7sei
Glucose-6-phosphate 1-dehydrogenase (K403Q)
Structural highlights
DiseaseG6PD_HUMAN Defects in G6PD are the cause of chronic non-spherocytic hemolytic anemia (CNSHA) [MIM:305900. Deficiency of G6PD is associated with hemolytic anemia in two different situations. First, in areas in which malaria has been endemic, G6PD-deficiency alleles have reached high frequencies (1% to 50%) and deficient individuals, though essentially asymptomatic in the steady state, have a high risk of acute hemolytic attacks. Secondly, sporadic cases of G6PD deficiency occur at a very low frequencies, and they usually present a more severe phenotype. Several types of CNSHA are recognized. Class-I variants are associated with severe NSHA; class-II have an activity <10% of normal; class-III have an activity of 10% to 60% of normal; class-IV have near normal activity.[1] FunctionG6PD_HUMAN Produces pentose sugars for nucleic acid synthesis and main producer of NADPH reducing power. Publication Abstract from PubMedGlucose-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. Stabilization of glucose-6-phosphate dehydrogenase oligomers enhances catalytic activity and stability of clinical variants.,Garcia AA, Mathews II, Horikoshi N, Matsui T, Kaur M, Wakatsuki S, Mochly-Rosen D J Biol Chem. 2022 Mar;298(3):101610. doi: 10.1016/j.jbc.2022.101610. Epub 2022, Jan 20. PMID:35065072[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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