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Allan G. Rasmusson - One of the best experts on this subject based on the ideXlab platform.
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suppression of external NADPH Dehydrogenase ndb1 in arabidopsis thaliana confers improved tolerance to ammonium toxicity via efficient glutathione redox metabolism
International Journal of Molecular Sciences, 2018Co-Authors: Anna Podgorska, Allan G. Rasmusson, Monika Ostaszewskabugajska, Klaudia Borysiuk, Agata Tarnowska, Monika Jakubiak, Maria Burian, Bozena SzalAbstract:Environmental stresses, including ammonium (NH4+) nourishment, can damage key mitochondrial components through the production of surplus reactive oxygen species (ROS) in the mitochondrial electron transport chain. However, alternative electron pathways are significant for efficient reductant dissipation in mitochondria during ammonium nutrition. The aim of this study was to define the role of external NADPH-Dehydrogenase (NDB1) during oxidative metabolism of NH4+-fed plants. Most plant species grown with NH4+ as the sole nitrogen source experience a condition known as “ammonium toxicity syndrome”. Surprisingly, transgenic Arabidopsis thaliana plants suppressing NDB1 were more resistant to NH4+ treatment. The NDB1 knock-down line was characterized by milder oxidative stress symptoms in plant tissues when supplied with NH4+. Mitochondrial ROS accumulation, in particular, was attenuated in the NDB1 knock-down plants during NH4+ treatment. Enhanced antioxidant defense, primarily concerning the glutathione pool, may prevent ROS accumulation in NH4+-grown NDB1-suppressing plants. We found that induction of glutathione peroxidase-like enzymes and peroxiredoxins in the NDB1-surpressing line contributed to lower ammonium-toxicity stress. The major conclusion of this study was that NDB1 suppression in plants confers tolerance to changes in redox homeostasis that occur in response to prolonged ammonium nutrition, causing cross tolerance among plants.
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the ca2 regulation of the mitochondrial external NADPH Dehydrogenase in plants is controlled by cytosolic ph
PLOS ONE, 2015Co-Authors: Mengshu Hao, Yunjun Liu, Anna M Jensen, Ann Sofie Boquist, Allan G. RasmussonAbstract:NADPH is a key reductant carrier that maintains internal redox and antioxidant status, and that links biosynthetic, catabolic and signalling pathways. Plants have a mitochondrial external NADPH oxidation pathway, which depends on Ca2+ and pH in vitro, but concentrations of Ca2+ needed are not known. We have determined the K0.5(Ca2+) of the external NADPH Dehydrogenase from Solanum tuberosum mitochondria and membranes of E. coli expressing Arabidopsis thaliana NDB1 over the physiological pH range using O2 and decylubiquinone as electron acceptors. The K0.5(Ca2+) of NADPH oxidation was generally higher than for NADH oxidation, and unlike the latter, it depended on pH. At pH 7.5, K0.5(Ca2+) for NADPH oxidation was high (≈100 μM), yet 20-fold lower K0.5(Ca2+) values were determined at pH 6.8. Lower K0.5(Ca2+) values were observed with decylubiquinone than with O2 as terminal electron acceptor. NADPH oxidation responded to changes in Ca2+ concentrations more rapidly than NADH oxidation did. Thus, cytosolic acidification is an important activator of external NADPH oxidation, by decreasing the Ca2+-requirements for NDB1. The results are discussed in relation to the present knowledge on how whole cell NADPH redox homeostasis is affected in plants modified for the NDB1 gene.
