Decrease in the efficiency of the electron donation to tyrosine Z of photosystem II in an SQDG‐deficient mutant of <i>Chlamydomonas</i>

Minoda, Ayumi; Sonoike, Kintake; Okada, Kotaro; Sato, Norihiro; Tsuzuki, Mikio

doi:10.1016/s0014-5793(03)00981-5

Cited by 64 publications

(37 citation statements)

References 13 publications

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“…Additionally, SQDG has been identified in PSII of Thermosynechococcus elongatus and cytochrome b6f of C. reinhardtii, with its headgroup embedded in the photosynthetic complexes and acyl chain located in the cytoplasm side of the thylakoid membranes (Stroebel et al, 2003;Loll et al, 2005Loll et al, , 2007. Recently, Chlamydomonas mutants deficient in SQDG biosynthesis have been obtained and characterization of the mutant suggested that SQDG plays a structural role for the Q B binding site of PSII, while maintaining a correct conformation at the PS II donor side (Minoda et al, 2003;Riekhof et al, 2003).…”

Section: Remodeling Of the Membrane Glycerolipids In Response To Chanmentioning

confidence: 99%

Metabolic Remodeling of Membrane Glycerolipids in the Microalga Nannochloropsis oceanica under Nitrogen Deprivation

Han

Jia

et al. 2017

Front. Mar. Sci.

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HIGHLIGHTS• An electrospray ionization mass spectrometry-based lipidomics method was developed and integrated with transcriptomics to elucidate metabolic remodeling and turnover of microalgal membrane lipids by using Nannochloropsis oceanica as a model.The lack of lipidome analytical tools has limited our ability to gain new knowledge about lipid metabolism in microalgae, especially for membrane glycerolipids. An electrospray ionization mass spectrometry-based lipidomics method was developed for Nannochloropsis oceanica IMET1, which resolved 41 membrane glycerolipids molecular species belonging to eight classes. Changes in membrane glycerolipids under nitrogen deprivation and high-light (HL) conditions were uncovered. The results showed that the amount of plastidial membrane lipids including monogalactosyldiacylglycerol, phosphatidylglycerol, and the extraplastidic lipids diacylglyceryl-O-4 ′ -(N, N, N,-trimethyl) homoserine and phosphatidylcholine decreased drastically under HL and nitrogen deprivation stresses. Algal cells accumulated considerably more digalactosyldiacylglycerol and sulfoquinovosyldiacylglycerols under stresses. The genes encoding enzymes responsible for biosynthesis, modification and degradation of glycerolipids were identified by mining a time-course global RNA-seq data set. It suggested that reduction in lipid contents under nitrogen deprivation is not attributable to the retarded biosynthesis processes, at least at the gene expression level, as most genes involved in their biosynthesis were unaffected by nitrogen supply, yet several genes were significantly up-regulated. Additionally, a conceptual eicosapentaenoic acid (EPA) biosynthesis network is proposed based on the lipidomic and transcriptomic data, which underlined import of EPA from cytosolic glycerolipids to the plastid for synthesizing EPA-containing chloroplast membrane lipids.

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Section: Remodeling Of the Membrane Glycerolipids In Response To Chanmentioning

confidence: 99%

Metabolic Remodeling of Membrane Glycerolipids in the Microalga Nannochloropsis oceanica under Nitrogen Deprivation

Han

Jia

et al. 2017

Front. Mar. Sci.

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“…However, SQD1 activity in SIR Ri plants was apparently insufficient to protect chloroplasts from sulfite. The increased SQDG level in the upper leaves of SIR Ri plants might be also related to additional stabilization of PSII (Minoda et al, 2002(Minoda et al, , 2003 required during enhanced sulfite production.…”

