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Erlich‐Hadad T, Hadad R, Feldman A, Greif H, Lictenstein M, Lorberboum‐Galski H. TAT-MTS-MCM fusion proteins reduce MMA levels and improve mitochondrial activity and liver function in MCM-deficient cells. J Cell Mol Med 2018; 22:1601-1613. [PMID: 29265583 PMCID: PMC5824393 DOI: 10.1111/jcmm.13435] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 09/25/2017] [Indexed: 12/14/2022] Open
Abstract
Methylmalonic aciduria (MMA) is a disorder of organic acid metabolism resulting from a functional defect of the mitochondrial enzyme, methylmalonyl-CoA mutase (MCM). The main treatments for MMA patients are dietary restriction of propiogenic amino acids and carnitine supplementation. Liver or combined liver/kidney transplantation has been used to treat those with the most severe clinical manifestations. Thus, therapies are necessary to help improve quality of life and prevent liver, renal and neurological complications. Previously, we successfully used the TAT-MTS-Protein approach for replacing a number of mitochondrial-mutated proteins. In this targeted system, TAT, an 11 a.a peptide, which rapidly and efficiently can cross biological membranes, is fused to a mitochondrial targeting sequence (MTS), followed by the mitochondrial mature protein which sends the protein into the mitochondria. In the mitochondria, the TAT-MTS is cleaved off and the native protein integrates into its natural complexes and is fully functional. In this study, we used heterologous MTSs of human, nuclear-encoded mitochondrial proteins, to target the human MCM protein into the mitochondria. All fusion proteins reached the mitochondria and successfully underwent processing. Treatment of MMA patient fibroblasts with these fusion proteins restored mitochondrial activity such as ATP production, mitochondrial membrane potential and oxygen consumption, indicating the importance of mitochondrial function in this disease. Treatment with the fusion proteins enhanced cell viability and most importantly reduced MMA levels. Treatment also enhanced albumin and urea secretion in a CRISPR/Cas9-engineered HepG2 MUT (-/-) liver cell line. Therefore, we suggest using this TAT-MTS-Protein approach for the treatment of MMA.
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Affiliation(s)
- Tal Erlich‐Hadad
- Department of Biochemistry and Molecular BiologyInstitute for Medical Research Israel‐Canada (IMRIC)Faculty of MedicineHebrew University of JerusalemJerusalemIsrael
| | - Rita Hadad
- Department of Biochemistry and Molecular BiologyInstitute for Medical Research Israel‐Canada (IMRIC)Faculty of MedicineHebrew University of JerusalemJerusalemIsrael
| | | | | | - Michal Lictenstein
- Department of Biochemistry and Molecular BiologyInstitute for Medical Research Israel‐Canada (IMRIC)Faculty of MedicineHebrew University of JerusalemJerusalemIsrael
| | - Haya Lorberboum‐Galski
- Department of Biochemistry and Molecular BiologyInstitute for Medical Research Israel‐Canada (IMRIC)Faculty of MedicineHebrew University of JerusalemJerusalemIsrael
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Marques SM, Daniel L, Buryska T, Prokop Z, Brezovsky J, Damborsky J. Enzyme Tunnels and Gates As Relevant Targets in Drug Design. Med Res Rev 2016; 37:1095-1139. [PMID: 27957758 DOI: 10.1002/med.21430] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 10/11/2016] [Accepted: 11/07/2016] [Indexed: 12/28/2022]
Abstract
Many enzymes contain tunnels and gates that are essential to their function. Gates reversibly switch between open and closed conformations and thereby control the traffic of small molecules-substrates, products, ions, and solvent molecules-into and out of the enzyme's structure via molecular tunnels. Many transient tunnels and gates undoubtedly remain to be identified, and their functional roles and utility as potential drug targets have received comparatively little attention. Here, we describe a set of general concepts relating to the structural properties, function, and classification of these interesting structural features. In addition, we highlight the potential of enzyme tunnels and gates as targets for the binding of small molecules. The different types of binding that are possible and the potential pharmacological benefits of such targeting are discussed. Twelve examples of ligands bound to the tunnels and/or gates of clinically relevant enzymes are used to illustrate the different binding modes and to explain some new strategies for drug design. Such strategies could potentially help to overcome some of the problems facing medicinal chemists and lead to the discovery of more effective drugs.