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suppression of the external mitochondrial NADPH Dehydrogenase ndb1 in arabidopsis thaliana affects central metabolism and vegetative growth
Molecular Plant, 2014Co-Authors: Saba V Wallstrom, Igor Florezsarasa, Wagner L Araujo, Mari Aidemark, Maria Fernandezfernandez, Alisdair R Fernie, Miquel Ribascarbo, Allan G. RasmussonAbstract:ABSTRACT Ca 2+ -dependent oxidation of cytosolic NADPH is mediated by NDB1, which is an external type II NADPH Dehydrogenase in the plant mitochondrial electron transport chain. Using RNA interference, the NDB1 transcript was suppressed by 80% in Arabidopsis thaliana plants, and external Ca 2+ -dependent NADPH Dehydrogenase activity became undetectable in isolated mitochondria. This was linked to a decreased level of NADP + in rosettes of the transgenic lines. Sterile-grown transgenic seedlings displayed decreased growth specifically on glucose, and respiratory metabolism of 14 C-glucose was increased. On soil, NDB1 -suppressing plants had a decreased vegetative biomass, but leaf maximum quantum efficiency of photosystem II and CO 2 assimilation rates, as well as total respiration, were similar to the wild-type. The in vivo alternative oxidase activity and capacity were also similar in all genotypes. Metabolic profiling revealed decreased levels of sugars, citric acid cycle intermediates, and amino acids in the transgenic lines. The NDB1 -suppression induced transcriptomic changes associated with protein synthesis and glucosinolate and jasmonate metabolism. The transcriptomic changes also overlapped with changes observed in a mutant lacking ABAINSENSITIVE4 and in A. thaliana overexpressing stress tolerance genes from rice. The results thus indicate that A. thaliana NDB1 modulates NADP(H) reduction levels, which in turn affect central metabolism and growth, and interact with defense signaling. SUMMARY The external mitochondrial NADPH Dehydrogenase in Arabidopsis is shown to modify the cellular NADP(H) reduction level. This is in turn associated with a modified citric acid cycle, sugar metabolism, and growth, as well as changes in stress defense-associated gene expression.
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a redox mediated modulation of stem bolting in transgenic nicotiana sylvestris differentially expressing the external mitochondrial NADPH Dehydrogenase
Plant Physiology, 2009Co-Authors: Yunjun Liu, Agnieszka M. Michalecka, Fredrik E B Norberg, Saba V Wallstrom, Alisdair R Fernie, Adriano Nunesnesi, Ida Lager, Susanne Widell, Kenneth M Fredlund, Allan G. RasmussonAbstract:Cytosolic NADPH can be directly oxidized by a calcium-dependent NADPH Dehydrogenase, NDB1, present in the plant mitochondrial electron transport chain. However, little is known regarding the impact of modified cytosolic NADPH reduction levels on growth and metabolism. Nicotiana sylvestris plants overexpressing potato (Solanum tuberosum) NDB1 displayed early bolting, whereas sense suppression of the same gene led to delayed bolting, with consequential changes in flowering time. The phenotype was dependent on light irradiance but not linked to any change in biomass accumulation. Whereas the leaf NADPH/NADP+ ratio was unaffected, the stem NADPH/NADP+ ratio was altered following the genetic modification and strongly correlated with the bolting phenotype. Metabolic profiling of the stem showed that the NADP(H) change affected relatively few, albeit central, metabolites, including 2-oxoglutarate, glutamate, ascorbate, sugars, and hexose-phosphates. Consistent with the phenotype, the modified NDB1 level also affected the expression of putative floral meristem identity genes of the SQUAMOSA and LEAFY types. Further evidence for involvement of the NADPH redox in stem development was seen in the distinct decrease in the stem apex NADPH/NADP+ ratio during bolting. Additionally, the potato NDB1 protein was specifically detected in mitochondria, and a survey of its abundance in major organs revealed that the highest levels are found in green stems. These results thus strongly suggest that NDB1 in the mitochondrial electron transport chain can, by modifying cell redox levels, specifically affect developmental processes.
