Symptoms of G6PD deficiency are triggered by exposure to certain foods, medications, infection and/or environmental factors 2, 4. This mechanism that results in limiting the propagation of the parasite in the bloodstream explains how G6PD deficiency provides resistance against malaria 4, 5, 6. Impaired anti-oxidant defense in G6PD-deficient erythrocytes makes them vulnerable to early membrane damage and ultimately phagocytosis when infected with malaria 5. G6PD deficiency afflicts more than an estimated 400 million individuals worldwide, many of whom live in malaria endemic regions. The G6PD gene maps to the X-chromosome thus, the phenotype is manifest fully in males whereas female heterozygotes display varying degrees of G6PD deficiency, due to alternate X-chromosome inactivation 3, 4. G6PD deficiency represents one of the most common inherited and sex-linked enzymopathies. NT: no treatment, WT: wild-type, Chy: chymotrypsin Statistical differences were calculated by two-tailed unpaired Student’s t-test. h, i, j Lymphocytes with Canton variant generated less GSH and more reactive oxygen species (ROS) and were less viable ( n = 4, ( n = 3 for Fig. g G6PD activity was lower in cell lysates with Canton variant ( n = 4, **** p < 0.0001). Protein levels were normalized to the level of each enzyme at 0 h (no treatment). f Protein stability assessment with cycloheximide treatment (50 μg mL −1), blocking de novo protein biosynthesis, in lymphocytes derived from corresponding subjects ( n = 3, * p = 0.013). e G6PD protein levels and residual G6PD activity (normalized to NT (no treatment) of each enzyme) after incubation with chymotrypsin for 1 h ( n = 3 for protein level assay, ** p = 0.0046 n = 2 for enzyme assay, * p = 0.024).
d Thermostability of WT G6PD and Canton G6PD enzyme ( n = 3, ** p = 0.003). c Catalytic activity of recombinant WT G6PD and Canton G6PD enzymes with kinetic parameters ( n = 5, **** p < 0.0001). b A linear map of G6PD domain structure with most common variants indicated. Our study suggests that a pharmacological agent, of which AG1 may be a lead, will likely alleviate the challenges associated with G6PD deficiency.Ĭanton G6PD (R459L) variant is biochemically different from WT G6PD. Furthermore, AG1 decreases chloroquine- or diamide-induced oxidative stress in human erythrocytes. AG1 reduces oxidative stress in cells and zebrafish. Using high-throughput screening, we subsequently identify AG1, a small molecule that increases the activity of the wild-type, the Canton mutant and several other common G6PD mutants. Crystallographic study and mutagenesis analysis identify the structural and functional defect of one common mutant (Canton, R459L). As no medications are available to treat G6PD deficiency, here we seek to identify a small molecule that corrects it. Glucose-6-phosphate dehydrogenase (G6PD) deficiency, one of the most common human genetic enzymopathies, is caused by over 160 different point mutations and contributes to the severity of many acute and chronic diseases associated with oxidative stress, including hemolytic anemia and bilirubin-induced neurological damage particularly in newborns.
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