Comparative analysis of two glyceraldehyde-3-phosphate dehydrogenases from a thermoacidophilic archaeon, Sulfolobus tokodaii

Sulfolobus tokodaii, a thermoacidophilic archaeon, possesses two structurally and functionally different enzymes that catalyze the oxidation of glyceraldehyde-3-phosphate (GAP): non-phosphorylating GAP dehydrogenase (St-GAPN) and phosphorylating GAP dehydrogenase (St-GAPDH). In contrast to previously characterized GAPN from Sulfolobus solfataricus, which exhibits V-type allosterism, St-GAPN showed K-type allosterism in which the positive cooperativity was abolished with concomitant activation by glucose 1-phosphate (G1P). St-GAPDH catalyzed the reversible oxidation of GAP to 1,3-bisphosphoglycerate (1,3-BPG) with high gluconeogenic activity, which was specific for NADPH, while both NAD(+) and NADP(+) were utilized in the glycolytic direction. Structured summary of protein interactions: GAPDH and GAPDH bind by molecular sieving (View interaction) GAPN and GAPN bind by 2.2molecular sieving (View interaction). (C) 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.