Evaluation of the importance of UDP-glucose and UDP-sugar pyrophosphorylases in paramylon accumulation in E. gracilis

GUERRERO SA

Conferencia; Euglena International Network 2020; 2020

European Bioinformatics Institute, UK. ? University of Nottingham, UK.Virginia Institute of Marine Science, USA

Euglena gracilis is a eukaryotic single-celled and photosynthetic organism placed under the kingdom Protista. This phytoflagellate can accumulate the photoassimilate CO2 as a linear β-1,3-glucan chains called paramylon. This storage polysaccharide can be quickly degraded, being the glucose units used for obtaining ATP and reducing power both in aerobic and anaerobic growth conditions. Our group has recently characterized an essential enzyme for the accumulation of the polysaccharide, the UDP-glucose pyrophosphorylase, which catalyzes the synthesis of UDP-glucose (the substrate of paramylon synthase). Additionally, the identification of a nucleotide sequence coding for a putative UDP-sugar pyrophosphorylase employing bioinformatics tools suggests the occurrence of an alternative source of UDP-glucose. In this study, we demonstrate the active involvement of both pyrophosphorylases for paramylon accumulation. Using techniques of single and combined selective knockdown of genes coding for these proteins, we evidenced a substantial decrease in the polysaccharide synthesis. Our findings indicate the existence in Euglena gracilis of a physiological dependence between paramylon accumulation and the partitioning of sugar nucleotides in other metabolic routes.