Research Article

The structure of the human mitochondrial ribosome

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Science  03 Apr 2015:
Vol. 348, Issue 6230, pp. 95-98
DOI: 10.1126/science.aaa1193

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The whole mitoribosome at high resolution

Mitochondria are thought to be the descendents of a prokaryotic cell that took up residence in a protoeukaryotic cell. Mitochondria retain a few genes involved in oxidative phosphorylation. To translate these genes, mitochondria contain highly divergent mitochondrial ribosomes, or mitoribosomes. Amunts et al. determined the high-resolution structures of complete mammalian mitoribosomes using cryoelectron microscopy. Mitoribosomes include an unusual mRNA binding channel. The findings elucidate how aminoglycoside antibiotics can inadvertently inhibit mitoribosomes and how mutations in mitoribosomes can lead to disease.

Science, this issue p. 95

Abstract

The highly divergent ribosomes of human mitochondria (mitoribosomes) synthesize 13 essential proteins of oxidative phosphorylation complexes. We have determined the structure of the intact mitoribosome to 3.5 angstrom resolution by means of single-particle electron cryogenic microscopy. It reveals 80 extensively interconnected proteins, 36 of which are specific to mitochondria, and three ribosomal RNA molecules. The head domain of the small subunit, particularly the messenger (mRNA) channel, is highly remodeled. Many intersubunit bridges are specific to the mitoribosome, which adopts conformations involving ratcheting or rolling of the small subunit that are distinct from those seen in bacteria or eukaryotes. An intrinsic guanosine triphosphatase mediates a contact between the head and central protuberance. The structure provides a reference for analysis of mutations that cause severe pathologies and for future drug design.

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