A cryoprotectant induces conformational change in glyceraldehyde-3-phosphate dehydrogenase

摘要

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a glycolytic enzyme, catalyses the conversion of d-glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate. While mammalian and yeast GAPDHs are multifunctional proteins that have additional functions beyond those involved in glycolysis, including reactions related to nuclear RNA transport, DNA replication/repair, membrane fusion and cellular apoptosis, Escherichia coli GAPDH (ecGAPDH) has only been reported to function in glycolysis. The S-loop of GAPDH is required for interaction with its cofactor and with other proteins. In this study, the threedimensional crystal structure of GAPDH treated with trehalose is reported at 2.0 ? resolution. Trehalose was used as a cryoprotectant for the GAPDH crystals. The structure of trehalose-bound ecGAPDH was compared with the structures of both NAD+-free and NAD+-bound ecGAPDH. At the S-loop, the bound trehalose in the GAPDH structure induces a 2.41 rotation compared with the NAD+-free ecGAPDH structure and a 3.11 rotation compared with the NAD+-bound ecGAPDH structure.