Oxygenic photosynthesis-specific subunits of cyanobacterial NADPH dehydrogenases (original) (raw)
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Higher Plant and Cyanobacterial Photosystem I: Connected Cytochrome Pathways
2016
Oxygenic photosynthesis is the principal converter of sunlight into chemical energy on earth. The conversion of solar energy is catalyzed by four multi-subunit membrane protein complexes: photosystem I (PSI), photosystem II (PSII), the cytochrome b6-f complex (cytb6f) and ATP-synthase (FOF1). These protein complexes are connected by soluble electron carriers that are vital not only for the proper function of ATP and NADPH production but also to render the system highly efficient in different organisms and various environments, some of which are quite harsh. While the main fabric of the membrane complexes is highly conserved, their surfaces and interaction with the soluble factors provide the specificity and fine regulation of the operating system. One of the prime examples for this phenomenon is the cyanobacterial photosynthetic electron transport chain that is situated alongside with respiratory complexes, yet it stays unique by virtue of the interacting soluble components. Cyanoba...
Novel Nuclear-encoded Subunits of the Chloroplast NAD(P)H Dehydrogenase Complex
Journal of Biological Chemistry, 2009
The NAD(P)H dehydrogenase (NDH) complex functions in photosystem I cyclic electron transfer in higher plant chloroplasts and is crucial for plant responses to environmental stress. Chloroplast NDH complex is a close relative to cyanobacterial NDH-1L complex, and all fifteen subunits so far identified in NDH-1L have homologs in the chloroplast NDH complex. Here we report on the identification of two nuclear-encoded proteins NDH48 and NDH45 in higher plant chloroplasts and show their intimate association with the NDH complex. These two membrane proteins are shown to interact with each other and with the NDH complex enriched in stroma thylakoids. Moreover, the deficiency of either the NDH45 protein or the NDH48 protein in respective mutant plants leads to severe defects in both the accumulation and the function of the NDH complex. The NDH48 and NDH45 proteins are not components of the hydrophilic connecting domain of the NDH complex but are strongly attached to the hydrophobic membrane domain. We conclude that NDH48 and NDH45 are novel nuclear-encoded subunits of the chloroplast NDH complex and crucial both for the stable structure and function of the NDH complex.
Frontiers of Biology in China, 2009
Cyanobacteria possess multiple, functionally distinct NADPH dehydrogenase (NDH-1) complexes. In this mini-review, we describe the cyanobacterial NDH-1 complexes by focusing on their identification, regulatory properties, and multiple functions. The multiple functions can be divided into basic and extending functions, and the basic functions are compared with those in chloroplasts. Many questions related to cyanobacterial NDH-1 complexes remain unanswered and are briefly summarized here.
PLANT PHYSIOLOGY, 2001
Tobacco (Nicotiana tabacum var Petit Havana) ndhB-inactivated mutants (ndhB Ϫ ) obtained by plastid transformation (E[2000] Plant Physiol 123: 1337-1350 were used to study the role of the NADH-dehydrogenase complex (NDH) during photosynthesis and particularly the involvement of this complex in cyclic electron flow around photosystem I (PSI). Photosynthetic activity was determined on leaf discs by measuring CO 2 exchange and chlorophyll fluorescence quenchings during a dark-to-light transition. In the absence of treatment, both non-photochemical and photochemical fluorescence quenchings were similar in ndhB Ϫ and wild type (WT). When leaf discs were treated with 5 m antimycin A, an inhibitor of cyclic electron flow around PSI, both quenchings were strongly affected. At steady state, maximum photosynthetic electron transport activity was inhibited by 20% in WT and by 50% in ndhB Ϫ . Under non-photorespiratory conditions (2% O 2 , 2,500 L L Ϫ1 CO 2 ), antimycin A had no effect on photosynthetic activity of WT, whereas a 30% inhibition was observed both on quantum yield of photosynthesis assayed by chlorophyll fluorescence and on CO 2 assimilation in ndhB Ϫ . The effect of antimycin A on ndhB Ϫ could not be mimicked by myxothiazol, an inhibitor of the mitochondrial cytochrome bc 1 complex, therefore showing that it is not related to an inhibition of the mitochondrial electron transport chain but rather to an inhibition of cyclic electron flow around PSI. We conclude to the existence