Dual Roles of Two Malic Enzymes in Lipid Biosynthesis and Salt Stress Response in Dunaliella salina

Abstract

Triacylglycerols (TAG) from microalgae can be used as feedstocks for biofuel production to address fuel shortages. Most of the current research has focused on the enzymes involved in TAG biosynthesis. In this study, the effects of malic enzyme (ME), which provides precursor and reducing power for TAG biosynthesis, on biomass and lipid accumulation and its response to salt stress in Dunaliella salina were investigated. The overexpression of DsME1 and DsME2 improved the lipid production, which reached 0.243 and 0.253 g/L and were 30.5 and 36.3% higher than wild type, respectively. The transcript levels of DsME1 and DsME2 increased with increasing salt concentration (0, 1, 2, 3, and 4.5 mol/L NaCl), indicating that DsMEs participated in the salt stress response in D. salina. It was found that cis-acting elements associated with the salt stress response were present on the promoters of two DsMEs. The deletion of the MYB binding site (MBS) on the DsME2 promoter confirmed that MBS drives the expression of DsME2 to participate in osmotic regulation in D. salina. In conclusion, MEs are the critical enzymes that play pivotal roles in lipid accumulation and osmotic regulation.

Functional Characterization of a CruP-Like Isomerase in Dunaliella

“…pZBEL-GP was preserved in our laboratory and used for the construction of gene overexpression in Dunaliella. We inserted DbLyISO gene fragment to pRSFDuet-1 ( Nco I- EcoR I) to construct pRSFDuet-LyISO. Plasmid multiplication was performed using E.…”

Towards Lipid from Microalgae: Products, Biosynthesis, and Genetic Engineering

“…To elevate DHA contents in Schizochytrium sp., CcME and MaELO3 were co-expressed; thus, DHA content was increased by 3.3-fold [137]. In Dunaliella salina, co-expression of DsME1 and DsME2 improved lipid production by up to 36.3% higher than the wild-type [138]. In Scenedesmus sp.…”