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the mitochondrial external NADPH Dehydrogenase modulates the leaf NADPH nadp ratio in transgenic nicotiana sylvestris
Plant and Cell Physiology, 2008Co-Authors: Yunjun Liu, Rosine De Paepe, Fredrik E B Norberg, Anna Szilagyi, Hanserik Akerlund, Allan G. RasmussonAbstract:Plant mitochondria contain alternative external NAD(P)H Dehydrogenases, which oxidise cytosolic NADH or NADPH and reduce ubiquinone without inherent linkage to proton pumping and ATP production. In potato, St-NDB1 is an external Ca2+-dependent NADPH Dehydrogenase. The physiological function of this enzyme was investigated in homozygous Nicotiana sylvestris lines overexpressing St-ndb1 and co-suppressing St-ndb1 and an N. sylvestris ndb1. In leaf mitochondria isolated from the overexpressor lines, higher activity of alternative oxidase (AOX) was detected. However, the AOX induction was substantially weaker than in the complex I deficient CMSII mutant, previously shown to contain elevated amounts of NAD(P)H Dehydrogenases and AOX. An aox1b and an aox2 gene were up-regulated in CMSII, but only aox1b showed a response, albeit smaller, in the transgenic lines, indicating differences in AOX activation between the genotypes. As in CMSII, the increase of AOX in the overexpressing lines was not due to a general oxidative stress. The lines overexpressing St-ndb1 had consistently lowered leaf NADPH/NADP+ ratios in the light and variably decreased levels in darkness, but unchanged NADH/NAD+ ratios. CMSII instead had similar NADPH/NADP+ and lower NADH/NAD+ ratios than wildtype. These results demonstrate that St-NDB1 is able to modulate the cellular balance of NADPH and NADP+ at least in the day and that reduction of NADP(H) and NAD(H) is independently controlled. Similar growth rates, chloroplast malate Dehydrogenase activation and xanthophyll ratios indicate that the change in reduction does not communicate to the chloroplast, and that the cell tolerates significant changes in NADP(H) reduction without deleterious effects. (Less)
Teruo Ogawa - One of the best experts on this subject based on the ideXlab platform.
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subunit q is required to stabilize the large complex of NADPH Dehydrogenase in synechocystis sp strain pcc 6803
Plant Physiology, 2015Co-Authors: Jiaohong Zhao, Fudan Gao, Weiqiong Rong, Teruo OgawaAbstract:Two major complexes of NADPH Dehydrogenase (NDH-1) have been identified in cyanobacteria. A large complex (NDH-1L) contains NdhD1, NdhF1, and NdhP, which are absent in a medium size complex (NDH-1M). They play important roles in respiration, NDH-1-dependent cyclic electron transport around photosystem I, and CO2 uptake. Two mutants sensitive to high light for growth and impaired in cyclic electron transport around photosystem I were isolated from the cyanobacterium Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in an open reading frame encoding a product highly homologous to NdhQ, a single-transmembrane small subunit of the NDH-1L complex, identified in Thermosynechococcus elongatus by proteomics strategy. Deletion of ndhQ disassembled about one-half of the NDH-1L to NDH-1M and consequently impaired respiration, but not CO2 uptake. During prolonged incubation of the thylakoid membrane with n-dodecyl-β-D-maltoside at room temperature, the rest of the NDH-1L in ΔndhQ was disassembled completely to NDH-1M and was much faster than in the wild type. In the ndhP-deletion mutant (ΔndhP) background, absence of NdhQ almost completely disassembled the NDH-1L to NDH-1M, similar to the results observed in the ΔndhD1/ΔndhD2 mutant. We therefore conclude that both NdhQ and NdhP are essential to stabilize the NDH-1L complex.
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ndho a subunit of NADPH Dehydrogenase destabilizes medium size complex of the enzyme in synechocystis sp strain pcc 6803
Journal of Biological Chemistry, 2014Co-Authors: Jiaohong Zhao, Jingsong Zhang, Teruo OgawaAbstract:Two mutants that grew faster than the wild-type (WT) strain under high light conditions were isolated from Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in ssl1690 encoding NdhO. Deletion of ndhO increased the activity of NADPH Dehydrogenase (NDH-1)-dependent cyclic electron transport around photosystem I (NDH-CET), while overexpression decreased the activity. Although deletion and overexpression of ndhO did not have significant effects on the amount of other subunits such as NdhH, NdhI, NdhK, and NdhM in the cells, the amount of these subunits in the medium size NDH-1 (NDH-1M) complex was higher in the ndhO-deletion mutant and much lower in the overexpression strain than in the WT. NdhO strongly interacts with NdhI and NdhK but not with other subunits. NdhI interacts with NdhK and the interaction was blocked by NdhO. The blocking may destabilize the NDH-1M complex and repress the NDH-CET activity. When cells were transferred from growth light to high light, the amounts of NdhI and NdhK increased without significant change in the amount of NdhO, thus decreasing the relative amount of NdhO. This might have decreased the blocking, thereby stabilizing the NDH-1M complex and increasing the NDH-CET activity under high light conditions.