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Affiliation(s)
- Sergio M Marques
- Loschmidt Laboratories, Faculty of Science, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, RECETOX, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Lukas Daniel
- Loschmidt Laboratories, Faculty of Science, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, RECETOX, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.,International Centre for Clinical Research, St. Anne's University Hospital, Pekarska 53, 656 91, Brno, Czech Republic
| | - Tomas Buryska
- Loschmidt Laboratories, Faculty of Science, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, RECETOX, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.,International Centre for Clinical Research, St. Anne's University Hospital, Pekarska 53, 656 91, Brno, Czech Republic
| | - Zbynek Prokop
- Loschmidt Laboratories, Faculty of Science, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, RECETOX, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.,International Centre for Clinical Research, St. Anne's University Hospital, Pekarska 53, 656 91, Brno, Czech Republic
| | - Jan Brezovsky
- Loschmidt Laboratories, Faculty of Science, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, RECETOX, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.,International Centre for Clinical Research, St. Anne's University Hospital, Pekarska 53, 656 91, Brno, Czech Republic
| | - Jiri Damborsky
- Loschmidt Laboratories, Faculty of Science, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, RECETOX, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.,International Centre for Clinical Research, St. Anne's University Hospital, Pekarska 53, 656 91, Brno, Czech Republic
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Kumari C, Kapoor S, Varughese B, Pollipali SK, Ramji S. Mutation Analyses in Selected Exons of the MUT Gene in Indian Patients with Methylmalonic Acidemia. Indian J Clin Biochem 2016; 32:266-274. [PMID: 28811685 DOI: 10.1007/s12291-016-0600-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 07/29/2016] [Indexed: 01/27/2023]
Abstract
Deficiency or diminished activity of a cobalamin dependent enzyme methylmalonyl-CoA mutase causes inborn error of metabolism called methylmalonic acidemia (MMA). In this study we elucidated the spectrum of mutations in 21 Indian mut MMA patients by direct sequencing. Sequence analysis identified a total of 70 mutations in exon 2, 9, 11 and 12 of MUT gene. Out of which 26 mutations were predicted to be deleterious and rest were benign. The 23 novel mutations consist of four nonsense mutations (p.N6*, p.G539*, p.E609* and p.I671*), twelve missense mutations (p.K128I, p.N547T, p.D554Y, p.A558T, p.R559P, p.A631T, p.I647T, p.E656D, p.V657E, p.Q660H, p.K679N, and p.G696Y) and seven frame shift mutations (c.375_376insA, c.1642delA, c.1655delC, c.1825_1826insT, c.1957delGA, c.2014delA and c.2062_2063insGA). All of them are point mutations or micro rearrangements. Three of these mutations (p.K621N, p.G648D, p.G630E) have been previously reported; all of them are missense mutations. The mutations are distributed throughout the exon 2, 9, 11 and 12, 38.4 % mutation are located in exon 12.
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Affiliation(s)
- Chandrawati Kumari
- Pediatrics Genetic and Research Laboratory, Department of Pediatrics, Maulana Azad Medical College, New Medical Block, Opposite Old Casualty, Lok Nayak Hospital, New Delhi, 110002 India
| | - Seema Kapoor
- Pediatrics Genetic and Research Laboratory, Department of Pediatrics, Maulana Azad Medical College, New Medical Block, Opposite Old Casualty, Lok Nayak Hospital, New Delhi, 110002 India
| | - Bijo Varughese
- Pediatrics Genetic and Research Laboratory, Department of Pediatrics, Maulana Azad Medical College, New Medical Block, Opposite Old Casualty, Lok Nayak Hospital, New Delhi, 110002 India
| | - Sunil Kumar Pollipali
- Pediatrics Genetic and Research Laboratory, Department of Pediatrics, Maulana Azad Medical College, New Medical Block, Opposite Old Casualty, Lok Nayak Hospital, New Delhi, 110002 India
| | - Siddarth Ramji
- Department of Neonatology, Maulana Azad Medical College, New Delhi, 110002 India
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Chu J, Pupavac M, Watkins D, Tian X, Feng Y, Chen S, Fenter R, Zhang VW, Wang J, Wong LJ, Rosenblatt DS. Next generation sequencing of patients with mut methylmalonic aciduria: Validation of somatic cell studies and identification of 16 novel mutations. Mol Genet Metab 2016; 118:264-71. [PMID: 27233228 DOI: 10.1016/j.ymgme.2016.05.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 05/18/2016] [Accepted: 05/18/2016] [Indexed: 12/13/2022]
Abstract
Mutations in the MUT gene, which encodes the mitochondrial enzyme methylmalonyl-CoA mutase, are responsible for the mut form of methylmalonic aciduria (MMA). In this study, a next generation sequencing (NGS) based gene panel was used to analyze 53 patients that had been diagnosed with mut MMA by somatic cell complementation analysis. A total of 54 different mutations in MUT were identified in 48 patients; 16 novel mutations were identified, including 1 initiation site mutation (c.2T>C [p.M1?]), 1 missense mutation (c.566A>T [p.N189I]), 2 nonsense mutations (c.129G>A [p.W43*] and c.1975C>T [p.Q659*]), 2 mutations affecting splice sites (c.753+3A>G and c.754-2A>G), 8 small insertions, deletions, and duplications (c.29dupT [p.L10Ffs*39], c.55dupG [p.V19Gfs*30], c.631_633delGAG [p.E211del], c.795_796insT [p.M266Yfs*7], c.1061delCinsGGA [p.S354Wfs*20], c.1065_1068dupATGG [p.S357Mfs*5], c.1181dupT [p.L394Ffs*30], c.1240delG [p.E414Kfs*17]), a large insertion (c.146_147ins279), and a large deletion involving exon 13. Phenotypic rescue and cDNA analysis were used to confirm that the c.146_147ins279 and c.631_633delGAG mutations were associated with the decreased methylmalonyl-CoA mutase function observed in the patient fibroblasts. In five patients, the NGS panel did not confirm the diagnosis made by complementation analysis. One of these patients was found to carry 2 novel mutations (c.433G > A [p.E145K] and c.511A>C [p.N171H]) in the SUCLG1 gene.
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Affiliation(s)
- Jordan Chu
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | - Mihaela Pupavac
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | - David Watkins
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | - Xia Tian
- Department of Molecular Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Yanming Feng
- Department of Molecular Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Stella Chen
- Department of Molecular Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Remington Fenter
- Department of Molecular Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Victor W Zhang
- Department of Molecular Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Jing Wang
- Department of Molecular Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Lee-Jun Wong
- Department of Molecular Genetics, Baylor College of Medicine, Houston, TX, United States
| | - David S Rosenblatt
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada.
