The diverse roles of glycogen branching enzymes and their synergistic activity
While plants can store energy in the form of starch, animals and yeasts use glycogen for energy storage. Glycogen accumulates when nutrients are scarce but carbon is available. Its structure, including chain length and branching, varies 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.
In her research, Hilda Bax focused on understanding GBE activity. Her research reveals that they not only create branches but also extend chains, showing α-1,4-transglycosylation activity. She also investigated how using both GH13 and GH57 GBEs together affects glycogen structure, finding a synergistic effect that increases branch density.
Finally, she characterized a new GBE from the microorganism Pontibacter sp., highlighting their unique branching behaviors and potential roles in glycogen synthesis. This thesis advances 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.