Mammalian mitochondrial ribosome (mitoribosome)

The mammalian mitochondrial ribosome (mitoribosome) is a specialized 55S ribonucleoprotein complex located within the mitochondrial matrix, responsible for translating the 13 essential proteins encoded by mitochondrial DNA (mtDNA) [Wikipedia, NIH]. These proteins are core subunits of the oxidative phosphorylation (OXPHOS) system, making the mitoribosome critical for cellular energy production and metabolic homeostasis [NIH]. Structurally, the mammalian mitoribosome consists of a 28S small subunit and a 39S large subunit, featuring a significantly higher protein-to-RNA ratio compared to bacterial or cytosolic ribosomes [NIH]. Due to its evolutionary origin from alphaproteobacteria, it shares structural similarities with bacterial ribosomes, which leads to off-target inhibition by several classes of antibiotics, such as phenicols (e.g., chloramphenicol) and oxazolidinones (e.g., linezolid) [NIH]. This unintended inhibition can result in clinical toxicities including myelosuppression, lactic acidosis, and ototoxicity, particularly in individuals with specific genetic predispositions like the m.1555A>G mutation [ASM, Frontiers, NIH]. Conversely, the mitoribosome is an emerging therapeutic target in oncology, as cancer stem cells often exhibit increased mitochondrial biogenesis and reliance on OXPHOS for survival, metastasis, and drug resistance [NIH, Aging-US]. Mutations in mitoribosomal components are also linked to primary mitochondrial diseases, manifesting as Leigh syndrome, cardiomyopathies, and sensorineural hearing loss [Wikipedia, NIH].

Other names

Mitochondrial ribosome55S ribosomemt-ribosome

Inhibition of mitochondrial protein synthesis through binding to the 28S or 39S subunits, leading to translation arrest and depletion of OXPHOS components.