6V0Z

Structure of ALDH7A1 mutant R441C complexed with NAD

Summary for 6V0Z

• Entry DOI: 10.2210/pdb6v0z/pdb
• Descriptor: Alpha-aminoadipic semialdehyde dehydrogenase, NICOTINAMIDE-ADENINE-DINUCLEOTIDE, 1,2-ETHANEDIOL, ... (4 entities in total)
• Functional Keywords: aldehyde dehydrogenase, nad, oxidoreductase, lysine catabolism
• Biological source: Homo sapiens (Human)
• Total number of polymer chains: 8
• Total formula weight: 449899.96

Authors

Korasick, D.A.,Tanner, J.J. (deposition date: 2019-11-19, release date: 2020-11-25, Last modification date: 2024-04-24)

Primary citation

Korasick, D.A.,Buckley, D.P.,Palpacelli, A.,Cursio, I.,Cesaroni, E.,Cheng, J.,Tanner, J.J.
Biochemical, structural, and computational analyses of two new clinically identified missense mutations of ALDH7A1.
Chem.Biol.Interact., :110993-110993, 2024

PubMed Abstract: Aldehyde dehydrogenase 7A1 (ALDH7A1) catalyzes a step of lysine catabolism. Certain missense mutations in the ALDH7A1 gene cause pyridoxine dependent epilepsy (PDE), a rare autosomal neurometabolic disorder with recessive inheritance that affects almost 1:65,000 live births and is classically characterized by recurrent seizures from the neonatal period. We report a biochemical, structural, and computational study of two novel ALDH7A1 missense mutations that were identified in a child with rare recurrent seizures from the third month of life. The mutations affect two residues in the oligomer interfaces of ALDH7A1, Arg134 and Arg441 (Arg162 and Arg469 in the HGVS nomenclature). The corresponding enzyme variants R134S and R441C (p.Arg162Ser and p.Arg469Cys in the HGVS nomenclature) were expressed in Escherichia coli and purified. R134S and R441C have 10,000- and 50-fold lower catalytic efficiency than wild-type ALDH7A1, respectively. Sedimentation velocity analytical ultracentrifugation shows that R134S is defective in tetramerization, remaining locked in a dimeric state even in the presence of the tetramer-inducing coenzyme NAD. Because the tetramer is the active form of ALDH7A1, the defect in oligomerization explains the very low catalytic activity of R134S. In contrast, R441C exhibits wild-type oligomerization behavior, and the 2.0 Å resolution crystal structure of R441C complexed with NAD revealed no obvious structural perturbations when compared to the wild-type enzyme structure. Molecular dynamics simulations suggest that the mutation of Arg441 to Cys may increase intersubunit ion pairs and alter the dynamics of the active site gate. Our biochemical, structural, and computational data on two novel clinical variants of ALDH7A1 add to the complexity of the molecular determinants underlying pyridoxine dependent epilepsy.

PubMed: 38604394
DOI: 10.1016/j.cbi.2024.110993

Experimental method

X-RAY DIFFRACTION (2.02 Å)