Design of New Plant Products: Engineering of Fatty Acid Metabolism

Ohlrogge, John B.

doi:10.1104/pp.104.3.821

Cited by 214 publications

(124 citation statements)

References 3 publications

Supporting

Mentioning

119

Contrasting

Unclassified

Order By: Relevance

“…Such fatty acids have utility in industrial applications such as the production of nylon precursors (31). As described, expression of a G188L mutant of the castor ⌬ 9 -18:0-ACP DES in Arabidopsis fab1 plants resulted in the accumulation of the unusual monoenes 16:1⌬ 9 , 18:1⌬ 11 , and 20:1⌬ 13 to amounts approaching 30% of the total fatty acids of the seed oil.…”

Section: Discussionmentioning

confidence: 99%

Substrate-dependent mutant complementation to select fatty acid desaturase variants for metabolic engineering of plant seed oils

Cahoon

Shanklin

2000

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

View full text Add to dashboard Cite

We demonstrate that naturally occurring C14 and C16-specific acylacyl carrier protein (ACP) desaturases from plants can complement the unsaturated fatty acid (UFA) auxotrophy of an Escherichia coli fabA͞fadR mutant. Under the same growth conditions, C 18-specific ⌬ 9 -stearoyl (18:0)-ACP desaturases are unable to complement the UFA auxotrophy. This difference most likely results from the presence of sufficient substrate pools of C 14 and C16 acyl-ACPs but a relative lack of C 18 acyl-ACP pools in E. coli to support the activities of the plant fatty acid desaturase. Based on this, a substrate-dependent selection system was devised with the use of the E. coli UFA auxotroph to isolate mutants of the castor ⌬ 9 -18:0-ACP desaturase that display enhanced specificity for C 14 and C16 acyl-ACPs. Using this selection system, a number of desaturase variants with altered substrate specificities were isolated from pools of randomized mutants. These included several G188L mutant isolates, which displayed a 15-fold increase in specific activity with 16:0-ACP relative to the wild-type castor ⌬ 9 -18:0-ACP desaturase. Expression of this mutant in Arabidopsis thaliana resulted in the accumulation of unusual monounsaturated fatty acids to amounts of >25% of the seed oil. The bacterial selection system described here thus provides a rapid means of isolating variant fatty acid desaturase activities for modification of seed oil composition.A cyl-acyl carrier protein (ACP)-desaturases (DES) are a family of soluble enzymes that are associated with the synthesis of monounsaturated fatty acids in plants (1). These enzymes catalyze the insertion of a double bond into saturated fatty acids bound to ACP in the plastids of plant cells, and thus serve as one of the primary determinants of the unsaturated fatty acid content of plant membranes and seed storage oils. The most widely occurring member of this family is the ⌬ 9 -stearoyl (18:0 ‡ )-ACP DES, which introduces the double bond of oleic acid (1). In addition, a number of other acyl-ACP DES have been identified that are associated with the synthesis of unusual monounsaturated fatty acids and have altered substrate and regio-specifities relative to the ⌬ 9 -18:0-ACP DES. Variant acyl-ACP DES identified to date include the ⌬ 4 -palmitoyl (16:0)-ACP DES from Umbelliferae seed (2, 3), the ⌬ 6 -16:0-ACP DES from black-eyed Susan vine (Thunbergia alata) seed (4), the ⌬ 9 -myristoyl (14:0)-ACP DES from geranium (Pelargonium xhortorum) trichomes (5), and ⌬ 9 -16:0-ACP DES from cat's claw (Doxantha unguis-cati) (6) and milkweed (Asclepias syriaca) (7) seeds. These enzymes share Ն60% amino acid sequence identity with the ⌬ 9 -18:0-ACP DES.This collection of structurally related, but functionally diverged, enzymes provides a tool for understanding how acyl-ACP DES recognize the chain length of substrates and position the placement of double bonds. Characterization of these properties also has been greatly aided by information from the crystal structure of the castor ⌬ 9 -18:0-ACP DES (8). From the...

show abstract

Section: Discussionmentioning

confidence: 99%

Substrate-dependent mutant complementation to select fatty acid desaturase variants for metabolic engineering of plant seed oils

Cahoon

Shanklin

2000

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

View full text Add to dashboard Cite

show abstract

“…Plant TAGs are a major agricultura1 commodity, with avalue of ~$ 2 5 billion annually. Recently, severa1 successes have been achieved in genetically engineering oilseed fatty acid composition to produce new or improved vegetable oils (reviewed by Kinney, 1994;Ohlrogge, 1994;Topfer et al, 1995). Almost all of the many soluble enzymes involved in producing oleic acid from acetyl-COA have now been cloned (Topfer and Martini, 1994).…”

Section: Summary and Perspectives For Future Researchmentioning

confidence: 99%

Lipid biosynthesis.

1995

View full text Add to dashboard Cite

“…Canola oil is of high nutritional value with high concentrations of unsaturated C18 fatty acids (FAs; .60%) and a low level of erucic acid (C22:1; ,1%), an undesirable FA in edible oil (Harvey and Downey, 1964;Dupont et al, 1989). Moreover, vegetable oil is a suitable source for biodiesel fuels and important raw materials in industry (Ohlrogge, 1994;Thelen and Ohlrogge, 2002). The demand for vegetable oil is sharply increased in recent years, and the increase of the oil content is thus a major challenge for genetic improvement of oilseed crops.…”

mentioning

confidence: 99%

Enhanced Seed Oil Production in Canola by Conditional Expression of Brassica napus LEAFY COTYLEDON1 and LEC1-LIKE in Developing Seeds

et al. 2011

View full text Add to dashboard Cite

The seed oil content in oilseed crops is a major selection trait to breeders. In Arabidopsis (Arabidopsis thaliana), LEAFY COTYLEDON1 (LEC1) and LEC1-LIKE (L1L) are key regulators of fatty acid biosynthesis. Overexpression of AtLEC1 and its orthologs in canola (Brassica napus), BnLEC1 and BnL1L, causes an increased fatty acid level in transgenic Arabidopsis plants, which, however, also show severe developmental abnormalities. Here, we use truncated napin A promoters, which retain the seed-specific expression pattern but with a reduced expression level, to drive the expression of BnLEC1 and BnL1L in transgenic canola. Conditional expression of BnLEC1 and BnL1L increases the seed oil content by 2% to 20% and has no detrimental effects on major agronomic traits. In the transgenic canola, expression of a subset of genes involved in fatty acid biosynthesis and glycolysis is up-regulated in developing seeds. Moreover, the BnLEC1 transgene enhances the expression of several genes involved in Suc synthesis and transport in developing seeds and the silique wall. Consistently, the accumulation of Suc and Fru is increased in developing seeds of the transgenic rapeseed, suggesting the increased carbon flux to fatty acid biosynthesis. These results demonstrate that BnLEC1 and BnL1L are reliable targets for genetic improvement of rapeseed in seed oil production.

show abstract

Design of New Plant Products: Engineering of Fatty Acid Metabolism

Cited by 214 publications

References 3 publications

Substrate-dependent mutant complementation to select fatty acid desaturase variants for metabolic engineering of plant seed oils

Substrate-dependent mutant complementation to select fatty acid desaturase variants for metabolic engineering of plant seed oils

Lipid biosynthesis.

Enhanced Seed Oil Production in Canola by Conditional Expression of Brassica napus LEAFY COTYLEDON1 and LEC1-LIKE in Developing Seeds

Contact Info

Product

Resources

About