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ndhp is an exclusive subunit of large complex of NADPH Dehydrogenase essential to stabilize the complex in synechocystis sp strain pcc 6803
Journal of Biological Chemistry, 2014Co-Authors: Jingsong Zhang, Teruo Ogawa, Fudan Gao, Jiaohong Zhao, Quanxi WangAbstract:Two major complexes of NADPH Dehydrogenase (NDH-1) have been identified in cyanobacteria. A large complex (NDH-1L) contains NdhD1 and NdhF1, which are absent in a medium size complex (NDH-1M). They play important roles in respiration, cyclic electron transport around photosystem I, and CO2 acquisition. Two mutants sensitive to high light for growth and impaired in NDH-1-mediated cyclic electron transfer were isolated from Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in sml0013 encoding NdhP, a single transmembrane small subunit of the NDH-1 complex. During prolonged incubation of the wild type thylakoid membrane with n-dodecyl β-d-maltoside (DM), about half of the NDH-1L was disassembled to NDH-1M and the rest decomposed completely without forming NDH-1M. In the ndhP deletion mutant (ΔndhP), disassembling of NDH-1L to NDH-1M occurred even on ice, and decomposition to a small piece occurred at room temperature much faster than in the wild type. Deletion of the C-terminal tail of NdhP gave the same result. The C terminus of NdhP was tagged by YFP-His6. Blue native gel electrophoresis of the DM-treated thylakoid membrane of this strain and Western analysis using the antibody against GFP revealed that NdhP-YFP-His6 was exclusively confined to NDH-1L. During prolonged incubation of the thylakoid membrane of the tagged strain with DM at room temperature, NDH-1L was partially disassembled to NDH-1M and the 160-kDa band containing NdhP-YFP-His6 and possibly NdhD1 and NdhF1. We therefore conclude that NdhP, especially its C-terminal tail, is essential to assemble NdhD1 and NdhF1 and stabilize the NDH-1L complex.
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Cyanobacterial NADPH Dehydrogenase complexes.
Photosynthesis Research, 2007Co-Authors: Teruo OgawaAbstract:Cyanobacteria possess functionally distinct multiple NADPH Dehydrogenase (NDH-1) complexes that are essential to CO2 uptake, photosystem-1 cyclic electron transport and respiration. The unique nature of cyanobacterial NDH-1 complexes is the presence of subunits involved in CO2 uptake. Other than CO2 uptake, chloroplastic NDH-1 complex has a similar role as cyanobacterial NDH-1 complexes in photosystem-1 cyclic electron transport and respiration (chlororespiration). In this mini-review we focus on the structure and function of cyanobacterial NDH-1 complexes and their phylogeny. The function of chloroplastic NDH-1 complex and characteristics of plants defective in NDH-1 are also described for comparison.
Lanzhen Wei - One of the best experts on this subject based on the ideXlab platform.
