Regulatory branch points affecting protein and lipid biosynthesis in the diatom Phaeodactylum tricornutum

Guerra, Thacia Rodrigues; Levitan, Orly; Frada, Miguel J.; Sun, Jennifer S; Falkowski, Paul G.; Dismukes, G. Charles

doi:10.1016/j.biombioe.2013.10.007

Cited by 69 publications

(78 citation statements)

References 38 publications

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“…2). This apparent paradox can be simply explained by the decreased overall metabolic flux of carbon in the cell caused by a higher quantum requirement for growth and lipid biosynthesis (11). Thus, based on our results and previously published studies, we suggest that the subsequent accumulation of TAGs under nitrogen stress seems to be a consequence of allocation of carbon and reductant, rather than an up-regulation of lipid biosynthesis genes (Figs.…”

Section: Discussionsupporting

confidence: 74%

“…Exponentially growing cultures were analyzed for their IPLs TAGs and FAMEs using previously described methods (11,12,(35)(36)(37)(38)(39). The percentage of carbon allocated to each biosynthetic compound was calculated given the following information: 16.5 and 9.4 pg C per cell, 13.6 and 3.6 pg protein per cell, and 7.7 and 5.5 pg carbohydrate per cell for the nitrogenreplete and -stressed cultures, respectively (11,12); TAG and IPL percentages are calculated based on the data provided in Tables S1 and S2. Total protein determination was performed as previously described (11).…”

Section: Methodsmentioning

confidence: 99%

“…The percentage of carbon allocated to each biosynthetic compound was calculated given the following information: 16.5 and 9.4 pg C per cell, 13.6 and 3.6 pg protein per cell, and 7.7 and 5.5 pg carbohydrate per cell for the nitrogenreplete and -stressed cultures, respectively (11,12); TAG and IPL percentages are calculated based on the data provided in Tables S1 and S2. Total protein determination was performed as previously described (11). The abundance of four selected proteins (PsbA, RbcL, NR, and DGAT2D) was determined by Western blots.…”

Section: Methodsmentioning

confidence: 99%

“…The kinetics of the single-turnover saturating flash were analyzed to obtain the maximum quantum efficiency of photochemistry (F V /F M ) and the functional absorption crosssection of PSII (σ PSII ). Samples for quantitative PCR were collected, extracted, processed, and analyzed as previously described (11). The NR activity was measured following the method described by Eppley et al (41) with modifications (3).…”

Section: Methodsmentioning

confidence: 99%

“…However, when nitrogen availability decreases, the sink for TCA cycle metabolites declines, and acetyl-CoA, the source of carbon for the cycle, can be shunted toward fatty acid (FA) biosynthesis. Therefore, under nitrogen stress, cellular protein content decreases, whereas storage lipids increase (11,12). This phenomenon has led to the hypothesis that overexpression of genes involved in lipid biosynthesis may increase the flux of carbon toward lipids (13,14).…”

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confidence: 99%

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Remodeling of intermediate metabolism in the diatom Phaeodactylum tricornutum under nitrogen stress

Levitan¹,

Dinamarca²,

Zelzion

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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210

217

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Diatoms are unicellular algae that accumulate significant amounts of triacylglycerols as storage lipids when their growth is limited by nutrients. Using biochemical, physiological, bioinformatics, and reverse genetic approaches, we analyzed how the flux of carbon into lipids is influenced by nitrogen stress in a model diatom, Phaeodactylum tricornutum. Our results reveal that the accumulation of lipids is a consequence of remodeling of intermediate metabolism, especially reactions in the tricarboxylic acid and the urea cycles. Specifically, approximately one-half of the cellular proteins are cannibalized; whereas the nitrogen is scavenged by the urea and glutamine synthetase/glutamine 2-oxoglutarate aminotransferase pathways and redirected to the de novo synthesis of nitrogen assimilation machinery, simultaneously, the photobiological flux of carbon and reductants is used to synthesize lipids. To further examine how nitrogen stress triggers the remodeling process, we knocked down the gene encoding for nitrate reductase, a key enzyme required for the assimilation of nitrate. The strain exhibits 40-50% of the mRNA copy numbers, protein content, and enzymatic activity of the wild type, concomitant with a 43% increase in cellular lipid content. We suggest a negative feedback sensor that couples photosynthetic carbon fixation to lipid biosynthesis and is regulated by the nitrogen assimilation pathway. This metabolic feedback enables diatoms to rapidly respond to fluctuations in environmental nitrogen availability.lipid | metabolism | stress | NR | RNAi

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Section: Discussionsupporting

confidence: 74%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Remodeling of intermediate metabolism in the diatom Phaeodactylum tricornutum under nitrogen stress

Levitan¹,

Dinamarca²,

Zelzion

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

210

217

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iTRAQ‐based quantitative proteomic analysis of a toxigenic dinoflagellate Alexandrium catenella and its non‐toxic mutant

Zhang

Xie

et al. 2015

Proteomics

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Paralytic shellfish toxins (PSTs) are a group of potent neurotoxic alkaloids produced by cyanobacteria and dinoflagellates. The PST biosynthesis gene cluster and several toxin-related proteins have been unveiled in cyanobacteria, yet little is known about dinoflagellates. Here, we compared the protein profiles of a toxin-producing dinoflagellate Alexandrium catenella (ACHK-T) and its non-toxic mutant (ACHK-NT), and characterized differentially displayed proteins using a combination of the iTRAQ-based proteomic approach and the transcriptomic database. Totally 3488 proteins were identified from A. catenella, and proteins involved in carbohydrate, amino acid and energy metabolism were the most abundant. Among them, 185 proteins were differentially displayed: proteins involved in amino acid biosynthesis, protein and carbohydrate metabolism and bioluminescence were more abundant in ACHK-T, while proteins participating in photosynthesis, fatty acid biosynthesis, and the processes occurring in peroxisome displayed higher abundances in ACHK-NT. Seven toxin-related proteins were identified but they varied insignificantly between the two strains. Different carbon and energy utilization strategies were potentially related to the toxin producing ability, and the regulation mechanism of PST biosynthesis was more complex in dinoflagellates. Our study provides the first comprehensive dataset on the dinoflagellate proteome and lays the groundwork for future proteomic study.

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Lipid Metabolism in Microalgae

Khozin‐Goldberg

2016

The Physiology of Microalgae

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Regulatory branch points affecting protein and lipid biosynthesis in the diatom Phaeodactylum tricornutum

Cited by 69 publications

References 38 publications

Remodeling of intermediate metabolism in the diatom Phaeodactylum tricornutum under nitrogen stress

Remodeling of intermediate metabolism in the diatom Phaeodactylum tricornutum under nitrogen stress

iTRAQ‐based quantitative proteomic analysis of a toxigenic dinoflagellate Alexandrium catenella and its non‐toxic mutant

Lipid Metabolism in Microalgae

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