Evidence for a membrane bound NADH-plastoquinone-oxidoreductase in Chlamydomonas reinhardii CW-15

Godde, Doris

doi:10.1007/bf00405878

Cited by 98 publications

(37 citation statements)

References 26 publications

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“…The rate of NADH oxidation in the same study can be calculated as 125 mol electrons mg Ϫ1 Chl h Ϫ1 . Ferricyanide, however, is a much more efficient acceptor of electrons than the more natural acceptor, plastoquinone-1 (Godde, 1982). When this factor is taken into account, the rate of NADH oxidation found by Cuello et al (1995) is comparable to the rate presented here.…”

Section: Discussionsupporting

confidence: 69%

The NAD(P)H Dehydrogenase in Barley Thylakoids Is Photoactivatable and Uses NADPH as well as NADH1

Teicher¹,

Scheller²

1998

Plant Physiology

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An improved light-dependent assay was used to characterize the NAD(P)H dehydrogenase (NDH) in thylakoids of barley (Hordeum vulgare L.). The enzyme was sensitive to rotenone, confirming the involvement of a complex I-type enzyme. NADPH and NADH were equally good substrates for the dehydrogenase. Maximum rates of activity were 10 to 19 mol electrons mg ؊1 chlorophyll h ؊1 , corresponding to about 3% of linear electron-transport rates, or to about 40% of ferredoxin-dependent cyclic electron-transport rates. The NDH was activated by light treatment. After photoactivation, a subsequent light-independent period of about 1 h was required for maximum activation. The NDH could also be activated by incubation of the thylakoids in low-ionic-strength buffer. The kinetics, substrate specificity, and inhibitor profiles were essentially the same for both induction strategies. The possible involvement of ferredoxin:NADP ؉ oxidoreductase (FNR) in the NDH activity could be excluded based on the lack of preference for NADPH over NADH. Furthermore, thenoyltrifluoroacetone inhibited the diaphorase activity of FNR but not the NDH activity. These results also lead to the conclusion that direct reduction of plastoquinone by FNR is negligible.

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Section: Discussionsupporting

confidence: 69%

The NAD(P)H Dehydrogenase in Barley Thylakoids Is Photoactivatable and Uses NADPH as well as NADH1

Teicher¹,

Scheller²

1998

Plant Physiology

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“…The absence of genes encoding subunits of the chloroplast NDH-1 complex was confirmed by the recent sequencing of the C. reinhardtii nuclear genome. Despite the absence of a plastidial NDH-1 complex, significant non-photochemical reduction of PQ has been reported in Chlamydomonas thylakoids (4,5,54). Moreover, both chlororespiration and cyclic electron flow activity around PSI have been reported in the algal species (6,7,55,56).…”

Section: Discussionmentioning

confidence: 99%

Characterization of Nda2, a Plastoquinone-reducing Type II NAD(P)H Dehydrogenase in Chlamydomonas Chloroplasts

Desplats¹,

Mus²,

Cuiné

et al. 2009

Journal of Biological Chemistry

139

100

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Electron transfer pathways associated to oxygenic photosynthesis, including cyclic electron flow around photosystem I and chlororespiration, rely on non-photochemical reduction of plastoquinones (PQs). In higher plant chloroplasts, a bacteriallike NDH complex homologous to complex I is involved in PQ reduction, but such a complex is absent from Chlamydomonas plastids where a type II NAD(P)H dehydrogenase activity has been proposed to operate. With the aim to elucidate the nature of the enzyme-supporting non-photochemical reduction of PQs, one of the type II NAD(P)H dehydrogenases identified in the Chlamydomonas reinhardtii genome (Nda2) was produced as a recombinant protein in Escherichia coli and further characterized. As many type II NAD(P)H dehydrogenases, Nda2 uses NADH as a preferential substrate, but in contrast to the eukaryotic enzymes described so far, contains non-covalently bound FMN as a cofactor. When expressed at a low level, Nda2 complements growth of an E. coli lacking both NDH-1 and NDH-2, but is toxic at high expression levels. Using an antibody raised against the recombinant protein and based on its mass spectrometric identification, we show that Nda2 is localized in thylakoid membranes. Chlorophyll fluorescence measurements performed on thylakoid membranes show that Nda2 is able to interact with thylakoid membranes of C. reinhardtii by reducing PQs from exogenous NADH or NADPH. We discuss the possible involvement of Nda2 in cyclic electron flow around PSI, chlororespiration, and hydrogen production.