Section: Sir Activity and Sulfite Homeostasis Impacts On Leaf Senescencementioning

confidence: 99%

Impairment in Sulfite Reductase Leads to Early Leaf Senescence in Tomato Plants

et al. 2014

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Sulfite reductase (SiR) is an essential enzyme of the sulfate assimilation reductive pathway, which catalyzes the reduction of sulfite to sulfide. Here, we show that tomato (Solanum lycopersicum) plants with impaired SiR expression due to RNA interference (SIR Ri) developed early leaf senescence. The visual chlorophyll degradation in leaves of SIR Ri mutants was accompanied by a reduction of maximal quantum yield, as well as accumulation of hydrogen peroxide and malondialdehyde, a product of lipid peroxidation. Interestingly, messenger RNA transcripts and proteins involved in chlorophyll breakdown in the chloroplasts were found to be enhanced in the mutants, while transcripts and their plastidic proteins, functioning in photosystem II, were reduced in these mutants compared with wild-type leaves. As a consequence of SiR impairment, the levels of sulfite, sulfate, and thiosulfate were higher and glutathione levels were lower compared with the wild type. Unexpectedly, in a futile attempt to compensate for the low glutathione, the activity of adenosine-59-phosphosulfate reductase was enhanced, leading to further sulfite accumulation in SIR Ri plants. Increased sulfite oxidation to sulfate and incorporation of sulfite into sulfoquinovosyl diacylglycerols were not sufficient to maintain low basal sulfite levels, resulting in accumulative leaf damage in mutant leaves. Our results indicate that, in addition to its biosynthetic role, SiR plays an important role in prevention of premature senescence. The higher sulfite is likely the main reason for the initiation of chlorophyll degradation, while the lower glutathione as well as the higher hydrogen peroxide and malondialdehyde additionally contribute to premature senescence in mutant leaves.

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“…By contrast, in the mutants of C. reinhardtii and Synechocystis sp. PCC6803, PSII activity decreased, and the functional site of PSII damaged in the C. reinhardtii mutant was specified as the electron transfer site from water to Tyr Z in the donor site of PSII (Minoda et al, 2003).…”

mentioning

confidence: 99%

Digalactosyldiacylglycerol Is Required for Stabilization of the Oxygen-Evolving Complex in Photosystem II

Sakurai¹,

Mizusawa²,

Wada³

et al. 2007

Plant Physiol.

128

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The galactolipid digalactosyldiacylglycerol (DGDG) is present in the thylakoid membranes of oxygenic photosynthetic organisms such as higher plants and cyanobacteria. Recent x-ray crystallographic analysis of protein-cofactor supercomplexes in thylakoid membranes revealed that DGDG molecules are present in the photosystem II (PSII) complex (four molecules per monomer), suggesting that DGDG molecules play important roles in folding and assembly of subunits in the PSII complex. However, the specific role of DGDG in PSII has not been fully clarified. In this study, we identified the dgdA gene (slr1508, a ycf82 homolog) of Synechocystis sp. PCC6803 that presumably encodes a DGDG synthase involved in the biosynthesis of DGDG by comparison of genomic sequence data. Disruption of the dgdA gene resulted in a mutant defective in DGDG synthesis. Despite the lack of DGDG, the mutant cells grew as rapidly as the wild-type cells, indicating that DGDG is not essential for growth in Synechocystis. However, we found that oxygen-evolving activity of PSII was significantly decreased in the mutant. Analyses of the PSII complex purified from the mutant cells indicated that the extrinsic proteins PsbU, PsbV, and PsbO, which stabilize the oxygen-evolving complex, were substantially dissociated from the PSII complex. In addition, we found that heat susceptibility but not dark-induced inactivation of oxygen-evolving activity was notably increased in the mutant cells in comparison to the wild-type cells, suggesting that the PsbU subunit is dissociated from the PSII complex even in vivo. These results demonstrate that DGDG plays important roles in PSII through the binding of extrinsic proteins required for stabilization of the oxygen-evolving complex.

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Decrease in the efficiency of the electron donation to tyrosine Z of photosystem II in an SQDG‐deficient mutant of Chlamydomonas

Cited by 64 publications

References 13 publications

Metabolic Remodeling of Membrane Glycerolipids in the Microalga Nannochloropsis oceanica under Nitrogen Deprivation

Metabolic Remodeling of Membrane Glycerolipids in the Microalga Nannochloropsis oceanica under Nitrogen Deprivation

Impairment in Sulfite Reductase Leads to Early Leaf Senescence in Tomato Plants

Digalactosyldiacylglycerol Is Required for Stabilization of the Oxygen-Evolving Complex in Photosystem II

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