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5
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Abstract
Defects in the human gene encoding methylmalonyl-CoA mutase enzyme (MCM) give rise to a rare autosomal recessive inherited disorder of propionate metabolism termed mut methylmalonic acidemia (MMA). Patients with mut MMA have been divided into two subgroups: mut0 with complete loss of MCM activity and mut- with residual activity in the presence of adenosylcobalamin (AdoCbl). The disease typically presents in the first weeks or months of life and is clinically characterized by recurrent vomiting, metabolic acidosis, hyperammonemia, lethargy, poor feeding, failure to thrive and neurological deficit. To better elucidate the spectrum of mutations causing mut MMA in Saudi patients, we screened a cohort of 60 Saudi patients affected by either forms of the disease for mutations in the MUT gene. A total of 13 different mutations, including seven previously reported missense changes and six novel mutations, were detected in a homozygous state except for two compound heterozygous cases. The six novel mutations identified herein consist of three nonsense, two missense and one frameshift, distributed throughout the whole protein. This study describes for the first time the clinical and mutational spectrum of mut MMA in Saudi Arabian patients.
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Clinical features and MUT gene mutation spectrum in Chinese patients with isolated methylmalonic acidemia: identification of ten novel allelic variants. World J Pediatr 2015; 11:358-65. [PMID: 26454439 DOI: 10.1007/s12519-015-0043-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Accepted: 07/14/2015] [Indexed: 01/07/2023]
Abstract
BACKGROUND This study aims to study MUT gene mutation spectrum in Chinese patients with isolated methylmalonic academia (MMA) and their clinical features for the potential genotype-phenotype correlation. METHODS Forty-three patients were diagnosed with isolated MMA by elevated blood propionylcarnitine, propionylcarnitine to acetylcarnitine ratio, and urine methylmalonate without hyperhomocysteinemia. The MUT gene was amplified by polymerase chain reaction and directly sequenced. Those patients with at least one variant allele were included. The novel missense mutations were assessed by bioinformatic analysis and screened against alleles sequenced from 50 control participants. RESULTS Among the 43 patients, 38 had typical clinical presentations, and the majority (30/38) experienced earlyonset MMA. Eight patients died and seven were lost to follow-up. Twenty patients had poor outcomes and eight showed normal development. The 43 identified MUT gene mutations had at least one variant allele, whereas 35 had two mutant alleles. Of the 33 mutations reported before, eight recurrent mutations were identified in 32 patients, and c.729_730insTT (p.D244Lfs*39) was the most common (12/78) in the mutant alleles. Of the 10 novel mutations, six were missense mutations and four were premature termination codon mutations. The six novel missense mutations seemed to be pathogenic. CONCLUSIONS A total of 10 novel MUT mutations were detected in the Chinese population. c.729_730insTT (p.D244Lfs*39) was the most frequent mutation. A genotype-phenotype correlation could not be found, but the genotypic characterization indicated the need of genetic counseling for MMA patients and early prenatal diagnoses for high-risk families.
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7
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Ghoraba DA, Mohammed MM, Zaki OK. Mutation analysis of methylmalonyl CoA mutase gene exon 2 in Egyptian families: Identification of 25 novel allelic variants. Meta Gene 2015; 3:71-88. [PMID: 25750861 PMCID: PMC4349194 DOI: 10.1016/j.mgene.2014.02.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Revised: 01/22/2014] [Accepted: 02/03/2014] [Indexed: 11/30/2022] Open
Abstract
Methylmalonic aciduria (MMA) is an autosomal recessive disorder of methylmalonate and cobalamin (cbl; vitamin B12) metabolism. It is an inborn error of organic acid metabolism which commonly results from a defect in the gene encoding the methylmalonyl-CoA mutase (MCM) apoenzyme. Here we report the results of mutation study of exon 2 of the methylmalonyl CoA mutase (MUT) gene, coding MCM residues from 1 to 128, in ten unrelated Egyptian families affected with methylmalonic aciduria. Patients were presented with a wide-anion gap metabolic acidosis. The diagnosis has established by the measurement of C3 (propionylcarnitine) and C3:C2 (propionylcarnitine/acetylcarnitine) in blood by using liquid chromatography–tandem mass spectrometry (LC/MS–MS) and was confirmed by the detection of an abnormally elevated level of methylmalonic acid in urine by using gas chromatography–mass spectrometry (GC/MS) and isocratic cation exchange high-performance liquid-chromatography (HPLC). Direct sequencing of gDNA of the MUT gene exon 2 has revealed a total of 26 allelic variants: ten of which were intronic, eight were located upstream to the exon 2 coding region, four were novel modifications predicted to affect the splicing region, three were novel mutations within the coding region: c.15G > A (p.K5K), c.165C > A (p.N55K) and c.7del (p.R3EfsX14), as well as the previously reported mutation c.323G > A (p.R108H).
