A specific acyl-ACP thioesterase implicated in medium-chain fatty acid production in immature cotyledons of Umbellularia californica

Pollard, Mike; Anderson, L; Chen, Fan; Hawkins, Deborah J.; Davies, H. Maelor

doi:10.1016/0003-9861(91)90300-8

Cited by 153 publications

(90 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There are several published studies of acyl-ACP thioesterases from a variety of plant species (7,8,12,17,18,24), and recently the purification and cloning of a 12:0-ACP thioesterase from California bay has been reported (6,30). We used as a starting point for our purification the protocol described by McKeon and Stumpf (12), but found that in our laboratory it did not yield the degree of purity reported by those authors.…”

Section: Discussionmentioning

confidence: 96%

“…The safflower thioesterase activities expressed in E. coli are inhibited by the sulfhydryl-specific reagent N-ethylmaleimide (D.S. Knutzon, unpublished data) and studies indicate that other higher plant acyl-ACP thioesterases are sensitive to N-ethylmaleimide, iodoacetamide, and 5,5'-dithiobis-(2-nitrobenzoic acid) (17,18), suggesting that a cysteine residue is involved at the active site. There are three cysteine residues conserved between the 2-1 and 5-2 encoded proteins, although none has the conserved active site motif (GXC followed by a hydrophobic residue) of the cysteine-based hydrolases (1).…”

Section: Discussionmentioning

confidence: 99%

“…Fatty acid biosynthesis in plants is catalyzed by a series of soluble, discrete enzymes (23) that are localized in the chloroplasts of leaves (16) nia bay (Umbellularia californica), which accumulates high levels of lauric acid (12:0) in its seed triacylglycerols. Recently, a 12:0-ACP-specific thioesterase has been isolated from this species and shown to redirect fatty acid synthesis to the production of laurate in transgenic plants (6,18,30). In plants that accumulate the longer-chain fatty acids, the specificity of the acyl-ACP thioesterase may also play a role in determining the final fatty acid composition of the storage oil.…”

mentioning

confidence: 99%

“…Fatty acid biosynthesis in plants is catalyzed by a series of soluble, discrete enzymes (23) that are localized in the chloroplasts of leaves (16) and the proplastids of developing seed tissue (14, 25,31). Fatty acids up to 18 carbon atoms in length are synthesized in twocarbon increments as ACP2 thioesters (15). Acyl-ACP thioesterase (EC 3.1.2.14) catalyzes the hydrolysis of these acyl-ACP thioesters (24) to release free fatty acds, which are transported to the cytoplasm for further modifications and incorporation into storage triacylglycerols (28).…”

mentioning

confidence: 99%

See 3 more Smart Citations

Isolation and Characterization of Two Safflower Oleoyl-Acyl Carrier Protein Thioesterase cDNA Clones

Knutzon¹,

Bleibaum²,

Nelsen³

et al. 1992

Plant Physiol.

View full text Add to dashboard Cite

Oleoyl-acyl carrier protein (18:1-ACP) thioesterase has been partially purified from developing safflower (Carthamus tinctorius) seeds. Protein species with molecular masses of 34 and 40 kD associated with thioesterase activity were identified and partially sequenced. Analysis of amino-terminal and internal cyanogen bromide peptide sequences revealed no differences in the primary structure of the two species. Amino acid sequence was used to design degenerate oligonucleotides for primers in a polymerase chain reaction (PCR) using safflower embryo cDNA as a template. A 380-base pair PCR product was used to isolate two classes of cDNA clones, designated 2-1 and 5-2, from the embryo cDNA library. Clone 2-1 encodes a 389-amino acid protein including a 60-amino acid transit peptide, and contains all of the protein sequence determined from the 34-and 40-kD proteins. Clone 5-2 encodes a 385-amino acid protein with 80% identity to that encoded by 2-1. Expression of the two safflower cDNA clones in Escherichia coli resulted in a 50-to 100-fold increase in the level of 18:1-ACP thioesterase activity. Both thioesterases are most active on 18:1-ACP; however, the enzyme encoded by 5-2 shows less discrimination against saturated 16-and 18-carbon acyl-ACP substrates.Fatty acids are important components of membrane phospholipids in all plant tissues and are also stored in the form of triacylglycerols in the seeds of many species for use as an energy source upon germination. Fatty acid biosynthesis in plants is catalyzed by a series of soluble, discrete enzymes (23) that are localized in the chloroplasts of leaves (16) nia bay (Umbellularia californica), which accumulates high levels of lauric acid (12:0) in its seed triacylglycerols. Recently, a 12:0-ACP-specific thioesterase has been isolated from this species and shown to redirect fatty acid synthesis to the production of laurate in transgenic plants (6,18,30). In plants that accumulate the longer-chain fatty acids, the specificity of the acyl-ACP thioesterase may also play a role in determining the final fatty acid composition of the storage oil.We are interested in studying acyl-ACP thioesterases with specificities for 16-and 18-carbon fatty acids. Acyl-ACP thioesterase activities have been characterized at various stages of purification from a number of plant species that accumulate 16-and 18-carbon fatty acids in their triacylglycerols, including avocado (17, 24), safflower (Carthamus tinctorius) (12), squash (8), and rapeseed (7). The enzymes show distinct preferences for 18:1-ACP over 18:0-ACP and 16:0-ACP substrates and are relatively inactive on acyl-CoAs.To investigate further the role of acyl-ACP thioesterase in the determination of seed oil composition, we have purified and obtained partial amino acid sequence of an 18:1-ACP thioesterase from developing safflower seeds. Two different classes of cDNA clones encoding 18:1-ACP thioesterase have been isolated and characterized. The substrate specificity of the protein encoded by each clone has been examined by ...

show abstract

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Isolation and Characterization of Two Safflower Oleoyl-Acyl Carrier Protein Thioesterase cDNA Clones

Knutzon¹,

Bleibaum²,

Nelsen³

et al. 1992

Plant Physiol.

