Allosteric role of a structural NADP+ molecule in glucose-6-phosphate dehydrogenase activity

Proc Natl Acad Sci U S A. 2022 Jul 19;119(29):e2119695119. doi: 10.1073/pnas.2119695119. Epub 2022 Jul 12.


Human glucose-6-phosphate dehydrogenase (G6PD) is the main cellular source of NADPH, and thus plays a key role in maintaining reduced glutathione to protect cells from oxidative stress disorders such as hemolytic anemia. G6PD is a multimeric enzyme that uses the cofactors β-D-glucose 6-phosphate (G6P) and "catalytic" NADP+ (NADP+c), as well as a "structural" NADP+ (NADP+s) located ∼25 Å from the active site, to generate NADPH. While X-ray crystallographic and biochemical studies have revealed a role for NADP+s in maintaining the catalytic activity by stabilizing the multimeric G6PD conformation, other potential roles for NADP+s have not been evaluated. Here, we determined the high resolution cryo-electron microscopy structures of human wild-type G6PD in the absence of bound ligands and a catalytic G6PD-D200N mutant bound to NADP+c and NADP+s in the absence or presence of G6P. A comparison of these structures, together with previously reported structures, reveals that the unliganded human G6PD forms a mixture of dimers and tetramers with similar overall folds, and binding of NADP+s induces a structural ordering of a C-terminal extension region and allosterically regulates G6P binding and catalysis. These studies have implications for understanding G6PD deficiencies and for therapy of G6PD-mediated disorders.

Keywords: G6PD; NADPH; allostery; cryo-EM.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Catalytic Domain / genetics
  • Cryoelectron Microscopy
  • Glucosephosphate Dehydrogenase Deficiency / drug therapy
  • Glucosephosphate Dehydrogenase Deficiency / enzymology
  • Glucosephosphate Dehydrogenase* / chemistry
  • Glucosephosphate Dehydrogenase* / genetics
  • Humans
  • Mutation
  • NADP* / chemistry
  • Protein Multimerization


  • NADP
  • G6PD protein, human
  • Glucosephosphate Dehydrogenase