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Mucha P, Kus F, Cysewski D, Smolenski RT, Tomczyk M. Vitamin B 12 Metabolism: A Network of Multi-Protein Mediated Processes. Int J Mol Sci 2024; 25:8021. [PMID: 39125597 PMCID: PMC11311337 DOI: 10.3390/ijms25158021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Revised: 07/12/2024] [Accepted: 07/19/2024] [Indexed: 08/12/2024] Open
Abstract
The water-soluble vitamin, vitamin B12, also known as cobalamin, plays a crucial role in cellular metabolism, particularly in DNA synthesis, methylation, and mitochondrial functionality. Its deficiency can lead to hematological and neurological disorders; however, the manifestation of these clinical outcomes is relatively late. It leads to difficulties in the early diagnosis of vitamin B12 deficiency. A prolonged lack of vitamin B12 may have severe consequences including increased morbidity to neurological and cardiovascular diseases. Beyond inadequate dietary intake, vitamin B12 deficiency might be caused by insufficient bioavailability, blood transport disruptions, or impaired cellular uptake and metabolism. Despite nearly 70 years of knowledge since the isolation and characterization of this vitamin, there are still gaps in understanding its metabolic pathways. Thus, this review aims to compile current knowledge about the crucial proteins necessary to efficiently accumulate and process vitamin B12 in humans, presenting these systems as a multi-protein network. The epidemiological consequences, diagnosis, and treatment of vitamin B12 deficiency are also highlighted. We also discuss clinical warnings of vitamin B12 deficiency based on the ongoing test of specific moonlighting proteins engaged in vitamin B12 metabolic pathways.
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Affiliation(s)
- Patryk Mucha
- Department of Biochemistry, Medical University of Gdansk, 80-210 Gdansk, Poland; (P.M.); (F.K.); (R.T.S.)
| | - Filip Kus
- Department of Biochemistry, Medical University of Gdansk, 80-210 Gdansk, Poland; (P.M.); (F.K.); (R.T.S.)
- Laboratory of Protein Biochemistry, Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, 80-307 Gdansk, Poland
| | - Dominik Cysewski
- Clinical Research Centre, Medical University of Bialystok, 15-276 Bialystok, Poland;
| | - Ryszard T. Smolenski
- Department of Biochemistry, Medical University of Gdansk, 80-210 Gdansk, Poland; (P.M.); (F.K.); (R.T.S.)
| | - Marta Tomczyk
- Department of Biochemistry, Medical University of Gdansk, 80-210 Gdansk, Poland; (P.M.); (F.K.); (R.T.S.)
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2
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Mathew AR, Di Matteo G, La Rosa P, Barbati SA, Mannina L, Moreno S, Tata AM, Cavallucci V, Fidaleo M. Vitamin B12 Deficiency and the Nervous System: Beyond Metabolic Decompensation-Comparing Biological Models and Gaining New Insights into Molecular and Cellular Mechanisms. Int J Mol Sci 2024; 25:590. [PMID: 38203763 PMCID: PMC10778862 DOI: 10.3390/ijms25010590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 12/16/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
Vitamin B12 (VitB12) is a micronutrient and acts as a cofactor for fundamental biochemical reactions: the synthesis of succinyl-CoA from methylmalonyl-CoA and biotin, and the synthesis of methionine from folic acid and homocysteine. VitB12 deficiency can determine a wide range of diseases, including nervous system impairments. Although clinical evidence shows a direct role of VitB12 in neuronal homeostasis, the molecular mechanisms are yet to be characterized in depth. Earlier investigations focused on exploring the biochemical shifts resulting from a deficiency in the function of VitB12 as a coenzyme, while more recent studies propose a broader mechanism, encompassing changes at the molecular/cellular levels. Here, we explore existing study models employed to investigate the role of VitB12 in the nervous system, including the challenges inherent in replicating deficiency/supplementation in experimental settings. Moreover, we discuss the potential biochemical alterations and ensuing mechanisms that might be modified at the molecular/cellular level (such as epigenetic modifications or changes in lysosomal activity). We also address the role of VitB12 deficiency in initiating processes that contribute to nervous system deterioration, including ROS accumulation, inflammation, and demyelination. Consequently, a complex biological landscape emerges, requiring further investigative efforts to grasp the intricacies involved and identify potential therapeutic targets.
