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Whole Exome Sequencing Enhanced Imputation Identifies 85 Metabolite Associations in the Alpine CHRIS Cohort. Metabolites 2022; 12:metabo12070604. [PMID: 35888728 PMCID: PMC9320943 DOI: 10.3390/metabo12070604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/24/2022] [Accepted: 06/24/2022] [Indexed: 11/16/2022] Open
Abstract
Metabolites are intermediates or end products of biochemical processes involved in both health and disease. Here, we take advantage of the well-characterized Cooperative Health Research in South Tyrol (CHRIS) study to perform an exome-wide association study (ExWAS) on absolute concentrations of 175 metabolites in 3294 individuals. To increase power, we imputed the identified variants into an additional 2211 genotyped individuals of CHRIS. In the resulting dataset of 5505 individuals, we identified 85 single-variant genetic associations, of which 39 have not been reported previously. Fifteen associations emerged at ten variants with >5-fold enrichment in CHRIS compared to non-Finnish Europeans reported in the gnomAD database. For example, the CHRIS-enriched ETFDH stop gain variant p.Trp286Ter (rs1235904433-hexanoylcarnitine) and the MCCC2 stop lost variant p.Ter564GlnextTer3 (rs751970792-carnitine) have been found in patients with glutaric acidemia type II and 3-methylcrotonylglycinuria, respectively, but the loci have not been associated with the respective metabolites in a genome-wide association study (GWAS) previously. We further identified three gene-trait associations, where multiple rare variants contribute to the signal. These results not only provide further evidence for previously described associations, but also describe novel genes and mechanisms for diseases and disease-related traits.
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Ali A, Almesmari FSA, Dhahouri NA, Saleh Ali AM, Aldhanhani MAAMA, Vijayan R, Al Tenaiji A, Al Shamsi A, Hertecant J, Al Jasmi F. Clinical, Biochemical, and Genetic Heterogeneity in Glutaric Aciduria Type II Patients. Genes (Basel) 2021; 12:1334. [PMID: 34573316 PMCID: PMC8466204 DOI: 10.3390/genes12091334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/19/2021] [Accepted: 08/25/2021] [Indexed: 12/03/2022] Open
Abstract
The variants of electron transfer flavoprotein (ETFA, ETFB) and ETF dehydrogenase (ETFDH) are the leading cause of glutaric aciduria type II (GA-II). In this study, we identified 13 patients harboring six variants of two genes associated with GA-II. Out of the six variants, four were missense, and two were frameshift mutations. A missense variant (ETFDH:p.Gln269His) was observed in a homozygous state in nine patients. Among nine patients, three had experienced metabolic crises with recurrent vomiting, abdominal pain, and nausea. In one patient with persistent metabolic acidosis, hypoglycemia, and a high anion gap, the ETFDH:p.Gly472Arg, and ETFB:p.Pro94Thrfs*8 variants were identified in a homozygous, and heterozygous state, respectively. A missense variant ETFDH:p.Ser442Leu was detected in a homozygous state in one patient with metabolic acidosis, hypoglycemia, hyperammonemia and liver dysfunction. The ETFDH:p.Arg41Leu, and ETFB:p.Ile346Phefs*19 variants were observed in a homozygous state in one patient each. Both these variants have not been reported so far. In silico approaches were used to evaluate the pathogenicity and structural changes linked with these six variants. Overall, the results indicate the importance of a newborn screening program and genetic investigations for patients with GA-II. Moreover, careful interpretation and correlation of variants of uncertain significance with clinical and biochemical findings are needed to confirm the pathogenicity of such variants.
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Affiliation(s)
- Amanat Ali
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates; (A.A.); (F.S.A.A.); (N.A.D.); (A.M.S.A.); (M.A.A.M.A.A.)
| | - Fatmah Saeed Ali Almesmari
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates; (A.A.); (F.S.A.A.); (N.A.D.); (A.M.S.A.); (M.A.A.M.A.A.)
| | - Nahid Al Dhahouri
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates; (A.A.); (F.S.A.A.); (N.A.D.); (A.M.S.A.); (M.A.A.M.A.A.)
| | - Arwa Mohammad Saleh Ali
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates; (A.A.); (F.S.A.A.); (N.A.D.); (A.M.S.A.); (M.A.A.M.A.A.)
| | - Mohammed Ahmed Ali Mohamed Ahmed Aldhanhani
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates; (A.A.); (F.S.A.A.); (N.A.D.); (A.M.S.A.); (M.A.A.M.A.A.)
| | - Ranjit Vijayan
- Department of Biology, College of Science, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates;
| | - Amal Al Tenaiji
- Department of Pediatrics, Sheikh Khalifa Medical City, Abu Dhabi P.O. Box 51900, United Arab Emirates;
| | - Aisha Al Shamsi
- Department of Pediatrics, Tawam Hospital, Al Ain P.O. Box 15551, United Arab Emirates; (A.A.S.); (J.H.)
| | - Jozef Hertecant
- Department of Pediatrics, Tawam Hospital, Al Ain P.O. Box 15551, United Arab Emirates; (A.A.S.); (J.H.)
| | - Fatma Al Jasmi
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates; (A.A.); (F.S.A.A.); (N.A.D.); (A.M.S.A.); (M.A.A.M.A.A.)
- Department of Pediatrics, Tawam Hospital, Al Ain P.O. Box 15551, United Arab Emirates; (A.A.S.); (J.H.)
