The Role of Acetyl-Coenzyme A Synthetase in Arabidopsis

Lin, Ming Tsan; Oliver, David J.

doi:10.1104/pp.108.121269

Cited by 109 publications

(107 citation statements)

References 42 publications

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Section: Resultsmentioning

confidence: 99%

“…To examine whether MDA might travel through acetate as a metabolic intermediate, we analyzed 14 C-MDA incorporation into lipids in the acetyl-CoA synthetase (ACS) mutant acs1 (29). ACS uses acetate, ATP and CoA to generate acetyl-CoA which can be used for FA synthesis and a 90% decrease of 14 C-acetate incorporation into FAs relative to the WT was reported for acs1 plants (29). We compared 14 C-MDA incorporation in mutant and WT plants after 6 h. As reported, incorporation of 14 Cacetate into FAs was found to be strongly reduced in acs1 plants compared with the WT.…”

Section: Resultsmentioning

confidence: 99%

“…thaliana (Columbia), fad3-2 fad7-2 fad8 (24), and acs1 (29) were grown on soil at 22°C for 5 weeks (metabolism studies) or ϳ3.5 weeks (for wounding) under short day conditions (light: 100 E m Ϫ2 s Ϫ1 , 9 h light/15 h dark). Reagents-Chemicals and analytic standards used were purchased from Sigma-Aldrich unless indicated.…”

Section: Plant Genotypes and Growth Conditions-wild-type (Wt)mentioning

confidence: 99%

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Membranes as Structural Antioxidants

Schmid‐Siegert

Stepushenko

Glauser

et al. 2016

Journal of Biological Chemistry

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Genetic evidence suggests that membranes rich in polyunsaturated fatty acids (PUFAs) act as supramolecular antioxidants that capture reactive oxygen species, thereby limiting damage to proteins. This process generates lipid fragmentation products including malondialdehyde (MDA), an archetypal marker of PUFA oxidation. We observed transient increases in levels of endogenous MDA in wounded Arabidopsis thaliana leaves, raising the possibility that MDA is metabolized. We developed a rigorous ion exchange method to purify enzymatically gener- The susceptibility of fatty acids to oxidation by reactive oxygen species (ROS) 3 increases with desaturation (1, 2), so that membranes rich in polyunsaturated fatty acids (PUFAs) are potentially vulnerable to oxidative damage. It is therefore remarkable that intra-organellar membranes in mitochondria and chloroplasts, organelles with highly oxidative metabolism, typically contain high percentages of PUFAs (3, 4). Both organelle types are active sites of ROS production (5, 6). For example, thylakoid membranes in chloroplasts are prone to photo-oxidative damage by singlet oxygen ( 1 O 2 ) that is produced through the interaction of excited (triplet-state) chlorophyll with oxygen (6 -8). Moreover, the major site of 1 O 2 generation in chloroplasts, photosystem II (PSII), is surrounded by polyunsaturated fatty acid (PUFA)-rich lipids (9) and, strikingly, twothirds of the FAs in thylakoids are triunsaturated fatty acids (TFAs), chiefly ␣-linolenic acid (10). These fatty acids are highly prone to oxidative fragmentation in vivo (11).Cells counter the threat posed by 1 O 2 and other ROS with multiple protection mechanisms known to involve low molecular mass antioxidants. Among the best characterized of these cellular protectants are tocopherols (reviewed in Ref. 12). Indeed, mutants that lack tocopherol and plastochromanol are less protected against 1 O 2 and show elevated levels of nonenzymatic lipid oxidation (nLPO; 13, 14). Additionally, carotenoids both physically and chemically quench 1 O 2 (15). We proposed recently that a further layer of protection may also exist, one that uses PUFA-rich membranes as structural antioxidants. This hypothesis emerged from the fact that, even when grown under mild and relatively low light conditions, plants that lack TFAs displayed hallmark features of oxidative stress (16). TFAs act to protect proteins by absorbing ROS such as 1 O 2 and hydroxyl radicals produced under both healthy and stressful conditions (7,11,16).The development of the supramolecular antioxidant hypothesis has been facilitated by the rigorous quantitative analysis of a PUFA fragmentation product, the 3-carbon dialdehyde malondialdehyde (MDA) that is generally considered to be harmful to the cells of humans (17, 18) and plants (19 -21). MDA may also have activities in redox signaling (reviewed in Ref. 11). This compound, one of a plethora of PUFA oxidation products, is a robust marker of nonenzymatic lipid oxidation in animals (1) and in plants (e.g. 22). Furthermore, protocol...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Plant Genotypes and Growth Conditions-wild-type (Wt)mentioning

confidence: 99%

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Membranes as Structural Antioxidants

