factor-4G; D011994:Recombinant Proteins; D039601:Eukaryotic Initiation Factor-4A