Defence Hilda Bax: " The diverse roles of glycogen branching enzymes and their synergistic activity"

Promotors: Dr. Edita Jurak, Prof. Marc van der Maarel, Dr. Hans Leemhuis

A bstract: Branched α-glucans like starch and glycogen are vital for storing energy in organisms. Glycogen accumulates when nutrients are scarce but carbon is available. Its structure, including chain length and branching, varies among bacteria and is crucial for its function. Glycogen synthesis involves two pathways, with glycogen branching enzymes (GBEs) creating branches in the structure. GBEs belong to GH13 and GH57 families, which differ in their ability to break and form bonds. This research focused on understanding GBE activity. This study revealed that they not only create branches but also extend chains, showing α-1,4-transglycosylation activity. It was also investigated how using both GH13 and GH57 GBEs together affects glycogen structure, finding a synergistic effect that increases branch density. Finally, a new GBE from the microorganism Pontibacter sp. was characterized, and highlighting their unique branching behaviors and potential roles in glycogen synthesis. This thesis advances our understanding of GBEs, showing their complex activities and interactions in glycogen synthesis. It highlights the potential of using both GH13 and GH57 GBEs to engineer glycogen with specific properties, which could have significant implications for biotechnology and carbohydrate metabolism.

Dessirtation