MISELIAS · Mechanistic Investigation of Microbial Secondary Lipid Assembly

Secondary lipid metabolites such as polyunsaturated fatty acids (PUFAs) are specialised fats that are essential for any organism optimal physiological functions. PUFAs are indeed vital for human normal development and functioning of the brain and the central nervous system, and are consumed as nutraceuticals for their numerous health benefits, including anti-inflammatory and immunoregulatory actions. The current major sources of PUFAs (fish, algae and fish oil products) are threatened by global warming, pollution and overfishing, therefore novel and sustainable sources are sought after. PUFAs are biosynthesised de novo in bacteria by multifunctional iterative enzymes, the polyunsaturated fatty acid (Pfa) synthases. Despite the enormous interest in these enzymes and their products, Pfa biocatalysis remains poorly understood due to the inability of acquiring direct information on the nature and on the processing of the biosynthetic intermediates. This lack of knowledge hampers the full utilization of the biocatalysis and of sustainable resources for essential fatty acids. The proposed project aims at elucidating the mechanistic details of secondary lipids assembly by Pfa synthases utilising in vitro enzymology and chemical probes capable of capturing Pfa biosynthetic intermediates. Specific research objectives include: (1) the cloning, the expression and the reconstitution of an active Pfa synthase in vitro; (2) the capture of Pfa synthases intermediates using chemical probes and their characterisation; and, on these bases, (3) the detailed reconstruction of the mechanisms involved in secondary lipid assembly by the Pfa synthase. This work will provide novel insights into the fundamentals of PfA enzyme workings and therefore the foundations of novel microbial biotechnology for the production of secondary lipid metabolites.