Poster - ?UDP-glucose, a key metabolite in carbohydrate metabolism in Euglena gracilis?

MUCHUT, ROBERTINO J.; CALLONI, RD; ARIAS, DG; IGLESIAS, AA; GUERRERO, SA

Paraná

Congreso; SAIB LIV Reunión Anual; 2018

SAIB

E. gracilis is a fresh water protist able to grow photosynthetic or heterotrophically using diverse organic compounds as sole source of carbon and energy for growth. E. gracilis is a suitable source for the generation of several compounds used for the production of cosmeceuticals, nutraceuticals, foods, paramylon and wax esters. When grown aerobically it produces an insoluble β?1,3?glucan (paramylon) as carbon storage. Paramylon and different oligo? and polysaccharides are synthesized by glycosyl transferases using UDP?glucose as substrate, being it generated in a reaction catalyzed by UDP?glucose pyrophosphorylase (EC 2.7.7.9; UDP?GlcPPase). In this sense, UDP?GlcPPase from E. gracilis wasexpressed in E. coli. Highly purified enzyme exhibited a monomeric structure, able to catalyze synthesis of UDP?Glc with a Vmax of 3350 U/mg. Glc?1P and UTP were the preferred substrates, although the enzyme also used (with lower catalytic efficiency) TTP, galactose?1P and mannose?1P. We identified redox modification of the enzyme that produces conformational changes, modifying the structure of the protein(monomers with different Stokes radii that interact forming oligomers). This change in the structure generates a loss of activity (also detected in vivo). RNAi assays were carried out against UDP?GlcPPase to analyze its functionality in vivo and to understand the importance of UDP?Glc in carbohydrate metabolism in E. gracilis.