Chlamydomonas starchless mutant defective in ADP-glucose pyrophosphorylase hyper-accumulates triacylglycerol

Li, Yantao; Han, Danxiang; Hu, Guongrong; Dauvillée, David; Sommerfeld, Milton R.; Ball, Steven; Hu, Qiang

doi:10.1016/j.ymben.2010.02.002

Cited by 343 publications

(250 citation statements)

References 22 publications

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“…Previous studies have assessed the responses of metabolic genes and proteins under non-steady state conditions when TAG accumulates (Miller et al, 2010;Boyle et al, 2012;Msanne et al, 2012;Blaby et al, 2013;Wase et al, 2014) or identified mutants that are defective for TAG accumulation or catabolism (Li et al, 2012;Boyle et al, 2012;Tsai et al, 2014;Xie et al, 2014;Ngan et al, 2015;Kajikawa et al, 2015). The relationship between starch synthesis and TAGs has also been investigated, and it appears that fixed carbon can be shunted toward TAGs when starch synthesis is blocked (Li et al, 2010a(Li et al, , 2010bWork et al, 2010;Siaut et al, 2011;Goodenough et al, 2014). One recently identified regulatory mutant, tar1, is defective in accumulation of lipid bodies in response to nutrient starvation, and the TAR1 locus was shown to encode a YAK subtype DYRK family protein kinase (Kajikawa et al, 2015).…”

Section: Insps As a Metabolic Signal For Carbon Metabolismmentioning

confidence: 99%

Synergism between Inositol Polyphosphates and TOR Kinase Signaling in Nutrient Sensing, Growth Control, and Lipid Metabolism in Chlamydomonas

et al. 2016

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The networks that govern carbon metabolism and control intracellular carbon partitioning in photosynthetic cells are poorly understood. Target of Rapamycin (TOR) kinase is a conserved growth regulator that integrates nutrient signals and modulates cell growth in eukaryotes, though the TOR signaling pathway in plants and algae has yet to be completely elucidated. We screened the unicellular green alga Chlamydomonas reinhardtii using insertional mutagenesis to find mutants that conferred hypersensitivity to the TOR inhibitor rapamycin. We characterized one mutant, vip1-1, that is predicted to encode a conserved inositol hexakisphosphate kinase from the VIP family that pyrophosphorylates phytic acid (InsP 6 ) to produce the low abundance signaling molecules InsP 7 and InsP 8 . Unexpectedly, the rapamycin hypersensitive growth arrest of vip1-1 cells was dependent on the presence of external acetate, which normally has a growth-stimulatory effect on Chlamydomonas. vip1-1 mutants also constitutively overaccumulated triacylglycerols (TAGs) in a manner that was synergistic with other TAG inducing stimuli such as starvation. vip1-1 cells had reduced InsP 7 and InsP 8 , both of which are dynamically modulated in wild-type cells by TOR kinase activity and the presence of acetate. Our data uncover an interaction between the TOR kinase and inositol polyphosphate signaling systems that we propose governs carbon metabolism and intracellular pathways that lead to storage lipid accumulation.

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Section: Insps As a Metabolic Signal For Carbon Metabolismmentioning

confidence: 99%

Synergism between Inositol Polyphosphates and TOR Kinase Signaling in Nutrient Sensing, Growth Control, and Lipid Metabolism in Chlamydomonas

et al. 2016

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“…However, the molecular and cellular mechanisms underlying lipid metabolism in microalgae are largely unknown. Identifying the pathways and regulatory networks that underlie the oleaginous phenotype should guide the rational genetic engineering of microalgae for the overproduction of TAG (Li et al, 2010a(Li et al, , 2010bGeorgianna and Mayfield, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…In C. reinhardtii, the excess photosynthetically fixed carbons and energy are mainly stored in the form of starch and to a much lesser extent TAG under high light or under high light plus N depletion (Buléon et al, 1997;Li et al, 2010aLi et al, , 2010b. In oleaginous microalgae (e.g., Nannochloropsis spp), TAG is the main carbon and energy reserve along with smaller amounts of the water-soluble polysaccharide chrysolaminarin under stress conditions (Radakovits et al, 2012;Vieler et al, 2012;Wang et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Choreography of Transcriptomes and Lipidomes ofNannochloropsisReveals the Mechanisms of Oil Synthesis in Microalgae