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Affiliation(s)
- Aimee Rachel Mathew
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University of Rome, 00185 Rome, Italy; (A.R.M.); (A.M.T.)
| | - Giacomo Di Matteo
- Department of Chemistry and Technology of Drugs, Sapienza University of Rome, 00185 Rome, Italy; (G.D.M.); (L.M.)
| | - Piergiorgio La Rosa
- Division of Neuroscience, Department of Psychology, Sapienza University of Rome, 00185 Rome, Italy;
- European Center for Brain Research, IRCCS Fondazione Santa Lucia, 00179 Rome, Italy
| | - Saviana Antonella Barbati
- Departmental Faculty of Medicine and Surgery, UniCamillus-Saint Camillus International University of Health Sciences, 00131 Rome, Italy;
| | - Luisa Mannina
- Department of Chemistry and Technology of Drugs, Sapienza University of Rome, 00185 Rome, Italy; (G.D.M.); (L.M.)
| | - Sandra Moreno
- Department of Science, University Roma Tre, 00146 Rome, Italy;
- Laboratory of Neurodevelopment, Neurogenetics and Neuromolecular Biology, IRCCS Fondazione Santa Lucia, 00179 Rome, Italy
| | - Ada Maria Tata
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University of Rome, 00185 Rome, Italy; (A.R.M.); (A.M.T.)
- Research Centre of Neurobiology “Daniel Bovet”, Sapienza University of Rome, 00185 Rome, Italy
| | - Virve Cavallucci
- Dipartimento di Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, 00168 Rome, Italy;
- Fondazione Policlinico Universitario “A. Gemelli” IRCCS, 00168 Rome, Italy
| | - Marco Fidaleo
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University of Rome, 00185 Rome, Italy; (A.R.M.); (A.M.T.)
- Research Center for Nanotechnology Applied to Engineering (CNIS), Sapienza University of Rome, 00185 Rome, Italy
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3
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McCorvie TJ, Ferreira D, Yue WW, Froese DS. The complex machinery of human cobalamin metabolism. J Inherit Metab Dis 2023; 46:406-420. [PMID: 36680553 DOI: 10.1002/jimd.12593] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 01/17/2023] [Accepted: 01/19/2023] [Indexed: 01/22/2023]
Abstract
Vitamin B12 (cobalamin, Cbl) is required as a cofactor by two human enzymes, 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR) and methylmalonyl-CoA mutase (MMUT). Within the body, a vast array of transporters, enzymes and chaperones are required for the generation and delivery of these cofactor forms. How they perform these functions is dictated by the structure and interactions of the proteins involved, the molecular bases of which are only now being elucidated. In this review, we highlight recent insights into human Cbl metabolism and address open questions in the field by employing a protein structure and interactome based perspective. We discuss how three very similar proteins-haptocorrin, intrinsic factor and transcobalamin-exploit slight structural differences and unique ligand receptor interactions to effect selective Cbl absorption and internalisation. We describe recent advances in the understanding of how endocytosed Cbl is transported across the lysosomal membrane and the implications of the recently solved ABCD4 structure. We detail how MMACHC and MMADHC cooperate to modify and target cytosolic Cbl to the client enzymes MTR and MMUT using ingenious modifications to an ancient nitroreductase fold, and how MTR and MMUT link with their accessory enzymes to sustainably harness the supernucleophilic potential of Cbl. Finally, we provide an outlook on how future studies may combine structural and interactome based approaches and incorporate knowledge of post-translational modifications to bring further insights.
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Affiliation(s)
- Thomas J McCorvie
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Douglas Ferreira
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Wyatt W Yue
- Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - D Sean Froese
- Division of Metabolism and Children's Research Center, University Children's Hospital Zürich, University of Zürich, Zürich, Switzerland
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4
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Esser AJ, Mukherjee S, Dereven‘kov IA, Makarov SV, Jacobsen DW, Spiekerkoetter U, Hannibal L. Versatile Enzymology and Heterogeneous Phenotypes in Cobalamin Complementation Type C Disease. iScience 2022; 25:104981. [PMID: 36105582 PMCID: PMC9464900 DOI: 10.1016/j.isci.2022.104981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Nutritional deficiency and genetic errors that impair the transport, absorption, and utilization of vitamin B12 (B12) lead to hematological and neurological manifestations. The cblC disease (cobalamin complementation type C) is an autosomal recessive disorder caused by mutations and epi-mutations in the MMACHC gene and the most common inborn error of B12 metabolism. Pathogenic mutations in MMACHC disrupt enzymatic processing of B12, an indispensable step before micronutrient utilization by the two B12-dependent enzymes methionine synthase (MS) and methylmalonyl-CoA mutase (MUT). As a result, patients with cblC disease exhibit plasma elevation of homocysteine (Hcy, substrate of MS) and methylmalonic acid (MMA, degradation product of methylmalonyl-CoA, substrate of MUT). The cblC disorder manifests early in childhood or in late adulthood with heterogeneous multi-organ involvement. This review covers current knowledge on the cblC disease, structure–function relationships of the MMACHC protein, the genotypic and phenotypic spectra in humans, experimental disease models, and promising therapies.
