Deciphering the mitochondrial co-translational import mechanism in mammals and identification of the main actors

  • Sébastien Absin

Student thesis: Master typesMaster en sciences biomédicales à finalité spécialisée en recherche préclinique


Mitochondrial post-translational import is considered as the canonical way for mitochondrial protein import, but new evidences suggest an alternative import mechanism for mitochondrial proteins. Indeed, the existence of a co-translational protein import process (translation-coupled translocation of mitochondrial proteins) has been more recently described in yeast and in higher eukaryotes.
In addition to the role played by Tom20 in the mitochondrial co-translational import process in yeast, RNA-binding proteins (RBPs) seem also involved but are still poorly characterized in mammals. To investigate the question, an unbiased proximity labeling technique has been developed in the laboratory to identify the Tom20 proxisome and screen for trans-acting proteins involved in mitochondrial co-translational import. In order to validate the candidates identified in the BioID screening, specific co-translational import reporters have been constructed and functionally characterized. The CLUH protein was selected as a hypothesis-driven candidate and SND1 was selected as a candidate from the results obtained after the BioID experiment screening the Tom20 proxisome. Both candidates were selected due to their RBP function in mammalian cells. Indeed, linked to mitochondrial physiology, Clueless, the Drosophila homolog of CLUH, was found to bind both ribosomes and mitochondria. For SND1, its enrichment at the human mitochondria surface was verified by Western Blotting and ultra-resolution confocal microscopy observations. Based on these features, we evaluated the role of CLUH and SND1 in the co-translational import mechanism in human cells. However, we show here that individual CLUH and SND1 depletion in the HCT116 human cell line did not disrupt the mitochondrial co-translational import process as could be assessed with our specific reporters. This suggests at least no decisive contribution of both the CLUH and SND1 proteins in the human mitochondrial co-translational import mechanism.
la date de réponse17 janv. 2022
langue originaleAnglais
L'institution diplômante
  • Universite de Namur
SuperviseurPatricia Renard (Promoteur) & Sebastien MEURANT (Copromoteur)

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