Structure and Function of the Mitochondrial Ribosome

Abstract

Mitochondrial ribosomes (mitoribosomes) perform protein synthesis inside mitochondria, the organelles responsible for energy conversion and adenosine triphosphate production in eukaryotic cells. Throughout evolution, mitoribosomes have become functionally specialized for synthesizing mitochondrial membrane proteins, and this has been accompanied by large changes to their structure and composition. We review recent high-resolution structural data that have provided unprecedented insight into the structure and function of mitoribosomes in mammals and fungi.

Biallelic Mutations in MRPS34 Lead to Instability of the Small Mitoribosomal Subunit and Leigh Syndrome

“…1 Mammalian mitoribosomes contain two subunits: a small (28S) subunit that decodes mRNA and mediates tRNA delivery of required amino acids and a large (39S) subunit that catalyzes the formation of peptide bonds between the amino acids. 2,3 In humans, 30 mitochondrial ribosomal small subunit proteins (MRPSs) assemble with the 12S mt-rRNA to form the small 28S subunit, while 50 mitochondrial ribosomal large subunit proteins (MRPLs) assemble with the 16S mt-rRNA and mt-tRNA Val to form the large 39S subunit. [4][5][6] Molecular defects that impair different components of the mitochondrial translation machinery can cause combined OXPHOS deficiency.…”

NSUN 3 and ABH 1 modify the wobble position of mt‐t RNA Met to expand codon recognition in mitochondrial translation

“…As a reconstituted mitochondrial in vitro translation system is not readily available, we tested binding of different modification states of mt‐tRNA Met in the presence of purified recombinant human mitochondrial translation factors on ribosomes from Escherichia coli . Even though the structure of bacterial and mitochondrial ribosomes is significantly different, the structure of the decoding centre of the ribosome is highly conserved (reviewed in Greber & Ban, 2016), allowing mitochondrial translation factors to bind at the conserved sites of bacterial ribosomes. To mimic codon recognition during translation initiation, we used recombinant human mitochondrial initiation factor 2 (MTIF2), which recruits mt‐tRNA Met to the P site of the ribosome.…”

Proteome Imbalance of Mitochondrial Electron Transport Chain in Brown Adipocytes Leads to Metabolic Benefits

“…The activation of UPR mt in neurons can induce metabolic fitness in C. elegans in a non-cell autonomous manner (Berendzen et al, 2016; Mardones et al, 2014). Some anti-bacteria antibiotics can cause ETC proteome imbalance in multiple species due to their activities to specifically suppress mtDNA translation (De Silva et al, 2015; Greber and Ban, 2016). For example, doxycycline can inhibit mitochondrial protein synthesis by blocking the recruitment of aminoacyl-tRNA to a small subunit (Wang et al, 2015).…”