6z1p
From Proteopedia
Structure of the mitochondrial ribosome from Tetrahymena thermophila
Structural highlights
Function[Q24C34_TETTS] One of two assembly initiator proteins, it binds directly to the 5'-end of the 23S rRNA, where it nucleates assembly of the 50S subunit.[ARBA:ARBA00004072] [Q22HG3_TETTS] One of the primary rRNA binding proteins, it binds directly near the 3'-end of the 23S rRNA, where it nucleates assembly of the 50S subunit.[ARBA:ARBA00002570] Publication Abstract from PubMedTo 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. Ciliate mitoribosome illuminates evolutionary steps of mitochondrial translation.,Tobiasson V, Amunts A Elife. 2020 Jun 18;9. pii: 59264. doi: 10.7554/eLife.59264. PMID:32553108[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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