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5
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Passantino R, Mangione MR, Ortore MG, Costa MA, Provenzano A, Amenitsch H, Sabbatella R, Alfano C, Martorana V, Vilasi S. Investigation on a MMACHC mutant from cblC disease: The c.394C>T variant. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2022; 1870:140793. [PMID: 35618206 DOI: 10.1016/j.bbapap.2022.140793] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 05/17/2022] [Accepted: 05/19/2022] [Indexed: 06/15/2023]
Abstract
The cblC disease is an inborn disorder of the vitamin B12 (cobalamin, Cbl) metabolism characterized by methylmalonic aciduria and homocystinuria. The clinical consequences of this disease are devastating and, even when early treated with current therapies, the affected children manifest symptoms involving vision, growth, and learning. The illness is caused by mutations in the gene codifying for MMACHC, a 282aa protein that transports and transforms the different Cbl forms. Here we present data on the structural properties of the truncated protein p.R132X resulting from the c.394C > T mutation that, along with c.271dupA and c.331C > T, is among the most common mutations in cblC. Although missing part of the Cbl binding domain, p.R132X is associated to late-onset symptoms and, therefore, it is supposed to retain residual function. However, to our knowledge structural-functional studies on c.394C > T mutant aimed at verifying this hypothesis are still lacking. By using a biophysical approach including Circular Dichroism, fluorescence, Small Angle X-ray Scattering, and Molecular Dynamics, we show that the mutant protein MMACHC-R132X retains secondary structure elements and remains compact in solution, partly preserving its binding affinity for Cbl. Insights on the fragile stability of MMACHC-R132X-Cbl are provided.
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Affiliation(s)
- Rosa Passantino
- Biophysics Institute, National Research Council, Palermo 90143, Italy
| | | | - Maria Grazia Ortore
- Dept. Life and Environmental Sciences, Marche Polytechnic University, Ancona 60131, Italy
| | | | | | | | | | | | | | - Silvia Vilasi
- Biophysics Institute, National Research Council, Palermo 90143, Italy.
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6
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Structural Study of the Complex of cblC Methylmalonic Aciduria and Homocystinuria-Related Protein MMACHC with Cyanocobalamin. CRYSTALS 2022. [DOI: 10.3390/cryst12040468] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
MMACHC is an essential protein for the body to metabolise vitamin B12, and its deficiency will cause cblC-type methylmalonic aciduria and homocystinuria. MMACHC can interact with cyanocobalamin (a type of vitamin B12) cofactor and plays an important role in targeting cyanocobalamin to the enzyme of interest. In this paper, the GST-tag fusion-tagged MMACHC protein was successfully expressed by Escherichia coli (E. coli) low-temperature induction, and the high-purity MMACHC protein was successfully purified by affinity chromatography and gel filtration. Further, the crystal structure of MMACHC and cyanocobalamin complex was obtained with a resolution of 1.93 Å using X-ray diffraction. By analysing the complex structure of MMACHC and cyanocobalamin, we revealed the reasons for the diversity of MMACHC substrates and explained the reasons for the differences in disease conditions caused by different MMACHC site mutations. The acquisition of the complex structure of MMACHC and cyanocobalamin will play a significant role in promoting research on the metabolic pathway of vitamin B12.
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7
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Hannibal L, Jacobsen DW. Intracellular processing of vitamin B 12 by MMACHC (CblC). VITAMINS AND HORMONES 2022; 119:275-298. [PMID: 35337623 DOI: 10.1016/bs.vh.2022.02.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Vitamin B12 (cobalamin, Cbl, B12) is a water-soluble micronutrient synthesized exclusively by a group of microorganisms. Human beings are unable to make B12 and thus obtain the vitamin via intake of animal products, fermented plant-based foods or supplements. Vitamin B12 obtained from the diet comprises three major chemical forms, namely hydroxocobalamin (HOCbl), methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl). The most common form of B12 present in supplements is cyanocobalamin (CNCbl). Yet, these chemical forms cannot be utilized directly as they come, but instead, they undergo chemical processing by the MMACHC protein, also known as CblC. Processing of dietary B12 by CblC involves removal of the upper-axial ligand (beta-ligand) yielding the one-electron reduced intermediate cob(II)alamin. Newly formed cob(II)alamin undergoes trafficking and delivery to the two B12-dependent enzymes, cytosolic methionine synthase (MS) and mitochondrial methylmalonyl-CoA mutase (MUT). The catalytic cycles of MS and MUT incorporate cob(II)alamin as a precursor to regenerate the coenzyme forms MeCbl and AdoCbl, respectively. Mutations and epimutations in the MMACHC gene result in cblC disease, the most common inborn error of B12 metabolism, which manifests with combined homocystinuria and methylmalonic aciduria. Elevation of metabolites homocysteine and methylmalonic acid occurs because the lack of an active CblC blocks formation of the indispensable precursor cob(II)alamin that is necessary to activate MS and MUT. Thus, in patients with cblC disease, vitamin B12 is absorbed and present in circulation in normal to high concentrations, yet, cells are unable to make use of it. Mutations in seemingly unrelated genes that modify MMACHC gene expression also result in clinical phenotypes that resemble cblC disease. We review current knowledge on structural and functional aspects of intracellular processing of vitamin B12 by the versatile protein CblC, its partners and possible regulators.