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Affiliation(s)
- Dina A Ghoraba
- Medical Genetics Unit, Children's Hospital, Faculty of Medicine and University Hospitals, Cairo, Egypt
| | - Magdy M Mohammed
- Department of Biochemistry, Faculty of Science, Ain Shams University, Cairo, Egypt
| | - Osama K Zaki
- Medical Genetics Unit, Children's Hospital, Faculty of Medicine and University Hospitals, Cairo, Egypt
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8
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Takahashi-Iñiguez T, García-Hernandez E, Arreguín-Espinosa R, Flores ME. Role of vitamin B12 on methylmalonyl-CoA mutase activity. J Zhejiang Univ Sci B 2012; 13:423-37. [PMID: 22661206 DOI: 10.1631/jzus.b1100329] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Vitamin B(12) is an organometallic compound with important metabolic derivatives that act as cofactors of certain enzymes, which have been grouped into three subfamilies depending on their cofactors. Among them, methylmalonyl-CoA mutase (MCM) has been extensively studied. This enzyme catalyzes the reversible isomerization of L-methylmalonyl-CoA to succinyl-CoA using adenosylcobalamin (AdoCbl) as a cofactor participating in the generation of radicals that allow isomerization of the substrate. The crystal structure of MCM determined in Propionibacterium freudenreichii var. shermanii has helped to elucidate the role of this cofactor AdoCbl in the reaction to specify the mechanism by which radicals are generated from the coenzyme and to clarify the interactions between the enzyme, coenzyme, and substrate. The existence of human methylmalonic acidemia (MMA) due to the presence of mutations in MCM shows the importance of its role in metabolism. The recent crystallization of the human MCM has shown that despite being similar to the bacterial protein, there are significant differences in the structural organization of the two proteins. Recent studies have identified the involvement of an accessory protein called MMAA, which interacts with MCM to prevent MCM's inactivation or acts as a chaperone to promote regeneration of inactivated enzyme. The interdisciplinary studies using this protein as a model in different organisms have helped to elucidate the mechanism of action of this isomerase, the impact of mutations at a functional level and their repercussion in the development and progression of MMA in humans. It is still necessary to study the mechanisms involved in more detail using new methods.
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Affiliation(s)
- Tóshiko Takahashi-Iñiguez
- Department of Molecular Biology and Biotechnology, Institute of Biomedical Research, National Autonomous University of Mexico, D.F. 04510, Mexico.
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Dündar H, Özgül RK, Güzel-Ozantürk A, Dursun A, Sivri S, Aliefendioğlu D, Coşkun T, Tokatli A. Microarray based mutational analysis of patients with methylmalonic acidemia: identification of 10 novel mutations. Mol Genet Metab 2012; 106:419-23. [PMID: 22727635 DOI: 10.1016/j.ymgme.2012.05.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 05/21/2012] [Accepted: 05/21/2012] [Indexed: 10/28/2022]
Abstract
Methylmalonic acidemia is an autosomal recessive metabolic disorder affecting the propionate oxidation pathway in the catabolism of several amino acids, odd-chain fatty acids, and cholesterol. Methylmalonic acidemia is characterized by elevated levels of methylmalonic acid in the blood and urine. Mutations in the MUT gene, encoding methylmalonyl-CoA mutase carries out isomerization of L-methylmalonyl-CoA to succinyl-CoA, cause methylmalonic acidemia. In this study, 30 Turkish patients diagnosed with mut methylmalonic acidemia were screened for mutations using custom designed sequencing microarrays. The study resulted in detection of 22 different mutations, 10 of which were novel: p.Q132*, p.A137G, c.753+1T, p.T387I, p.Q514E, p.P615L, p.D625V, c.1962_1963delTC, p.L674F, and c.2115_2116insA. The most common, p.P615T, was identified in 28.0% of patients. These results suggest that microarray based sequencing is a useful tool for the detection of mutations in MUT in patients with mut methylmalonic acidemia.
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Affiliation(s)
- Halil Dündar
- Metabolism Unit, Department of Pediatrics, Hacettepe University, Ankara, Turkey
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10
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Abstract
Vitamin B12 (cobalamin, Cbl) is an essential nutrient in human metabolism. Genetic diseases of vitamin B12 utilisation constitute an important fraction of inherited newborn disease. Functionally, B12 is the cofactor for methionine synthase and methylmalonyl CoA mutase. To function as a cofactor, B12 must be metabolised through a complex pathway that modifies its structure and takes it through subcellular compartments of the cell. Through the study of inherited disorders of vitamin B12 utilisation, the genes for eight complementation groups have been identified, leading to the determination of the general structure of vitamin B12 processing and providing methods for carrier testing, prenatal diagnosis and approaches to treatment.
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Hazra A, Kraft P, Lazarus R, Chen C, Chanock SJ, Jacques P, Selhub J, Hunter DJ. Genome-wide significant predictors of metabolites in the one-carbon metabolism pathway. Hum Mol Genet 2009; 18:4677-87. [PMID: 19744961 DOI: 10.1093/hmg/ddp428] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Low plasma B-vitamin levels and elevated homocysteine have been associated with cancer, cardiovascular disease and neurodegenerative disorders. Common variants in FUT2 on chromosome 19q13 were associated with plasma vitamin B12 levels among women in a genome-wide association study in the Nurses' Health Study (NHS) NCI-Cancer Genetic Markers of Susceptibility (CGEMS) project. To identify additional loci associated with plasma vitamin B12, homocysteine, folate and vitamin B6 (active form pyridoxal 5'-phosphate, PLP), we conducted a meta-analysis of three GWA scans (total n = 4763, consisting of 1658 women in NHS-CGEMS, 1647 women in Framingham-SNP-Health Association Resource (SHARe) and 1458 men in SHARe). On chromosome 19q13, we confirm the association of plasma vitamin B12 with rs602662 and rs492602 (P-value = 1.83 x 10(-15) and 1.30 x 10(-14), respectively) in strong linkage disequilibrium (LD) with rs601338 (P = 6.92 x 10(-15)), the FUT2 W143X nonsense mutation. We identified additional genome-wide significant loci for plasma vitamin B12 on chromosomes 6p21 (P = 4.05 x 10(-08)), 10p12 (P-value=2.87 x 10(-9)) and 11q11 (P-value=2.25 x 10(-10)) in genes with biological relevance. We confirm the association of the well-studied functional candidate SNP 5,10-methylene tetrahydrofolate reductase (MTHFR) Ala222Val (dbSNP ID: rs1801133; P-value=1.27 x 10(-8)), on chromosome 1p36 with plasma homocysteine and identify an additional genome-wide significant locus on chromosome 9q22 (P-value=2.06 x 10(-8)) associated with plasma homocysteine. We also identified genome-wide associations with variants on chromosome 1p36 with plasma PLP (P-value=1.40 x 10(-15)). Genome-wide significant loci were not identified for plasma folate. These data reveal new biological candidates and confirm prior candidate genes for plasma homocysteine, plasma vitamin B12 and plasma PLP.
