5h1s | pdb_00005h1s
Structure of the large subunit of the chloro-ribosome
Structural highlights
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Function[RK4_SPIOL] Probably binds the 23S rRNA (By similarity). This protein (expressed without the transit peptide) is able to provoke transcription termination from the spinach chloroplast rDNA operon and the E.coli S10 operon in vitro. [RK5_SPIOL] Binds 5S rRNA, forms part of the central protuberance of the 50S subunit (By similarity). [RK23_SPIOL] Binds to 23S rRNA (By similarity). Located at the polypeptide exit tunnel on the outside of the subunit. [RK19_SPIOL] Located at the 30S-50S ribosomal subunit interface and binds directly to 23S ribosomal RNA (By similarity).[:] [RK20_SPIOL] 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 (By similarity).[HAMAP-Rule:MF_00382] [RK34_SPIOL] This protein binds directly to 23S ribosomal RNA (By similarity). [RK22_SPIOL] This protein binds specifically to 23S rRNA (By similarity). The globular domain of the protein is located near the polypeptide exit tunnel on the outside of the subunit, while an extended beta-hairpin is found that lines the wall of the exit tunnel in the center of the 70S ribosome (By similarity). Binds an erythromycin derivative added to the 50S subunit. [RK21_SPIOL] This protein binds to 23S ribosomal RNA in the presence of protein L20 (By similarity). [RK24_SPIOL] 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 (By similarity). Located at the polypeptide exit tunnel on the outside of the subunit. [RK14_SPIOL] Binds to 23S rRNA (By similarity). Publication Abstract from PubMedProtein synthesis in the chloroplast is mediated by the chloroplast ribosome (chloro-ribosome). Overall architecture of the chloro-ribosome is considerably similar to the Escherichia coli (E. coli) ribosome but certain differences are evident. The chloro-ribosome proteins are generally larger because of the presence of chloroplast-specific extensions in their N- and C-termini. The chloro-ribosome harbours six plastid-specific ribosomal proteins (PSRPs); four in the small subunit and two in the large subunit. Deletions and insertions occur throughout the rRNA sequence of the chloro-ribosome (except for the conserved peptidyl transferase center region) but the overall length of the rRNAs do not change significantly, compared to the E. coli. Although, recent advancements in cryo-electron microscopy (cryo-EM) have provided detailed high-resolution structures of ribosomes from many different sources, a high-resolution structure of the chloro-ribosome is still lacking. Here, we present a cryo-EM structure of the large subunit of the chloro-ribosome from spinach (Spinacia oleracea) at an average resolution of 3.5 A. High-resolution map enabled us to localize and model chloro-ribosome proteins, chloroplast-specific protein extensions, two PSRPs (PSRP5 and 6) and three rRNA molecules present in the chloro-ribosome. Although comparable to E. coli, the polypeptide tunnel and the tunnel exit site show chloroplast-specific features. Cryo-EM structure of the large subunit of the spinach chloroplast ribosome.,Ahmed T, Yin Z, Bhushan S Sci Rep. 2016 Oct 20;6:35793. doi: 10.1038/srep35793. PMID:27762343[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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