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Affiliation(s)
- Luciana Hannibal
- Laboratory of Clinical Biochemistry and Metabolism, Department of General Pediatrics, Adolescent Medicine and Neonatology, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany.
| | - Donald W Jacobsen
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
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8
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Guéant JL, Guéant-Rodriguez RM, Kosgei VJ, Coelho D. Causes and consequences of impaired methionine synthase activity in acquired and inherited disorders of vitamin B 12 metabolism. Crit Rev Biochem Mol Biol 2021; 57:133-155. [PMID: 34608838 DOI: 10.1080/10409238.2021.1979459] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Methyl-Cobalamin (Cbl) derives from dietary vitamin B12 and acts as a cofactor of methionine synthase (MS) in mammals. MS encoded by MTR catalyzes the remethylation of homocysteine to generate methionine and tetrahydrofolate, which fuel methionine and cytoplasmic folate cycles, respectively. Methionine is the precursor of S-adenosyl methionine (SAM), the universal methyl donor of transmethylation reactions. Impaired MS activity results from inadequate dietary intake or malabsorption of B12 and inborn errors of Cbl metabolism (IECM). The mechanisms at the origin of the high variability of clinical presentation of impaired MS activity are classically considered as the consequence of the disruption of the folate cycle and related synthesis of purines and pyrimidines and the decreased synthesis of endogenous methionine and SAM. For one decade, data on cellular and animal models of B12 deficiency and IECM have highlighted other key pathomechanisms, including altered interactome of MS with methionine synthase reductase, MMACHC, and MMADHC, endoplasmic reticulum stress, altered cell signaling, and genomic/epigenomic dysregulations. Decreased MS activity increases catalytic protein phosphatase 2A (PP2A) and produces imbalanced phosphorylation/methylation of nucleocytoplasmic RNA binding proteins, including ELAVL1/HuR protein, with subsequent nuclear sequestration of mRNAs and dramatic alteration of gene expression, including SIRT1. Decreased SAM and SIRT1 activity induce ER stress through impaired SIRT1-deacetylation of HSF1 and hypomethylation/hyperacetylation of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α), which deactivate nuclear receptors and lead to impaired energy metabolism and neuroplasticity. The reversibility of these pathomechanisms by SIRT1 agonists opens promising perspectives in the treatment of IECM outcomes resistant to conventional supplementation therapies.
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Affiliation(s)
- Jean-Louis Guéant
- UMR Inserm 1256 N-GERE (Nutrition, Génetique et Exposition aux Risques Environmentaux), Université de Lorraine, Vandoeuvre-lès-Nancy, France.,Departments of Digestive Diseases and Molecular Medicine and National Center of Inborn Errors of Metabolism, University Hospital Center, Université de Lorraine, Vandoeuvre-lès-Nancy, France
| | - Rosa-Maria Guéant-Rodriguez
- UMR Inserm 1256 N-GERE (Nutrition, Génetique et Exposition aux Risques Environmentaux), Université de Lorraine, Vandoeuvre-lès-Nancy, France.,Departments of Digestive Diseases and Molecular Medicine and National Center of Inborn Errors of Metabolism, University Hospital Center, Université de Lorraine, Vandoeuvre-lès-Nancy, France
| | - Viola J Kosgei
- UMR Inserm 1256 N-GERE (Nutrition, Génetique et Exposition aux Risques Environmentaux), Université de Lorraine, Vandoeuvre-lès-Nancy, France
| | - David Coelho
- UMR Inserm 1256 N-GERE (Nutrition, Génetique et Exposition aux Risques Environmentaux), Université de Lorraine, Vandoeuvre-lès-Nancy, France
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9
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Sorin M, Watkins D, Gilfix BM, Rosenblatt DS. Methionine dependence in tumor cells: The potential role of cobalamin and MMACHC. Mol Genet Metab 2021; 132:155-161. [PMID: 33487542 DOI: 10.1016/j.ymgme.2021.01.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 01/08/2021] [Accepted: 01/08/2021] [Indexed: 12/27/2022]
Abstract
Methionine dependence of tumor cell lines, the inability to grow in tissue culture media lacking methionine but supplemented with homocysteine, has been known for decades, but an understanding of the mechanism underlying this phenomenon remains incomplete. Methionine dependence of certain glioma and melanoma cell lines has been linked to alterations in the metabolism of cobalamin (vitamin B12). In the MeWo LC1 melanoma line, complementation analysis demonstrated that the genetic defect affected the same locus mutated in the cblC inborn error of cobalamin metabolism; hypermethylation of the MMACHC promoter was subsequently demonstrated. Analysis of data in the Cancer Cell Line Encyclopedia showed increased MMACHC methylation levels in melanoma lines compared to other types of cancer. RNA sequencing data from isolated tumors, tabulated at the cBioPortal for Cancer Genomics website, showed decreased MMACHC expression compared to other tumors; and methylation data tabulated at the TGGA Wanderer website demonstrated increased MMACHC methylation. These data suggest that disruptions in cobalamin metabolism might play a more general role in methionine dependence, and potentially in the pathogenesis of melanoma cell lines and primary tumors.
