The Plastid Ribosomal Proteins

Yamaguchi, Kensei; Subramanian, Alap R.

doi:10.1074/jbc.m004350200

Cited by 208 publications

(69 citation statements)

References 50 publications

(25 reference statements)

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“…In the Calvin cycle, the rubisco large subunit assumes a quaternary structure with the small subunit in yielding a functional enzyme, and phosphoglycerate kinase forms a complex with glyceraldehyde 3-phosphate dehydrogenase -an association that likely results in substrate channeling (Wang et al 1996). Similarly, the 24 and 41 kDa RNA binding proteins as well as ribosomal proteins S1, S5, L4 and L21 are known to form complexes with other thioredoxin target proteins -namely, the 28 kDa ribonucleoprotein and ribosomal protein S30, respectively (Hayes et al 1996;Yamaguchi et al 2000). Finally, the chloroplast ATP synthase alpha subunit may co-elute with the enzyme's gamma subunit, an established thioredoxin target.…”

Section: Resultsmentioning

confidence: 99%

Proteomics Uncovers Proteins Interacting Electrostatically with Thioredoxin in Chloroplasts

Balmer

Koller

Val

et al. 2004

Photosynthesis Research

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The ability of thioredoxin f to form an electrostatic (non-covalent) complex, earlier found with fructose-1,6-bisphosphatase, was extended to include 27 previously unrecognized proteins functional in 11 processes of chloroplasts. The proteins were identified by combining thioredoxin f affinity chromatography with proteomic analysis using tandem mass spectrometry. The results provide evidence that an association with thioredoxin enables the interacting protein to achieve an optimal conformation, so as to facilitate: (i) the transfer of reducing equivalents from the ferredoxin/ferredoxin-thioredoxin reductase complex to a target protein; (ii) in some cases, to enable the channeling of metabolite substrates; (iii) to function as a subunit in the formation of multienzyme complexes.Abbreviations: FBPase -fructose-1,6-bisphosphatase; FTR -ferredoxin-thioredoxin reductase

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Section: Resultsmentioning

confidence: 99%

Proteomics Uncovers Proteins Interacting Electrostatically with Thioredoxin in Chloroplasts

Balmer

Koller

Val

et al. 2004

Photosynthesis Research

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“…In addition, the chloro-ribosome possesses six nonorthologous proteins, which are termed ''plastid-specific ribosomal proteins'' (PSRPs): four of these proteins (PSRP1-4) are associated with the 30S subunit, and two (PSRP5 and PSRP6) are associated with the 50S subunit. The larger size of the PRPs as well as the presence of six PSRPs leads to a significantly altered protein/RNA mass ratio of 2/3 in the case of chlororibosomes, as compared with 1/3 for E. coli (5,6). The higher protein content of chloro-ribosomes, and especially the presence of PSRPs, has prompted the suggestion that chloroplasts have evolved specific proteins that play unique functional roles during chloroplast translation, such as the light-dependent stimulation of protein synthesis (5-7).…”

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“…The ribosomal RNAs (rRNAs) are similar in length and exhibit relatively few differences [see supporting information (SI) Figs. [6][7][8]. The 16S rRNAs of the Escherichia coli 30S subunit has 1,542 nt, whereas the spinach chloro-30S subunit is slightly smaller, containing 1,491 nt.…”

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“…Proteomic studies reveal that the chloro-ribosomes possess in total 58 ribosomal proteins, 25 and 33 proteins in the 30S and 50S subunits, respectively (5,6), and have orthologs to all 52 E. coli ribosomal proteins, with the exception of L25 and L30. Plastid ribosomal proteins (PRPs) generally are larger than their E. coli counterparts, containing extensions predominantly at the N and C termini.…”

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Cryo-EM study of the spinach chloroplast ribosome reveals the structural and functional roles of plastid-specific ribosomal proteins

