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The structure of the yeast mitochondrial ribosome

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Science  03 Feb 2017:
Vol. 355, Issue 6324, pp. 528-531
DOI: 10.1126/science.aal2415

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The yeast mitoribosome

Mitochondria are eukaryotic organelles that produce ATP, the energy source of the cell. They have dedicated ribosomes (mitoribosomes) that encode some of the membrane proteins that are essential to ATP production. Desai et al. present a high-resolution structure of the 75-component yeast mitoribosome, determined by electron cryomicroscopy. Mitoribosomes share an ancestor with modern bacterial ribosomes. Comparing the structure of the yeast mitoribosome with mammalian mitoribosomes suggests how they have evolved differently to perform species-specific functions.

Science, this issue p. 528

Abstract

Mitochondria have specialized ribosomes (mitoribosomes) dedicated to the expression of the genetic information encoded by their genomes. Here, using electron cryomicroscopy, we have determined the structure of the 75-component yeast mitoribosome to an overall resolution of 3.3 angstroms. The mitoribosomal small subunit has been built de novo and includes 15S ribosomal RNA (rRNA) and 34 proteins, including 14 without homologs in the evolutionarily related bacterial ribosome. Yeast-specific rRNA and protein elements, including the acquisition of a putatively active enzyme, give the mitoribosome a distinct architecture compared to the mammalian mitoribosome. At an expanded messenger RNA channel exit, there is a binding platform for translational activators that regulate translation in yeast but not mammalian mitochondria. The structure provides insights into the evolution and species-specific specialization of mitochondrial translation.

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