Biosynthesis of plastocyanin: identification of precursors

Bohner, Herbert; Böhme, Herbert; Böger, Peter

doi:10.1016/0014-5793(81)80410-3

Cited by 14 publications

(8 citation statements)

References 13 publications

(19 reference statements)

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“…The messages for preapoplastocyanin (17,000) and preapopcytochrome c552 (14,000) are both selectable on poly(U)-Sepharose ( Fig. 5 and 6 (8), although reconstitution of spectroscopically visible plastocyanin was not achieved (9). Our experiments were therefore designed to detect immunoreactive precursors in C. reinhardi, if present.…”

Section: Resultsmentioning

confidence: 99%

“…In the green alga Chlamydomonas reinhardi, the Cu2+, plastocyanin is found at a ratio of 1 per 150 chlorophyll molecules (9); whereas when Cu2+ is not available for plastocyanin synthesis S. acutus cells accumulate an immunoreactive polypeptide precursor of plastocyanin of higher apparent molecular weight (approximately 14,000) and perhaps an apoprotein (7,8). At the same time the level of soluble plastidic cytochrome C553 increases to about 1 per 100 chlorophyll molecules (9,40).…”

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confidence: 99%

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Regulation by copper of the expression of plastocyanin and cytochrome c552 in Chlamydomonas reinhardi.

Merchant¹,

Bogorad²

1986

Mol. Cell. Biol.

196

137

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Plastocyanin and cytochrome c552 are interchangeable electron carriers in the photosynthetic electron transfer chains of some cyanobacteria and green algae (P. M. Wood, Eur. J. Biochem. 87:9-19, 1978; G. Sandmann et al., Arch. Microbiol. 134:23-27, 1983). Chlamydomonas reinhardi cells respond to the availability of copper in the medium and accordingly accumulate either plastocyanin (if copper is available) or cytochrome c552 (if copper is not available). The response occurs in both heterotrophically and phototrophically grown cells. We have studied the molecular level at which this response occurs. No immunoreactive polypeptide is detectable under conditions where the mature protein is not spectroscopically detectable. Both plastocyanin and cytochrome c552 appear to be translated (in vitro) from polyadenylated mRNA as precursors of higher molecular weight. RNA was isolated from cells grown either under conditions favorable for the accumulation of plastocyanin (medium with Cu2+) or for the accumulation of cytochrome c552 (without Cu2+ added to the medium). Translatable mRNA for preapoplastocyanin was detected in both RNA preparations, although mature plastocyanin was detected in C. reinhardi cells only when copper was added to the culture. Translatable mRNA for preapocytochrome, on the other hand, was detected only in cells grown under conditions where cytochrome c552 accumulates (i.e., in the absence of copper). We conclude that copper-mediated regulation of plastocyanin and cytochrome c552 accumulation is effected at different levels, the former at the level of stable protein and the latter at the level of stable mRNA.

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Regulation by copper of the expression of plastocyanin and cytochrome c552 in Chlamydomonas reinhardi.

Merchant¹,

Bogorad²

1986

Mol. Cell. Biol.

196

137

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“…Preliminary experiments, using preparations enriched in b6/f complexes after pulse labelling the cells of C. reinhardtii with inhibitors of chloroplast translation, favor this hypothesis. It should be noted that plastocyanin is also of low molecular weight, 10 kDa [39], and is translated in the cytoplasm [40]. However, thylakoids from the ac208 mutant from C. reinhardtii, lacking in plastocyanin [41], still showed a 19.5 kDa polypeptide upon urea-SDS-polyacrylamide gel electrophoresis (unpublished observation).…”

Section: Characterization Of the Subunits Of The B 6/f Complexmentioning

confidence: 99%

Studies on the cytochrome b 6 / f complex. I. Characterization of the complex subunits in Chlamydomonas reinhardtii

Lemaire

Girard‐Bascou

Wollman

et al. 1986

Biochimica et Biophysica Acta (BBA) - Bioenergetics

124

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We have analyzed the heme-associated peroxidase activity in thylakoid membranes from the. green algae Chlamydomonas reinhardtii after electrophoresis in the presence of sodium dodecyl sulfate. Besides cytochrome f and cytochrome b6, we observed peroxidase activity in two other bands, of 34 and 11 kDa, of unknown origin. Characterization of the b6/f complex subunits was undertaken by means of a comparison of the polypeptide deficiencies in several b6/f mutants with the polypeptide content of preparations enriched in b6/f complexes. We conclude that the b6/f complex consists of five subunits. Using site-specific translation inhibitors, we show that cytochrome f, cytochrome b 6 and subunit IV are of chloroplast origin, whereas the Rieske protein and probably subunit V are translated on cytoplasmic ribosomes. A model of assembly of the complex is proposed: a cytochrome moiety, comprising the subunits of chloroplast origin, is assembled in the thylakoid membranes prior to the insertion and assembly of the subunits encoded in the nuclear genome.