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Affiliation(s)
- Mark Sorin
- Department of Human Genetics, McGill University and Research Institute of the McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada
| | - David Watkins
- Department of Human Genetics, McGill University and Research Institute of the McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada.
| | - Brian M Gilfix
- Division of Medical Biochemistry, Department of Specialized Medicine, McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada
| | - David S Rosenblatt
- Department of Human Genetics, McGill University and Research Institute of the McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada; Division of Medical Biochemistry, Department of Specialized Medicine, McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada; Division of Medical Genetics, Department of Specialized Medicine, McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada
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10
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Torices L, de las Heras J, Arango-Lasprilla JC, Cortés JM, Nunes-Xavier CE, Pulido R. MMADHC premature termination codons in the pathogenesis of cobalamin D disorder: Potential of translational readthrough reconstitution. Mol Genet Metab Rep 2021; 26:100710. [PMID: 33552904 PMCID: PMC7847965 DOI: 10.1016/j.ymgmr.2021.100710] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 12/31/2020] [Indexed: 11/21/2022] Open
Abstract
Mutations in the MMADHC gene cause cobalamin D disorder (cblD), an autosomal recessive inborn disease with defects in intracellular cobalamin (cbl, vitamin B12) metabolism. CblD patients present methylmalonic aciduria (MMA), homocystinuria (HC), or combined MMA/HC, and usually suffer developmental delay and cognitive deficits. The most frequent MMADHC genetic alterations associated with disease generate MMADHC truncated proteins, in many cases due to mutations that create premature termination codons (PTC). In this study, we have performed a comprehensive and global characterization of MMADHC protein variants generated by all annotated MMADHC PTC mutations in cblD patients, and analyzed the potential of inducible translational PTC readthrough to reconstitute MMADHC biosynthesis. MMADHC protein truncation caused by disease-associated PTC differentially affected the alternative usage of translation initiation sites, protein abundance, and subcellular localization of MMADHC. Aminoglycoside compounds induced translational PTC readthrough of MMADHC truncated variants, allowing the biosynthesis of full-length MMADHC in a PTC-specific manner. Our results suggest that translational PTC readthrough-based interventions could complement current therapies for cblD patients carrying specific MMADHC PTC mutations.
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Affiliation(s)
- Leire Torices
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
| | - Javier de las Heras
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
- Division of Pediatric Metabolism (CIBER-ER), Cruces University Hospital, Barakaldo, Spain
- Department of Pediatrics, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Juan Carlos Arango-Lasprilla
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
- Department of Cell Biology and Histology, University of the Basque Country (UPV/EHU), Leioa, Spain
- Ikerbasque, The Basque Foundation for Science, 48013 Bilbao, Spain
| | - Jesús M. Cortés
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
- Department of Cell Biology and Histology, University of the Basque Country (UPV/EHU), Leioa, Spain
- Ikerbasque, The Basque Foundation for Science, 48013 Bilbao, Spain
| | - Caroline E. Nunes-Xavier
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
- Institute of Cancer Research, Oslo University Hospital Radiumhospitalet, N-0424 Oslo, Norway
| | - Rafael Pulido
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
- Ikerbasque, The Basque Foundation for Science, 48013 Bilbao, Spain
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11
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Li Z, Mascarenhas R, Twahir UT, Kallon A, Deb A, Yaw M, Penner-Hahn J, Koutmos M, Warncke K, Banerjee R. An Interprotein Co-S Coordination Complex in the B 12-Trafficking Pathway. J Am Chem Soc 2020; 142:16334-16345. [PMID: 32871076 DOI: 10.1021/jacs.0c06590] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The CblC and CblD chaperones are involved in early steps in the cobalamin trafficking pathway. Cobalamin derivatives entering the cytoplasm are converted by CblC to a common cob(II)alamin intermediate via glutathione-dependent alkyltransferase or reductive elimination activities. Cob(II)alamin is subsequently converted to one of two biologically active alkylcobalamins by downstream chaperones. The function of CblD has been elusive although it is known to form a complex with CblC under certain conditions. Here, we report that CblD provides a sulfur ligand to cob(II)alamin bound to CblC, forming an interprotein coordination complex that rapidly oxidizes to thiolato-cob(III)alamin. Cysteine scanning mutagenesis and EPR spectroscopy identified Cys-261 on CblD as the sulfur donor. The unusual interprotein Co-S bond was characterized by X-ray absorption spectroscopy and visualized in the crystal structure of the human CblD thiolato-cob(III)alamin complex. Our study provides insights into how cobalamin coordination chemistry could be utilized for cofactor translocation in the trafficking pathway.