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Ye Z, Shi J, Lu X, Meng Y, Lu W, Wu B, Huang Y. Recurrent abdominal pain, vomiting, velvet-like changes in the small intestine in a patient with multiple acyl-CoA dehydrogenase deficiency: a case report. Transl Pediatr 2021; 10:183-187. [PMID: 33633951 PMCID: PMC7882281 DOI: 10.21037/tp-20-253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Multiple acyl-CoA dehydrogenase deficiency (MADD) is an inborn error of metabolism in fatty acid oxidation. We described an unusual case of recurrent vomiting and abdominal pain in a child with MADD, presenting with velvet-like changes in the small intestine. Because of prominent gastrointestinal manifestations and small intestine ulcers, the patient was first diagnosed as Crohn's disease. The patient was admitted to our institution because of recurrent symptoms despite treatment. Upper and lower endoscopy, computed tomography and trios exome sequencing were performed. This patient underwent a repeated video endoscopy, which showed velvet-like changes in the small intestine rather than ulcers. Liver steatosis was identified by computed tomography. Serum tandem mass spectrometry showed elevated C8 and C10. Trios exome sequencing revealed compound heterozygous variants of c.250G>A, 524G>T in ETFDH. The diagnosis of MADD was made. Patient responded to oral riboflavin treatment. With this case, we aimed to highlight the importance of tandem mass spectrometry and genetic sequencing, especially when the endoscopic findings are not pathognomonic in pediatric cases with recurrent gastrointestinal complaints. We confirmed the diagnosis with next generation sequencing, and described unusual findings of velvet-like changes mimicking ulcers in the small intestine in this patient with MADD.
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Affiliation(s)
- Ziqing Ye
- Department of Gastroenterology, Children's Hospital of Fudan University, Shanghai, China
| | - Jieru Shi
- Department of Gastroenterology, Children's Hospital of Fudan University, Shanghai, China
| | - Xiaolan Lu
- Department of Gastroenterology, Children's Hospital of Fudan University, Shanghai, China
| | - Yingying Meng
- Department of Gastroenterology, Children's Hospital of Fudan University, Shanghai, China
| | - Wei Lu
- Department of Pediatric Endocrinology and Inborn Metabolic Diseases, Children's Hospital of Fudan University, Shanghai, China
| | - Bingbing Wu
- Key Laboratory of Birth Defects, Children's Hospital of Fudan University, Shanghai, China
| | - Ying Huang
- Department of Gastroenterology, Children's Hospital of Fudan University, Shanghai, China
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Lucas TG, Henriques BJ, Gomes CM. Conformational analysis of the riboflavin-responsive ETF:QO-p.Pro456Leu variant associated with mild multiple acyl-CoA dehydrogenase deficiency. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2020; 1868:140393. [PMID: 32087359 DOI: 10.1016/j.bbapap.2020.140393] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 02/09/2020] [Accepted: 02/17/2020] [Indexed: 01/07/2023]
Abstract
Multiple-CoA dehydrogenase deficiency (MADD) is an inborn disorder of fatty acid and amino acid metabolism caused by mutations in the genes encoding for human electron transfer flavoprotein (ETF) and its partner electron transfer flavoprotein:ubiquinone oxidoreductase (ETF:QO). Albeit a rare disease, extensive newborn screening programs contributed to a wider coverage of MADD genotypes. However, the impact of non-lethal mutations on ETF:QO function remains scarcely understood from a structural perspective. To this end, we here revisit the relatively common MADD mutation ETF:QO-p.Pro456Leu, in order to clarify how it affects enzyme structure and folding. Given the limitation in recombinant expression of human ETF:QO, we resort to its bacterial homologue from Rhodobacter sphaeroides (Rs), in which the corresponding mutation (p.Pro389Leu) was inserted. The in vitro biochemical and biophysical investigations of the Rs ETF:QO-p.Pro389Leu variant showed that, while the mutation does not significantly affect the protein α/β fold, it introduces some plasticity on the tertiary structure and within flavin interactions. Indeed, in the p.Pro389Leu variant, FAD exhibits a higher thermolability during thermal denaturation and a faster rate of release in temperature-induced dissociation experiments, in comparison to the wild type. Therefore, although this clinical mutation occurs in the ubiquinone domain, its effect likely propagates to the nearby FAD binding domain, probably influencing electron transfer and redox potentials. Overall, our results provide a molecular rational for the decreased enzyme activity observed in patients and suggest that compromised FAD interactions in ETF:QO might account for the known riboflavin responsiveness of this mutation.
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Affiliation(s)
- Tânia G Lucas
- Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Bárbara J Henriques
- Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Cláudio M Gomes
- Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal.
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Chokchaiwong S, Kuo YT, Lin SH, Hsu YC, Hsu SP, Liu YT, Chou AJ, Kao SH. Coenzyme Q10 serves to couple mitochondrial oxidative phosphorylation and fatty acid β-oxidation, and attenuates NLRP3 inflammasome activation. Free Radic Res 2018; 52:1445-1455. [PMID: 30003820 DOI: 10.1080/10715762.2018.1500695] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Multiple acyl-CoA dehydrogenase deficiency (MADD), an autosomal recessive metabolic disorder of fatty acid metabolism, is mostly caused by mutations in the ETFA, ETFB or ETFDH genes that result in dysfunctions in electron transfer flavoprotein (ETF) or electron transfer flavoprotein-ubiquinone dehydrogenase (ETFDH). In β-oxidation, fatty acids are processed to generate acyl-CoA, which is oxidised by flavin adenine dinucleotide and transfers an electron to ETF and, through ETFDH, to mitochondrial respiratory complex III to trigger ATP synthesis. Coenzyme Q10 (CoQ10) is believed to be a potential treatment that produces symptom relief in some MADD patients. CoQ10 acts as a key regulator linking ETFDH and mitochondrial respiratory complex III. Our aim is to investigate the effectiveness of CoQ10 in serving in the ETF/ETFDH system to improve mitochondrial function and to reduce lipotoxicity. In this study, we used lymphoblastoid cells with an ETFDH mutation from MADD patients. ETFDH dysfunction caused insufficient β-oxidation, leading to increasing lipid droplet and lipid peroxide accumulation. In contrast, supplementation with CoQ10 significantly recovered mitochondrial function and concurrently decreased the generation of reactive oxygen species and lipid peroxides, inhibited the accumulation of lipid droplets and the formation of the NOD-like receptor family pyrin domain-containing three (NLRP3) inflammasome, and reduced interleukin-1β release and cell death. These results clarify the causal role of CoQ10 in coupling the electron transport chain with β-oxidation, which may promote the development of CoQ10-directed therapies for MADD patients.