View full text Add to dashboard Cite

show abstract

“…The FatBs from U. californica (Pollard et al 1991;Voelker et al 1992), A. thaliana (Dormann et al 1995), U. americana (Voelker et al 1997) and nutmeg (Myristica fragrans; Voelker et al 1997) are specific for 12 : 0-ACP and play a critical role in MCFA production. Unlike these FatBs, CocoFatB1 shows a preference for 14 : 0-ACP, 16 : 0-ACP and 18 : 0-ACP.…”

Section: Discussionmentioning

confidence: 99%

Molecular cloning and characterisation of an acyl carrier protein thioesterase gene (CocoFatB1) expressed in the endosperm of coconut (Cocos nucifera) and its heterologous expression in Nicotiana tabacum to engineer the accumulation of different fatty acids

Yang

Chen

Liang

et al. 2014

Functional Plant Biol.

View full text Add to dashboard Cite

Abstract. Coconut (Cocos nucifera L.) contains large amounts of medium chain fatty acids, which mostly recognise acylacyl carrier protein (ACP) thioesterases that hydrolyse acyl-ACP into free fatty acids to terminate acyl chain elongation during fatty acid biosynthesis. A full-length cDNA of an acyl-ACP thioesterase, designated CocoFatB1, was isolated from cDNA libraries prepared from coconut endosperm during fruit development. The gene contained an open reading frame of 1254 bp, encoding a 417-amino acid protein. The amino acid sequence of the CocoFatB1 protein showed 100% and 95% sequence similarity to CnFatB1 and oil palm (Elaeis guineensis Jacq.) acyl-ACP thioesterases, respectively. Real-time fluorescent quantitative PCR analysis indicated that the CocoFatB1 transcript was most abundant in the endosperm from 8-month-old coconuts; the leaves and endosperm from 15-month-old coconuts had~80% and~10% of this level. The CocoFatB1 coding region was overexpressed in tobacco (Nicotiana tabacum L.) under the control of the seed-specific napin promoter following Agrobacterium tumefaciens-mediated transformation. CocoFatB1 transcript expression varied 20-fold between different transgenic plants, with 21 plants exhibiting detectable levels of CocoFatB1 expression. Analysis of the fatty acid composition of transgenic tobacco seeds showed that the levels of myristic acid (14 : 0), palmitic acid (16 : 0) and stearic acid (18 : 0) were increased by 25%, 34% and 17%, respectively, compared with untransformed plants. These results indicated that CocoFatB1 acts specifically on 14 : 0-ACP, 16 : 0-ACP and 18 : 0-ACP, and can increase medium chain saturated fatty acids. The gene may valuable for engineering fatty acid metabolism in crop improvement programmes.

show abstract

Lipid Metabolism

Schmid

2004

Handbook of Plant Biotechnology

View full text Add to dashboard Cite

Lipids are an immensely diverse group of compounds, technically including all biomolecules that dissolve more readily in non‐polar solvents than in water. This review will emphasisze two prominent groups of lipids: the acyl lipids, whose hydrophobic units are derived from fatty acids, and the isoprenoids, made up of five‐carbon isopentene units. Acyl lipids, in the form of the triacylglycerols stored as energy reserves, underpin the vegetable oil industry. In addition, acyl lipids that dominate the bilayers of plant membranes, are indispensable for the protective layers that prevent plant desiccation and pathogen attack, and include several signalling molecules. Isoprenoids are even more diverse than acyl lipids, with more than 25,000known. Two prominent groups are the sterols, which are important membrane constituents, and the carotenoids, which collect light for photosynthesis, protect plants from excessive light, attract pollinators and fruit dispersal agents, and provide vitamin A precursors for consumers. Biotechnology has provided both a tool for understanding plant lipid metabolism, and a means of altering quality and quantity of these constituents to better serve the needs of industry and human nutrition better.

show abstract

A specific acyl-ACP thioesterase implicated in medium-chain fatty acid production in immature cotyledons of Umbellularia californica

Cited by 153 publications

References 10 publications

Isolation and Characterization of Two Safflower Oleoyl-Acyl Carrier Protein Thioesterase cDNA Clones

Isolation and Characterization of Two Safflower Oleoyl-Acyl Carrier Protein Thioesterase cDNA Clones

Molecular cloning and characterisation of an acyl carrier protein thioesterase gene (CocoFatB1) expressed in the endosperm of coconut (Cocos nucifera) and its heterologous expression in Nicotiana tabacum to engineer the accumulation of different fatty acids

Lipid Metabolism

Contact Info

Product

Resources

About