How to build a ribosome from RNA fragments in Chlamydomonas mitochondria
Waltz, Florent; Salinas-Giegé, Thalia; Englmeier, Robert; Meichel, Herrade; Soufari, Heddy; Kuhn, Lauriane; Pfeffer, Stefan; Förster, Friedrich; Engel, Benjamin D.; Giegé, Philippe; Drouard, Laurence; Hashem, Yaser
(2021) Nature Communications, volume 12, issue 1, pp. 1 - 15
(Article)
Abstract
Mitochondria are the powerhouse of eukaryotic cells. They possess their own gene expression machineries where highly divergent and specialized ribosomes, named hereafter mitoribosomes, translate the few essential messenger RNAs still encoded by mitochondrial genomes. Here, we present a biochemical and structural characterization of the mitoribosome in the model green alga
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Chlamydomonas reinhardtii, as well as a functional study of some of its specific components. Single particle cryo-electron microscopy resolves how the Chlamydomonas mitoribosome is assembled from 13 rRNA fragments encoded by separate non-contiguous gene pieces. Additional proteins, mainly OPR, PPR and mTERF helical repeat proteins, are found in Chlamydomonas mitoribosome, revealing the structure of an OPR protein in complex with its RNA binding partner. Targeted amiRNA silencing indicates that these ribosomal proteins are required for mitoribosome integrity. Finally, we use cryo-electron tomography to show that Chlamydomonas mitoribosomes are attached to the inner mitochondrial membrane via two contact points mediated by Chlamydomonas-specific proteins. Our study expands our understanding of mitoribosome diversity and the various strategies these specialized molecular machines adopt for membrane tethering.
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Keywords: General Chemistry, General Biochemistry,Genetics and Molecular Biology, General Physics and Astronomy
ISSN: 2041-1723
Publisher: Nature Publishing Group
Note: Funding Information: We are grateful to Pr. Claire Remacle (University of Liège) for her kind gifts of strains and antibodies. We also thank, J. Chicher and P. Hamman of the Strasbourg Esplanade proteomic platform for the proteomic analysis, and S. Graindorge and D. Pflieger of the IBMP bioinformatics core facility for the bioinformatic analysis. We thank Miroslava Schaffer and Wojciech Wietrzynski for help with FIB milling and cryo-ET acquisition. We thank Jürgen Plitzko and Wolfgang Baumeister for access to cryo-EM instrumentation and support. This work has benefitted from the facilities and expertise of the Biophysical and Structural Chemistry platform (BPCS) at IECB, CNRS UMS3033, Inserm US001, University of Bordeaux. The mass spectrometry instrumentation was funded by the University of Strasbourg, IdEx “Equipement mi-lourd” 2015. This work was supported by a European Research Council Starting Grant (TransTryp ID:759120) to Y.H., by the LabEx consortium‘MitoCross’ (ANR-11-LABX-0057_MITOCROSS), by the ITI 2021-2028 program of the University of Strasbourg, CNRS, and Inserm supported by IdEx Unistra (ANR-10-IDEX-0002), and EUR IMCBio (ANR-17-EURE-0023) under the framework of the French Investments for the Future Program to P.G. and L.D., and by the Agence Nationale de la Recherche (ANR) grants [MITRA, ANR-16-CE11-0024-02], [DAMIA, ANR-20-CE11-0021], and [ARAMIS, ANR-21-CE12] to Y.H., P.G., and L.D. Additional funding was provided by the Max Planck Society and the Helmholtz Zentrum München to F.W. and B.E., and the Nederlandse Organisatie voor Wetenschappelijke Onderzoek (Vici 724.016.001) to F.F., as well as by an Alexander von Humboldt Postdoctoral Fellowship to F.W. Publisher Copyright: © 2021, The Author(s).
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