Association of ferredoxin‐NADP<sup>+</sup> oxidoreductase with the chloroplast cytochrome <i>b‐f</i> complex

Clark, Robert D.; Hawkesford, Malcolm J.; Coughlan, Sean; Bennett, John; Hínd, Geoffrey

doi:10.1016/0014-5793(84)81092-3

Cited by 96 publications

(47 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Leaf form FNR has also been implicated in cyclic electron transfer around photosystem I (PSI), which generates a proton gradient across the thylakoid membrane, resulting in ATP production without accumulation of reducing equivalents (Johnson, 2005). In cyclic electron transfer, electrons can be recycled from reduced ferredoxin or NADPH either directly to plastoquinone (Clark et al, 1984;Zhang et al, 2001), or alternatively via the type I NAD(P)H dehydrogenase (NDH-1) complex to plastoquinone and subsequently to the cytochrome (cyt)-b 6 f complex. The latter route is known to be involved in dark reduction of the plastoquinone pool (Burrows et al, 1998;Joet et al, 2001;Kofer et al, 1998;Shikanai et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Structural and functional characterization of ferredoxin‐NADP⁺‐oxidoreductase using knock‐out mutants of Arabidopsis

et al. 2007

View full text Add to dashboard Cite

SummaryIn Arabidopsis thaliana, the chloroplast-targeted enzyme ferredoxin-NADP + -oxidoreductase (FNR) exists as two isoforms, AtLFNR1 and AtLFNR2, encoded by the genes At5g66190 and At1g20020, respectively. Both isoforms are evenly distributed between the thylakoids and soluble stroma, and they are separated by twodimensional electrophoresis in four distinct spots, suggesting post-translational modification of both isoforms. To reveal the functional specificity of AtLFNR1, we have characterized the T-DNA insertion mutants with an interrupted At5g66190 gene. Absence of AtLFNR1 resulted in a reduced size of the rosette with pale green leaves, which was accompanied by a low content of chlorophyll and light-harvesting complex proteins. Also the photosystem I/photosystem II (PSI/PSII) ratio was significantly lower in the mutant, but the PSII activity, measured as the F V /F M ratio, remained nearly unchanged and the excitation pressure of PSII was lower in the mutants than in the wild type. A slow re-reduction rate of P700 measured in the mutant plants suggested that AtLFNR1 is involved in PSI-dependent cyclic electron flow. Impaired function of FNR also resulted in decreased capacity for carbon fixation, whereas nitrogen metabolism was upregulated. In the absence of AtLFNR1, we found AtLFNR2 exclusively in the stroma, suggesting that AtLFNR1 is required for membrane attachment of FNR. Structural modeling supports the formation of a AtLFNR1-AtLFNR2 heterodimer that would mediate the membrane attachment of AtLFNR2. Dimer formation, in turn, might regulate the distribution of electrons between the cyclic and linear electron transfer pathways according to environmental cues.

show abstract

Section: Introductionmentioning

confidence: 99%

Structural and functional characterization of ferredoxin‐NADP⁺‐oxidoreductase using knock‐out mutants of Arabidopsis

et al. 2007

View full text Add to dashboard Cite

show abstract

“…It has been reported that FNR in higher plant chloroplasts is localized peripherally on the stromal side of thylakoid membranes through association with an intrinsic protein (Vallejos et al, 1984;Matthijs et al, 1986), PSI (Andersen et al, 1992), cytochrome (cyt) b 6 f complex (Clark et al, 1984;Zhang et al, 2001), and NAD(P)H dehydrogenase complex (Quiles et al, 2000).…”

Section: In Higher Plants Ferredoxin (Fd):nadph Oxidoreductase (Fnr)mentioning

confidence: 99%

Three Maize Leaf Ferredoxin:NADPH Oxidoreductases Vary in Subchloroplast Location, Expression, and Interaction with Ferredoxin

et al. 2005

View full text Add to dashboard Cite

In higher plants, ferredoxin (Fd):NADPH oxidoreductase (FNR) catalyzes reduction of NADP1 in the final step of linear photosynthetic electron transport and is also implicated in cyclic electron flow. We have identified three leaf FNR isoenzymes (LFNR1, LFNR2, and LFNR3) in maize (Zea mays) chloroplasts at approximately equivalent concentrations. Fractionation of chloroplasts showed that, while LFNR3 is an exclusively soluble enzyme, LFNR1 is only found at the thylakoid membrane and LFNR2 has a dual location. LFNR1 and LFNR2 were found to associate with the cytochrome b 6 f complex following its partial purification. We cloned LFNR3 and produced all three isoenzymes as stable, soluble proteins. Measurement of Fd reduction ability showed no significant differences between these recombinant enzymes. Column chromatography revealed variation between the interaction mechanisms of LFNR1 and LFNR2 with Fd, as detected by differential dependence on specific intermolecular salt bridges and variable sensitivity of interactions to changes in pH. A comparison of LFNR transcripts in leaves of plants grown on variable nitrogen regimes revealed that LFNR1 and LFNR2 transcripts are relatively more abundant under conditions of high demand for NADPH. These results are discussed in terms of the functional differentiation of maize LFNR isoenzymes.Ferredoxin (Fd):NADPH oxidoreductase (FNR; EC 1.18.1.2) is a flavoenzyme that catalyzes reduction of NADP 1 or oxidation of NADPH through electron transfer with Fd. In the final step of photosynthetic electron transport, FNR reduces NADP 1