et al. 2014

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To reveal the molecular mechanisms of oleaginousness in microalgae, transcriptomic and lipidomic dynamics of the oleaginous microalga Nannochloropsis oceanica IMET1 under nitrogen-replete (N+) and N-depleted (N-) conditions were simultaneously tracked. At the transcript level, enhanced triacylglycerol (TAG) synthesis under N-conditions primarily involved upregulation of seven putative diacylglycerol acyltransferase (DGAT) genes and downregulation of six other DGAT genes, with a simultaneous elevation of the other Kennedy pathway genes. Under N-conditions, despite downregulation of most de novo fatty acid synthesis genes, the pathways that shunt carbon precursors from protein and carbohydrate metabolic pathways into glycerolipid synthesis were stimulated at the transcript level. In particular, the genes involved in supplying carbon precursors and energy for de novo fatty acid synthesis, including those encoding components of the pyruvate dehydrogenase complex (PDHC), glycolysis, and PDHC bypass, and suites of specific transporters, were substantially upregulated under N-conditions, resulting in increased overall TAG production. Moreover, genes involved in the citric acid cycle and b-oxidation in mitochondria were greatly enhanced to utilize the carbon skeletons derived from membrane lipids and proteins to produce additional TAG or its precursors. This temporal and spatial regulation model of oil accumulation in microalgae provides a basis for improving our understanding of TAG synthesis in microalgae and will also enable more rational genetic engineering of TAG production.

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“…Although biomass from terrestrial plants can be processed and used as a feedstock for generating alcohols and other fuels (8) oil from photoautotrophically grown algae or seeds represents another fuel source, with algae offering distinct advantages over traditional oil crops (9,10). The green alga Chlamydomonas reinhardtii accumulates increased amounts of triacylglycerols (TAGs) 5 under conditions of growth-inhibiting macro-or micronutrient deficiency such as sulfur (11), nitrogen (12)(13)(14)(15)(16)(17)(18)(19)(20), phosphorus (15), zinc, or iron deficiency (21) or other growthinhibiting stressors such as high salt (22) or high light (23). With a sequenced genome (24) and the potential for application of metabolic engineering (25), C. reinhardtii is a powerful reference organism for discovering green algal TAG biosynthetic pathway(s) and the ways in which they are regulated by nutrient deprivation.…”

mentioning

confidence: 99%

Three Acyltransferases and Nitrogen-responsive Regulator Are Implicated in Nitrogen Starvation-induced Triacylglycerol Accumulation in Chlamydomonas

Boyle

Page

Liu

et al. 2012

Journal of Biological Chemistry

382

445

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Background: Nitrogen-starvation and other stresses induce triacylglycerol (TAG) accumulation in algae, but the relevant enzymes and corresponding signal transduction pathways are unknown. Results: RNA-Seq and genetic analysis revealed three acyltransferases that contribute to TAG accumulation. Conclusion: TAG synthesis results from recycling of membrane lipids and also by acylation of DAG. Significance: The genes are potential targets for manipulating TAG hyperaccumulation.

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Chlamydomonas starchless mutant defective in ADP-glucose pyrophosphorylase hyper-accumulates triacylglycerol

Cited by 343 publications

References 22 publications

Synergism between Inositol Polyphosphates and TOR Kinase Signaling in Nutrient Sensing, Growth Control, and Lipid Metabolism in Chlamydomonas

Synergism between Inositol Polyphosphates and TOR Kinase Signaling in Nutrient Sensing, Growth Control, and Lipid Metabolism in Chlamydomonas

Choreography of Transcriptomes and Lipidomes ofNannochloropsisReveals the Mechanisms of Oil Synthesis in Microalgae

Three Acyltransferases and Nitrogen-responsive Regulator Are Implicated in Nitrogen Starvation-induced Triacylglycerol Accumulation in Chlamydomonas

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