Elongational stalling activates mitoribosome-associated quality control

Quality control in mitochondria Human mitochondria have their own genome and ribosomes called mitoribosomes that respectively encode and synthesize essential subunits of complexes that use the energy from the oxidation of metabolites to drive the synthesis of adenosine triphosphate (ATP). These complexes are key to the health of the cell. Desaiet al. studied a mitoribosome-associated quality control pathway that prevents aberrant translation. They purified mitoribosomes under conditions designed to induce stalling and determined the structures of two intermediates in the rescue pathway. These structures revealed two proteins that eject the unfinished polypeptide chain and peptidyl transfer RNA from the ribosome. Their cryo–electron microscopy dataset also revealed additional states that may correspond to intermediates in the mitochondrial translation elongation cycle.Science , this issue p.1105