Overexpression of Two New Acyl-CoA:Diacylglycerol Acyltransferase 2-Like Acyl-CoA:Sterol Acyltransferases Enhanced Squalene Accumulation in

Overview

Journal Front Microbiol

Specialty Microbiology

Date 2022 Feb 11

PMID 35145505

Authors

E-Ming Rau

Zdenka Bartosova

Kare Andre Kristiansen

Inga Marie Aasen

Per Bruheim

Helga Ertesvag

Affiliations

Soon will be listed here.

Abstract

Thraustochytrids are heterotrophic marine eukaryotes known to accumulate large amounts of triacylglycerols, and they also synthesize terpenoids like carotenoids and squalene, which all have an increasing market demand. However, a more extensive knowledge of the lipid metabolism is needed to develop thraustochytrids for profitable biomanufacturing. In this study, two putative type-2 Acyl-CoA:diacylglycerol acyltransferases (DGAT2) genes of sp. T66, , and , and their homologs in SR21, and , were characterized. In SR21, genomic knockout of reduced the amount of the steryl esters of palmitic acid, SE (16:0), and docosahexaenoic acid, SE (22:6). The double mutant of and produced even less of these steryl esters. The expression and overexpression of and , respectively, enhanced SE (16:0) and SE (22:6) production more significantly than those of and . In contrast, these mutations did not significantly change the level of triacylglycerols or other lipid classes. The results suggest that the four genes encoded proteins possessing acyl-CoA:sterol acyltransferase (ASAT) activity synthesizing both SE (16:0) and SE (22:6), but with the contribution from AlASATb and T66ASATb being more important than that of AlASATa and T66ASATa. Furthermore, the expression and overexpression of and enhanced squalene accumulation in SR21 by up to 88%. The discovery highlights the functional diversity of DGAT2-like proteins and provides valuable information on steryl ester and squalene synthesis in thraustochytrids, paving the way to enhance squalene production through metabolic engineering.

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