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| - | [[Image:3bbn.jpg|left|200px]] | + | #REDIRECT [[4v61]] This PDB entry is obsolete and replaced by 4v61 |
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| - | {{STRUCTURE_3bbn| PDB=3bbn | SCENE= }}
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| - | '''Homology model for the Spinach chloroplast 30S subunit fitted to 9.4A cryo-EM map of the 70S chlororibosome.'''
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| - | ==Overview==
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| - | 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.
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| - | ==About this Structure==
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| - | 3BBN is a [[Protein complex]] structure of sequences from [http://en.wikipedia.org/wiki/Arabidopsis_thaliana Arabidopsis thaliana], [http://en.wikipedia.org/wiki/Cucumis_sativus Cucumis sativus], [http://en.wikipedia.org/wiki/Mesembryanthemum_crystallinum Mesembryanthemum crystallinum], [http://en.wikipedia.org/wiki/Oryza_sativa Oryza sativa] and [http://en.wikipedia.org/wiki/Spinacia_oleracea Spinacia oleracea]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3BBN OCA].
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| - | ==Reference==
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| - | 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:[http://www.ncbi.nlm.nih.gov/pubmed/18042701 18042701]
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| - | [[Category: Arabidopsis thaliana]]
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| - | [[Category: Cucumis sativus]]
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| - | [[Category: Mesembryanthemum crystallinum]]
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| - | [[Category: Oryza sativa]]
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| - | [[Category: Protein complex]]
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| - | [[Category: Spinacia oleracea]]
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| - | [[Category: Agrawal, R K.]]
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| - | [[Category: Barat, C.]]
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| - | [[Category: Datta, P P.]]
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| - | [[Category: Fucini, P.]]
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| - | [[Category: Schluenzen, F.]]
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| - | [[Category: Sharma, M R.]]
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| - | [[Category: Wilson, D N.]]
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| - | [[Category: Macromolecular complex]]
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| - | [[Category: Ribonucleoprotein particle]]
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| - | [[Category: Small ribosomal subunit]]
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| - | [[Category: Spinach chloroplast ribosome]]
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| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed May 14 11:30:54 2008''
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