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Affiliation(s)
- Suphannee Chokchaiwong
- a Ph.D. Program in Medical Biotechnology , College of Medical Science and Technology, Taipei Medical University , Taipei , Taiwan
| | - Yung-Ting Kuo
- b Department of Pediatrics, School of Medicine , College of Medicine, Taipei Medical University , Taipei , Taiwan.,c Department of Pediatrics , Shuang Ho Hospital, Taipei Medical University , Taipei , Taiwan
| | - Shih-Hsiang Lin
- d School of Medical Laboratory Science and Biotechnology , College of Medical Science and Technology, Taipei Medical University , Taipei , Taiwan
| | - Yi-Ching Hsu
- d School of Medical Laboratory Science and Biotechnology , College of Medical Science and Technology, Taipei Medical University , Taipei , Taiwan
| | - Sung-Po Hsu
- e Department of Physiology, School of Medicine , College of Medicine, Taipei Medical University , Taipei , Taiwan
| | - Yu-Ting Liu
- f Taipei First Girls' High School , Taipei , Taiwan
| | - An-Je Chou
- f Taipei First Girls' High School , Taipei , Taiwan
| | - Shu-Huei Kao
- a Ph.D. Program in Medical Biotechnology , College of Medical Science and Technology, Taipei Medical University , Taipei , Taiwan.,d School of Medical Laboratory Science and Biotechnology , College of Medical Science and Technology, Taipei Medical University , Taipei , Taiwan
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Goh LL, Lee Y, Tan ES, Lim JSC, Lim CW, Dalan R. Patient with multiple acyl-CoA dehydrogenase deficiency disease and ETFDH mutations benefits from riboflavin therapy: a case report. BMC Med Genomics 2018; 11:37. [PMID: 29615056 PMCID: PMC5883299 DOI: 10.1186/s12920-018-0356-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 03/26/2018] [Indexed: 12/03/2022] Open
Abstract
Background Lipid storage myopathy (LSM) is a diverse group of lipid metabolic disorders with great variations in the clinical phenotype and age of onset. Classical multiple acyl-CoA dehydrogenase deficiency (MADD) is known to occur secondary to mutations in electron transfer flavoprotein dehydrogenase (ETFDH) gene. Whole exome sequencing (WES) with clinical correlations can be useful in identifying genomic alterations for targeted therapy. Case presentation We report a patient presented with severe muscle weakness and exercise intolerance, suggestive of LSM. Diagnostic testing demonstrated lipid accumulation in muscle fibres and elevated plasma acyl carnitine levels. Exome sequencing of the proband and two of his unaffected siblings revealed compound heterozygous mutations, c.250G > A (p.Ala84Thr) and c.770A > G (p.Tyr257Cys) in the ETFDH gene as the probable causative mutations. In addition, a previously unreported variant c.1042C > T (p.Arg348Trp) in ACOT11 gene was found. This missense variant was predicted to be deleterious but its association with lipid storage in muscle is unclear. The diagnosis of MADD was established and the patient was treated with riboflavin which resulted in rapid clinical and biochemical improvement. Conclusions Our findings support the role of WES as an effective tool in the diagnosis of highly heterogeneous disease and this has important implications in the therapeutic strategy of LSM treatment. Electronic supplementary material The online version of this article (10.1186/s12920-018-0356-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Liuh Ling Goh
- Molecular Diagnostic Laboratory, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore
| | - Yingshan Lee
- Department of Endocrinology, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore
| | - Ee Shien Tan
- Department of Paediatrics, Genetics Services, KK Women's and Children's Hospital, 100 Bukit Timah Road, Singapore, 229899, Singapore
| | - James Soon Chuan Lim
- Biochemical Genetics and National Expanded Newborn Screening, Department of Pathology and Laboratory Medicine, KK Women's and Children's Hospital, 100 Bukit Timah Road, Singapore, 229899, Singapore
| | - Chia Wei Lim
- Molecular Diagnostic Laboratory, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore
| | - Rinkoo Dalan
- Department of Endocrinology, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, 308433, Singapore. .,Lee Kong Chian School of Medicine, Nanyang Technological University, 11 Mandalay Road, Singapore, 308232, Singapore. .,Yong Loo Lin School of Medicine, National University of Singapore, 12 Science Drive 2, Singapore, 117549, Singapore.
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Wang Z, Hong D, Zhang W, Li W, Shi X, Zhao D, Yang X, Lv H, Yuan Y. Severe sensory neuropathy in patients with adult-onset multiple acyl-CoA dehydrogenase deficiency. Neuromuscul Disord 2016; 26:170-5. [DOI: 10.1016/j.nmd.2015.12.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Revised: 11/24/2015] [Accepted: 12/08/2015] [Indexed: 12/11/2022]
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Cornelius N, Frerman FE, Corydon TJ, Palmfeldt J, Bross P, Gregersen N, Olsen RKJ. Molecular mechanisms of riboflavin responsiveness in patients with ETF-QO variations and multiple acyl-CoA dehydrogenation deficiency. Hum Mol Genet 2012; 21:3435-48. [PMID: 22611163 DOI: 10.1093/hmg/dds175] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Riboflavin-responsive forms of multiple acyl-CoA dehydrogenation deficiency (RR-MADD) have been known for years, but with presumed defects in the formation of the flavin adenine dinucleotide (FAD) co-factor rather than genetic defects of electron transfer flavoprotein (ETF) or electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO). It was only recently established that a number of RR-MADD patients carry genetic defects in ETF-QO and that the well-documented clinical efficacy of riboflavin treatment may be based on a chaperone effect that can compensate for inherited folding defects of ETF-QO. In the present study, we investigate the molecular mechanisms and the genotype-phenotype relationships for the riboflavin responsiveness in MADD, using a human HEK-293 cell expression system. We studied the influence of riboflavin and temperature on the steady-state level and the activity of variant ETF-QO proteins identified in patients with RR-MADD, or non- and partially responsive MADD. Our results showed that variant ETF-QO proteins associated with non- and partially responsive MADD caused severe misfolding of ETF-QO variant proteins when cultured in media with supplemented concentrations of riboflavin. In contrast, variant ETF-QO proteins associated with RR-MADD caused milder folding defects when cultured at the same conditions. Decreased thermal stability of the variants showed that FAD does not completely correct the structural defects induced by the variation. This may cause leakage of electrons and increased reactive oxygen species, as reflected by increased amounts of cellular peroxide production in HEK-293 cells expressing the variant ETF-QO proteins. Finally, we found indications of prolonged association of variant ETF-QO protein with the Hsp60 chaperonin in the mitochondrial matrix, supporting indications of folding defects in the variant ETF-QO proteins.
