Abstract
BackgroundOleate-enriched triacylglycerides are well-suited for lubricant applications that require high oxidative stability. Fatty acid carbon chain length and degree of desaturation are key determinants of triacylglyceride properties and the ability to manipulate fatty acid composition in living organisms is critical to developing a source of bio-based oil tailored to meet specific application requirements.ResultsWe sought to engineer the oleaginous yeast Yarrowia lipolytica for production of high-oleate triacylglyceride oil. We studied the effect of deletions and overexpressions in the fatty acid and triacylglyceride synthesis pathways to identify modifications that increase oleate levels. Oleic acid accumulation in triacylglycerides was promoted by exchanging the native ∆9 fatty acid desaturase and glycerol-3-phosphate acyltransferase with heterologous enzymes, as well as deletion of the Δ12 fatty acid desaturase and expression of a fatty acid elongase. By combining these engineering steps, we eliminated polyunsaturated fatty acids and created a Y. lipolytica strain that accumulates triglycerides with > 90% oleate content.ConclusionsHigh-oleate content and lack of polyunsaturates distinguish this triacylglyceride oil from plant and algal derived oils. Its composition renders the oil suitable for applications that require high oxidative stability and further demonstrates the potential of Y. lipolytica as a producer of tailored lipid profiles.
Highlights
Oleate-enriched triacylglycerides are well-suited for lubricant applications that require high oxidative stability
Lipid accumulation is induced by nutrient limitation in the presence of excess carbon and involves fatty acylCoA synthesis via a type I fatty acid synthase (FAS), modification of chain length and degree of desaturation by elongases and desaturases, and incorporation into triacylglyceride (TAG) via a series of enzymatic steps: glycerol-3-phosphate acyltransferase (GPAT) attaches the first fatty acid onto the glycerol backbone to produce lysophosphatidic acid (LPA); lysophosphatidic acid acyltransferase (LPAT) attaches a second fatty acid to produce phosphatidic acid (PA); PA is dephosphorylated by phosphatidate phosphatase (PAP) to produce diacylglycerol (DAG); diacylglycerol acyltransferase (DGAT) activities add a final fatty acid to produce TAGs
We report the engineering of a Y. lipolytica strain that produces oil highly enriched in monounsaturated and devoid of polyunsaturated fatty acids with an oleate content exceeding 90% of total fatty acids
Summary
Oleate-enriched triacylglycerides are well-suited for lubricant applications that require high oxidative stability. Fatty acid carbon chain length and degree of desaturation are key determinants of triacylglyceride properties and the ability to manipulate fatty acid composition in living organisms is critical to developing a source of bio-based oil tailored to meet specific application requirements. Lipid accumulation is induced by nutrient limitation in the presence of excess carbon and involves fatty acylCoA synthesis via a type I fatty acid synthase (FAS), modification of chain length and degree of desaturation by elongases and desaturases, and incorporation into triacylglyceride (TAG) via a series of enzymatic steps (reviewed in [16]): glycerol-3-phosphate acyltransferase (GPAT) attaches the first fatty acid onto the glycerol backbone to produce lysophosphatidic acid (LPA); lysophosphatidic acid acyltransferase (LPAT) attaches a second fatty acid to produce phosphatidic acid (PA); PA is dephosphorylated by phosphatidate phosphatase (PAP) to produce diacylglycerol (DAG); diacylglycerol acyltransferase (DGAT) activities add a final fatty acid to produce TAGs. The Y. lipolytica genome encodes two elongases (YALI0F06754, YALI0B20196), a Δ9 desaturase (OLE1 YALI0C05951), a Δ12 desaturase (FAD2 YALI0B10153), two GPATs (SCT1 YALI0C00209, GPA YALI0A10362), one LPAT (SLC1 YALI0E18964), one PAP (PAH1 YALI0D27016), and two DGATs (DGA1 YALI0E32769, DGA2 YALI0D07986) [17,18,19]. Pathway conservation between Saccharomyces cerevisiae [20, 21] and Y. lipolytica suggests that there is significant crosstalk between the TAG biosynthesis pathway and phospholipid synthesis
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