Mitochondrial ribosomal small subunit (28S) (28S subunit)

The mitochondrial ribosomal small subunit (28S) is a specialized ribonucleoprotein complex essential for the translation of the 13 proteins encoded by the mitochondrial genome (Amunts et al., 2015, Science [1]). It consists of the 12S ribosomal RNA and approximately 30 proteins, which together facilitate the assembly of the oxidative phosphorylation (OXPHOS) machinery (Greber & Ban, 2016, Annu Rev Biochem [2]). Because of its evolutionary descent from alphaproteobacteria, the 28S subunit shares significant structural homology with the bacterial 30S ribosome, making it a frequent off-target for antibiotics such as aminoglycosides and tetracyclines (Guan, 2011, Nucleic Acids Res [3]). This interaction is a primary cause of drug-induced toxicities, including permanent ototoxicity and nephrotoxicity, particularly in patients with pre-existing mitochondrial mutations (Cunningham et al., 2018, Genetics in Medicine [4]). Conversely, the 28S subunit is increasingly recognized as a viable therapeutic target in oncology, as cancer stem cells often exhibit a heightened dependency on mitochondrial biogenesis and translation for survival (Skrtic et al., 2011, Cancer Cell [5]). Inhibiting this subunit with repurposed antibiotics like doxycycline or novel small molecules can selectively disrupt the metabolic stability of malignant cells while sparing healthy tissues with lower mitochondrial turnover (Lamb et al., 2015, Oncotarget [6]).

Other names

28S mitoribosomal subunitSmall mitochondrial ribosomal subunitmS subunit12S rRNA-protein complexMitoribosomal small subunit

Inhibition of mitochondrial protein synthesis by binding to the 12S rRNA or associated ribosomal proteins, thereby blocking the initiation of translation or the binding of aminoacyl-tRNA to the ribosomal A-site (Guan, 2011, Nucleic Acids Res [3]; Skrtic et al., 2011, Cancer Cell [5]).