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Affiliation(s)
- Aditi Hazra
- Program in Molecular and Genetic Epidemiology, Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA.
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12
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Oyama C, Takahashi T, Matsumori M, Shoji Y, Tajima G, Sakura N, Hasegawa Y, Yamaguchi S, Kakinuma H, Takada G. Novel mutation of methylmalonyl-CoA mutase gene causing the mut0 form of methylmalonic acidemia in a Japanese girl. Pediatr Int 2007; 49:232-4. [PMID: 17445044 DOI: 10.1111/j.1442-200x.2007.02325.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Chikako Oyama
- Department of Pediatrics, Akita University School of Medicine, Akita, Japan
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13
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Lempp TJ, Suormala T, Siegenthaler R, Baumgartner ER, Fowler B, Steinmann B, Baumgartner MR. Mutation and biochemical analysis of 19 probands with mut0 and 13 with mut- methylmalonic aciduria: identification of seven novel mutations. Mol Genet Metab 2007; 90:284-90. [PMID: 17113806 DOI: 10.1016/j.ymgme.2006.10.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 10/10/2006] [Accepted: 10/10/2006] [Indexed: 10/23/2022]
Abstract
Isolated methylmalonic acidurias (MMA-urias) comprise a group of rare autosomal recessively inherited disorders characterised by accumulation of MMA in urine and other body fluids, resulting from deficient activity of the mitochondrial enzyme methylmalonyl-CoA mutase (MCM). Isolated MMA-uria results from either MCM apoenzyme defects (mut(0) and mut(-)) or defects in synthesis of its cofactor 5-deoxyadenosylcobalamin, i.e. cblA, cblB and cblD-variant 2. To date various studies have identified 171 disease-causing mutations in the MCM gene (MUT). We report mutation analysis in 32 probands with mut MMA-uria including 13 probands with a mut(-) defect. Sixty two of 64 possible mutant alleles were identified, seven of which were novel missense alleles. We found three novel mutations (c.427C>T/p.H143Y; c.862T>C/p.S288P; c.1361G>A/p.G454E) among 19 probands with a mut(0) defect and four novel mutations (c.299A>G/p.Y100C; c.1031C>T/p.S344F; c.1097A>G/p.N366S; c.2081G>T/p.R694L) among 13 probands with a mut(-) defect. Our study provides evidence that the p.Y100C, p.R108H, p.N366S, p.V633G, p.R694W, p.R694L and p.M700K mutations are associated with a mut(-) phenotype.
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Affiliation(s)
- Thomas J Lempp
- Division of Metabolism and Molecular Pediatrics, University Children's Hospital Zurich, Switzerland
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14
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Worgan LC, Niles K, Tirone JC, Hofmann A, Verner A, Sammak A, Kucic T, Lepage P, Rosenblatt DS. Spectrum of mutations in mut methylmalonic acidemia and identification of a common Hispanic mutation and haplotype. Hum Mutat 2006; 27:31-43. [PMID: 16281286 DOI: 10.1002/humu.20258] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Cobalamin nonresponsive methylmalonic acidemia (MMA, mut complementation class) results from mutations in the nuclear gene MUT, which codes for the mitochondrial enzyme methylmalonyl CoA mutase (MCM). To better elucidate the spectrum of mutations that cause MMA, the MUT gene was sequenced in 160 patients with mut MMA. Sequence analysis identified mutations in 96% of disease alleles. Mutations were found in all coding exons, but predominantly in exons 2, 3, 6, and 11. A total of 116 different mutations, 68 of which were novel, were identified. Of the 116 different mutations, 53% were missense mutations, 22% were deletions, duplications or insertions, 16% were nonsense mutations, and 9% were splice-site mutations. Sixty-one of the mutations have only been identified in one family. A novel mutation in exon 2, c.322C>T (p.R108C), was identified in 16 of 27 Hispanic patients. SNP genotyping data demonstrated that Hispanic patients with this mutation share a common haplotype. Three other mutations were seen exclusively in Hispanic patients: c.280G>A (p.G94R), c.1022dupA, and c.970G>A (p.A324T). Seven mutations were seen almost exclusively in black patients, including the previously reported c.2150G>T (p.G717V) mutation, which was identified in 12 of 29 black patients. Two mutations were seen only in Asian patients. Some frequently identified mutations were not population-specific and were identified in patients of various ethnic backgrounds. Some of these mutations were found in mutation clusters in exons 2, 3, 6, and 11, suggesting a recurrent mutation.
