Involvement of sulfoquinovosyl diacylglycerol in the structural integrity and heat-tolerance of photosystem II

Sato, Norihiro; Aoki, Motohide; Maru, Yukihiro; Sonoike, Kintake; Minoda, Ayumi; Tsuzuki, Mikio

doi:10.1007/s00425-003-0992-9

Cited by 75 publications

(45 citation statements)

References 21 publications

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“…Similar observations, i.e. the lowered specific activity of PSII and the enhanced sensitivity to DCMU, were made for SQDG-deficient mutants of C. reinhardtii [9,10,31]. Yu et al [32] also indicated that the effective quantum yield of PSII was slightly but significantly reduced in SQDG-deficient mutants of Arabidopsis thaliana.…”

Section: Discussionsupporting

confidence: 63%

“…However, the conclusion drawn from in vitro experiments is not necessarily valid in vivo.The mutants of some lipid metabolism pathways have proved to be useful tools for investigating in vivo the specific roles of lipids in photosynthesis. A mutant of Chlamydomonas reinhardtii, defective in SQDG (hf-2), showed PSII activity that was 40% lower than that of the wild-type, an increase in sensitivity of the PSII activity to 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and a lower growth rate [9][10][11][12]. In accordance with these observations, the incubation of isolated thylakoid membranes of hf-2 with SQDG in vitro reversed the lowered PSII activity.…”

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confidence: 99%

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Differing involvement of sulfoquinovosyl diacylglycerol in photosystem II in two species of unicellular cyanobacteria

Aoki

Sato

Meguro

et al. 2004

European Journal of Biochemistry

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Biochem. 269, 2353Biochem. 269, -2358. To understand the spread of the taxa in which PSII interacts with SQDG, especially in cyanobacteria, we produced a mutant defective in the putative sqdB gene responsible for SQDG synthesis from two cyanobacteria, Synechocystis sp. PCC6803 and Synechococcus sp. PCC7942. The mutant of PCC6803, designated SD1, lacked SQDG synthetic ability and required SQDG supplementation for its growth. After transfer from SQDG-supplemented to SQDG-free conditions, SD1 showed decreased net photosynthetic and PSII activities on a chlorophyll (Chl) basis with a decrease in the SQDG content. Moreover, the sensitivity of PSII activity to 3-(3,4-dichlorophenyl)-1,1-dimethylurea and atrazine was increased in SD1. However, SD1 maintained normal amounts of cytochrome b 559 and D1 protein (the subunits comprising the PSII complex) on a Chl basis, indicating that the PSII complex content changed little, irrespective of a decrease in the SQDG content. These results suggest that the role of SQDG is the conservation of the PSII properties in PCC6803, consistent with the results obtained with C. reinhardtii. In contrast, the SQDG-null mutant of PCC7942 showed the normal level of PSII activity with little effect on its sensitivity to PSII herbicides. Therefore, the difference in the SQDG requirement for PSII is species-specific in cyanobacteria; this could be of use when investigating the molecular evolution of the PSII complex.Keywords: cyanobacteria; glycolipid; photosystem; sulfoquinovosyl diacylglycerol; thylakoid membranes.Biomembranes constructed predominantly from lipids and proteins are sites of energy production, metabolism such as lipid synthesis, and the transportation of substances such as metabolites between the inside and outside of membrane systems. Thylakoid membranes in plant chloroplasts and cyanobacterial cells are unique in possessing photosynthetic electron transport and photophosphorylation systems for the conversion of light to chemical energy. The lipid composition of thylakoid membranes is highly conserved among higher plants, algae, and cyanobacteria, comprised mainly of the following four glycerolipids, monogalactosyl diacylglycerol (MGDG), digalactosyl diacylglycerol (DGDG), phosphatidylglycerol (PG), and sulfoquinovosyl diacylglycerol (SQDG) [1][2][3]. PG and SQDG possess negatively charged head groups, whereas MGDG and DGDG are noncharged lipids.Lipid analyses of subfractions and protein complexes of thylakoid membranes have shown specific lipid compositions, implying roles of some lipid classes in photosynthesis [4]. Significant differences in lipid composition and the fatty acid saturation state were observed, e.g. in extraction of photosystem II (PSII) from photosynthetic membranes with different detergents [5][6][7]. On the other hand, reconstitution of photosynthetic activity with the addition or removal of thylakoid lipids in vitro has also been performed with thylakoid membranes, subfractions of thylakoid membranes and purified protein complexes, with important observ...

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Section: Discussionsupporting

confidence: 63%

mentioning

confidence: 99%

Differing involvement of sulfoquinovosyl diacylglycerol in photosystem II in two species of unicellular cyanobacteria

Aoki

Sato

Meguro

et al. 2004

European Journal of Biochemistry

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“…This observation may be interpreted as a response to adjust the membrane fluidity of photosynthetic membranes. PUFAs in membranes are also important for adjusting membrane fluidity during shifts in salinity and light intensity [75]. It has been shown that a temperature-shift from 25 to 10 °C will enhance the proportion of PUFAs, especially EPA, by 120% in P. tricornutum [76].…”