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Affiliation(s)
- Nanna Cornelius
- The Research Unit for Molecular Medicine, Aarhus University Hospital and Department of Clinical Medicine, Aarhus University, Denmark.
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Alves E, Henriques BJ, Rodrigues JV, Prudêncio P, Rocha H, Vilarinho L, Martinho RG, Gomes CM. Mutations at the flavin binding site of ETF:QO yield a MADD-like severe phenotype in Drosophila. Biochim Biophys Acta Mol Basis Dis 2012; 1822:1284-92. [PMID: 22580358 DOI: 10.1016/j.bbadis.2012.05.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 05/03/2012] [Accepted: 05/04/2012] [Indexed: 11/30/2022]
Abstract
Following a screening on EMS-induced Drosophila mutants defective for formation and morphogenesis of epithelial cells, we have identified three lethal mutants defective for the production of embryonic cuticle. The mutants are allelic to the CG12140 gene, the fly homologue of electron transfer flavoprotein:ubiquinone oxidoreductase (ETF:QO). In humans, inherited defects in this inner membrane protein account for multiple acyl-CoA dehydrogenase deficiency (MADD), a metabolic disease of β-oxidation, with a broad range of clinical phenotypes, varying from embryonic lethal to mild forms. The three mutant alleles carried distinct missense mutations in ETF:QO (G65E, A68V and S104F) and maternal mutant embryos for ETF:QO showed lethal morphogenetic defects and a significant induction of apoptosis following germ-band elongation. This phenotype is accompanied by an embryonic accumulation of short- and medium-chain acylcarnitines (C4, C8 and C12) as well as long-chain acylcarnitines (C14 and C16:1), whose elevation is also found in severe MADD forms in humans under intense metabolic decompensation. In agreement the ETF:QO activity in the mutant embryos is markedly decreased in relation to wild type activity. Amino acid sequence analysis and structural mapping into a molecular model of ETF:QO show that all mutations map at FAD interacting residues, two of which at the nucleotide-binding Rossmann fold. This structural domain is composed by a β-strand connected by a short loop to an α-helix, and its perturbation results in impaired cofactor association via structural destabilisation and consequently enzymatic inactivation. This work thus pinpoints the molecular origins of a severe MADD-like phenotype in the fruit fly and establishes the proof of concept concerning the suitability of this organism as a potential model organism for MADD.
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Affiliation(s)
- Ema Alves
- Instituto Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
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Molecular analysis of 51 unrelated pedigrees with late-onset multiple acyl-CoA dehydrogenation deficiency (MADD) in southern China confirmed the most common ETFDH mutation and high carrier frequency of c.250G>A. J Mol Med (Berl) 2011; 89:569-76. [PMID: 21347544 DOI: 10.1007/s00109-011-0725-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 12/12/2010] [Accepted: 12/14/2010] [Indexed: 10/18/2022]
Abstract
Multiple acyl-CoA dehydrogenation deficiency (MADD) is an autosomal recessive disease affecting amino acid, fatty acid, and choline metabolisms and is a common genetic defect responsible for lipid storage myopathy. Most forms of MADD are caused by a deficiency of electron transfer flavoprotein (ETF) or ETF dehydrogenase (ETFDH). However, its molecular feature has not been found uniformly in previous reports of Chinese patients. A large cohort of 56 late-onset MADD patients from 51 unrelated pedigrees in southern China was recruited to investigate a clear correlation between clinical phenotype and molecular genetic basis. All exons of ETFA, ETFB, and ETFDH, including the intron-exon boundaries, and 5' and 3' untranslated regions were directly sequenced. ETFDH deficiencies affected 94.1% (48/51) of the pedigrees. ETFDH-c.250G>A is the most common mutation, representing a high allelic frequency of 83.3% (80/96). Carrier frequency of c.250G>A is estimated to be 1.35% (7/520) in the normal population. A significant reduced expression of ETFDH was identified in the muscle of ETFDH-deficient patients. ETFDH deficiency is a major cause of riboflavin-responsive MADD in southern China, and c.250G>A is an important mutation that could be employed as a fast and reliable screening method.
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The electron transfer flavoprotein: ubiquinone oxidoreductases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1910-6. [PMID: 20937244 DOI: 10.1016/j.bbabio.2010.10.007] [Citation(s) in RCA: 161] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 07/20/2010] [Accepted: 10/05/2010] [Indexed: 12/30/2022]
Abstract
Electron transfer flavoprotein: ubiqionone oxidoreductase (ETF-QO) is a component of the mitochondrial respiratory chain that together with electron transfer flavoprotein (ETF) forms a short pathway that transfers electrons from 11 different mitochondrial flavoprotein dehydrogenases to the ubiquinone pool. The X-ray structure of the pig liver enzyme has been solved in the presence and absence of a bound ubiquinone. This structure reveals ETF-QO to be a monotopic membrane protein with the cofactors, FAD and a [4Fe-4S](+1+2) cluster, organised to suggests that it is the flavin that serves as the immediate reductant of ubiquinone. ETF-QO is very highly conserved in evolution and the recombinant enzyme from the bacterium Rhodobacter sphaeroides has allowed the mutational analysis of a number of residues that the structure suggested are involved in modulating the reduction potential of the cofactors. These experiments, together with the spectroscopic measurement of the distances between the cofactors in solution have confirmed the intramolecular pathway of electron transfer from ETF to ubiquinone. This approach can be extended as the R. sphaeroides ETF-QO provides a template for investigating the mechanistic consequences of single amino acid substitutions of conserved residues that are associated with a mild and late onset variant of the metabolic disease multiple acyl-CoA dehydrogenase deficiency (MADD).
