This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
3bbo
From Proteopedia
OCA (Talk | contribs)
(New page: 200px <!-- The line below this paragraph, containing "STRUCTURE_3bbo", creates the "Structure Box" on the page. You may change the PDB parameter (which sets the PD...)
Next diff →
Revision as of 06:19, 28 May 2008
Homology model for the Spinach chloroplast 50S subunit fitted to 9.4A cryo-EM map of the 70S chlororibosome
Overview
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.
About this Structure
3BBO is a Protein complex structure of sequences from Arabidopsis thaliana, Nicotiana tabacum, Pisum sativum, Spinacia oleracea and Vitis vinifera. Full crystallographic information is available from OCA.
Reference
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 Page seeded by OCA on Wed May 28 09:19:16 2008
Categories: Arabidopsis thaliana | Nicotiana tabacum | Pisum sativum | Protein complex | Spinacia oleracea | Vitis vinifera | Agrawal, R K. | Barat, C. | Datta, P P. | Fucini, P. | Schluenzen, F. | Sharma, M R. | Wilson, D N. | Large ribosomal subunit | Macromolecular complex | Ribonucleoprotein particle | Spinach chloroplast ribosome