Schmid‐Siegert

Stepushenko

Glauser

et al. 2016

Journal of Biological Chemistry

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“…The oxp1-1 mutant is a result of a T-DNA insertion into the second exon of the OXP1 gene. The homozygous plants containing the insert were screened by PCR using the gene-specific primers OXP1-1F (5#-CGTTGACGTACCACCCATATCA-3#) and OXP1-1R (5#-GGG-AACTACTGTGGCAACGAAT-3#) and the T-DNA left-border primer pROKr3 (5#-CCTTTCGCTTTCTTCCCTTCCTTTCT-3#; Lin and Oliver, 2008).…”

Section: Plant Materialsmentioning

confidence: 99%

Aγ-Glutamyl Transpeptidase-Independent Pathway of Glutathione Catabolism to Glutamate via 5-Oxoproline in Arabidopsis

et al. 2008

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The degradation pathway of glutathione (GSH) in plants is not well understood. In mammals, GSH is predominantly metabolized through the g-glutamyl cycle, where GSH is degraded by the sequential reaction of g-glutamyl transpeptidase (GGT), g-glutamyl cyclotransferase, and 5-oxoprolinase to yield glutamate (Glu) and dipeptides that are subject to peptidase action. In this study, we examined if GSH is degraded through the same pathway in Arabidopsis (Arabidopsis thaliana) as occurs in mammals. In Arabidopsis, the oxoprolinase knockout mutants (oxp1-1 and oxp1-2) accumulate more 5-oxoproline (5OP) and less Glu than wild-type plants, suggesting substantial metabolite flux though 5OP and that 5OP is a major contributor to Glu steady-state levels. In the ggt1-1/ggt4-1/oxp1-1 triple mutant with no GGT activity in any organs except young siliques, the 5OP concentration in leaves was not different from that in oxp1-1, suggesting that GGTs are not major contributors to 5OP production in Arabidopsis. 5OP formation strongly tracked the level of GSH in Arabidopsis plants, suggesting that GSH is the precursor of 5OP in a GGT-independent reaction. Kinetics analysis suggests that g-glutamyl cyclotransferase is the major source of GSH degradation and 5OP formation in Arabidopsis. This discovery led us to propose a new pathway for GSH turnover in plants where GSH is converted to 5OP and then to Glu by the combined action of g-glutamyl cyclotransferase and 5-oxoprolinase in the cytoplasm.

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“…It is possible that a peroxisomal thioesterase (k TE ) active with a acetyl-CoA exists, as has been identified in Saccharomyces cerevisiae [22]. Also, we assumed that extraperoxisomal acetyl-CoA synthetase activity (k AC ) was greater than that of ACN1 (k ACN1 ) [35,36]. It is known that acetylCoA can be produced in the cytosol from citrate by the ATP:citrate lyase (k MC ) [24].…”

Section: Creating Models and Fitting Parametersmentioning

confidence: 98%

Modelling the peroxisomal carbon leak during lipid mobilization in Arabidopsis

Hooks

Allen

Wattis

2010

Biochemical Society Transactions

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Mutation of the ACN1 (acetate non-utilizing 1) locus of Arabidopsis results in altered acetate assimilation into gluconeogenic sugars and anapleurotic amino acids and leads to an overall depression in primary metabolite levels by approx. 50% during seedling development. Levels of acetyl-CoA were higher in acn1 compared with wild-type, which is counterintuitive to the activity of ACN1 as a peroxisomal acetyl-CoA synthetase. We hypothesize that ACN1 recycles free acetate to acetyl-CoA within peroxisomes in order that carbon remains fed into the glyoxylate cycle. When ACN1 is not present, carbon in the form of acetate can leak out of peroxisomes and is reactivated to acetyl-CoA within the cytosol. Kinetic models incorporating estimates of carbon input and pathway dynamics from a variety of literature sources have proven useful in explaining how ACN1 may prevent the carbon leak and even contribute to the control of peroxisomal carbon metabolism.

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The Role of Acetyl-Coenzyme A Synthetase in Arabidopsis

Cited by 109 publications

References 42 publications

Membranes as Structural Antioxidants

Membranes as Structural Antioxidants

Aγ-Glutamyl Transpeptidase-Independent Pathway of Glutathione Catabolism to Glutamate via 5-Oxoproline in Arabidopsis

Modelling the peroxisomal carbon leak during lipid mobilization in Arabidopsis

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