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“…In photosynthetic electron transport, electrons can enter the PQ pool by the direct binding of PQ at either the QB or the Qc site; electrons from Fd are known to reduce the PQ pool in PSI cyclic electron transport, although the exact mechanism is unknown. Chlororespiratory electron flow components involved in PQ pool reduction are thought to include the membrane-bound NAD(P)H-PQ oxidoreductase and succinate dehydrogenase (Godde, 1982). Additional mechanisms have been studied in some cyanobacteria where both respiratory and photosynthetic electron transport pathways intersect at the site of the PQ pool (Dominy and Williams, 1987).…”

Section: Discussionmentioning

confidence: 99%

Photochemical and Nonphotochemical Fluorescence Quenching Processes in the Diatom Phaeodactylum tricornutum

1993

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Nonphotochemical fluorescence quenching was found to exist in the dark-adapted state in the diatom Pbaeodactyhm tricornutum. Pretreatment of cells with the uncoupler carbonylcyanide mchlorophenylhydrazone (CCCP) or with nigericin resulted in increases in dark-adapted minimum and maximum fluorescence yields. This suggests that a pH gradient exists across the thylakoid membrane in the dark, which serves to quench fluorescence levels nonphotochemically. The physiological processes involved in establishing this proton gradient were sensitive to anaerobiosis and antimycin A. Based on these results, it is likely that this energization of the thylakoid membrane is due in part to chlororespiration, which involves oxygen-dependent electron flow through the plastoquinone pool. Chlororespiration has been shown previously to occur in diatoms. In addition, we observed that cells treated with 3-(3,4-dichlorophenyI)-l,l-dimethylurea exhibited very strong nonphotochemical quenching when illuminated with actinic light.The rate and extent of this quenching were light-intensity dependent. This quenching was reversed upon addition of CCCP or nigericin and was thus due primarily to the establishment of a pH gradient across the thylakoid membrane. Preincubation of cells with CCCP or nigericin or antimycin A completely abolished this quenching. Cyclic electron transport processes around photosystem I may be involved in establishing this proton gradient across the thylakoid membrane under conditions where linear electron transport is inhibited. At steady state under normal physiological conditions, the qualitative changes in photochemical and nonphotochemical fluorescence quenching at increasing photon flux densities were similar to those in higher plants. However, important quantitative differences existed at limiting and saturating intensities. Dissimilarities in the factors that regulate fluorescence quenching mechanisms in these organisms may account for these differences.One process that competes directly with photochemistry for deactivation of excited-state energy is fluorescence emission from Chl a molecules of the PSII antenna. Changes in the proportion of excited states utilized for photochemistry will result in changes in fluorescence intensity. In recent years, it has been shown that both photochemical and nonphotochemical processes reduce the yield of fluorescence during photosynthesis (Krause et al., 1982). However, our current knowledge of these processes is based primarily on studies with higher plants and green algae. The components involved in qP are present in the PSII reaction center, which has been found to be highly conserved throughout evolution (Thornber, 1986). It is therefore likely that the mechanism of photochemical quenching has also been conserved. In contrast, a diverse group of underlying processes controls qN, whose primary site of action is thought to be in the lightharvesting antennae. With the extensive diversity in the composition of light-harvesting complexes among the algae, it is likely that the m...

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Evidence for a membrane bound NADH-plastoquinone-oxidoreductase in Chlamydomonas reinhardii CW-15

Cited by 98 publications

References 26 publications

The NAD(P)H Dehydrogenase in Barley Thylakoids Is Photoactivatable and Uses NADPH as well as NADH1

The NAD(P)H Dehydrogenase in Barley Thylakoids Is Photoactivatable and Uses NADPH as well as NADH1

Characterization of Nda2, a Plastoquinone-reducing Type II NAD(P)H Dehydrogenase in Chlamydomonas Chloroplasts

Photochemical and Nonphotochemical Fluorescence Quenching Processes in the Diatom Phaeodactylum tricornutum

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