Laboratories: CERMAV and LPCV - 01/10/2022 - 30/09/2025

Thesis project holders: Christelle Breton and Eric Marechal
Young thesis researcher: Batoul Moubarak

Abstract: Galactolipids are characteristic components of photosynthetic membranes, but the molecular bases explaining the marked preference of plastidial glycolipid synthases for galactose over glucose remains unknown. In Arabidopsis, MGD1 catalyzes the bulk synthesis of monogalactosyldiacylglycerol (MGDG) and exhibits remarkable specificity for its sugar donor, UDP-galactose. Using a structure-guided mutational approach, we dissected the molecular constraints governing the selectivity of sugar donor in this essential plastidial enzyme. Bifunctional galactosyl/glucosyltransferases were generated, providing new tools for studying the biogenesis of thylakoid glycolipids. Intriguingly, functional MGD-like enzymes were identified in non-photosynthetic Eugregarinorida parasites, suggesting an unexpected evolutionary conservation and a previously unrecognized role of galactolipid synthesis outside plastids.

Publication: Moubarak, B., Jabeguero, D., Chazalet, V., Maréchal, E., Makashakova, O., & Breton, C. Expanding the sugar donor selectivity of MGD1, the major galactolipid synthase in Arabidopsis thaliana. Submitted.