Multiple Acyl-Coenzyme A Dehydrogenation Disorder Responsive to Riboflavin: Substrate Oxidation, Flavin Metabolism, and Flavoenzyme Activities in Fibroblasts

Rhead, William J.; Roettger,; Marshall, Tricia K.; Amendt, Brad A.

doi:10.1203/00006450-199302000-00008

Cited by 37 publications

(26 citation statements)

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“…In most cases, the disorder is due to a defect in either the alpha-or beta-subunit of electron transfer flavoprotein (ETFA; MIM# 231680, ETFB; MIM# 130410) or ETF dehydrogenase (ETFDH; MIM# HUMAN MUTATION 22:12^23 (2003) 231675), but in some patients the disorder may be due to some as yet unidentified disturbances of riboflavin metabolism [Gregersen, 1985;Gregersen et al, 1990;Rhead et al, 1993;Vergani et al, 1999]. ETF exists in the mitochondrial matrix as a heterodimer of alpha-30-kDa) and beta-(28-kDa) subunits and contains one flavin adenine dinucleotide (FAD) and one adenosine 5 0 -monophosphate (AMP) per heterodimer [Thorpe, 1991;Sato et al, 1993].…”

Section: Introductionmentioning

confidence: 99%

Clear relationship betweenETF/ETFDH genotype and phenotype in patients with multiple acyl-CoA dehydrogenation deficiency

et al. 2003

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Mutations in electron transfer flavoprotein (ETF) and its dehydrogenase (ETFDH) are the molecular basis of multiple acyl-CoA dehydrogenation deficiency (MADD), an autosomal recessively inherited and clinically heterogeneous disease that has been divided into three clinical forms: a neonatal-onset form with congenital anomalies (type I), a neonatal-onset form without congenital anomalies (type II), and a late-onset form (type III). To examine whether these different clinical forms could be explained by different ETF/ETFDH mutations that result in different levels of residual ETF/ETFDH enzyme activity, we have investigated the molecular genetic basis for disease development in nine patients representing the phenotypic spectrum of MADD. We report the genomic structures of the ETFA, ETFB, and ETFDH genes and the identification and characterization of seven novel and three previously reported disease-causing mutations. Our molecular genetic investigations of these nine patients are consistent with three clinical forms of MADD showing a clear relationship between the nature of the mutations and the severity of disease. Interestingly, our data suggest that homozygosity for two null mutations causes fetal development of congenital anomalies resulting in a type I disease phenotype. Even minute amounts of residual ETF/ETFDH activity seem to be sufficient to prevent embryonic development of congenital anomalies giving rise to type II disease. Overexpression studies of an ETFB-D128N missense mutation identified in a patient with type III disease showed that the residual activity of the mutant enzyme could be rescued up to 59% of that of wild-type activity when ETFB-D128N-transformed E. coli cells were grown at low temperature. This indicates that the effect of the ETF/ETFDH genotype in patients with milder forms of MADD, in whom residual enzyme activity allows modulation of the enzymatic phenotype, may be influenced by environmental factors like cellular temperature.

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Section: Introductionmentioning

confidence: 99%

Clear relationship betweenETF/ETFDH genotype and phenotype in patients with multiple acyl-CoA dehydrogenation deficiency

et al. 2003

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“…After ribo¯avin depletion by culturing cells for 2 weeks in ribo¯avin-free medium [18], ®broblast 14 C-butyrate incorporation rates were 33% of controls. Fibroblast studies con®rmed therefore riboavin responsiveness of the defect, although the degree of response to ribo¯avin depletion was not as great as in the ®rst description of a patient with ribo¯avin-responsive MAD [9].…”

Section: Resultsmentioning

confidence: 99%

“…[14]. Studies of [9,10(n)-3 H] palmitate oxidation and [1-14 C] butyrate incorporation into cellular protein in skin ®broblasts after culture in ribo¯avin-supplemented and depleted medium were carried out as described previously [10,18].…”

Section: Case Reportmentioning

confidence: 99%

Stridor as the major presenting symptom in riboflavin-responsive multiple acyl-CoA dehydrogenation deficiency

Sperl

Geiger

Lehnert

et al. 1997

European Journal of Pediatrics

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“…The enzymatic activity of the purified proteins was measured monitoring DCPIP reduction, in a coupled assay in which recombinant human MCAD (0.13 M) and octanoyl-CoA (13 M), were employed, as described in Ref. 20. One unit of catalytic activity is defined as nmol of DCPIP reduced per minute, in the conditions used in the assay.…”

Section: Methodsmentioning

confidence: 99%

“…Data were fitted to a sigmoid curve allowing the determination of an apparent C m (denaturant concentration at the curve midpoint). The biological activity of the samples incubated overnight was also determined using the assay described above (20).…”

Section: Methodsmentioning

confidence: 99%

Role of Flavinylation in a Mild Variant of Multiple Acyl-CoA Dehydrogenation Deficiency

Henriques

Rodrigues

Olsen

et al. 2009

Journal of Biological Chemistry

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Mutations in the genes encoding the ␣-subunit and ␤-subunit of the mitochondrial electron transfer flavoprotein (ETF) and the electron transfer flavoprotein:ubiquinone oxidoreductase (ETF:QO) cause multiple acyl-CoA dehydrogenation deficiency (MADD), a disorder of fatty acid and amino acid metabolism. Point mutations in ETF, which may compromise folding, and/or activity, are associated with both mild and severe forms of MADD. Here we report the investigation on the conformational and stability properties of the disease-causing variant ETF␤-D128N, and our findings on the effect of flavinylation in modulating protein conformational stability and activity. A combination of biochemical and biophysical methods including circular dichroism, visible absorption, flavin, and tryptophan fluorescence emission allowed the analysis of structural changes and of the FAD moiety. The ETF␤-D128N variant retains the overall fold of the wild type, but under stress conditions its flavin becomes less tightly bound. Flavinylation is shown to improve the conformational stability and biological activity of a destabilized D128N variant protein. Moreover, the presence of flavin prevented proteolytic digestion by avoiding protein destabilization. A patient homozygous for the ETF␤-D128N mutation developed severe disease symptoms in association with a viral infection and fever. In agreement, our results suggest that heat inactivation of the mutant may be more relevant at temperatures above 37°C. To mimic a situation of fever in vitro, the flavinylation status was tested at 39°C. FAD exerts the effect of a pharmacological chaperone, improving ETF conformation, and yielding a more stable and active enzyme. Our results provide a structural and functional framework that could help to elucidate the role that an increased cellular FAD content obtained from riboflavin supplementation may play in the molecular pathogenesis of not only MADD, but genetic disorders of flavoproteins in general.

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Multiple Acyl-Coenzyme A Dehydrogenation Disorder Responsive to Riboflavin: Substrate Oxidation, Flavin Metabolism, and Flavoenzyme Activities in Fibroblasts

Cited by 37 publications

References 10 publications

Clear relationship betweenETF/ETFDH genotype and phenotype in patients with multiple acyl-CoA dehydrogenation deficiency

Clear relationship betweenETF/ETFDH genotype and phenotype in patients with multiple acyl-CoA dehydrogenation deficiency

Stridor as the major presenting symptom in riboflavin-responsive multiple acyl-CoA dehydrogenation deficiency

Role of Flavinylation in a Mild Variant of Multiple Acyl-CoA Dehydrogenation Deficiency

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