4V61

Homology model for the Spinach chloroplast 30S subunit fitted to 9.4A cryo-EM map of the 70S chlororibosome.

This is a non-PDB format compatible entry.

Summary for 4V61

• Entry DOI: 10.2210/pdb4v61/pdb
• Related: 3BBO
• EMDB information: 1417
• Descriptor: 16S rRNA, Ribosomal Protein S10, Ribosomal Protein S11, ... (53 entities in total)
• Functional Keywords: small ribosomal subunit, spinach chloroplast ribosome, ribonucleoprotein particle, macromolecular complex, ribosome
• Biological source: Spinacea oleracea (spinach); More
• Total number of polymer chains: 53
• Total formula weight: 2447890.70

Authors

Sharma, M.R.,Wilson, D.N.,Datta, P.P.,Barat, C.,Schluenzen, F.,Fucini, P.,Agrawal, R.K. (deposition date: 2007-11-09, release date: 2014-07-09, Last modification date: 2024-02-28)

Primary citation

Sharma, M.R.,Wilson, D.N.,Datta, P.P.,Barat, C.,Schluenzen, F.,Fucini, P.,Agrawal, R.K.
Cryo-EM study of the spinach chloroplast ribosome reveals the structural and functional roles of plastid-specific ribosomal proteins
Proc.Natl.Acad.Sci.Usa, 104:19315-19320, 2007

PubMed Abstract: Protein 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.

PubMed: 18042701
DOI: 10.1073/pnas.0709856104

Experimental method

ELECTRON MICROSCOPY (9.4 Å)