The 9th International Conference on Agricultural and Biological Sciences (ABS 2023)

Abstract: Glycogen is a storage polysaccharide commonly found in bacteria and animals, consisting of a linear chain of α-1,4 glycosidic linkages of glucose with many branches due to α-1,6 glycosidic linkages. In recent years, glycogen has been studied not only as a nutritional source but also for its functional properties. Various changes in the structure of glycogen may enable the development of new uses of glycogen and novel application. Glycogen metabolism in Escherichia coli is mediated by GlgC (ADP-Glucose pyrophosphorylase), which synthesizes ADPG, a substrate of glycogen, from glucose-1-phosphate (G1P), GlgA (Glycogen Synthase, GS), GlgB (Glycogen Branching Enzyme), which transfers one glucan chain to the C6 position of another, GlgX (Glycogen Debranching Enzyme), which is responsible for hydrolysis of the α-1,6 glycosidic linkage, and α-1 4 glycosidic linkages at the non-reducing end, and GlgP (Glycogen Phosphorylase), which catalyzes the hydrolysis of α-1,4 glycosidic linkages at the non-reducing end. On the other hand, the rice GBSSI (Granule-Bound Starch Synthase I) is an enzyme that catalyzes α-1,4 glycosidic linkages using ADPG as a substrate, similar to GS, to synthesize linear chains of amylose and amylopectin of storage starch. In this study, the OsGBSSI was introduced into E. coli BW25113 and various mutant strains ΔglgA, ΔglgX, and ΔglgP to investigate changes in the structure of the glycogen and metabolic profile of the modified glycogen producing E. coli. Glycogen from BW25113 expressing GBSSI showed a slight reduction in mean particle size, while OsGBSSI expressing ΔglgP showed a significant increase in mean particle size. Anion exchange-pulsed amperometric high-performance chromatography (HPAEC-PAD) was used to analyze the chain length distribution of the constituent unit chains. The results showed that in BW25113+GBSSI, the Degree of Polymarization (DP) 3-4 unit chains decreased and the DP5-11 unit chains clearly increased compared to BW25113. This suggests that GBSSI may elongate DP3-4. These results indicated that the OsGBSSI can modified particle size of glycogen, and changes in distribution of unit chains in E. coli.

Biography: Dr. Kimiko Itoh was awarded Ph. D in field of plant molecular biology at Toho University, Japan, in 1994. She started her career in PlanTech Research Institute, Mitsubishi Chemical Corporation, Yokohama, Japan and she was engaged in molecular biological studies of rice, and Brassica genome, development of disease resistant and insect resistant transgenic rice for 10 years, then she moved to Niigata University in 1995. Currently, she is professor of Institute of Science and Technology, Niigata University and is engaged in education at Faculty of Agriculture, and Graduate School of Science and Technology. She is also manager of Radioactive Isotope division and Chemical Biology Unit in Center for Coordination Research Facilities, Niigata University. 　Her major is Applied Glycoscience and Plant Science and Her research group currently focused on molecular mechanisms of abiotic stress responses in rice and application of fungal volatile compounds on improvement rice yielding and stress tolerance.