Overexpression of recombinant human antiquitin in E-coli: Partial enzyme activity in selected ALDH7A1 missense mutations associated with pyridoxine-dependent epilepsy

Pyridoxine-dependent epilepsy (PDE) is an autosomal recessive disorder characterized by early onset seizures responsive to pyridoxine and caused by a defect in the a-aminoadipic semialdehyde dehydrogenase (antiquitin) gene (ALDH7A1). We selected four POE-associated missense ALDH7A1 mutations, p.V367F, p.F410L, p.Q425R, and p.C450S, generated them in a recombinant human antiquitin cDNA with expression in E. coli at either 30 degrees C or 37 degrees C One mutation, p.C450S, demonstrated substantial activity after expression at both temperatures, potentially contributing to milder biochemical and clinical phenotypes. The p.Q425R mutation yielded no activity at either temperature. The other two mutations yielded significant enzymatic activity at 30 degrees C and markedly reduced activity at 37 C For these latter three mutations, the markedly reduced or absent enzymatic activity resulting from expression at 37 degrees C may be consistent with pathogenicity. (C) 2014 Elsevier Inc. All rights reserved.