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ndhv is a subunit of NADPH Dehydrogenase essential for cyclic electron transport in synechocystis sp strain pcc 6803
Plant Physiology, 2016Co-Authors: Fudan Gao, Jiaohong Zhao, Xiaozhuo Wang, Shen Qin, Lanzhen WeiAbstract:Two mutants sensitive to heat stress for growth and impaired in NADPH Dehydrogenase (NDH-1)-dependent cyclic electron transport around photosystem I (NDH-CET) were isolated from the cyanobacterium Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in the same sll0272 gene, encoding a protein highly homologous to NdhV identified in Arabidopsis (Arabidopsis thaliana). Deletion of the sll0272 gene (ndhV) did not influence the assembly of NDH-1 complexes and the activities of CO2 uptake and respiration but reduced the activity of NDH-CET. NdhV interacted with NdhS, a ferredoxin-binding subunit of cyanobacterial NDH-1 complex. Deletion of NdhS completely abolished NdhV, but deletion of NdhV had no effect on the amount of NdhS. Reduction of NDH-CET activity was more significant in ΔndhS than in ΔndhV. We therefore propose that NdhV cooperates with NdhS to accept electrons from reduced ferredoxin.
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effect of cell water amount on photosynthetic yield in the cyanobacterium nostoc flagelliforme and involvement of NADPH Dehydrogenase mediated cyclic electron transport
Journal of Applied Phycology, 2009Co-Authors: Lanzhen Wei, Quanxi WangAbstract: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 O2 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 O2 evolution. However, the highest photochemical activity of photosystem II, reflected by Fv/Fm 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.
Jiaohong Zhao - One of the best experts on this subject based on the ideXlab platform.
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ndhv is a subunit of NADPH Dehydrogenase essential for cyclic electron transport in synechocystis sp strain pcc 6803
Plant Physiology, 2016Co-Authors: Fudan Gao, Jiaohong Zhao, Xiaozhuo Wang, Shen Qin, Lanzhen WeiAbstract:Two mutants sensitive to heat stress for growth and impaired in NADPH Dehydrogenase (NDH-1)-dependent cyclic electron transport around photosystem I (NDH-CET) were isolated from the cyanobacterium Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in the same sll0272 gene, encoding a protein highly homologous to NdhV identified in Arabidopsis (Arabidopsis thaliana). Deletion of the sll0272 gene (ndhV) did not influence the assembly of NDH-1 complexes and the activities of CO2 uptake and respiration but reduced the activity of NDH-CET. NdhV interacted with NdhS, a ferredoxin-binding subunit of cyanobacterial NDH-1 complex. Deletion of NdhS completely abolished NdhV, but deletion of NdhV had no effect on the amount of NdhS. Reduction of NDH-CET activity was more significant in ΔndhS than in ΔndhV. We therefore propose that NdhV cooperates with NdhS to accept electrons from reduced ferredoxin.
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subunit q is required to stabilize the large complex of NADPH Dehydrogenase in synechocystis sp strain pcc 6803
Plant Physiology, 2015Co-Authors: Jiaohong Zhao, Fudan Gao, Weiqiong Rong, Teruo OgawaAbstract:Two major complexes of NADPH Dehydrogenase (NDH-1) have been identified in cyanobacteria. A large complex (NDH-1L) contains NdhD1, NdhF1, and NdhP, which are absent in a medium size complex (NDH-1M). They play important roles in respiration, NDH-1-dependent cyclic electron transport around photosystem I, and CO2 uptake. Two mutants sensitive to high light for growth and impaired in cyclic electron transport around photosystem I were isolated from the cyanobacterium Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in an open reading frame encoding a product highly homologous to NdhQ, a single-transmembrane small subunit of the NDH-1L complex, identified in Thermosynechococcus elongatus by proteomics strategy. Deletion of ndhQ disassembled about one-half of the NDH-1L to NDH-1M and consequently impaired respiration, but not CO2 uptake. During prolonged incubation of the thylakoid membrane with n-dodecyl-β-D-maltoside at room temperature, the rest of the NDH-1L in ΔndhQ was disassembled completely to NDH-1M and was much faster than in the wild type. In the ndhP-deletion mutant (ΔndhP) background, absence of NdhQ almost completely disassembled the NDH-1L to NDH-1M, similar to the results observed in the ΔndhD1/ΔndhD2 mutant. We therefore conclude that both NdhQ and NdhP are essential to stabilize the NDH-1L complex.
