2018 journal article
Diacylglycerol acyltransferase 1 is activated by phosphatidate and inhibited by SnRK1-catalyzed phosphorylation
PLANT JOURNAL, 96(2), 287–299.
author keywords: triacylglycerol biosynthesis; DGAT; Brassica napus; biochemical regulation; allostery
MeSH headings : Acyl Coenzyme A / metabolism; Brassica napus / enzymology; Brassica napus / genetics; Carbohydrate Metabolism; Catalysis; Diacylglycerol O-Acyltransferase / genetics; Diacylglycerol O-Acyltransferase / metabolism; Energy Metabolism; Homeostasis; Lipids / physiology; Phosphatidic Acids / metabolism; Phosphorylation; Plant Proteins / genetics; Plant Proteins / metabolism; Protein Serine-Threonine Kinases / genetics; Protein Serine-Threonine Kinases / metabolism; Triglycerides / biosynthesis
TL;DR:
Phosphatidate (PA) was identified as a feed-forward activator of BnaDGAT1, enabling the final enzyme in the Kennedy pathway to adjust to the incoming flow of carbon leading to TAG, indicating that PA facilitates the transition of the enzyme into the more active state.
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UN Sustainable Development Goal Categories
3. Good Health and Well-being
(Web of Science)
Source: Web Of Science
Added: October 22, 2018
SummaryDiacylglycerol acyltransferase 1 (DGAT1) catalyzes the final and committed step in the Kennedy pathway for triacylglycerol (TAG) biosynthesis and, as such, elucidating its mode of regulation is critical to understand the fundamental aspects of carbon metabolism in oleaginous crops. In this study, purified Brassica napus diacylglycerol acyltransferase 1 (BnaDGAT1) in n‐dodecyl‐β‐d‐maltopyranoside micelles was lipidated to form mixed micelles and subjected to detailed biochemical analysis. The degree of mixed micelle fluidity appeared to influence acyltransferase activity. BnaDGAT1 exhibited a sigmoidal response and eventual substrate inhibition with respect to increasing concentrations of oleoyl‐CoA. Phosphatidate (PA) was identified as a feed‐forward activator of BnaDGAT1, enabling the final enzyme in the Kennedy pathway to adjust to the incoming flow of carbon leading to TAG. In the presence of PA, the oleoyl‐CoA saturation plot became more hyperbolic and desensitized to substrate inhibition indicating that PA facilitates the transition of the enzyme into the more active state. PA may also relieve possible autoinhibition of BnaDGAT1 brought about by the N‐terminal regulatory domain, which was shown to interact with PA. Indeed, PA is a key effector modulating lipid homeostasis, in addition to its well recognized role in lipid signaling. BnaDGAT1 was also shown to be a substrate of the sucrose non‐fermenting‐1‐related kinase 1 (SnRK1), which catalyzed phosphorylation of the enzyme and converted it to a less active form. Thus, this known regulator of carbon metabolism directly influences TAG biosynthesis.