Computational analysis of a novel mutation in ETFDH gene highlights its long-range effects on the FAD-binding motif

Yen-Yi Liu,Yin-Hsiu Chien,Chih-Chieh Chen,Yuh-Jyh Jong,Jenn-Kang Hwang,Tze-Kiong Er,Jan-Gowth Chang,Hui-Chiu Chang

doi:10.1186/1472-6807-11-43

Abstract

BackgroundMultiple acyl-coenzyme A dehydrogenase deficiency (MADD) is an autosomal recessive disease caused by the defects in the mitochondrial electron transfer system and the metabolism of fatty acids. Recently, mutations in electron transfer flavoprotein dehydrogenase (ETFDH) gene, encoding electron transfer flavoprotein:ubiquinone oxidoreductase (ETF:QO) have been reported to be the major causes of riboflavin-responsive MADD. To date, no studies have been performed to explore the functional impact of these mutations or their mechanism of disrupting enzyme activity.ResultsHigh resolution melting (HRM) analysis and sequencing of the entire ETFDH gene revealed a novel mutation (p.Phe128Ser) and the hotspot mutation (p.Ala84Thr) from a patient with MADD. According to the predicted 3D structure of ETF:QO, the two mutations are located within the flavin adenine dinucleotide (FAD) binding domain; however, the two residues do not have direct interactions with the FAD ligand. Using molecular dynamics (MD) simulations and normal mode analysis (NMA), we found that the p.Ala84Thr and p.Phe128Ser mutations are most likely to alter the protein structure near the FAD binding site as well as disrupt the stability of the FAD binding required for the activation of ETF:QO. Intriguingly, NMA revealed that several reported disease-causing mutations in the ETF:QO protein show highly correlated motions with the FAD-binding site.ConclusionsBased on the present findings, we conclude that the changes made to the amino acids in ETF:QO are likely to influence the FAD-binding stability.

Highlights

Multiple acyl-coenzyme A dehydrogenase deficiency (MADD) is an autosomal recessive disease caused by the defects in the mitochondrial electron transfer system and the metabolism of fatty acids
In the majority of cases, the disorder is caused by a defect in either the alpha- or beta-subunit of the electron transfer flavoprotein (ETFA; OMIM 608053, ETFB; OMIM 130410) or the electron transfer flavoprotein dehydrogenase (ETFDH; OMIM 231675) genes
Phe128Ser) (Figures 1C and 1D) in the ETFDH gene were identified in this patient

Summary

Introduction

Multiple acyl-coenzyme A dehydrogenase deficiency (MADD) is an autosomal recessive disease caused by the defects in the mitochondrial electron transfer system and the metabolism of fatty acids. Mutations in electron transfer flavoprotein dehydrogenase (ETFDH) gene, encoding electron transfer flavoprotein: ubiquinone oxidoreductase (ETF:QO) have been reported to be the major causes of riboflavin-responsive MADD. Ala84Thr) mutation in Taiwanese patients with riboflavinresponsive MADD, as well as in the normal population using a high-resolution melting (HRM) analysis [6]. A total of 69 patients were examined from the above referenced literature and diagnosed with late-onset MADD. Amongst these patients, the mutation c.250G > A in the ETFDH gene was detected in 49 patients with homozygous mutations and 20 patients with heterozygous mutations. The patient had compound heterozygous mutations (p.Ala84Thr/p.Phe128Ser) of the ETFDH gene. There is no related study to explore the underlying mechanism for the most common mutation (p.Ala84Thr)

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