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ndho a subunit of NADPH Dehydrogenase destabilizes medium size complex of the enzyme in synechocystis sp strain pcc 6803
Journal of Biological Chemistry, 2014Co-Authors: Jiaohong Zhao, Jingsong Zhang, Teruo OgawaAbstract:Two mutants that grew faster than the wild-type (WT) strain under high light conditions were isolated from Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in ssl1690 encoding NdhO. Deletion of ndhO increased the activity of NADPH Dehydrogenase (NDH-1)-dependent cyclic electron transport around photosystem I (NDH-CET), while overexpression decreased the activity. Although deletion and overexpression of ndhO did not have significant effects on the amount of other subunits such as NdhH, NdhI, NdhK, and NdhM in the cells, the amount of these subunits in the medium size NDH-1 (NDH-1M) complex was higher in the ndhO-deletion mutant and much lower in the overexpression strain than in the WT. NdhO strongly interacts with NdhI and NdhK but not with other subunits. NdhI interacts with NdhK and the interaction was blocked by NdhO. The blocking may destabilize the NDH-1M complex and repress the NDH-CET activity. When cells were transferred from growth light to high light, the amounts of NdhI and NdhK increased without significant change in the amount of NdhO, thus decreasing the relative amount of NdhO. This might have decreased the blocking, thereby stabilizing the NDH-1M complex and increasing the NDH-CET activity under high light conditions.
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deletion of an electron donor binding subunit of the ndh 1 complex ndhs results in a heat sensitive growth phenotype in synechocystis sp pcc 6803
Chinese Science Bulletin, 2014Co-Authors: Fudan Gao, Jiaohong Zhao, Zijian Qiu, Quanxi WangAbstract:In cyanobacteria and higher plants, NdhS is suggested to be an electron donor-binding subunit of NADPH Dehydrogenase (NDH-1) complexes and its absence impairs NDH-1-dependent cyclic electron transport around photosystem I (NDH-CET). Despite significant advances in the study of NdhS during recent years, its functional role in resisting heat stress is poorly understood. Here, our results revealed that the absence of NdhS resulted in a serious heat-sensitive growth phenotype in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803. Furthermore, the rapid and significant increase in NDH-CET caused by heat treatment was completely abolished, and the repair of photosystem II under heat stress conditions was greatly impaired when compared to that of other photosynthetic apparatus in the thylakoid membrane. We therefore conclude that NdhS plays an important role in resistance to heat stress, possibly by stabilizing the electron input module of cyanobacterial NDH-1 complexes.
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ndhp is an exclusive subunit of large complex of NADPH Dehydrogenase essential to stabilize the complex in synechocystis sp strain pcc 6803
Journal of Biological Chemistry, 2014Co-Authors: Jingsong Zhang, Teruo Ogawa, Fudan Gao, Jiaohong Zhao, Quanxi WangAbstract:Two major complexes of NADPH Dehydrogenase (NDH-1) have been identified in cyanobacteria. A large complex (NDH-1L) contains NdhD1 and NdhF1, which are absent in a medium size complex (NDH-1M). They play important roles in respiration, cyclic electron transport around photosystem I, and CO2 acquisition. Two mutants sensitive to high light for growth and impaired in NDH-1-mediated cyclic electron transfer were isolated from Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in sml0013 encoding NdhP, a single transmembrane small subunit of the NDH-1 complex. During prolonged incubation of the wild type thylakoid membrane with n-dodecyl β-d-maltoside (DM), about half of the NDH-1L was disassembled to NDH-1M and the rest decomposed completely without forming NDH-1M. In the ndhP deletion mutant (ΔndhP), disassembling of NDH-1L to NDH-1M occurred even on ice, and decomposition to a small piece occurred at room temperature much faster than in the wild type. Deletion of the C-terminal tail of NdhP gave the same result. The C terminus of NdhP was tagged by YFP-His6. Blue native gel electrophoresis of the DM-treated thylakoid membrane of this strain and Western analysis using the antibody against GFP revealed that NdhP-YFP-His6 was exclusively confined to NDH-1L. During prolonged incubation of the thylakoid membrane of the tagged strain with DM at room temperature, NDH-1L was partially disassembled to NDH-1M and the 160-kDa band containing NdhP-YFP-His6 and possibly NdhD1 and NdhF1. We therefore conclude that NdhP, especially its C-terminal tail, is essential to assemble NdhD1 and NdhF1 and stabilize the NDH-1L complex.