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Affiliation(s)
- Lisa C Worgan
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
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15
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Cavicchi C, Donati MA, Funghini S, la Marca G, Malvagia S, Ciani F, Poggi GM, Pasquini E, Zammarchi E, Morrone A. Genetic and biochemical approach to early prenatal diagnosis in a family with mut methylmalonic aciduria. Clin Genet 2006; 69:72-6. [PMID: 16451139 DOI: 10.1111/j.1399-0004.2005.00547.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Genetic and biochemical prenatal diagnosis was performed at 11 weeks of gestation in a family with a proband affected by mut methylmalonic aciduria (MMA) and homozygotes for the MUT gene c.643G>A (p.Gly215Ser) mutation. Both chorionic villus and amniotic fluid samples were used. The presence of high levels of methylmalonic acid and propionylcarnitine determined by gas chromatography/mass spectrometry and LC/MS/MS analysis, respectively, and the identification of the p.Gly215Ser at a homozygous level in foetal DNA allowed a certain, rapid and early diagnosis. To our knowledge, this is the first mut MMA prenatal diagnosis carried out by genetic and biochemical approach.
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Affiliation(s)
- C Cavicchi
- Metabolic and Muscular Unit, Department of Paediatrics, University of Florence, Meyer Children's Hospital, Florence, Italy
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16
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Abstract
BACKGROUND Patients with a defect in methylmalonyl-coenzyme A mutase (MCM) are classified as having methylmalonic acidemia, which is divided into two subclasses: mut(0) and mut(-). Fifty-five disease-causing mutations have been identified. Although most are private mutations, only three (E117X, G717V, and N219Y) are reportedly common in Japanese, Black, and Caucasian populations, respectively. Here we identified mutations in 11 Japanese patients with MCM deficiency. METHODS Mutational analysis was performed in 11 unrelated Japanese patients with MCM deficiency using polymerase chain reaction and direct sequencing. RESULTS Three novel (L494X, R727X, and 449_461del) and six previously reported (R93H, E117X, N219Y, R369H, G648D and IVS2 + 5G>A) mutations were identified. The L494X mutation was found in three unrelated patients, and the R93H, E117X, R369H, G648D, and IVS2 + 5G>A mutations occurred more than once. Two of the patients were classified as mut(-) phenotype because of residual [(14)C]-propionate incorporation in the presence of a high concentration of hydroxocobalamin. The two mut(-) patients were heterozygous for the G648D mutation and presented with lethargy and metabolic acidosis after 2 years of life. Their psychomotor development has been documented as normal. The patients with the R727X or c.374_385del [corrected] mutations clinically exhibited mut(0) phenotype. Two patients with mut(0) phenotype died in infancy. One presented early in the neonatal period; the other was symptomatic in the late infantile period. CONCLUSIONS The L494X, R93H, E117X, R369H, G648D, and IVS2 + 5G>A mutations are found in more than two unrelated families in the Japanese population. The short-term outcome was generally poor in patients with mut(0), and therefore alternative treatments should be considered.
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Affiliation(s)
- Azusa Kobayashi
- Department of Pediatrics, Kanazawa Medical University, Ishikawa, Japan
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17
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Martínez MA, Rincón A, Desviat LR, Merinero B, Ugarte M, Pérez B. Genetic analysis of three genes causing isolated methylmalonic acidemia: identification of 21 novel allelic variants. Mol Genet Metab 2005; 84:317-25. [PMID: 15781192 DOI: 10.1016/j.ymgme.2004.11.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2004] [Revised: 11/23/2004] [Accepted: 11/29/2004] [Indexed: 11/20/2022]
Abstract
Isolated methylmalonic aciduria (MMA) is an inborn error of metabolism due to the impaired isomerization of l-methylmalonyl-CoA to succinyl-CoA. This reaction is catalyzed by the mitochondrial protein methylmalonyl-CoA mutase (MCM, EC 5.4.99.2), an adenosylcobalamin-dependent enzyme. Four different forms of isolated MMA have been described: mut MMA associated with defects in the MCM apoenzyme, and phenotypically divided into two subtypes mut- and mut0 MMA, and three different defects involved in the synthesis of the active form of the cofactor adenosylcobalamin, termed cbl MMA, and classified into three different complementation groups cblA, cblB, and cblH associated with defects in the MMAA and MMAB genes and with an unidentified protein, respectively. In this work we describe the genetic analysis of 25 MMA patients, mainly from Spain. Using biochemical and cellular approaches our patients have been classified, identifying 13 mut MMA, 7 cblA, 2 cblB, and 3 noncblA, noncblB deficient patients. cDNA and genomic DNA sequence analysis of the MUT, MMAA, and MMAB genes have allowed us to identify 27 different changes, 21 novel ones. Among the missense mutations identified in the MUT gene only one, the c.970G>A (p.A324T) variant located in the substrate binding domain is likely a mut- mutation. The remaining missense mutations c.326A>G (p.Q109R), c.983T>C (p.L328P), c.1846C>T (p.R616C), and c.1850T>G (p.L617R) are probably mut0. In the MMAA patients analyzed, frameshift mutations are prevalent. We have explored the genotype-phenotype correlation for this clinically heterogeneous disease.
