Figure 1. Illustration of how the aminoglycoside antibiotic streptomycin causes ototoxicity.

Ototoxicity is a condition where drugs, such as streptomycin, can cause hearing problems and even deafness. It has previously been shown that patients, who are more likely to get ototoxicity, have mutations in the nucleotides located in the mitochondrial ribosome, or mitoribosome. These mutations introduce new RNA base pairings that harden the structure of the small unit of the ribosome (grey). Itoh et al. have shown that streptomycin (red and blue sticks, experimental cryo-EM map is shown as mesh) binds directly to the nucleotides A1555 and C1556 (orange) of the small subunit of the mitoribosome via hydrogen bonds (dashed grey lines), making it even more rigid. This impairs the ribosome’s ability to translate mRNA into proteins (pink ladder mRNA cartoon has been superimposed from the E. coli ribosome structure PDB: 7K00 to show where the mRNA is likely positioned in relation to the streptomycin).