Crystal structures of glycogen-debranching enzyme mutants in complex with oligosaccharides.
Shen, M., Gong, X., Xiang, S.(2021) Acta Crystallogr F Struct Biol Commun 77: 420-426
- PubMed: 34726181 
- DOI: https://doi.org/10.1107/S2053230X21010918
- Primary Citation of Related Structures:  
7EIM, 7EJP, 7EJT, 7EKW, 7EKX - PubMed Abstract: 
Debranching is a critical step in the mobilization of the important energy store glycogen. In eukaryotes, including fungi and animals, the highly conserved glycogen-debranching enzyme (GDE) debranches glycogen by a glucanotransferase (GT) reaction followed by a glucosidase (GC) reaction. Previous work indicated that these reactions are catalyzed by two active sites located more than 50 Å apart and provided insights into their catalytic mechanisms and substrate recognition. Here, five crystal structures of GDE in complex with oligosaccharides with 4-9 glucose residues are presented. The data suggest that the glycogen main chain plays a critical role in binding to the GT and GC active sites of GDE and that a minimum of five main-chain residues are required for optimal binding.
Organizational Affiliation: 
Department of Biochemistry and Molecular Biology, Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, 22 Qixiangtai Road, Heping District, Tianjin 300070, People's Republic of China.