show abstract

“…Alternatively, electrons may be transferred from PSI to the high-potential cyt b localized on the stromal side of the cyt bf complex. This transfer could involve either Fd alone or an additional stromal enzyme able to bind the cyt bf complex, for instance Fd-NADP-reductase (FNR), which stoichiometrically copurifies with the cyt bf complex (14,15). It has been proposed that the cyclic electron transfer chain can be organized in supercomplexes that associate PSI, cyt bf, and FNR (reviewed in ref.…”

mentioning

confidence: 99%

Cyclic electron transfer in plant leaf

Joliot

2002

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

330

222

View full text Add to dashboard Cite

The turnover of linear and cyclic electron flows has been determined in fragments of dark-adapted spinach leaf by measuring the kinetics of fluorescence yield and of the transmembrane electrical potential changes under saturating illumination. When Photosystem (PS) II is inhibited, a cyclic electron flow around PSI operates transiently at a rate close to the maximum turnover of photosynthesis. When PSII is active, the cyclic flow operates with a similar rate during the first seconds of illumination. The high efficiency of the cyclic pathway implies that the cyclic and the linear transfer chains are structurally isolated one from the other. We propose that the cyclic pathway operates within a supercomplex including one PSI, one cytochrome bf complex, one plastocyanin, and one ferredoxin. The cyclic process induces the synthesis of ATP needed for the activation of the Benson-Calvin cycle. A fraction of PSI (ϳ50%), not included in the supercomplexes, participates in the linear pathway. The illumination would induce a dissociation of the supercomplexes that progressively increases the fraction of PSI involved in the linear pathway.I t is widely assumed that the photosynthetic process in algae or plants operates according to two nonmutually exclusive modes: linear and cyclic electron flows. In the linear mode, electrons are transferred from water to the NADP via the three major complexes of the photosynthetic chain, Photosystem (PS) II, cytochrome b 6 f (cyt bf), and PSI (1). Little is known, however, about the mechanism of the cyclic process that was first characterized by Arnon (2) in broken chloroplasts. In unicellular algae, a cyclic electron flow operates in anaerobic conditions (3, 4). In higher plants, the occurrence of a cyclic flow in vivo is a subject of controversy (reviewed in refs. 5 and 6). On the basis of a parallel measurement of PSI and PSII yield, Harbinson and Foyer (7) concluded that a cyclic process operates at a significant rate during the induction period but not in steady-state conditions. Heber et al. (8) reported that a decrease of CO 2 concentration stimulates the cyclic flow. At variance, Klughammer and Schreiber (9) conclude that no significant cyclic flow contributes to PSI turnover during the induction period or in the absence of CO 2 . It is generally reported that in steady-state conditions in the presence of CO 2 , the linear pathway is largely favored with respect to the cyclic flow. Bendall and Manasse (6) concluded that the rate of the cyclic process is no more than 3% of that of the linear pathway.It is agreed that both PSI and cyt bf complexes are involved in the cyclic flow. Yet, the mechanism of electron transfer between the PSI acceptor side and the cyt bf complex is not clearly identified. It has been proposed that reduced ferredoxin (Fd) or NADP may transfer electrons to plastoquinone (PQ) by way of a membrane-bound Fd PQ-reductase or NADP dehydrogenase (NDH). Plastoquinol (PQH 2 ) is then reoxidized at the PQH 2 -oxidizing site Q o of the cyt bf complex. This hypothesis i...

show abstract

Association of ferredoxin‐NADP⁺ oxidoreductase with the chloroplast cytochrome b‐f complex

Cited by 96 publications

References 30 publications

Structural and functional characterization of ferredoxin‐NADP⁺‐oxidoreductase using knock‐out mutants of Arabidopsis

Structural and functional characterization of ferredoxin‐NADP⁺‐oxidoreductase using knock‐out mutants of Arabidopsis

Three Maize Leaf Ferredoxin:NADPH Oxidoreductases Vary in Subchloroplast Location, Expression, and Interaction with Ferredoxin

Cyclic electron transfer in plant leaf

Contact Info

Product

Resources

About

Association of ferredoxin‐NADP+ oxidoreductase with the chloroplast cytochrome b‐f complex

Cited by 96 publications

References 30 publications

Structural and functional characterization of ferredoxin‐NADP+‐oxidoreductase using knock‐out mutants of Arabidopsis

Structural and functional characterization of ferredoxin‐NADP+‐oxidoreductase using knock‐out mutants of Arabidopsis

Three Maize Leaf Ferredoxin:NADPH Oxidoreductases Vary in Subchloroplast Location, Expression, and Interaction with Ferredoxin

Cyclic electron transfer in plant leaf

Contact Info

Product

Resources

About

Association of ferredoxin‐NADP⁺ oxidoreductase with the chloroplast cytochrome b‐f complex

Structural and functional characterization of ferredoxin‐NADP⁺‐oxidoreductase using knock‐out mutants of Arabidopsis

Structural and functional characterization of ferredoxin‐NADP⁺‐oxidoreductase using knock‐out mutants of Arabidopsis