TY - JOUR T1 - Interconnected assembly factors regulate the biogenesis of mitoribosomal large subunit JF - bioRxiv DO - 10.1101/2020.06.28.176446 SP - 2020.06.28.176446 AU - Victor Tobiasson AU - Ondřej Gahura AU - Shintaro Aibara AU - Rozbeh Baradaran AU - Alena Zíková AU - Alexey Amunts Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/07/19/2020.06.28.176446.abstract N2 - Mitoribosomes synthesize essential proteins encoded in mitochondria. They consist of RNA and protein components, coordinated assembly of which is critical for function. We used mitoribosomes with reduced RNA and increased protein mass from a mammalian parasite Trypanosoma brucei to provide insights into the biogenesis of mitoribosomal large subunit.Structural characterisation of a stable assembly intermediate revealed 16 assembly factors, 10 of which were not previously implicated in biogenesis. Most of the reported factors are also encoded in mammalian genomes. In the structure, the assembly factors form a protein network that spans over 180 Å, shielding the ribosomal RNA surface. The entire central protuberance and L7/L12 stalk are not assembled, and require removal of the factors and remodeling to become functional sites. The conserved mt-RbgA and mt-EngA are bound together in proximity to the peptidyl transferase center. A mitochondrial acyl-carrier protein plays a role in stably docking the L1 stalk that needs to be repositioned during maturation. Together, the extensive network of the assembly factors stabilizes the immature domains and connects between the functionally important regions.Competing Interest StatementThe authors have declared no competing interest. ER -