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Law LK, Tang NLS, Hui J, Fung SLM, Ruiter J, Wanders RJA, Fok TF, Lam CWK. Novel mutations in ETFDH gene in Chinese patients with riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency. Clin Chim Acta 2009; 404:95-9. [PMID: 19265687 DOI: 10.1016/j.cca.2009.02.015] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Revised: 02/19/2009] [Accepted: 02/19/2009] [Indexed: 11/19/2022]
Abstract
BACKGROUND Multiple acyl-CoA dehydrogenase deficiency (MADD, OMIM 231680) or glutaric aciduria type II (GAII) is an inherited autosomal recessive disease affecting fatty acid, amino acid and choline metabolism, due to mutations in one of three genes namely, electron transfer flavoprotein alpha-subunit, ETFA (OMIM 608053), electron transfer flavoprotein beta-subunit, ETFB (OMIM 130410) and electron transfer flavoprotein dehydrogenase, ETFDH (OMIM 231675). Some MADD patients are responsive to riboflavin treatment with an excellent prognosis. Recently, mutations in ETFDH were found to be responsible for all riboflavin-responsive MADD patients. In this study, we present the clinical features and molecular studies of 2 Chinese families with riboflavin-responsive MADD. METHODS Genomic DNA was extracted from peripheral blood samples or skin fibroblast cultures from the patients and normal controls. The thirteen exons of ETFDH were amplified by PCR. PCR products were sequenced in both forward and reverse directions. To rule out mutations in other genes, phenotype segregation was studied in the families by microsatellite markers in the proximity of the 3 genes, ETFA, ETFB and ETFDH. RESULTS Four novel mutations in ETFDH were detected in the 2 families. In family 1, a frame shift mutation, c.1355delG which introduced a premature-termination codon (PTC), I454X in exon 11 of ETFDH was found. Another mutation was a c.250G>A transition in exon 3 of ETFDH, A84T. In family 2, two novel missense mutations were identified, P137S, in exon 4 and G467R in exon 11. No carrier of these four mutations was identified from about 150 alleles of healthy Chinese control subjects. CONCLUSIONS Four novel mutations (3 missenses and 1 deletion) in ETFDH were found in Chinese families that presented with riboflavin-responsive MADD, which further expands the list of mutations found in patients with riboflavin-responsive MADD. Furthermore, we illustrated the utility of phenotype-genotype segregation in MADD families to prioritize genes for sequencing or to rule out the presence of disease causing mutation in other genes in MADD and other diseases caused by multiple genes.
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Affiliation(s)
- Lap-Kay Law
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, N.T., Hong Kong
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Swanson MA, Usselman RJ, Frerman FE, Eaton GR, Eaton SS. The iron-sulfur cluster of electron transfer flavoprotein-ubiquinone oxidoreductase is the electron acceptor for electron transfer flavoprotein. Biochemistry 2008; 47:8894-901. [PMID: 18672901 DOI: 10.1021/bi800507p] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) accepts electrons from electron transfer flavoprotein (ETF) and reduces ubiquinone from the ubiquinone pool. It contains one [4Fe-4S] (2+,1+) and one FAD, which are diamagnetic in the isolated oxidized enzyme and can be reduced to paramagnetic forms by enzymatic donors or dithionite. In the porcine protein, threonine 367 is hydrogen bonded to N1 and O2 of the flavin ring of the FAD. The analogous site in Rhodobacter sphaeroides ETF-QO is asparagine 338. Mutations N338T and N338A were introduced into the R. sphaeroides protein by site-directed mutagenesis to determine the impact of hydrogen bonding at this site on redox potentials and activity. The mutations did not alter the optical spectra, EPR g-values, spin-lattice relaxation rates, or the [4Fe-4S] (2+,1+) to FAD point-dipole interspin distances. The mutations had no impact on the reduction potential for the iron-sulfur cluster, which was monitored by changes in the continuous wave EPR signals of the [4Fe-4S] (+) at 15 K. For the FAD semiquinone, significantly different potentials were obtained by monitoring the titration at 100 or 293 K. Based on spectra at 293 K the N338T mutation shifted the first and second midpoint potentials for the FAD from +47 and -30 mV for wild type to -11 and -19 mV, respectively. The N338A mutation decreased the potentials to -37 and -49 mV. Lowering the midpoint potentials resulted in a decrease in the quinone reductase activity and negligible impact on disproportionation of ETF 1e (-) catalyzed by ETF-QO. These observations indicate that the FAD is involved in electron transfer to ubiquinone but not in electron transfer from ETF to ETF-QO. Therefore, the iron-sulfur cluster is the immediate acceptor from ETF.
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Affiliation(s)
- Michael A Swanson
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, USA
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14
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Fielding AJ, Usselman RJ, Watmough N, Simkovic M, Frerman FE, Eaton GR, Eaton SS. Electron spin relaxation enhancement measurements of interspin distances in human, porcine, and Rhodobacter electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO). JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2008; 190:222-32. [PMID: 18037314 PMCID: PMC2262937 DOI: 10.1016/j.jmr.2007.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Revised: 10/20/2007] [Accepted: 11/02/2007] [Indexed: 05/25/2023]
Abstract
Electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) is a membrane-bound electron transfer protein that links primary flavoprotein dehydrogenases with the main respiratory chain. Human, porcine, and Rhodobacter sphaeroides ETF-QO each contain a single [4Fe-4S](2+,1+) cluster and one equivalent of FAD, which are diamagnetic in the isolated enzyme and become paramagnetic on reduction with the enzymatic electron donor or with dithionite. The anionic flavin semiquinone can be reduced further to diamagnetic hydroquinone. The redox potentials for the three redox couples are so similar that it is not possible to poise the proteins in a state where both the [4Fe-4S](+) cluster and the flavoquinone are fully in the paramagnetic form. Inversion recovery was used to measure the electron spin-lattice relaxation rates for the [4Fe-4S](+) between 8 and 18K and for semiquinone between 25 and 65K. At higher temperatures the spin-lattice relaxation rates for the [4Fe-4S](+) were calculated from the temperature-dependent contributions to the continuous wave linewidths. Although mixtures of the redox states are present, it was possible to analyze the enhancement of the electron spin relaxation of the FAD semiquinone signal due to dipolar interaction with the more rapidly relaxing [4Fe-4S](+) and obtain point-dipole interspin distances of 18.6+/-1A for the three proteins. The point-dipole distances are within experimental uncertainty of the value calculated based on the crystal structure of porcine ETF-QO when spin delocalization is taken into account. The results demonstrate that electron spin relaxation enhancement can be used to measure distances in redox poised proteins even when several redox states are present.