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18
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Acquaviva C, Benoist JF, Pereira S, Callebaut I, Koskas T, Porquet D, Elion J. Molecular basis of methylmalonyl‐CoA mutase apoenzyme defect in 40 European patients affected by
mut
° and
mut
– forms of methylmalonic acidemia: Identification of 29 novel mutations in the MUT gene. Hum Mutat 2005; 25:167-76. [PMID: 15643616 DOI: 10.1002/humu.20128] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Methylmalonyl-CoA mutase (MCM) apoenzyme deficiency is a rare metabolic disease that may result in distinct biochemical phenotypes of methylmalonic acidemia (MMA), namely mut(o) and mut-. We analyzed a cohort of 40 MCM-deficient patients with MMA affected by either the mut(o) or the mut- form of the disease. By direct sequencing of cDNA and gDNA of the MUT gene, we detected 42 mutations, 29 of which were novel mutations. These included five frameshift mutations (insertion, deletion, or duplication of a single nucleotide), five sequence modifications in consensus splice sites, six nonsense and 12 missense mutations, and a large genomic deletion including exon 12. We explored how the 12 novel missense mutations might cause the observed phenotype by mapping them onto a three-dimensional model of the human MCM generated by homology with the P. shermanii enzyme. In this work we update the spectrum of MCM mutations (n=84), and then discuss their prevalence and distribution throughout the coding sequence in relation to the enzyme structure.
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Affiliation(s)
- Cécile Acquaviva
- Fédération de Génétique, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
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19
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Acquaviva C, Benoist JF, Callebaut I, Guffon N, Ogier de Baulny H, Touati G, Aydin A, Porquet D, Elion J. N219Y, a new frequent mutation among mut(degree) forms of methylmalonic acidemia in Caucasian patients. Eur J Hum Genet 2001; 9:577-82. [PMID: 11528502 DOI: 10.1038/sj.ejhg.5200675] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2000] [Revised: 03/13/2001] [Accepted: 05/02/2001] [Indexed: 11/09/2022] Open
Abstract
Mutations in the MUT locus encoding for the methylmalonyl-CoA mutase (MCM) apoenzyme are responsible for the mut forms of methylmalonic acidemia (MMA). To date, 49 different mutations have been identified in mut MMA. Only two frequent mutations have been reported in the Japanese population and in African-Americans. Here we report a new missense mutation N219Y (731 A-->T) which we found in five unrelated families of French and Turkish descent. All the patients exhibited a severe mut(degree) phenotype and three of them were homozygotes for N219Y. Direct involvement of the mutation in the loss of enzyme activity was demonstrated by mutagenesis and transient expression study. Mapping of the mutation onto a three-dimensional model of human MCM constructed by homology with the Propionibacterium shermanii enzyme shows that it lies in a highly conserved secondary structure motif and might suggest impaired folding and/or poor stability compatible with the mut(degree) phenotype. Finally, a 1% N219Y carrier frequency was observed in a French anonymous control population. Thus, N219Y is the first frequent mut mutation to be reported in the Caucasian population.
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Affiliation(s)
- C Acquaviva
- Service de Biochimie-Génétique/INSERM U458, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
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20
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Benoist JF, Acquaviva C, Callebaut I, Guffon N, Ogier de Baulny H, Mornon JP, Porquet D, Elion J. Molecular and structural analysis of two novel mutations in a patient with mut(-) methylmalonyl-CoA deficiency. Mol Genet Metab 2001; 72:181-4. [PMID: 11161845 DOI: 10.1006/mgme.2000.3122] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Inherited defects in the gene encoding the methylmalonyl-CoA mutase (MCM) result in the mut forms of methylmalonic aciduria (MMA). Twelve mutations have been identified associated with the mut(-) phenotype. We report two novel mutations (K621N and D156N) in a compound heterozygote mut(-) patient. These two mutations and three previously published ones (H627N, A191E, Y231N) were mapped onto a three-dimensional homology model of the human MCM constructed from the crystal structure of the Propionibacterium shermanii enzyme.
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Affiliation(s)
- J F Benoist
- Service de Biochimie-Hormonologie, Assitanace Publique-Hôpitaux de Paris, Hôpital Robert Debré, 48 Bd Sérurier, 75019 Paris, France.
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21
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Adjalla CE, Hosack AR, Gilfix BM, Lamothe E, Sun S, Chan A, Evans S, Matiaszuk NV, Rosenblatt DS. Seven novel mutations in mut methylmalonic aciduria. Hum Mutat 2000; 11:270-4. [PMID: 9554742 DOI: 10.1002/(sici)1098-1004(1998)11:4<270::aid-humu3>3.0.co;2-t] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Methylmalonic aciduria (MMA) is an autosomal recessive inborn error of metabolism that results from functional defects in methylmalonyl CoA mutase (MCM), a nuclear-encoded, mitochondrial enzyme that uses the vitamin B12 derivative, adenosylcobalamin (AdoCbl) as a cofactor. To date, 23 mutations have been identified at the MUT locus on the short arm of chromosome 6, causing the mut forms of MMA (mut complementation group; mut MMA, McKusick #251000). We now report seven novel mutations. Three were found inmut0 patients: R228Q (c759G-->A) was found as a heterozygous change; G312V (c1011G-->T) and 346delL (c1112delCTT) were both found as homozygous changes. Four mutations were found in mut patients: A191E (c648C-->A) and V633G (c1974T-->G) were found in the same patient; 684insL (c2128insCTC) and L685R (c2130T-->G) were both found as homozygous changes. The recent modelling of the human methylmalonyl CoA mutase allowed for an interpretation of the identified mutations.