Sharma

Wilson

Datta

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

106

146

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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 threedimensional 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 chlororibosome 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.chloroplast protein synthesis ͉ cryo-EM structure ͉ ribosomal RNA ͉ plastid ribosome recycling factor ͉ protein synthesis C ellular organelles, like mitochondria and chloroplasts, possess their own genome and components of gene-expression system, including ribosomes (for reviews, see refs. 1 and 2). The chloroplast (or plastid) ribosome (henceforth referred to as the ''chlororibosome'') is specialized in that it is involved in the biosynthesis of only the small number of proteins encoded by the chloroplast genome. The complete genome sequence of the spinach (Spinacea oleracea) chloroplast identified a total of 146 genes, of which 98 encode protein products, and 45 represent structural RNAs (3). The majority of the chloroplast-encoded proteins is targeted to the thylakoid membranes and include components of the ATP synthase, cytochrome b/f, and especially photosystem I and II complexes (3). In addition, chloro-ribosomes translate NADH dehydrogenase, the large subunit of RuBisCO, RNA polymerase subunits, and a distinct subset of ribosomal proteins: 12 from the small (30S) subunit and 8 from the large (50S) subunit, and the rest are nuclear-encoded and imported into the chloroplast.The origin of chloroplasts is understood to be through an early endosymbiotic event between a photosynthetic prokaryotic ancestor related to cyanobacteria and a eukaryotic cell (4). In fa...

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“…Post-translational modifications are found in many E. coli RPs, although a modification in L16 (Arg 81 ) remains yet to be characterized (see "Results" for plastid L16). We have recently identified all the RPs in spinach plastid 30 S ribosomal subunit, including all its PSRPs and many post-translational modifications (83). The number of RPs in plastid 50 S subunits has so far only been estimated (ϳ35-39; reviewed in Ref.…”

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The Plastid Ribosomal Proteins

Yamaguchi

Subramanian

2000

Journal of Biological Chemistry

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199

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We have completed identification of all the ribosomal proteins (RPs) in spinach plastid (chloroplast) ribosomal 50 S subunit via a proteomic approach using twodimensional electrophoresis, electroblotting/protein sequencing, high performance liquid chromatography purification, polymerase chain reaction-based screening of cDNA library/nucleotide sequencing, and mass spectrometry (reversed-phase HPLC coupled to electrospray ionization mass spectrometry and electrospray ionization mass spectrometry). Spinach plastid 50 S subunit comprises 33 proteins, of which 31 are orthologues of Escherichia coli RPs and two are plastid-specific RPs The plastid (chloroplast) ribosome is a plant-specific, organelle ribosome that produces proteins encoded by the plastid genome. Plastid ribosomes are responsible for the synthesis of huge amounts of biomass, since the large subunit of ribulose 1,5-bisphophate carboxylase/oxygenase (a most abundant protein in the biosphere) is synthesized in plastids. Plastid ribosomes are very similar to the eubacterial 70 S-type ribosome, in composition and general mode of function (1-4). The rRNAs and most of the characterized ribosomal proteins (RPs) 1 in plastid ribosomes also bear close resemblance to the corresponding components so far identified in cyanobacteria, a correlation supporting the importance of endosymbiotic theory in plastid evolution (5).The Escherichia coli ribosome, the most well studied of the eubacterial ribosomes (6), is composed of 21 RPs in the 30 S subunit and 33 RPs in the 50 S subunit. Two more possible E. coli RPs have been suggested: protein Y, the product of E. coli yfia gene (7), bearing a distant sequence homology to a chloroplast-specific RP (PSRP-1), and a protein designated S22 (8). Post-translational modifications are found in many E. coli RPs, although a modification in L16 (Arg 81 ) remains yet to be characterized (see "Results" for plastid L16). We have recently identified all the RPs in spinach plastid 30 S ribosomal subunit, including all its PSRPs and many post-translational modifications (83). The number of RPs in plastid 50 S subunits has so far only been estimated (ϳ35-39; reviewed in Ref.2) and has not been determined.Although the constituents of plastid translational machinery in general are similar to those of E. coli, the genes are distributed in two genome compartments: the plastid and the nucleus. The rRNA and tRNA genes are located in the plastid genome, whereas the genes for processing/modification enzymes, aminoacyl tRNA synthetases, and 60% of the RPs are located in the nuclear genome (1-4). The plastid translation system also differs from the eubacterial system in other significant ways, e.g. chloroplast mRNA is often edited (9); about 60% of chloroplast mRNAs lack canonical ribosome-binding sites found in E. coli mRNAs (10); mRNA levels in chloroplasts remain relatively unchanged through dark/light transitions, whereas protein

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The Plastid Ribosomal Proteins

Cited by 208 publications

References 50 publications

Proteomics Uncovers Proteins Interacting Electrostatically with Thioredoxin in Chloroplasts

Proteomics Uncovers Proteins Interacting Electrostatically with Thioredoxin in Chloroplasts

Cryo-EM study of the spinach chloroplast ribosome reveals the structural and functional roles of plastid-specific ribosomal proteins

The Plastid Ribosomal Proteins

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