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Affiliation(s)
- Alistair J. Fielding
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208
| | - Robert J. Usselman
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208
| | - Nicholas Watmough
- Center for Metalloprotein Spectroscopy and Biology and School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ
| | - Martin Simkovic
- Department of Pediatrics, University of Colorado School of Medicine, Denver, CO 80262
| | - Frank E. Frerman
- Department of Pediatrics, University of Colorado School of Medicine, Denver, CO 80262
| | - Gareth R. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208
| | - Sandra S. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208
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15
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Usselman RJ, Fielding AJ, Frerman FE, Watmough NJ, Eaton GR, Eaton SS. Impact of mutations on the midpoint potential of the [4Fe-4S]+1,+2 cluster and on catalytic activity in electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO). Biochemistry 2007; 47:92-100. [PMID: 18069858 DOI: 10.1021/bi701859s] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Electron-transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) is an iron-sulfur flavoprotein that accepts electrons from electron-transfer flavoprotein (ETF) and reduces ubiquinone from the Q-pool. ETF-QO contains a single [4Fe-4S]2+,1+ cluster and one equivalent of FAD, which are diamagnetic in the isolated oxidized enzyme and can be reduced to paramagnetic forms by enzymatic donors or dithionite. Mutations were introduced by site-directed mutagenesis of amino acids in the vicinity of the iron-sulfur cluster of Rhodobacter sphaeroides ETF-QO. Y501 and T525 are equivalent to Y533 and T558 in the porcine ETF-QO. In the porcine protein, these residues are within hydrogen-bonding distance of the Sgamma of the cysteine ligands to the iron-sulfur cluster. Y501F, T525A, and Y501F/T525A substitutions were made to determine the effects on midpoint potential, activity, and EPR spectral properties of the cluster. The integrity of the mutated proteins was confirmed by optical spectra, EPR g-values, and spin-lattice relaxation rates, and the cluster to flavin point-dipole distance was determined by relaxation enhancement. Potentiometric titrations were monitored by changes in the CW EPR signals of the cluster and semiquinone. Single mutations decreased the midpoint potentials of the iron-sulfur cluster from +37 mV for wild type to -60 mV for Y501F and T525A and to -128 mV for Y501F/T525A. Lowering the midpoint potential resulted in a decrease in steady-state ubiquinone reductase activity and in ETF semiquinone disproportionation. The decrease in activity demonstrates that reduction of the iron-sulfur cluster is required for activity. There was no detectable effect of the mutations on the flavin midpoint potentials.
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Affiliation(s)
- Robert J Usselman
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, USA
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16
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Zhang J, Frerman FE, Kim JJP. Structure of electron transfer flavoprotein-ubiquinone oxidoreductase and electron transfer to the mitochondrial ubiquinone pool. Proc Natl Acad Sci U S A 2006; 103:16212-7. [PMID: 17050691 PMCID: PMC1637562 DOI: 10.1073/pnas.0604567103] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) is a 4Fe4S flavoprotein located in the inner mitochondrial membrane. It catalyzes ubiquinone (UQ) reduction by ETF, linking oxidation of fatty acids and some amino acids to the mitochondrial respiratory chain. Deficiencies in ETF or ETF-QO result in multiple acyl-CoA dehydrogenase deficiency, a human metabolic disease. Crystal structures of ETF-QO with and without bound UQ were determined, and they are essentially identical. The molecule forms a single structural domain. Three functional regions bind FAD, the 4Fe4S cluster, and UQ and are closely packed and share structural elements, resulting in no discrete structural domains. The UQ-binding pocket consists mainly of hydrophobic residues, and UQ binding differs from that of other UQ-binding proteins. ETF-QO is a monotopic integral membrane protein. The putative membrane-binding surface contains an alpha-helix and a beta-hairpin, forming a hydrophobic plateau. The UQ-flavin distance (8.5 A) is shorter than the UQ-cluster distance (18.8 A), and the very similar redox potentials of FAD and the cluster strongly suggest that the flavin, not the cluster, transfers electrons to UQ. Two possible electron transfer paths can be envisioned. First, electrons from the ETF flavin semiquinone may enter the ETF-QO flavin one by one, followed by rapid equilibration with the cluster. Alternatively, electrons may enter via the cluster, followed by equilibration between centers. In both cases, when ETF-QO is reduced to a two-electron reduced state (one electron at each redox center), the enzyme is primed to reduce UQ to ubiquinol via FAD.
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Affiliation(s)
- Jian Zhang
- *Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226; and
| | - Frank E. Frerman
- Department of Pediatrics, University of Colorado Health Sciences Center, Denver, CO 80262
| | - Jung-Ja P. Kim
- *Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226; and
- To whom correspondence should be addressed. E-mail:
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17
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Schiff M, Froissart R, Olsen RKJ, Acquaviva C, Vianey-Saban C. Electron transfer flavoprotein deficiency: functional and molecular aspects. Mol Genet Metab 2006; 88:153-8. [PMID: 16510302 DOI: 10.1016/j.ymgme.2006.01.009] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Revised: 01/15/2006] [Accepted: 01/18/2006] [Indexed: 11/22/2022]
Abstract
Multiple acyl-CoA dehydrogenase deficiency (MADD) is a recessively inherited metabolic disorder that can be due to a deficiency of electron transfer flavoprotein (ETF) or its dehydrogenase (ETF-ubiquinone oxidoreductase). ETF is a mitochondrial matrix protein consisting of alpha- (30kDa) and beta- (28kDa) subunits encoded by the ETFA and ETFB genes, respectively. In the present study, we have analysed tissue samples from 16 unrelated patients with ETF deficiency, and we report the results of ETF activity, Western blot analysis and mutation analysis. The ETF assay provides a reliable diagnostic tool to confirm ETF deficiency in patients suspected to suffer from MADD. Activity ranged from less than 1 to 16% of controls with the most severely affected patients disclosing the lowest activity values. The majority of patients had mutations in the ETFA gene while only two of them harboured mutations in the ETFB gene. Nine novel disease-causing ETF mutations are reported.
