4v61 | pdb_00004v61
Homology model for the Spinach chloroplast 30S subunit fitted to 9.4A cryo-EM map of the 70S chlororibosome.
Structural highlights
Function[RK11_SPIOL] This protein binds directly to 23S ribosomal RNA (By similarity). [RR7_SPIOL] One of the primary rRNA binding proteins, it binds directly to 16S rRNA where it nucleates assembly of the head domain of the 30S subunit (By similarity).[HAMAP-Rule:MF_00480] [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. [RK1_SPIOL] This protein binds directly to 23S ribosomal RNA (By similarity). [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. [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] [RR14_SPIOL] Binds 16S rRNA, required for the assembly of 30S particles (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. [RR13_SPIOL] Located at the top of the head of the 30S subunit, it contacts several helices of the 16S rRNA.[HAMAP-Rule:MF_01315] [RK5_SPIOL] Binds 5S rRNA, forms part of the central protuberance of the 50S subunit (By similarity). [RR6_SPIOL] Binds together with S18 to 16S ribosomal RNA (By similarity).[UniProtKB:O78447] [RK19_SPIOL] Located at the 30S-50S ribosomal subunit interface and binds directly to 23S ribosomal RNA (By similarity).[:] [RR9_SPIOL] Binds directly to 16S ribosomal RNA.[1] [:] [RK34_SPIOL] This protein binds directly to 23S ribosomal RNA (By similarity). [RK21_SPIOL] This protein binds to 23S ribosomal RNA in the presence of protein L20 (By similarity). [RR12_SPIOL] With S4 and S5 plays an important role in translational accuracy. Located at the interface of the 30S and 50S subunits (By similarity).[HAMAP-Rule:MF_00403_B] [RR8_SPIOL] One of the primary rRNA binding proteins, it binds directly to 16S rRNA central domain where it helps coordinate assembly of the platform of the 30S subunit (By similarity).[HAMAP-Rule:MF_01302] [RR4_SPIOL] One of the primary rRNA binding proteins, it binds directly to 16S rRNA where it nucleates assembly of the body of the 30S subunit (By similarity).[HAMAP-Rule:MF_01306] With S5 and S12 plays an important role in translational accuracy (By similarity).[HAMAP-Rule:MF_01306] [RK14_SPIOL] Binds to 23S rRNA (By similarity). [RK23_SPIOL] Binds to 23S rRNA (By similarity). Located at the polypeptide exit tunnel on the outside of the subunit. [RR19_SPIOL] This protein binds directly to 16S ribosomal RNA.[2] [RR5_SPIOL] Binds directly to 16S ribosomal RNA. Involved in spectinomycin and neamine resistance and streptomycin independence.[:] Publication Abstract from PubMedProtein synthesis in the chloroplast is carried out by chloroplast ribosomes (chloro-ribosome) and regulated in a light-dependent manner. Chloroplast or plastid ribosomal proteins (PRPs) generally are larger than their bacterial counterparts, and chloro-ribosomes contain additional plastid-specific ribosomal proteins (PSRPs); however, it is unclear to what extent these proteins play structural or regulatory roles during translation. We have obtained a three-dimensional cryo-EM map of the spinach 70S chloro-ribosome, revealing the overall structural organization to be similar to bacterial ribosomes. Fitting of the conserved portions of the x-ray crystallographic structure of the bacterial 70S ribosome into our cryo-EM map of the chloro-ribosome reveals the positions of PRP extensions and the locations of the PSRPs. Surprisingly, PSRP1 binds in the decoding region of the small (30S) ribosomal subunit, in a manner that would preclude the binding of messenger and transfer RNAs to the ribosome, suggesting that PSRP1 is a translation factor rather than a ribosomal protein. PSRP2 and PSRP3 appear to structurally compensate for missing segments of the 16S rRNA within the 30S subunit, whereas PSRP4 occupies a position buried within the head of the 30S subunit. One of the two PSRPs in the large (50S) ribosomal subunit lies near the tRNA exit site. Furthermore, we find a mass of density corresponding to chloro-ribosome recycling factor; domain II of this factor appears to interact with the flexible C-terminal domain of PSRP1. Our study provides evolutionary insights into the structural and functional roles that the PSRPs play during protein synthesis in chloroplasts. Cryo-EM study of the spinach chloroplast ribosome reveals the structural and functional roles of plastid-specific ribosomal proteins.,Sharma MR, Wilson DN, Datta PP, Barat C, Schluenzen F, Fucini P, Agrawal RK Proc Natl Acad Sci U S A. 2007 Dec 4;104(49):19315-20. Epub 2007 Nov 27. PMID:18042701[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
| ||||||||||||||||||