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Affiliation(s)
- C E Adjalla
- Medical Research Council of Canada Genetics Group and Department of Human Genetics, McGill University, Montreal, Quebec
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22
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Calabrese V, Rizza V. Formation of propionate after short-term ethanol treatment and its interaction with the carnitine pool in rat. Alcohol 1999; 19:169-76. [PMID: 10548162 DOI: 10.1016/s0741-8329(99)00036-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Organic acidurias are genetic disorders of mitochondrial metabolism that lead to the accumulation in tissues and biological fluids of organic acids. It has been demonstrated that interaction of carnitine with the cellular CoA pool, through the production of acyl-carnitines, is potentially critical for maintaining normal cellular metabolism under conditions of impaired acyl-CoA use and that exposure of humans and other mammals to ethanol effects leads to impairment of mitochondrial function. The aim of the present study was to evaluate the role of ethanol on urinary excretion of short-chain organic acids and endogenous carnitines in rats. The data reported show that ethanol significantly increases urinary excretion of propionate, methylmalonate, as well as free acetate, butyrate, pyruvate, lactate, and beta-hydroxybutyrate. Furthermore, the increased formation of propionate and methylmalonate was dependent on the dose of ethanol; did not require the metabolism of ethanol, as was shown in experiments with pyrazole treatment of ethanol rats; and appears to be mediated by beta-adrenergic mechanisms because propranolol almost completely suppresses propionate accumulation. Alcohol administration also increased excretion of specific acyl-carnitines, corresponding to the accumulating acyl groups, whereas excretion of free carnitine was significantly reduced, with respect to control values. The data presented indicate that the short-term ethanol administration is associated with increased excretion of selected organic acids. This study suggests that endogenous carnitine pool might play a role against the deleterious effects of accumulating short-chain organic acids.
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Affiliation(s)
- V Calabrese
- Biochemistry, Faculty of Medicine, University of Catania, Italy.
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23
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Zámocký M, Koller F. Understanding the structure and function of catalases: clues from molecular evolution and in vitro mutagenesis. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1999; 72:19-66. [PMID: 10446501 DOI: 10.1016/s0079-6107(98)00058-3] [Citation(s) in RCA: 213] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This review gives an overview about the structural organisation of different evolutionary lines of all enzymes capable of efficient dismutation of hydrogen peroxide. Major potential applications in biotechnology and clinical medicine justify further investigations. According to structural and functional similarities catalases can be divided in three subgroups. Typical catalases are homotetrameric haem proteins. The three-dimensional structure of six representatives has been resolved to atomic resolution. The central core of each subunit reveals a characteristic "catalase fold", extremely well conserved among this group. In the native tetramer structure pairs of subunits tightly interact via exchange of their N-terminal arms. This pseudo-knot structures implies a highly ordered assembly pathway. A minor subgroup ("large catalases") possesses an extra flavodoxin-like C-terminal domain. A > or = 25 A long channel leads from the enzyme surface to the deeply buried active site. It enables rapid and selective diffusion of the substrates to the active center. In several catalases NADPH is tightly bound close to the surface. This cofactor may prevent and reverse the formation of compound II, an inactive reaction intermediate. Bifunctional catalase-peroxidase are haem proteins which probably arose via gene duplication of an ancestral peroxidase gene. No detailed structural information is currently available. Even less is know about manganese catalases. Their di-manganese reaction centers may be evolutionary.
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Affiliation(s)
- M Zámocký
- Institut für Biochemie and Molekulare Zellbiologie, Vienna, Austria.
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24
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Abstract
Two X-ray structures of cobalamin (B12) bound to proteins have now been determined. These structures reveal that the B12 cofactor undergoes a major conformational change on binding to the apoenzymes of methionine synthase and methylmalonyl-coenzyme A mutase: The dimethylbenzimidazole ligand to the cobalt is displaced by a histidine residue from the protein. Two methyltransferases from archaebacteria that catalyze methylation of mercaptoethanesulfonate (coenzyme M) during methanogenesis have also been shown to contain histidine-ligated cobamides. In corrinoid iron-sulfur methyltransferases from acetogenic and methanogenic organisms, benzimidazole is dissociated from cobalt, but without replacement by histidine. Thus, dimethylbenzimidazole displacement appears to be an emerging theme in cobamide-containing methyltransferases. In methionine synthase, the best studied of the methyltransferases, the histidine ligand appears to be required for competent methyl transfer between methyl-tetrahydrofolate and homocysteine but dissociates for reductive reactivation of the inactive oxidized enzyme. Replacement of dimethylbenzimidazole by histidine may allow switching between the catalytic and activation cycles. The best-characterized B12-dependent mutases that catalyze carbon skeleton rearrangement, for which methylmalonyl-coenzyme A mutase is the prototype, also bind cobalamin cofactors with histidine as the cobalt ligand, although other cobalamin-dependent mutases do not appear to utilize histidine ligation. It is intriguing to find that mutases, which catalyze homolytic rather than heterolytic cleavage of the carbon-cobalt bond, can use this structural motif. In methylmalonylCoA mutase a significant feature, which may be important in facilitating homolytic cleavage, is the long cobalt-nitrogen bond linking histidine to the co-factor. The intermediate radical species generated in catalysis are sequestered in the relatively hydrophilic core of an alpha/beta barrel domain of the mutase.
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Affiliation(s)
- M L Ludwig
- Biophysics Research Division, University of Michigan, Ann Arbor 48109-1055, USA
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