Heterologous expression of MiMLDP, a major lipid droplet protein of the microalga Myrmecia incisa, in Saccharomyces cerevisiae promotes more triacylglycerol storage principally by enlarging lipid droplet size

In some algae, lipid droplets (LDs) are surrounded by phospholipid monolayers containing specialized proteins such as major lipid droplet protein (MLDP), which serves as a principal structural component and makes significant contributions to the enrichment of LDs. In the present study, a new MLDP gene from green alga Myrmecia incisa was reported for the first time, and was comprehensively investigated with respect to its identification, localization and function. The gene product MiMLDP was 35.46 % identical to the reported ortholog in the synonym Lobosphaera incisa. A polyclonal antibody was prepared and the subcellular localization was confirmed to be on the LDs. By flow cytometry and TLC-FID analyses, MiMLDP was demonstrated to improve the accumulation of triacylglycerol. By fusing the coding sequence with eYFP and transforming into yeast strain BY4741, MiMLDP was found to be able to increase the size of LDs and decrease the content of steryl esters, which consequently enhanced the triacylglycerol storage. •A new MLDP isoform of M. incisa was identified and characterized.•Predicted subcellular localization of MiMLDP was experimentally validated.•Heterologous expression of MiMLDP promoted triacylglycerol production in yeast.•MiMLDP was responsible for enlarged lipid droplets and reduced steryl esters.