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Affiliation(s)
- Manuel Schiff
- Centre de Référence Maladies Héréditaires du Métabolisme, Service de Biochimie Pédiatrique, Hôpital Debrousse, Lyon, France.
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18
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Okumura N, Hashida-Okumura A, Kita K, Matsubae M, Matsubara T, Takao T, Nagai K. Proteomic analysis of slow- and fast-twitch skeletal muscles. Proteomics 2005; 5:2896-906. [PMID: 15981298 DOI: 10.1002/pmic.200401181] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Skeletal muscles are composed of slow- and fast-twitch muscle fibers, which have high potential in aerobic and anaerobic ATP production, respectively. To investigate the molecular basis of the difference in their functions, we examined protein profiles of skeletal muscles using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional gel electrophoresis with pH 4-7 and 6-11 isoelectric focusing gels. A comparison between rat soleus and extensol digitorum longus (EDL) muscles that are predominantly slow- and fast-twitch fibers, respectively, showed that the EDL muscle had higher levels of glycogen phosphorylase, most glycolytic enzymes, glycerol 3-phosphate dehydrogenase, and creatine kinase; while the soleus muscle had higher levels of myoglobin, TCA cycle enzymes, electron transfer flavoprotein, and carbonic anhydrase III. The two muscles also expressed different isoforms of contractile proteins including myosin heavy and light chains. These protein patterns were further compared with those of red and white gastrochnemius as well as red and white quadriceps muscles. It was found that metabolic enzymes showed a concerted regulation dependent on muscle fiber types. On the other hand, expression of contractile proteins seemed to be independent of the metabolic characteristics of muscle fibers. These results suggest that metabolic enzymes and contractile proteins show different expression patterns in skeletal muscles.
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MESH Headings
- Animals
- Electrophoresis, Gel, Two-Dimensional
- Muscle Contraction
- Muscle Fibers, Fast-Twitch/chemistry
- Muscle Fibers, Fast-Twitch/metabolism
- Muscle Fibers, Slow-Twitch/chemistry
- Muscle Fibers, Slow-Twitch/metabolism
- Muscle Proteins/isolation & purification
- Muscle Proteins/metabolism
- Muscle, Skeletal/chemistry
- Muscle, Skeletal/innervation
- Muscle, Skeletal/metabolism
- Peptide Mapping
- Proteomics
- Rats
- Rats, Wistar
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
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Affiliation(s)
- Nobuaki Okumura
- Division of Protein Metabolism, Institute for Protein Research, Osaka University, Osaka, Japan.
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19
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Simkovic M, Frerman FE. Alternative quinone substrates and inhibitors of human electron-transfer flavoprotein-ubiquinone oxidoreductase. Biochem J 2004; 378:633-40. [PMID: 14640977 PMCID: PMC1223987 DOI: 10.1042/bj20031272] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2003] [Revised: 10/28/2003] [Accepted: 11/26/2003] [Indexed: 11/17/2022]
Abstract
Electron-transfer flavoprotein (ETF)-ubiquinone (2,3-dimethoxy-5-methyl-1,4-benzoquinone) oxidoreductase (ETF-QO) is a membrane-bound iron-sulphur flavoprotein that participates in an electron-transport pathway between eleven mitochondrial flavoprotein dehydrogenases and the ubiquinone pool. ETF is the intermediate electron carrier between the dehydrogenases and ETF-QO. The steady-state kinetic constants of human ETF-QO were determined with ubiquinone homologues and analogues that contained saturated n-alkyl substituents at the 6 position. These experiments show that optimal substrates contain a ten-carbon-atom side chain, consistent with a preliminary crystal structure that shows that only the first two of ten isoprene units of co-enzyme Q10 (CoQ10) interact with the protein. Derivatives with saturated alkyl side chains are very good substrates, indicating that, unlike other ubiquinone oxidoreductases, there is little preference for the methyl branches or rigidity of the CoQ side chain. Few of the compounds that inhibit ubiquinone oxidoreductases inhibit ETF-QO. Compounds found to act as inhibitors of ETF-QO include 2-n-heptyl-4-hydroxyquinoline N-oxide, a naphthoquinone analogue, 2-(3-methylpentyl)-4,6-dinitrophenol and pentachlorophenol. 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), which inhibits the mitochondrial bc1 complex and the chloroplast b6 f complex in redox-dependent fashion, can serve as an electron acceptor for human ETF-QO. The observation of simple Michaelis-Menten kinetic patterns and a single type of quinone-binding site, determined by fluorescence titrations of the protein with DBMIB and 6-(10-bromodecyl)ubiquinone, are consistent with one ubiquinone-binding site per ETF-QO monomer.