of two different pathways of cyclic electron flow operating around PSI in higher plant chloroplasts. One of these pathways, sensitive to antimycin A, probably involves ferredoxin plastoquinone reductase, whereas the other involves the NDH complex. The absence of visible phenotype in ndhB Ϫ plants under normal conditions is explained by the complement of these two pathways in the supply of extra-ATP for photosynthesis. von Jagow G, Engel WD (1981) Complete inhibition of electron transfer from ubiquinol to cytochrome b by the combined action of antimycin and myxothiazol. FEBS Lett 136: 19-24 Woo KC (1983) Evidence for cyclic photophosphorylation during 14 CO 2 fixation in intact chloroplasts: studies with antimycin A, nitrite, and oxaloacetate. Plant Physiol 72: 313-320 Yu L, Zhao J, Mü hlenhoff U, Bryant DA, Golbeck JH (1993) Psae is required for in vivo cyclic electron flox around PS I in the cyanobacterium Synechococcus sp PCC 7002. Plant Physiol 103: 171-180 NADH-Dehydrogenase Complex in Cyclic Electron Flow
Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2000
Relative to ferredoxin :NADP reductase (FNR) from chloroplasts, the comparable enzyme in cyanobacteria contains an additional 9 kDa domain at its amino-terminus. The domain is homologous to the phycocyanin associated linker polypeptide CpcD of the light harvesting phycobilisome antennae. The phenotypic consequences of the genetic removal of this domain from the petH gene, which encodes FNR, have been studied in Synechocystis PCC 6803. The in frame deletion of 75 residues at the amino-terminus, rendered chloroplast length FNR enzyme with normal functionality in linear photosynthetic electron transfer. Salt shock correlated with increased abundance of petH mRNA in the wild-type and mutant alike. The truncation stopped salt stress-inducible increase of Photosystem I-dependent cyclic electron flow. Both photoacoustic determination of the storage of energy from Photosystem I specific far-red light, and the re-reduction kinetics of P700 , suggest lack of function of the truncated FNR in the plastoquinone^cytochrome b 6 f complex reductase step of the PS I-dependent cyclic electron transfer chain. Independent gold-immunodecoration studies and analysis of FNR distribution through activity staining after native polyacrylamide gelelectrophoresis showed that association of FNR with the thylakoid membranes of Synechocystis PCC 6803 requires the presence of the extended amino-terminal domain of the enzyme. The truncated vpetH gene was also transformed into a NAD(P)H dehydrogenase (NDH1) deficient mutant of Synechocystis PCC 6803 (strain M55) (T. Ogawa, Proc. Natl. Acad. Sci. USA 88 (1991) 4275^4279). Phenotypic characterisation of the double mutant supported our conclusion that both the NAD(P)H dehydrogenase complex and FNR contribute independently to the quinone cytochrome b 6 f reductase step in PS I-dependent cyclic electron transfer. The distribution, binding properties and function of FNR in the model cyanobacterium Synechocystis PCC 6803 will be discussed. ß 2000 Elsevier Science B.V. All rights reserved. 0005-2728 / 00 / $^see front matter ß 2000 Elsevier Science B.V. All rights reserved. PII: S 0 0 0 5 -2 7 2 8 ( 0 0 ) 0 0 0 7 2 -4 Abbreviations
Journal of Applied Phycology, 2009
Nostoc flagelliforme is a terrestrial cyanobacterium, and water is one of the most important factors limiting its photosynthetic yield. The aims of the present study were to investigate the effect of cell water amount on photosynhetic yield and the role of NADPH dehydrogenase (NDH-1)mediated cyclic electron transport in this effect. The role of NDH-1-mediated cyclic electron transport was assessed by measuring NDH-1 expression, several chlorophyll fluorescence parameters, and photosynthetic O 2 evolution at several time points after cell water had been redried. The results indicated that the highest rate of NDH-1-mediated cyclic electron transport, reflected by post-illumination increase in chlorophyll fluorescence and NDH-1 amount, was only obtained when the cells contained about 1.8 times water relative to dry weight. This was consistent with observed changes in photosynthetic yield, reflected by O 2 evolution. However, the highest photochemical activity of photosystem II, reflected by F v /F m and qP, could be maintained when N. flagelliforme cells included water in a broad range. This implies that the effect of cell water amount on photosynthetic yield is related to NDH-1-mediated cyclic electron transport. The possible mechanisms of this effect are discussed.