Primary Citation of Related Structures:   6ZM5, 6ZM6
PubMed Abstract: 
Mitochondrial ribosomes (mitoribosomes) are tethered to the mitochondrial inner membrane to facilitate the cotranslational membrane insertion of the synthesized proteins. We report cryo-electron microscopy structures of human mitoribosomes with nascent polypeptide, bound to the insertase oxidase assembly 1-like (OXA1L) through three distinct contact sites. OXA1L binding is correlated with a series of conformational changes in the mitoribosomal large subunit that catalyze the delivery of newly synthesized polypeptides. The mechanism relies on the folding of mL45 inside the exit tunnel, forming two specific constriction sites that would limit helix formation of the nascent chain. A gap is formed between the exit and the membrane, making the newly synthesized proteins accessible. Our data elucidate the basis by which mitoribosomes interact with the OXA1L insertase to couple protein synthesis and membrane delivery.
Organizational Affiliation: 
Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165 Solna, Stockholm, Sweden. abarrientos@med.miami.edu brendan.battersby@helsinki.fi amunts@scilifelab.se.
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177 Stockholm, Sweden.
Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA. abarrientos@med.miami.edu brendan.battersby@helsinki.fi amunts@scilifelab.se.
Institute of Biotechnology, University of Helsinki, 00790 Helsinki, Finland. abarrientos@med.miami.edu brendan.battersby@helsinki.fi amunts@scilifelab.se.
Faculty of Biological and Environmental Sciences, University of Helsinki, 00790 Helsinki, Finland.
Wellcome Centre for Mitochondrial Research, Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA.