title: Mechanism of eIF6 release from the nascent 60S ribosomal subunit.
abstract: SBDS protein (deficient in the inherited leukemia-predisposition disorder Shwachman-Diamond syndrome) and the GTPase EFL1 (an EF-G homolog) activate nascent 60S ribosomal subunits for translation by catalyzing eviction of the antiassociation factor eIF6 from nascent 60S ribosomal subunits. However, the mechanism is completely unknown. Here, we present cryo-EM structures of human SBDS and SBDS-EFL1 bound to Dictyostelium discoideum 60S ribosomal subunits with and without endogenous eIF6. SBDS assesses the integrity of the peptidyl (P) site, bridging uL16 (mutated in T-cell acute lymphoblastic leukemia) with uL11 at the P-stalk base and the sarcin-ricin loop. Upon EFL1 binding, SBDS is repositioned around helix 69, thus facilitating a conformational switch in EFL1 that displaces eIF6 by competing for an overlapping binding site on the 60S ribosomal subunit. Our data reveal the conserved mechanism of eIF6 release, which is corrupted in both inherited and sporadic leukemias.
authors.affiliation: Cambridge Institute for Medical Research, Cambridge, UK.|Medical Research Council Laboratory of Molecular Biology, University of Cambridge Research Unit, Cambridge, UK.|Department of Haematology, University of Cambridge, Cambridge, UK.|Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK.
authors.forename: Félix
authors.initials: F
authors.lastname: Weis
authors.affiliation: Université de Rennes 1, Centre Nationale de la Recherche Scientifique, Unité Mixte de Recherche 6290, Institut de Génétique et Développement de Rennes, Rennes, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Giudice
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, University of Cambridge Research Unit, Cambridge, UK.|Department of Haematology, University of Cambridge, Cambridge, UK.|Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Churcher
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, University of Cambridge Research Unit, Cambridge, UK.|Department of Haematology, University of Cambridge, Cambridge, UK.|Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK.|Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.
authors.forename: Li
authors.initials: L
authors.lastname: Jin
authors.affiliation: Cambridge Institute for Medical Research, Cambridge, UK.|Medical Research Council Laboratory of Molecular Biology, University of Cambridge Research Unit, Cambridge, UK.|Department of Haematology, University of Cambridge, Cambridge, UK.|Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK.
authors.forename: Christine
authors.initials: C
authors.lastname: Hilcenko
authors.affiliation: Experimental Cancer Genetics, Wellcome Trust Sanger Institute, Cambridge, UK.
authors.forename: Chi C
authors.initials: CC
authors.lastname: Wong
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.
authors.forename: David
authors.initials: D
authors.lastname: Traynor
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.
authors.forename: Robert R
authors.initials: RR
authors.lastname: Kay
authors.affiliation: Cambridge Institute for Medical Research, Cambridge, UK.|Medical Research Council Laboratory of Molecular Biology, University of Cambridge Research Unit, Cambridge, UK.|Department of Haematology, University of Cambridge, Cambridge, UK.|Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Warren
mesh_terms: D020285:Cryoelectron Microscopy; D004023:Dictyostelium / Q000235:genetics; D039642:Eukaryotic Initiation Factors / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008954:Models, Biological; D008958:Models, Molecular; D008968:Molecular Conformation; D010442:Peptide Chain Initiation, Translational; D010445:Peptide Elongation Factors; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism*; D017415:Ribonucleoprotein, U5 Small Nuclear; D054683:Ribosome Subunits, Large, Eukaryotic / Q000737:chemistry / Q000378:metabolism*
chemical_list: C000599132:EFL1 protein, human; D039642:Eukaryotic Initiation Factors; D010445:Peptide Elongation Factors; D011506:Proteins; D015800:Protozoan Proteins; D017415:Ribonucleoprotein, U5 Small Nuclear; C470521:SBDS protein, human; D020558:GTP Phosphohydrolases