RESEARCH ARTICLE Mechanism of completion of peptidyltransferase centre assembly in eukaryotes Vasileios Kargas1,2,3†, Pablo Castro-Hartmann1,2,3†, Norberto Escudero-Urquijo1,2,3, Kyle Dent1,2,3, Christine Hilcenko1,2,3, Carolin Sailer4, Gertrude Zisser5, Maria J Marques-Carvalho1,2,3, Simone Pellegrino1,2,3, Leszek Wawio´ rka1,2,3,6, Stefan MV Freund7, Jane L Wagstaff7, Antonina Andreeva7, Alexandre Faille1,2,3, Edwin Chen8, Florian Stengel4, Helmut Bergler5, Alan John Warren1,2,3* 1Cambridge Institute for Medical Research, Cambridge, United Kingdom; 2Department of Haematology, University of Cambridge, Cambridge, United Kingdom; 3Wellcome Trust–Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, United Kingdom; 4Department of Biology, University of Konstanz, Konstanz, Germany; 5Institute of Molecular Biosciences, University of Graz, Graz, Austria; 6Department of Molecular Biology, Maria Curie-Skłodowska University, Lublin, Poland; 7MRC Laboratory of Molecular Biology, Cambridge, United Kingdom; 8Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom Abstract During their final maturation in the cytoplasm, pre-60S ribosomal particles are converted to translation-competent large ribosomal subunits. Here, we present the mechanism of peptidyltransferase centre (PTC) completion that explains how integration of the last ribosomal *For correspondence:
[email protected] proteins is coupled to release of the nuclear export adaptor Nmd3. Single-particle cryo-EM reveals that eL40 recruitment stabilises helix 89 to form the uL16 binding site. The loading of uL16 unhooks † These authors contributed helix 38 from Nmd3 to adopt its mature conformation. In turn, partial retraction of the L1 stalk is equally to this work coupled to a conformational switch in Nmd3 that allows the uL16 P-site loop to fully accommodate Competing interests: The into the PTC where it competes with Nmd3 for an overlapping binding site (base A2971).