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Type 1 diacylglycerol acyltransferases of Brassica napus preferentially incorporate oleic acid into triacylglycerol.

Aznar-Moreno J, Denolf P, Van Audenhove K, De Bodt S, Engelen S, Fahy D, Wallis JG, Browse J - J. Exp. Bot. (2015)

Bottom Line: Thorough understanding of the enzymology of oil accumulation is critical to the goal of modifying oilseeds for improved vegetable oil production.This strong sensitivity of the BnDGAT1 isozymes to the relative concentrations of acyl-CoA substrates substantially explains the observed fatty acid composition of B. napus seed oil.Understanding these enzymes that are critical for triacylglycerol synthesis will facilitate genetic and biotechnological manipulations to improve this oilseed crop.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA.

No MeSH data available.


Related in: MedlinePlus

Selectivity BnDGAT1 isozymes with low palmitoyl-CoA concentration. Microsome aliquots from the yeast TAG mutant H1246 expressing the indicated BnDGAT1 isozyme were supplied with [14C]-palmitoyl-CoA simultaneously with [3H]-oleoyl-CoA, along with either 1-palmitoyl-2-oleoyl-sn-glycerol (PO-DAG) or dioleoyl-sn-glycerol (OO-DAG). 5µM palmitoyl-CoA and 15 µM oleoyl-CoA were supplied. The DGAT1 activity was calculated based on radioactivity incorporated into TAG; results are means ±SD, n=3.
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Figure 7: Selectivity BnDGAT1 isozymes with low palmitoyl-CoA concentration. Microsome aliquots from the yeast TAG mutant H1246 expressing the indicated BnDGAT1 isozyme were supplied with [14C]-palmitoyl-CoA simultaneously with [3H]-oleoyl-CoA, along with either 1-palmitoyl-2-oleoyl-sn-glycerol (PO-DAG) or dioleoyl-sn-glycerol (OO-DAG). 5µM palmitoyl-CoA and 15 µM oleoyl-CoA were supplied. The DGAT1 activity was calculated based on radioactivity incorporated into TAG; results are means ±SD, n=3.

Mentions: While equimolar substrates are typically used in selectivity experiments (Lung and Weselake, 2006), a 1:3 ratio of palmitoyl-CoA to oleoyl-CoA is more representative of the acyl-CoA pool in B. napus between 30 and 40 days after pollination, when rapid deposition of storage TAG is taking place (Perry and Harwood, 1993; Larson et al., 2002). Therefore additional experiments were conducted with the acyl-CoA substrates present at a 1:3 ratio, with 5 µM 16:0-CoA and 15 µM 18:1-CoA. The effect of approximating the physiological ratio of substrates was striking. All the enzymes incorporated 16:0 at much lower rates, while maintaining or increasing 18:1 incorporation using PO-DAG (Fig. 7). Incorporation of 18:1 with OO-DAG was essentially unchanged. It was questioned whether this difference was simply due to the lower 16:0 concentration, but when 5 µM 16:0 was provided as the sole acyl-CoA substrate, incorporation was comparable to the rates measured at 15 µM (Table 1).


Type 1 diacylglycerol acyltransferases of Brassica napus preferentially incorporate oleic acid into triacylglycerol.

Aznar-Moreno J, Denolf P, Van Audenhove K, De Bodt S, Engelen S, Fahy D, Wallis JG, Browse J - J. Exp. Bot. (2015)

Selectivity BnDGAT1 isozymes with low palmitoyl-CoA concentration. Microsome aliquots from the yeast TAG mutant H1246 expressing the indicated BnDGAT1 isozyme were supplied with [14C]-palmitoyl-CoA simultaneously with [3H]-oleoyl-CoA, along with either 1-palmitoyl-2-oleoyl-sn-glycerol (PO-DAG) or dioleoyl-sn-glycerol (OO-DAG). 5µM palmitoyl-CoA and 15 µM oleoyl-CoA were supplied. The DGAT1 activity was calculated based on radioactivity incorporated into TAG; results are means ±SD, n=3.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4588894&req=5

Figure 7: Selectivity BnDGAT1 isozymes with low palmitoyl-CoA concentration. Microsome aliquots from the yeast TAG mutant H1246 expressing the indicated BnDGAT1 isozyme were supplied with [14C]-palmitoyl-CoA simultaneously with [3H]-oleoyl-CoA, along with either 1-palmitoyl-2-oleoyl-sn-glycerol (PO-DAG) or dioleoyl-sn-glycerol (OO-DAG). 5µM palmitoyl-CoA and 15 µM oleoyl-CoA were supplied. The DGAT1 activity was calculated based on radioactivity incorporated into TAG; results are means ±SD, n=3.
Mentions: While equimolar substrates are typically used in selectivity experiments (Lung and Weselake, 2006), a 1:3 ratio of palmitoyl-CoA to oleoyl-CoA is more representative of the acyl-CoA pool in B. napus between 30 and 40 days after pollination, when rapid deposition of storage TAG is taking place (Perry and Harwood, 1993; Larson et al., 2002). Therefore additional experiments were conducted with the acyl-CoA substrates present at a 1:3 ratio, with 5 µM 16:0-CoA and 15 µM 18:1-CoA. The effect of approximating the physiological ratio of substrates was striking. All the enzymes incorporated 16:0 at much lower rates, while maintaining or increasing 18:1 incorporation using PO-DAG (Fig. 7). Incorporation of 18:1 with OO-DAG was essentially unchanged. It was questioned whether this difference was simply due to the lower 16:0 concentration, but when 5 µM 16:0 was provided as the sole acyl-CoA substrate, incorporation was comparable to the rates measured at 15 µM (Table 1).

Bottom Line: Thorough understanding of the enzymology of oil accumulation is critical to the goal of modifying oilseeds for improved vegetable oil production.This strong sensitivity of the BnDGAT1 isozymes to the relative concentrations of acyl-CoA substrates substantially explains the observed fatty acid composition of B. napus seed oil.Understanding these enzymes that are critical for triacylglycerol synthesis will facilitate genetic and biotechnological manipulations to improve this oilseed crop.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA.

No MeSH data available.


Related in: MedlinePlus