Mitochondrial Ribosome Structures Captured

Two research groups have obtained the first structures of complete mitoribosomes, ribosomes from mammalian mitochondria, at near-atomic resolution. Ribosomes translate genetically transcribed mRNA templates to synthesize cellular proteins. Most mammalian ribosomes are found in the cell cytoplasm. But mitochondria, the energy-producing organelles of cells, have their own ribosomes. Researchers had previously structurally analyzed the larger of the mitoribosome’s two subunits. Now, some of the same researchers have obtained structures of the complete complex. Venki Ramakrishnan and coworkers at the Medical Research Council Laboratory of Molecular Biology, in Cambridge, England, determined the structure of the human mitoribosome, including 80 proteins and three ribosomal RNAs, at 3.5-Å resolution (Science 2015, DOI: 10.1126/science.aaa1193). And Nenad Ban of ETH Zurich and coworkers determined the 3.8-Å structure of the pig mitoribosome with an mRNA and two tRNAs bound (Science 2015, DOI: 10.1126/science.aaa3872). The structures may help scientists improve antibiotics that target the bacterial ribosome but that have severe side effects, in part because they also interact with the human mitoribosome.