Small‐Molecule Activators of Glucose‐6‐phosphate Dehydrogenase (G6PD) Bridging the Dimer Interface

Abstract

We recently identified AG1, as mall-molecule activatort hat functions by promoting oligomerization of glucose-6-phosphate dehydrogenase (G6PD) to the catalytically competent forms. Biochemical experiments indicatet hat the activation of G6PD by the original hit molecule (AG1) is noncovalent and that one C 2 -symmetric region of the G6PD homodimer is important for ligand function. Consequently,t he disulfide in AG1 is not required for activationo fG 6PD, and an umber of analogues were prepared without this reactive moiety.O ur study supports am echanism of action whereby AG1 bridges the dimer interface at the structuraln icotinamide adenine dinucleotide phosphate (NADP + )b inding sites of two interacting G6PD monomers. Smallm olecules that promoteG 6PD oligomerization have the potential to provide af irst-in-class treatment for G6PD deficiency. Thisg eneral strategy could be applied to othere nzymed eficienciesi nw hichc ontrol of oligomerization can enhancee nzymatica ctivity and/or stability.

Discovery of Small-Molecule Activators for Glucose-6-Phosphate Dehydrogenase (G6PD) Using Machine Learning Approaches

“…Furthermore, AG1 decreases chloroquine or diamide-induced oxidative stress in human erythrocytes. Raub et al [7] studies reported small-molecule activators of G6PD bridging the dimer interface at the structural nicotinamide adenine dinucleotide phosphate (NADP + ) binding sites of two interacting G6PD monomers. Genetic mutation causes reduced efficiency of the dimerization of G6PD monomers affecting its biological activity; in many cases, the pathological effects of G6PD deficiency were not associated with the reduced expression, but reduced binding energy affecting formation of G6PD homodimers (active form), such as class I G6PD variants, associated with chronic nonspherocytic hemolytic anemia (CNSHA), the most severe phenotypic expression of G6PD deficiency [25].…”

“…The two domains are linked by an α helix, containing the totally conserved eight-residue peptide that acts as the substrate-binding site (amino acids 198-206) [6]. G6PD is the only enzyme known to have evolved a second NADP+ binding site, close to the dimer interface; this second structural site is essential for maintaining the activity, stability, and oligomeric state of the enzyme [7].…”

Glucose-6-phosphate Dehydrogenase Deficiency: A Review

“…A group of researchers, in 2019, looked at devising therapeutic measures for G6PD deficiency. 44 They postulate that the use of small molecule activators of the enzyme can promote the activity of the enzyme in deficient patients. The primary principle behind this is protein-protein interactions (PPIs).…”

“…Apart from signalling events, the interactome comprises of interactions between the quaternary structure of proteins to modulate enzyme stability, activity and function. 44 Hence the use of small molecules that target this aspect of the interactome is essential in enhancing enzymatic activity of G6PD.…”

“…This is because only the homodimer and homtetrameric forms of the enzyme are active and stable. Raub et al, 44 identified AG1, a small molecule activator, from a common pathogenic mutation of g6pdx. In order to develop a suitable therapeutic agent, the mechanism of the molecule, AG1, was studied by the group.…”