Identification of P700—Chlorophyll <i>a</i>—Protein complex as a product of chloroplast protein synthesis

Geetha, V.; Gnanam, A.

doi:10.1016/0014-5793(80)80808-8

Cited by 10 publications

(5 citation statements)

References 20 publications

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“…Since no distinct zone corresponds to LHCP in 2B, we tentatively conclude that also in Euglena the proteins of LHCP are synthesized in and imported from the cytoplasm. With respect to CPr, our results align with reports that isolated spinach and Sorghuin chloroplasts synthesize CPr [ 19,201 respectively. However, CPr was not synthesized in isolated pea chloroplasts [2 11.…”

Section: Resultssupporting

confidence: 91%

Synthesis of polypeptides of the chlorophyll—protein complexes in isolated chloroplasts of Euglena gracilis

Ortiz

Stutz

1980

FEBS Letters

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Section: Resultssupporting

confidence: 91%

Synthesis of polypeptides of the chlorophyll—protein complexes in isolated chloroplasts of Euglena gracilis

Ortiz

Stutz

1980

FEBS Letters

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“…Our experiments, as well as the observations of most other investigators (2,3,5), have shown that isolated chloroplasts using light as an energy source synthesize the a, 13, and E subunits of CF1. In the analysis of total thylakoid membrane proteins from the labeled chloroplasts by radioautography of NaDodSO4/ polyacrylamide gel electrophoresis, we were never able to detect a trace of incorporation of labeled amino acids into either the y or subunits.…”

Section: Discussionsupporting

confidence: 48%

“…3. From these results it appears likely that the y and 8 subunits are synthesized in the cytoplasm as larger precursors and that (3 is synthesized within the chloroplast as a precursor.…”

mentioning

confidence: 78%

Translation of mRNAs for subunits of chloroplast coupling factor 1 in spinach

Watanabe¹,

Price²

1982

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

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The chloroplast coupling factor 1 consists of five nonidentical subunits, three of which (a, P, and e subunits) have been shown in several laboratories to be synthesized within chloroplasts. The site of synthesis of the remaining two (y and 8 subunits) was investigated by analyzing products directed by spinach leaf RNAs in wheat germ and reticulocyte translation systems in vitro. It was found that poly(A)+ RNA directs the synthesis of two distinct polypeptides, one of which is immunochemically related to the y subunit but is 4,000 daltons larger. The other shares antigenic sites with the 8 subunit but is 8,000 daltons larger. When wheat germ or reticulocyte translation systems were programmed with RNAs from purified chloroplasts, the only products related to CF1 that we could detect were a putative precursor of (3, 2,000 daltons larger than the mature subunit, and some smaller polypeptides, which appear to be incomplete translation products of .3. From these results it appears likely that the y and 8 subunits are synthesized in the cytoplasm as larger precursors and that (3 is synthesized within the chloroplast as a precursor.It has been demonstrated in several laboratories that isolated intact chloroplasts, using light as a sole energy source, incorporate labeled amino acids into a, /3, and e subunits of chloroplast coupling factor 1 (CF1) (1-5). Inhibitor studies of CF1 biosynthesis suggested that the remaining subunits of CF1, y and 8, are synthesized in the cytoplasm and imported into the chloroplasts, where the five subunits are assembled into the CF1 complex (6,7). In contrast to this model, Nelson et al. (8) recently reported that, in addition to the a, /3, and E subunits, the y subunit was synthesized within isolated chloroplasts.Using antibodies specific to individual CF1 subunits, Nelson et al. (8) also detected precursors ofthe 8 subunit in the in vitro translation products ofa reticulocyte lysate system programmed by total cell RNA from spinach leaves. A trace amount of radiolabeled polypeptide was immunoprecipitated by anti-'y, but it was not characterized further.Using wheat germ and reticulocyte translation systems in vitro, we find that poly(A)+ RNA from spinach leaves contains mRNAs for polypeptides that may be precursors of y and 8 subunits, whereas chloroplast RNA directs only the synthesis of polypeptides antigenically related to the /3 subunit. MATERIALS AND METHODSExtraction and Fractionation ofSpinach Leaf RNA. Spinach leaves (Spinacia oleracea Linnaeus) were harvested from plants grown in the field, deribbed, washed with water, and used for RNA extraction and chloroplast preparation (9, 10). Total leaf RNA was extracted from 30 g of the leaves by homogenization with 150 ml of 50 mM Tris-HCI, pH 9.0/1% (wt/vol) NaDodSO4 and an equal volume of 90% (vol/vol) phenol (11) in a Waring Blendor. The aqueous phase was collected after centrifugation of the homogenate at 1,500 X g for 15 min and extracted twice more with equal volumes of90% phenol. RNA was precipitated by the addition of 2 ...

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“…We have been able to show that pre-incubation completely eliminates the background incorporation due to native transcripts and renders the organelles an efficient in vitro translation assay system for transcripts of different origin -both prokaryotic and eukaryotic. We effectively substituted this system for other well-known in vitro protein synthesis systems such as wheat germ or rabbit reticulocyte lysate in our studies to establish the origin of messages for different chloroplast proteins such as PSI apoprotein, castorbean chloroplast glycosidase and pyruvate dikinase (Geetha and Gnanam 1980a, 1980b, Geetha et al 1981, Mariappan 1984, Valliammai 1985, Uma Bai 1985, Ananda Krishnan and Gnanam 1987. Cammerino et al (1982), working basically on the same idea, used lysed chloroplasts after treatment with micrococcal nuclease to remove pre-existing mRNAs, since the lysates could not stand the preincubation step we used in our experiments.…”

Section: Isolated Chloroplasts As a Potential In Vitro Transcription mentioning

confidence: 99%

Protein synthesis by isolated chloroplasts

1988

Self Cite

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Isolated chloroplasts show substantial rates of protein synthesis when illuminated. This 'in organello' protein synthesis system has been advantageously utilised to elucidate the coding capacity of chloroplast and the regulation of chloroplast genes. The system is also being used recently to transcribe and translate homologous and heterologous templates. In this mini-review, we attempt to critically ecaluate the available literature and present the current and the prospective lines of research.

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Identification of P700—Chlorophyll a—Protein complex as a product of chloroplast protein synthesis

Cited by 10 publications

References 20 publications

Synthesis of polypeptides of the chlorophyll—protein complexes in isolated chloroplasts of Euglena gracilis

Synthesis of polypeptides of the chlorophyll—protein complexes in isolated chloroplasts of Euglena gracilis

Translation of mRNAs for subunits of chloroplast coupling factor 1 in spinach

Protein synthesis by isolated chloroplasts

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