Structural Biology of PUFA synthesis in Schizochytrium sp.

ABSTRACT : Dietary consumption of omega-3 polyunsaturated fatty acids (ω-3 PUFAs), especially docosahexaenoic acid (DHA, 22:6 ω-3), has been related to diverse human health benefits such as brain, immune and cardiovascular correct function. Currently, PUFAs main source are fish oils. However, unsustainability of fish wild catch due to steady growth of global population has forced to search for alternatives. The heterotrophic microalgae-like protist Schizochytrium sp. can accumulate high amounts of DHA compared to other DHA main producers like marine bacteria. Thus, it has become an ideal microorganism for ω-3 production due to its DHA content and easy cultivation. Still, current state of Schizochytrium sp. DHA viability to completely out-market fish oil is still unclear owing to its high costs compared to the latter. In order to overcome this limitation, metabolic engineering for enhancing DHA production in Schizochytrium sp. is being assessed. Nevertheless, absence of structural information of its PUFA synthase enzymatic system limits the understanding of this cumbersome process. This master’s thesis work has focused on trying to obtain an improved comprehension of the protein structure of pfa genes forming the Schizochytrium sp. PUFA synthase. To achieve this ambitious goal different cloning, purification and crystallization strategies have been devised. The in silico structural analysis of the proteins conforming the PUFA megasynthase complex has shown the existence of two separate ER PUFA synthase domains non-present in other DHA producers. A model for this ER duplication is proposed in this work.Máster en Biología Molecular y Biomedicin