Affiliation:
1. Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden
2. Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Solna, Sweden
Abstract
To understand the steps involved in the evolution of translation, we used Tetrahymena thermophila, a ciliate with high coding capacity of the mitochondrial genome, as the model organism and characterized its mitochondrial ribosome (mitoribosome) using cryo-EM. The structure of the mitoribosome reveals an assembly of 94-ribosomal proteins and four-rRNAs with an additional protein mass of ~700 kDa on the small subunit, while the large subunit lacks 5S rRNA. The structure also shows that the small subunit head is constrained, tRNA binding sites are formed by mitochondria-specific protein elements, conserved protein bS1 is excluded, and bacterial RNA polymerase binding site is blocked. We provide evidence for anintrinsic protein targeting system through visualization of mitochondria-specific mL105 by the exit tunnel that would facilitate the recruitment of a nascent polypeptide. Functional protein uS3m is encoded by three complementary genes from the nucleus and mitochondrion, establishing a link between genetic drift and mitochondrial translation. Finally, we reannotated nine open reading frames in the mitochondrial genome that code for mitoribosomal proteins.
Funder
Ragnar Söderbergs stiftelse
Cancerfonden
H2020 European Research Council
Knut och Alice Wallenbergs Stiftelse
European Molecular Biology Organization
Swedish Foundation for Strategic Research
Swedish Research Council
Publisher
eLife Sciences Publications, Ltd
Subject
General Immunology and Microbiology,General Biochemistry, Genetics and Molecular Biology,General Medicine,General Neuroscience
Cited by
35 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献