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Affiliation(s)
- Zhu Li
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
| | - Romila Mascarenhas
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
| | - Umar T Twahir
- Department of Physics, Emory University, Atlanta, Georgia 30322-2430, United States
| | - Albert Kallon
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
| | - Aniruddha Deb
- Departments of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Madeline Yaw
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
| | - James Penner-Hahn
- Departments of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Markos Koutmos
- Departments of Chemistry and Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Kurt Warncke
- Department of Physics, Emory University, Atlanta, Georgia 30322-2430, United States
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
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12
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Chern T, Achilleos A, Tong X, Hsu CW, Wong L, Poché RA. Mouse models to study the pathophysiology of combined methylmalonic acidemia and homocystinuria, cblC type. Dev Biol 2020; 468:1-13. [PMID: 32941884 DOI: 10.1016/j.ydbio.2020.09.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 02/06/2023]
Abstract
Combined methylmalonic acidemia and homocystinuria, cblC type, is the most common inherited disorder of cobalamin metabolism and is characterized by severe fetal developmental defects primarily impacting the central nervous system, hematopoietic system, and heart. CblC was previously shown to be due to mutations in the MMACHC gene, which encodes a protein thought to function in intracellular cobalamin trafficking and biosynthesis of adenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl). These coenzymes are required for the production of succinyl-CoA and methionine, respectively. However, it is currently unclear whether additional roles for MMACHC exist outside of cobalamin metabolism. Furthermore, due to a lack of sufficient animal models, the exact pathophysiology of cblC remains unknown. Here, we report the generation and characterization of two new mouse models to study the role of MMACHC in vivo. CRISPR/Cas9 genome editing was used to develop a Mmachc floxed allele (Mmachcflox/flox), which we validated as a conditional null. For a gain-of-function approach, we generated a transgenic mouse line that over-expresses functional Mmachc (Mmachc-OE+/tg) capable of rescuing Mmachc homozygous mutant lethality. Surprisingly, our data also suggest that these mice may exhibit a partially penetrant maternal-effect rescue, which might have implications for in utero therapeutic interventions to treat cblC. Both the Mmachcflox/flox and Mmachc-OE+/tg mouse models will be valuable resources for understanding the biological roles of MMACHC in a variety of tissue contexts and allow for deeper understanding of the pathophysiology of cblC.
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Affiliation(s)
- Tiffany Chern
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA; Graduate Program in Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Annita Achilleos
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Xuefei Tong
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Chih-Wei Hsu
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Leeyean Wong
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ross A Poché
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA; Graduate Program in Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA; Development, Disease Models and Therapeutics Graduate Program, Baylor College of Medicine, Houston, TX 77030, USA; Genetics and Genomics Graduate Program, Baylor College of Medicine, Houston, TX 77030, USA.
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13
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Binding analysis between monomeric β-casein and hydrophobic bioactive compounds investigated by surface plasmon resonance and fluorescence spectroscopy. Food Chem 2019; 286:289-296. [DOI: 10.1016/j.foodchem.2019.01.176] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 01/12/2019] [Accepted: 01/28/2019] [Indexed: 11/18/2022]
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14
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Hannibal L, Bolisetty K, Axhemi A, DiBello PM, Quadros EV, Fedosov S, Jacobsen DW. Transcellular transport of cobalamin in aortic endothelial cells. FASEB J 2018; 32:5506-5519. [PMID: 29741927 DOI: 10.1096/fj.201701141rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Cobalamin [Cbl (or B12)] deficiency causes megaloblastic anemia and a variety of neuropathies. However, homeostatic mechanisms of cyanocobalamin (CNCbl) and other Cbls by vascular endothelial cells are poorly understood. Herein, we describe our investigation into whether cultured bovine aortic endothelial cells (BAECs) perform transcytosis of B12, namely, the complex formed between serum transcobalamin and B12, designated as holo-transcobalamin (holo-TC). We show that cultured BAECs endocytose [57Co]-CNCbl-TC (source material) via the CD320 receptor. The bound Cbl is transported across the cell both via exocytosis in its free form, [57Co]-CNCbl, and via transcytosis as [57Co]-CNCbl-TC. Transcellular mobilization of Cbl occurred in a bidirectional manner. A portion of the endocytosed [57Co]-CNCbl was enzymatically processed by methylmalonic aciduria combined with homocystinuria type C (cblC) with subsequent formation of hydroxocobalamin, methylcobalamin, and adenosylcobalamin, which were also transported across the cell in a bidirectional manner. This demonstrates that transport mechanisms for Cbl in vascular endothelial cells do not discriminate between various β-axial ligands of the vitamin. Competition studies with apoprotein- and holo-TC and holo-intrinsic factor showed that only holo-TC was effective at inhibiting transcellular transport of Cbl. Incubation of BAECs with a blocking antibody against the extracellular domain of the CD320 receptor inhibited uptake and transcytosis by ∼40%. This study reveals that endothelial cells recycle uncommitted intracellular Cbl for downstream usage by other cell types and suggests that the endothelium is self-sufficient for the specific acquisition and subsequent distribution of circulating B12 via the CD320 receptor. We posit that the endothelial lining of the vasculature is an essential component for the maintenance of serum-tissue homeostasis of B12.-Hannibal, L., Bolisetty, K., Axhemi, A., DiBello, P. M., Quadros, E. V., Fedosov, S., Jacobsen, D. W. Transcellular transport of cobalamin in aortic endothelial cells.
