The synthesis of short- and long-chain acylarnitine by etio-chloroplasts of greening barley leaves

Thomas, David; Jalil, Muhammad; Ariffin, Azis; Cooke, R. J.; Mclaren, I.; Yong, Bob C. S.; Wood, C.

doi:10.1007/bf01075262

Cited by 19 publications

(6 citation statements)

References 16 publications

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“…Recent evidence indicates that free fatty acids are quickly transported to the cytosol in the form of acyl-CoAs due to the action of an acyl-CoA synthetase located in the outer plastidial membrane (Koo et al 2004). This export model involving free fatty acid intermediates created certain controversy when it was Wrst hypothesized, and alternative models suggest that acyl-CoA or acyl-carnitine derivatives are exported instead (Joyard and Stumpf 1980;Thomas et al 1983;McLaren et al 1985). However, 18 O labeling experiments demonstrated that unesteriWed acyl moieties were indeed released during the fatty acid biosynthesis in plants (Pollard and Ohlrogge 1999).…”

Section: Introductionmentioning

confidence: 94%

Reduced expression of FatA thioesterases in Arabidopsis affects the oil content and fatty acid composition of the seeds

Moreno‐Pérez

Venegas-Calerón

Vaistij

et al. 2011

Planta

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Acyl-acyl carrier protein (ACP) thioesterases are enzymes that control the termination of intraplastidial fatty acid synthesis by hydrolyzing the acyl-ACP complexes. Among the different thioesterase gene families found in plants, the FatA-type fulfills a fundamental role in the export of the C18 fatty acid moieties that will be used to synthesize most plant glycerolipids. A reverse genomic approach has been used to study the FatA thioesterase in seed oil accumulation by screening different mutant collections of Arabidopsis thaliana for FatA knockouts. Two mutants were identified with T-DNA insertions in the promoter region of each of the two copies of FatA present in the Arabidopsis genome, from which a double FatA Arabidopsis mutant was made. The expression of both forms of FatA thioesterases was reduced in this double mutant (fata1 fata2), as was FatA activity. This decrease did not cause any evident morphological changes in the mutant plants, although the partial reduction of this activity affected the oil content and fatty acid composition of the Arabidopsis seeds. Thus, dry mutant seeds had less triacylglycerol content, while other neutral lipids like diacylglycerols were not affected. Furthermore, the metabolic flow of the different glycerolipid species into seed oil in the developing seeds was reduced at different stages of seed formation in the fata1 fata2 line. This diminished metabolic flow induced increases in the proportion of linolenic and erucic fatty acids in the seed oil, in a similar way as previously reported for the wri1 Arabidopsis mutant that accumulates oil poorly. The similarities between these two mutants and the origin of their phenotype are discussed in function of the results.

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Section: Introductionmentioning

confidence: 94%

Reduced expression of FatA thioesterases in Arabidopsis affects the oil content and fatty acid composition of the seeds

Moreno‐Pérez

Venegas-Calerón

Vaistij

et al. 2011

Planta

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“…The free fatty acids released by thioesterases are only detected at very low levels in developing seeds, as they are rapidly converted to their corresponding acyl‐CoAs by long chain acyl‐CoA synthetases (LACSs, EC 6.2.1.3; Schnurr et al ). Although initially controversial (Thomas et al , ), the existence of free fatty acids as intermediates of fatty acid synthesis was confirmed in labeling experiments (Pollard and Ohlrogge ).…”

Section: Introductionmentioning

confidence: 98%

“…Although initially controversial (Thomas et al 1982(Thomas et al , 1983, the existence of free fatty acids as intermediates of fatty acid synthesis was confirmed in labeling experiments (Pollard and Ohlrogge 1999).…”

mentioning

confidence: 98%

Sunflower (Helianthus annuus) long‐chain acyl‐coenzyme A synthetases expressed at high levels in developing seeds

Aznar-Moreno

Venegas-Calerón

Martı́nez-Force

et al. 2013

Physiologia Plantarum

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Long chain fatty acid synthetases (LACSs) activate the fatty acid chains produced by plastidial de novo biosynthesis to generate acyl-CoA derivatives, important intermediates in lipid metabolism. Oilseeds, like sunflower, accumulate high levels of triacylglycerols (TAGs) in their seeds to nourish the embryo during germination. This requires that sunflower seed endosperm supports very active glycerolipid synthesis during development. Sunflower seed plastids produce large amounts of fatty acids, which must be activated through the action of LACSs, in order to be incorporated into TAGs. We cloned two different LACS genes from developing sunflower endosperm, HaLACS1 and HaLACS2, which displayed sequence homology with Arabidopsis LACS9 and LACS8 genes, respectively. These genes were expressed at high levels in developing seeds and exhibited distinct subcellular distributions. We generated constructs in which these proteins were fused to green fluorescent protein and performed transient expression experiments in tobacco cells. The HaLACS1 protein associated with the external envelope of tobacco chloroplasts, whereas HaLACS2 was strongly bound to the endoplasmic reticulum. Finally, both proteins were overexpressed in Escherichia coli and recovered as active enzymes in the bacterial membranes. Both enzymes displayed similar substrate specificities, with a very high preference for oleic acid and weaker activity toward stearic acid. On the basis of our findings, we discuss the role of these enzymes in sunflower oil synthesis.

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“…[3]). Enzymatic activities related to carnitine transfer on acyl moieties have also been measured in plant tissues and localised in mitochondria [4,5] and plastids [6,7]. The recent identification and characterisation of an Arabidopsis thaliana knockout mutant for a putative carnitine transmembrane carrier (BOU) suggest that carnitine may have a much more critical role than expected [8].…”

Section: Introductionmentioning

confidence: 98%

Carnitine is associated with fatty acid metabolism in plants

Bourdin

Adenier

Perrin

2007

Plant Physiology and Biochemistry

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The synthesis of short- and long-chain acylarnitine by etio-chloroplasts of greening barley leaves

Cited by 19 publications

References 16 publications

Reduced expression of FatA thioesterases in Arabidopsis affects the oil content and fatty acid composition of the seeds

Reduced expression of FatA thioesterases in Arabidopsis affects the oil content and fatty acid composition of the seeds

Sunflower (Helianthus annuus) long‐chain acyl‐coenzyme A synthetases expressed at high levels in developing seeds

Carnitine is associated with fatty acid metabolism in plants

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