Quanxi Wang - One of the best experts on this subject based on the ideXlab platform.
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deletion of an electron donor binding subunit of the ndh 1 complex ndhs results in a heat sensitive growth phenotype in synechocystis sp pcc 6803
Chinese Science Bulletin, 2014Co-Authors: Fudan Gao, Jiaohong Zhao, Zijian Qiu, Quanxi WangAbstract:In cyanobacteria and higher plants, NdhS is suggested to be an electron donor-binding subunit of NADPH Dehydrogenase (NDH-1) complexes and its absence impairs NDH-1-dependent cyclic electron transport around photosystem I (NDH-CET). Despite significant advances in the study of NdhS during recent years, its functional role in resisting heat stress is poorly understood. Here, our results revealed that the absence of NdhS resulted in a serious heat-sensitive growth phenotype in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803. Furthermore, the rapid and significant increase in NDH-CET caused by heat treatment was completely abolished, and the repair of photosystem II under heat stress conditions was greatly impaired when compared to that of other photosynthetic apparatus in the thylakoid membrane. We therefore conclude that NdhS plays an important role in resistance to heat stress, possibly by stabilizing the electron input module of cyanobacterial NDH-1 complexes.
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ndhp is an exclusive subunit of large complex of NADPH Dehydrogenase essential to stabilize the complex in synechocystis sp strain pcc 6803
Journal of Biological Chemistry, 2014Co-Authors: Jingsong Zhang, Teruo Ogawa, Fudan Gao, Jiaohong Zhao, Quanxi WangAbstract:Two major complexes of NADPH Dehydrogenase (NDH-1) have been identified in cyanobacteria. A large complex (NDH-1L) contains NdhD1 and NdhF1, which are absent in a medium size complex (NDH-1M). They play important roles in respiration, cyclic electron transport around photosystem I, and CO2 acquisition. Two mutants sensitive to high light for growth and impaired in NDH-1-mediated cyclic electron transfer were isolated from Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in sml0013 encoding NdhP, a single transmembrane small subunit of the NDH-1 complex. During prolonged incubation of the wild type thylakoid membrane with n-dodecyl β-d-maltoside (DM), about half of the NDH-1L was disassembled to NDH-1M and the rest decomposed completely without forming NDH-1M. In the ndhP deletion mutant (ΔndhP), disassembling of NDH-1L to NDH-1M occurred even on ice, and decomposition to a small piece occurred at room temperature much faster than in the wild type. Deletion of the C-terminal tail of NdhP gave the same result. The C terminus of NdhP was tagged by YFP-His6. Blue native gel electrophoresis of the DM-treated thylakoid membrane of this strain and Western analysis using the antibody against GFP revealed that NdhP-YFP-His6 was exclusively confined to NDH-1L. During prolonged incubation of the thylakoid membrane of the tagged strain with DM at room temperature, NDH-1L was partially disassembled to NDH-1M and the 160-kDa band containing NdhP-YFP-His6 and possibly NdhD1 and NdhF1. We therefore conclude that NdhP, especially its C-terminal tail, is essential to assemble NdhD1 and NdhF1 and stabilize the NDH-1L complex.
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effect of cell water amount on photosynthetic yield in the cyanobacterium nostoc flagelliforme and involvement of NADPH Dehydrogenase mediated cyclic electron transport
Journal of Applied Phycology, 2009Co-Authors: Lanzhen Wei, Quanxi WangAbstract: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 O2 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 O2 evolution. However, the highest photochemical activity of photosystem II, reflected by Fv/Fm 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.