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“…--a.& a S& chlorophyll a/b complex (25, 26), plastocyanin (27,28), and ferredoxin-NADP+ oxidoreductase (28). Because most chloroplast proteins are encoded in the nucleus, the elucidation of their biosynthetic pathways and the underlying control mechanisms on the one hand and their phylogenetic origin and evolution on the other will contribute decisively to our understanding of chloroplast biogenesis and evolution.…”

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confidence: 99%

Structural diversity and differential light control of mRNAs coding for angiosperm glyceraldehyde-3-phosphate dehydrogenases

Cerff

Kloppstech

1982

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

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Subunits A and B of chloroplast glyceraldehyde-3-phosphate dehydrogenase are synthesized as higher molecular weight precursors when polyadenylylated mRNA from angiosperm seedlings is translated in vitro by wheat germ ribosomes. The in vivo levels of mRNA coding for these precursors are strongly light dependent, and the increase in translational activity stimulated by continuous white light, relative to dark-grown seedlings, is at least 5-to 10-fold for the seven plant species investigated. As opposed to this, light does not seem to change mRNA levels coding for cytosolic glyceraldehyde-3-phosphate dehydrogenase, and the polypeptides synthesized in vitro have the same size as the authentic subunits. In addition, precursors of the chloroplast enzyme were identified for 12 different angiosperm species and compared with their respective subunits synthesized in vivo. The patterns of the in vitro and in vivo products correlate in several major characteristics. They both display a remarkable interspecific heterogeneity with respect to size and number of polypeptides. The peptide extensions of the enzyme precursors calculated from these data vary between 4,000 and 12,000 daltons and seem to fall into three major size classes. The present data demonstrate that chloroplast glyceraldehyde-3-phosphate dehydrogenase, like its cytosolic counterpart, is encoded in the nucleus. Yet, the two dehydrogenases are controlled differently at both the ontogenetic and phylogenetic levels. They follow separate biosynthetic pathways with respect to light regulation, post-translational processing, and transport and also exhibit different evolutionary rates. The fast evolutionary change observed for the chloroplast enzyme contrasts sharply with the conservative structure and sequence of the cytosolic enzyme.Chloroplast and cytosolic glyceraldehyde-3-phosphate dehydrogenases (GAPDHs) of higher plants are marker proteins for important aspects of chloroplast evolution and biogenesis. Although descendants of a common phylogenetic ancestor (1, 2), they differ in several structural features. The cytosolic NADspecific dehydrogenase is a single homotetramer like the corresponding enzymes from other sources. Chloroplast NADPdependent dehydrogenase is composed of two major isoenzymes A2B2 (isoenzyme 1) and A4 (isoenzyme 2); subunits A and B are distinguished by slightly different molecular weights (A s B) (3). The primary structures ofsubunits A and B are similar but differ considerably from the subunit structure of the cytosolic enzyme (1). The two dehydrogenases also differ in their evolutionary rates, as shown by a recent electrophoretic survey of the enzymes from 12 different angiosperm species (4). Whereas the cytosolic enzyme is an extremely conservative protein, the chloroplast enzyme seems to change rapidly during evolution.This differential control of the two dehydrogenases is not restricted to their evolutionary rates but also can be observed at the ontogenetic level. It has long been known that formation of the chloroplast dehydro...

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Biosynthesis of plastocyanin: identification of precursors

Cited by 14 publications

References 13 publications

Regulation by copper of the expression of plastocyanin and cytochrome c552 in Chlamydomonas reinhardi.

Regulation by copper of the expression of plastocyanin and cytochrome c552 in Chlamydomonas reinhardi.

Studies on the cytochrome b 6 / f complex. I. Characterization of the complex subunits in Chlamydomonas reinhardtii

Structural diversity and differential light control of mRNAs coding for angiosperm glyceraldehyde-3-phosphate dehydrogenases

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