Section: Chromista and Their Lc-pufa Content And Functionmentioning

confidence: 99%

“…Because LC-PUFAs are enriched in galactosylglycerides such as SQDG and M/DGDG in the thylakoid membranes, it is assumed that they contribute to the photosynthetic function of algae. For instance, studies of the green algae Chlamydomondas reinhardtii showed the importance of the glycosylglyceride SQDG for maintaining photosystem II functionality during environmental changes (e.g., temperature), and thus indicates, as well, a role of PUFAs in maintaining the photosynthetic machinery [75]. …”

Section: Chromista and Their Lc-pufa Content And Functionmentioning

confidence: 99%

Pathways of Lipid Metabolism in Marine Algae, Co-Expression Network, Bottlenecks and Candidate Genes for Enhanced Production of EPA and DHA in Species of Chromista

et al. 2013

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The importance of n-3 long chain polyunsaturated fatty acids (LC-PUFAs) for human health has received more focus the last decades, and the global consumption of n-3 LC-PUFA has increased. Seafood, the natural n-3 LC-PUFA source, is harvested beyond a sustainable capacity, and it is therefore imperative to develop alternative n-3 LC-PUFA sources for both eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). Genera of algae such as Nannochloropsis, Schizochytrium, Isochrysis and Phaedactylum within the kingdom Chromista have received attention due to their ability to produce n-3 LC-PUFAs. Knowledge of LC-PUFA synthesis and its regulation in algae at the molecular level is fragmentary and represents a bottleneck for attempts to enhance the n-3 LC-PUFA levels for industrial production. In the present review, Phaeodactylum tricornutum has been used to exemplify the synthesis and compartmentalization of n-3 LC-PUFAs. Based on recent transcriptome data a co-expression network of 106 genes involved in lipid metabolism has been created. Together with recent molecular biological and metabolic studies, a model pathway for n-3 LC-PUFA synthesis in P. tricornutum has been proposed, and is compared to industrialized species of Chromista. Limitations of the n-3 LC-PUFA synthesis by enzymes such as thioesterases, elongases, acyl-CoA synthetases and acyltransferases are discussed and metabolic bottlenecks are hypothesized such as the supply of the acetyl-CoA and NADPH. A future industrialization will depend on optimization of chemical compositions and increased biomass production, which can be achieved by exploitation of the physiological potential, by selective breeding and by genetic engineering.

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“…Sulfoquinovosyl diacylglycerol (SQDG) is one of the membrane lipids specific to chloroplasts, and is responsible for the structural and functional integrity of the photosystem II complex in C. reinhardtii (Sato et al, 1995, 2003a; Minoda et al, 2003; Sato, 2004). Intriguingly, we recently reported that cells of C. reinhardtii degrade SQDG for utilization of it as a major intracellular sulfur (S)-source for the synthesis of protein, especially at an early phase of S-starvation (Sugimoto et al, 2007, 2008, 2010).…”

Section: Introductionmentioning

confidence: 99%

Responsibility of regulatory gene expression and repressed protein synthesis for triacylglycerol accumulation on sulfur-starvation in Chlamydomonas reinhardtii

et al. 2014

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Triacylglycerol (TG) synthesis is induced for energy and carbon storage in algal cells under nitrogen(N)-starved conditions, and helps prevent reactive oxygen species (ROS) production through fatty acid synthesis that consumes excessive reducing power. Here, the regulatory mechanism for the TG content in sulfur(S)-starved cells of Chlamydomonas reinhardtii was examined, in comparison to that in N- or phosphorus(P)-starved cells. S- and N- starved cells exhibited markedly increased TG contents with up-regulation of mRNA levels of diacylglycerol acyltransferase (DGAT) genes. S-Starvation also induced expression of the genes for phosphatidate synthesis. In contrast, P-starved cells exhibited little alteration of the TG content with almost no induction of these genes. The results implied deficient nutrient-specific regulation of the TG content. An arg9 disruptant defective in arginine synthesis, even without nutritional deficiencies, exhibited an increased TG content upon removal of supplemented arginine, which repressed protein synthesis. Repression of protein synthesis thus seemed crucial for TG accumulation in S- or N- starved cells. Meanwhile, the results of inhibitor experiments involving cells inferred that TG accumulation during S-starvation is supported by photosynthesis and de novo fatty acid synthesis. During S-starvation, sac1 and snrk2.2 disruptants, which are defective in the response to the ambient S-status, accumulated TG at lower and higher levels, respectively, than the wild type. The sac1 and snrk2.2 disruptants showed no or much greater up-regulation of DGAT genes, respectively. In conclusion, TG synthesis would be activated in S-starved cells, through the diversion of metabolic carbon-flow from protein to TG synthesis, and simultaneously through up-regulation of the expression of a particular set of genes for TG synthesis at proper levels through the actions of SAC1 and SNRK2.2.

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Involvement of sulfoquinovosyl diacylglycerol in the structural integrity and heat-tolerance of photosystem II

Cited by 75 publications

References 21 publications

Differing involvement of sulfoquinovosyl diacylglycerol in photosystem II in two species of unicellular cyanobacteria

Differing involvement of sulfoquinovosyl diacylglycerol in photosystem II in two species of unicellular cyanobacteria

Pathways of Lipid Metabolism in Marine Algae, Co-Expression Network, Bottlenecks and Candidate Genes for Enhanced Production of EPA and DHA in Species of Chromista

Responsibility of regulatory gene expression and repressed protein synthesis for triacylglycerol accumulation on sulfur-starvation in Chlamydomonas reinhardtii

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