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Affiliation(s)
- Luciana Hannibal
- Laboratory of Clinical Biochemistry and Metabolism, Department for Pediatrics, Medical Center, University of Freiburg, Freiburg, Germany.,Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Keerthana Bolisetty
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Armend Axhemi
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Patricia M DiBello
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Edward V Quadros
- Department of Medicine, State University of New York (SUNY) Downstate Medical Center, Brooklyn, New York, USA; and
| | - Sergey Fedosov
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Donald W Jacobsen
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
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15
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Richard E, Brasil S, Leal F, Navarrete R, Vega A, Ecay MJ, Desviat LR, Pérez-Cerda C, Ugarte M, Merinero B, Pérez B. Isolated and Combined Remethylation Disorders. JOURNAL OF INBORN ERRORS OF METABOLISM AND SCREENING 2017. [DOI: 10.1177/2326409816685732] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Eva Richard
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular-SO UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- IdiPAZ, Madrid, Spain
| | - Sandra Brasil
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular-SO UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- IdiPAZ, Madrid, Spain
| | - Fátima Leal
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular-SO UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- IdiPAZ, Madrid, Spain
| | - Rosa Navarrete
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular-SO UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- IdiPAZ, Madrid, Spain
| | - Ana Vega
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular-SO UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- IdiPAZ, Madrid, Spain
| | - María Jesús Ecay
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular-SO UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- IdiPAZ, Madrid, Spain
| | - Lourdes R. Desviat
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular-SO UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- IdiPAZ, Madrid, Spain
| | - Celia Pérez-Cerda
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular-SO UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- IdiPAZ, Madrid, Spain
| | - Magdalena Ugarte
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular-SO UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- IdiPAZ, Madrid, Spain
| | - Begoña Merinero
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular-SO UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- IdiPAZ, Madrid, Spain
| | - Belén Pérez
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular-SO UAM-CSIC, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
- IdiPAZ, Madrid, Spain
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Methionine synthase and methionine synthase reductase interact with MMACHC and with MMADHC. Biochim Biophys Acta Mol Basis Dis 2017; 1863:103-112. [DOI: 10.1016/j.bbadis.2016.10.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 10/01/2016] [Accepted: 10/18/2016] [Indexed: 01/02/2023]
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17
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Evidence of recent signatures of selection during domestication in an Atlantic salmon population. Mar Genomics 2016; 26:41-50. [DOI: 10.1016/j.margen.2015.12.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 11/25/2015] [Accepted: 12/16/2015] [Indexed: 11/17/2022]
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18
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Yamada K, Gherasim C, Banerjee R, Koutmos M. Structure of Human B12 Trafficking Protein CblD Reveals Molecular Mimicry and Identifies a New Subfamily of Nitro-FMN Reductases. J Biol Chem 2015; 290:29155-66. [PMID: 26364851 PMCID: PMC4705922 DOI: 10.1074/jbc.m115.682435] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Indexed: 01/07/2023] Open
Abstract
In mammals, B12 (or cobalamin) is an essential cofactor required by methionine synthase and methylmalonyl-CoA mutase. A complex intracellular pathway supports the assimilation of cobalamin into its active cofactor forms and delivery to its target enzymes. MMADHC (the methylmalonic aciduria and homocystinuria type D protein), commonly referred to as CblD, is a key chaperone involved in intracellular cobalamin trafficking, and mutations in CblD cause methylmalonic aciduria and/or homocystinuria. Herein, we report the first crystal structure of the globular C-terminal domain of human CblD, which is sufficient for its interaction with MMADHC (the methylmalonic aciduria and homocystinuria type C protein), or CblC, and for supporting the cytoplasmic cobalamin trafficking pathway. CblD contains an α+β fold that is structurally reminiscent of the nitro-FMN reductase superfamily. Two of the closest structural relatives of CblD are CblC, a multifunctional enzyme important for cobalamin trafficking, and the activation domain of methionine synthase. CblD, CblC, and the activation domain of methionine synthase share several distinguishing features and, together with two recently described corrinoid-dependent reductive dehalogenases, constitute a new subclass within the nitro-FMN reductase superfamily. We demonstrate that CblD enhances oxidation of cob(II)alamin bound to CblC and that disease-causing mutations in CblD impair the kinetics of this reaction. The striking structural similarity of CblD to CblC, believed to be contiguous in the cobalamin trafficking pathway, suggests the co-option of molecular mimicry as a strategy for achieving its function.
