6xyw
From Proteopedia
Structure of the plant mitochondrial ribosome
Structural highlights
Function[RM21_ARATH] This protein binds to 23S ribosomal RNA in the presence of protein L20 (By similarity). Required for karyogamy during female gametophyte development, when the two polar nuclei fuse to form the diploid central cell nucleus, and during double fertilization of the egg cell and the central cell (PubMed:16698901).[1] [HLP_ARATH] Binds to 23S rRNA in mitochondrion. [RT11_ARATH] Required for karyogamy during female gametophyte development, when the two polar nuclei fuse to form the diploid central cell nucleus.[2] [PP438_ARATH] RNA-binding protein that functions in both mitochondrion and nucleus. In mitochondrion, it is associated with polysomes and may play a role in translation. Required during embryogenesis. In nucleus, might be involved in the regulation of its own gene expression.[3] [Q8LCN1_ARATH] Binds directly to 23S ribosomal RNA and is necessary for the in vitro assembly process of the 50S ribosomal subunit. It is not involved in the protein synthesizing functions of that subunit.[RuleBase:RU004311] [RT13_ARATH] Located at the top of the head of the small subunit, it contacts several helices of the 18S rRNA. [RK3B_ARATH] 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. [RT19_ARATH] The RNA-binding domain found in RPS19 may functionally replaces the missing mitochondrial RPS13. [RPS9M_ARATH] Mitochondrial ribosomal protein required for central cell maturation. May work together with PIA2 in controlling female gametophyte development, possibly by regulating the expression of some mitochondrial proteins.[4] Publication Abstract from PubMedThe vast majority of eukaryotic cells contain mitochondria, essential powerhouses and metabolic hubs(1). These organelles have a bacterial origin and were acquired during an early endosymbiosis event(2). Mitochondria possess specialized gene expression systems composed of various molecular machines, including the mitochondrial ribosomes (mitoribosomes). Mitoribosomes are in charge of translating the few essential mRNAs still encoded by mitochondrial genomes(3). While chloroplast ribosomes strongly resemble those of bacteria(4,5), mitoribosomes have diverged significantly during evolution and present strikingly different structures across eukaryotic species(6-10). In contrast to animals and trypanosomatids, plant mitoribosomes have unusually expanded ribosomal RNAs and have conserved the short 5S rRNA, which is usually missing in mitoribosomes(11). We have previously characterized the composition of the plant mitoribosome(6), revealing a dozen plant-specific proteins in addition to the common conserved mitoribosomal proteins. In spite of the tremendous recent advances in the field, plant mitoribosomes remained elusive to high-resolution structural investigations and the plant-specific ribosomal features of unknown structures. Here, we present a cryo-electron microscopy study of the plant 78S mitoribosome from cauliflower at near-atomic resolution. We show that most of the plant-specific ribosomal proteins are pentatricopeptide repeat proteins (PPRs) that deeply interact with the plant-specific rRNA expansion segments. These additional rRNA segments and proteins reshape the overall structure of the plant mitochondrial ribosome, and we discuss their involvement in the membrane association and mRNA recruitment prior to translation initiation. Finally, our structure unveils an rRNA-constructive phase of mitoribosome evolution across eukaryotes. Cryo-EM structure of the RNA-rich plant mitochondrial ribosome.,Waltz F, Soufari H, Bochler A, Giege P, Hashem Y Nat Plants. 2020 Apr;6(4):377-383. doi: 10.1038/s41477-020-0631-5. Epub 2020 Apr , 6. PMID:32251374[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Arabidopsis thaliana | Large Structures | Bochler, A | Giege, P | Hashem, Y | Soufari, H | Waltz, F | Mitochondria | Plant | Ribosome