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Affiliation(s)
- Martin Simkovic
- Department of Pediatrics, University of Colorado Health Sciences Center, Denver, CO 80262, USA
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20
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Abstract
Corynebacterium glutamicum is an aerobic bacterium that requires oxygen as exogenous electron acceptor for respiration. Recent molecular and biochemical analyses together with information obtained from the genome sequence showed that C. glutamicum possesses a branched electron transport chain to oxygen with some remarkable features. Reducing equivalents obtained by the oxidation of various substrates are transferred to menaquinone via at least eight different dehydrogenases, i.e. NADH dehydrogenase, succinate dehydrogenase, malate:quinone oxidoreductase, pyruvate:quinone oxidoreductase, D-lactate dehydrogenase, L-lactate dehydrogenase, glycerol-3-phosphate dehydrogenase and L-proline dehydrogenase. All these enzymes contain a flavin cofactor and, except succinate dehydrogenase, are single subunit peripheral membrane proteins located inside the cell. From menaquinol, the electrons are passed either via the cytochrome bc(1) complex to the aa(3)-type cytochrome c oxidase with low oxygen affinity, or to the cytochrome bd-type menaquinol oxidase with high oxygen affinity. The former branch is exceptional, in that it does not involve a separate cytochrome c for electron transfer from cytochrome c(1) to the Cu(A) center in subunit II of cytochrome aa(3). Rather, cytochrome c(1) contains two covalently bound heme groups, one of which presumably takes over the function of a separate cytochrome c. The bc(1) complex and cytochrome aa(3) oxidase form a supercomplex in C. glutamicum. The phenotype of defined mutants revealed that the bc(1)-aa(3) branch, but not the bd branch, is of major importance for aerobic growth in minimal medium. Changes of the efficiency of oxidative phosphorylation caused by qualitative changes of the respiratory chain or by a defective F(1)F(0)-ATP synthase were found to have strong effects on metabolism and amino acid production. Therefore, the system of oxidative phosphorylation represents an attractive target for improving amino acid productivity of C. glutamicum by metabolic engineering.
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Affiliation(s)
- Michael Bott
- Institut für Biotechnologie 1, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany.
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21
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Westover JB, Goodman SI, Frerman FE. Pathogenic mutations in the carboxyl-terminal domain of glutaryl-CoA dehydrogenase: effects on catalytic activity and the stability of the tetramer. Mol Genet Metab 2003; 79:245-56. [PMID: 12948740 DOI: 10.1016/s1096-7192(03)00109-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Inherited defects in glutaryl-CoA dehydrogenase cause the neurometabolic disease, glutaric acidemia type I. Five of over 80 mutations that have been identified are located in a carboxyl-terminal domain. The five mutations were generated by site directed mutagenesis and expressed in Escherichia coli. The mutant dehydrogenases were purified and characterized by circular dichroism and fluorescence spectroscopy, analytical size exclusion chromatography, thermal stability, and steady state kinetic analysis. There is no significant change in the alpha-helical content of the mutant proteins and little effect on tertiary structure; however, spectral properties of the mutant proteins indicate that the FAD prosthetic group can dissociate from the mutant proteins. Size exclusion chromatography shows that four mutant proteins dissociate to dimers or a mixture of monomers and dimers. Steady state kinetic analyses show that K(m) for glutaryl-CoA is affected by the mutations, but there is little effect on k(cat) compared with the wild type dehydrogenase. The lack of effects of the mutations on the K(m) for the electron acceptor, electron transfer flavoprotein, and on secondary structure suggests that the mutations do not result in long-range structural effects. The crystal structures of the acyl-CoA dehydrogenases show that their overall folding patterns are very similar and that the carboxyl-terminal domain is involved in substrate binding, FAD binding and intersubunit interactions. Investigations of mutations in the carboxyl-terminal domain of glutaryl-CoA dehydrogenase clearly illustrate these multiple roles of this domain. The results also indicate that a primary effect of the mutations is to cause alterations that promote aggregation.
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Affiliation(s)
- Jonna B Westover
- The Program in Human Medical Genetics, University of Colorado Health Sciences Center, Denver, CO 80262, USA
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22
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Brereton PS, Verhagen MF, Zhou ZH, Adams MW. Effect of iron-sulfur cluster environment in modulating the thermodynamic properties and biological function of ferredoxin from Pyrococcus furiosus. Biochemistry 1998; 37:7351-62. [PMID: 9585549 PMCID: PMC2731698 DOI: 10.1021/bi972864b] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The ferredoxin (7.5 kDa) of the hyperthermophilic archaeon, Pyrococcus furiosus, contains a single [4Fe-4S]1+,2+ cluster that is coordinated by three Cys and one Asp residue rather than the expected four Cys. The role of this Asp residue was investigated using a series of mutants, D14X, where X = C, S, H, N, V, and Y, prepared by heterologous gene expression in Escherichia coli. While the recombinant form of the wild-type and the D14S and D14C mutants contained a [4Fe-4S]1+,2+ cluster, the D14V, D14H, D14Y, and D14N proteins contained a [3Fe-4S]0,+ center, as determined by visible spectroscopy and electrochemistry. The redox potentials (at pH 7.0, 23 degrees C) of the D14C and D14S mutants were decreased by 58 and 133 mV, respectively, compared to those of the wild-type 4Fe-ferredoxin (Em -368 mV), while those of the 3Fe-protein mutants (including the 3Fe-form of the D14S, generated by chemical oxidation) were between 15 and 118 mV more positive than that of wild-type 3Fe-form (obtained by chemical oxidation, Em -203 mV). The reduction potentials of all of the 3Fe-forms, except the D14S mutant, showed a pH response over the range 3.0-10.0 with a pK of 3.3-4.7, and this was assigned to cluster protonation. The D14H mutant and the wild-type 3Fe-proteins showed an additional pK (both at 5.9) assumed to arise from protonation of the amino acid side chain. With the 4Fe-proteins, there was no dramatic change in the potentials of the wild-type or D14C form, while the pH response of the D14S mutant (pK 4.75) was ascribed to protonation of the serinate. While the ferredoxin variants exhibited a range of thermal stabilities (measured at 80 degrees C, pH 2.5), none of them showed any temperature-dependent transitions (0-80 degrees C) in their reduction potentials, and there was no correlation between the calculated DeltaS degrees' values and the absorbance maximum, reduction potential, or hydrophobicity of residue 14. In contrast, there was a linear correlation between the DeltaH degrees' value and reduction potential. Kinetic analyses were carried out at 80 degrees C using the ferredoxin as either an electron acceptor to pyruvate oxidoreductase (POR) or as an electron donor to ferredoxin:NADP oxidoreductase (FNOR, both from P. furiosus). The data showed that the reduction potential of the ferredoxin, rather than cluster type or the nature of the residue at position 14, appears to be the predominant factor in determining efficiency of electron transfer in both systems. However, compared to all the variants, the reduction potential of WT Fd makes it the most appropriate protein to both accept electrons from POR and donate them to FNOR.
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Affiliation(s)
- P S Brereton
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens 30602-7229, USA
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