Betaine Lipids in euKaryotes

• Applicant: Professor Dr. Emanuel Schneck
• Subject Area: Plant Biochemistry and Biophysics ; Biophysics ; Metabolism, Biochemistry and Genetics of Microorganisms
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 406647862

Microalgae are today considered a new feedstock to produce a variety of biomolecules, most prominently triacylglycerol (TAG, containing three fatty acids) and essential omega3 fatty acids (FAs). The purposeful exertion of stress conditions, like phosphate starvation, is a common route to accumulate TAG in microalgae. A better understanding of why and how microalgae induce the biosynthesis of FAs and TAG under such stress conditions would help advancing the development of genetically engineered strains to produce biofuels or high-value products. Under phosphate starvation, phospholipids in extraplastidial membranes are replaced by betaine lipids in microalgae. Betaine lipids, which are glycerolipids with two FAs, are hypothesized to be analogues of the main eukaryote phosphoglycerolipid phosphatidylcholine (PC) and they often contain a high proportion of omeag3 fatty acids. In higher plants, the synthesis of betaine lipid is lost, driving plants to other strategies to cope with phosphate starvation: they replace theirphospholipids by glycolipids and do not accumulate TAG as much as microalgae.The objective of the BLinK project is to evaluate to what extent betaine lipids and PC lipids share physicochemical properties and could substitute each other in vivo, and how the presence of betaine lipid affects the lipid remodelling response to phosphate starvation. The project is organized in three axes:1.) the comparison of betaine and PC lipids’ biosynthetic pathways throughout algae evolution,2.) the analysis of betaine lipids’ physicochemical properties in terms of membrane fluidity, bending rigidity, as well as membrane-membrane interactions, for comparison with those of PC lipids, and3.) the in vivo investigation in two microalgae species, Phaeodactylum tricornutum (a diatom) and Nannochloropsis gaditana (an eustigmatophyte), genetically engineered to lack either PC or betaine lipids.The results obtained in these axes will be integrated in a scheme picturing the interplay between betaine lipids and PC lipids and addressing the puzzling question of betaine lipids’ absence in higher plants. Moreover, the project will provide missing data on the evolution of lipid metabolism that may help comprehend the control of phospholipid versus non-phosphorus lipid balance and, on longer term, enhance omega3 FA production and TAG accumulation for industrial applications. Additional deliverables include the identification of new enzymes involved in betaine lipid synthesis and the phylogenetic reconstruction of betaine lipid synthases and enzymes involved in PC synthesis.

• DFG Programme: Research Grants
• International Connection: France
• Partner Organisation: Agence Nationale de la Recherche / The French National Research Agency
• Cooperation Partner: Dr. Juliette Jouhet