Stabilization of glucose-6-phosphate dehydrogenase oligomers enhances catalytic activity and stability of clinical variants

Adriana Ann Garcia; Irimpan I Mathews; Naoki Horikoshi; Tsutomu Matsui; Manat Kaur; Soichi Wakatsuki; Daria Mochly-Rosen

doi:10.1016/j.jbc.2022.101610

Stabilization of glucose-6-phosphate dehydrogenase oligomers enhances catalytic activity and stability of clinical variants

J Biol Chem. 2022 Mar;298(3):101610. doi: 10.1016/j.jbc.2022.101610. Epub 2022 Jan 20.

Authors

Adriana Ann Garcia¹, Irimpan I Mathews², Naoki Horikoshi³, Tsutomu Matsui², Manat Kaur⁴, Soichi Wakatsuki⁵, Daria Mochly-Rosen⁶

Affiliations

¹ Department of Chemical and Systems Biology, School of Medicine, Stanford University, Stanford, California, USA.
² Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California, USA.
³ Life Science Center for Survival Dynamics, University of Tsukuba, Tsukuba, Ibaraki, Japan; Biological Sciences Division, SLAC National Accelerator Laboratory, Menlo Park, California, USA; Department of Structural Biology, School of Medicine, Stanford University, Stanford, California, USA.
⁴ Department of Structural Biology, School of Medicine, Stanford University, Stanford, California, USA.
⁵ Biological Sciences Division, SLAC National Accelerator Laboratory, Menlo Park, California, USA; Department of Structural Biology, School of Medicine, Stanford University, Stanford, California, USA. Electronic address: soichi.wakatsuki@stanford.edu.
⁶ Department of Chemical and Systems Biology, School of Medicine, Stanford University, Stanford, California, USA. Electronic address: mochly@stanford.edu.

Abstract

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a genetic trait that can cause hemolytic anemia. To date, over 150 nonsynonymous mutations have been identified in G6PD, with pathogenic mutations clustering near the dimer and/or tetramer interface and the allosteric NADP⁺-binding site. Recently, our lab identified a small molecule that activates G6PD variants by stabilizing the allosteric NADP⁺ and dimer complex, suggesting therapeutics that target these regions may improve structural defects. Here, we elucidated the connection between allosteric NADP⁺ binding, oligomerization, and pathogenicity to determine whether oligomer stabilization can be used as a therapeutic strategy for G6PD deficiency (G6PD^def). We first solved the crystal structure for G6PD^K403Q, a mutant that mimics the physiological acetylation of wild-type G6PD in erythrocytes and demonstrated that loss of allosteric NADP⁺ binding induces conformational changes in the dimer. These structural changes prevent tetramerization, are unique to Class I variants (the most severe form of G6PD^def), and cause the deactivation and destabilization of G6PD. We also introduced nonnative cysteines at the oligomer interfaces and found that the tetramer complex is more catalytically active and stable than the dimer. Furthermore, stabilizing the dimer and tetramer improved protein stability in clinical variants, regardless of clinical classification, with tetramerization also improving the activity of G6PD^K403Q and Class I variants. These findings were validated using enzyme activity and thermostability assays, analytical size-exclusion chromatography (SEC), and SEC coupled with small-angle X-ray scattering (SEC-SAXS). Taken together, our findings suggest a potential therapeutic strategy for G6PD^def and provide a foundation for future drug discovery efforts.

Keywords: G6PD deficiency; enzymopathy; erythrocytes; oligomer stabilization; therapeutic strategy.

MeSH terms

Glucosephosphate Dehydrogenase Deficiency* / genetics
Glucosephosphate Dehydrogenase* / genetics
Glucosephosphate Dehydrogenase* / metabolism
Humans
Mutation
NADP / metabolism
Scattering, Small Angle
X-Ray Diffraction

Substances

NADP
Glucosephosphate Dehydrogenase

Grants and funding

R01 HD084422/HD/NICHD NIH HHS/United States