Andrew J. Finch1, Christine Hilcenko2,3, Nicolas Basse4, Lesley Drynan3, Beatriz Goyenechea2,3, Tobias Menne2,3, África González‐Fernández, Paul J. Simpson2,3, Clive S. D’Santos5, Mark J. Arends6, Jean Donadieu7, Christine Bellanné‐Chantelot8, Michael Costanzo9,10,11, Charles Boone9,10,11, Andrew N. J. McKenzie3, Stefan Freund3, Alan J. Warren2,3
1Edinburgh Cancer Research Centre
2Department of Haematology, University of Cambridge, Cambridge CB2 0XY, United Kingdom;
3Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
4University of Edinburgh
5Cancer Research UK, Cambridge Research Institute, Cambridge, CB2 0RE, United Kingdom;
6Pathology Department, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, United Kingdom;
7Service d'He ´mato Oncologie Pe ´diatrique, Registre des Neutrope ´nies Conge ´nitales, Ho ˆpital Trousseau, Paris F 75012, France;
8Department of Genetics, Ho ˆpital Pitie ´-Salpe ´trie `re, Universite ´Pierre et Marie Curie, Paris 75651, France;
9Banting and Best Department of Medical Research, Terrence Donnelly Center for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario M5S 3E1, Canada;
10Department of Molecular Genetics and Microbiology
11Terrence Donnelly Center for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario M5S 3E1, Canada
Tóm tắt
Removal of the assembly factor eukaryotic initiation factor 6 (eIF6) is critical for late cytoplasmic maturation of 60S ribosomal subunits. In mammalian cells, the current model posits that eIF6 release is triggered following phosphorylation of Ser 235 by activated protein kinase C. In contrast, genetic studies in yeast indicate a requirement for the ortholog of theSBDS(Shwachman-Bodian-Diamond syndrome) gene that is mutated in the inherited leukemia predisposition disorder Shwachman-Diamond syndrome (SDS). Here, by isolating late cytoplasmic 60S ribosomal subunits fromSbds-deleted mice, we show that SBDS and the GTPase elongation factor-like 1 (EFL1) directly catalyze eIF6 removal in mammalian cells by a mechanism that requires GTP binding and hydrolysis by EFL1 but not phosphorylation of eIF6 Ser 235. Functional analysis of disease-associated missense variants reveals that the essential role of SBDS is to tightly couple GTP hydrolysis by EFL1 on the ribosome to eIF6 release. Furthermore, complementary NMR spectroscopic studies suggest unanticipated mechanistic parallels between this late step in 60S maturation and aspects of bacterial ribosome disassembly. Our findings establish a direct role for SBDS and EFL1 in catalyzing the translational activation of ribosomes in all eukaryotes, and define SDS as a ribosomopathy caused by uncoupling GTP hydrolysis from eIF6 release.
