Long-range structural defects by pathogenic mutations in most severe glucose-6-phosphate dehydrogenase deficiency

Area of Science:

• Biochemistry
• Molecular Biology
• Genetics

Background:

• Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a prevalent blood disorder affecting 400 million globally, characterized by hemolytic anemia.
• Over 160 G6PD mutations exist, with 70 severe Class I mutations causing >90% enzyme activity loss.
• The molecular basis for Class I G6PD mutant dysfunction remains unclear, impeding therapeutic development.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying severe G6PD deficiency caused by Class I mutations.
• To investigate the structural and functional impact of mutations near the NADP+ binding site and dimer interface.

Main Methods:

• Integral structural characterization of five G6PD mutants (four Class I) using X-ray crystallography, SAXS, and cryo-EM.
• Biophysical analyses and molecular dynamics simulations were employed.
• Comparison with wild-type G6PD structure and properties.

Main Results:

• A universal mechanism for Class I G6PD deficiency was identified.
• Mutations near the noncatalytic NADP+ site destabilize dimer interface β-strands.
• This destabilization propagates to the active site via interconnected interactions.

Conclusions:

• The noncatalytic NADP+ binding site plays a critical role in stabilizing the G6PD dimer interface.
• Structural aberrations distant from the active site can be communicated to it, explaining severe G6PD deficiency.
• This provides a mechanistic basis for developing targeted therapies for G6PD deficiency.