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Affiliation(s)
- Kazuhiro Yamada
- From the Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814 and
| | - Carmen Gherasim
- the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0600
| | - Ruma Banerjee
- the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0600, To whom correspondence may be addressed. Tel.: 734-615-5238; E-mail:
| | - Markos Koutmos
- From the Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814 and , To whom correspondence may be addressed. Tel.: 301-295-9419; E-mail:
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19
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Froese DS, Kopec J, Fitzpatrick F, Schuller M, McCorvie TJ, Chalk R, Plessl T, Fettelschoss V, Fowler B, Baumgartner MR, Yue WW. Structural Insights into the MMACHC-MMADHC Protein Complex Involved in Vitamin B12 Trafficking. J Biol Chem 2015; 290:29167-77. [PMID: 26483544 PMCID: PMC4705923 DOI: 10.1074/jbc.m115.683268] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Indexed: 11/06/2022] Open
Abstract
Conversion of vitamin B12 (cobalamin, Cbl) into the cofactor forms methyl-Cbl (MeCbl) and adenosyl-Cbl (AdoCbl) is required for the function of two crucial enzymes, mitochondrial methylmalonyl-CoA mutase and cytosolic methionine synthase, respectively. The intracellular proteins MMACHC and MMADHC play important roles in processing and targeting the Cbl cofactor to its destination enzymes, and recent evidence suggests that they may interact while performing these essential trafficking functions. To better understand the molecular basis of this interaction, we have mapped the crucial protein regions required, indicate that Cbl is likely processed by MMACHC prior to interaction with MMADHC, and identify patient mutations on both proteins that interfere with complex formation, via different mechanisms. We further report the crystal structure of the MMADHC C-terminal region at 2.2 Å resolution, revealing a modified nitroreductase fold with surprising homology to MMACHC despite their poor sequence conservation. Because MMADHC demonstrates no known enzymatic activity, we propose it as the first protein known to repurpose the nitroreductase fold solely for protein-protein interaction. Using small angle x-ray scattering, we reveal the MMACHC-MMADHC complex as a 1:1 heterodimer and provide a structural model of this interaction, where the interaction region overlaps with the MMACHC-Cbl binding site. Together, our findings provide novel structural evidence and mechanistic insight into an essential biological process, whereby an intracellular "trafficking chaperone" highly specific for a trace element cofactor functions via protein-protein interaction, which is disrupted by inherited disease mutations.
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Affiliation(s)
- D Sean Froese
- From the Division of Metabolism and Children's Research Center, University Children's, Hospital, CH-8032 Zurich, Switzerland, radiz - Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, CH-8032 Zurich, Switzerland
| | - Jolanta Kopec
- the Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7DQ, United Kingdom, and
| | - Fiona Fitzpatrick
- the Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7DQ, United Kingdom, and
| | - Marion Schuller
- the Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7DQ, United Kingdom, and
| | - Thomas J McCorvie
- the Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7DQ, United Kingdom, and
| | - Rod Chalk
- the Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7DQ, United Kingdom, and
| | - Tanja Plessl
- From the Division of Metabolism and Children's Research Center, University Children's, Hospital, CH-8032 Zurich, Switzerland
| | - Victoria Fettelschoss
- From the Division of Metabolism and Children's Research Center, University Children's, Hospital, CH-8032 Zurich, Switzerland
| | - Brian Fowler
- From the Division of Metabolism and Children's Research Center, University Children's, Hospital, CH-8032 Zurich, Switzerland
| | - Matthias R Baumgartner
- From the Division of Metabolism and Children's Research Center, University Children's, Hospital, CH-8032 Zurich, Switzerland, radiz - Rare Disease Initiative Zurich, Clinical Research Priority Program for Rare Diseases, University of Zurich, CH-8032 Zurich, Switzerland, the Zurich Center for Integrative Human Physiology, University of Zurich, 8057 Zurich, Switzerland
| | - Wyatt W Yue
- the Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7DQ, United Kingdom, and
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Deme JC, Hancock MA, Xia X, Shintre CA, Plesa M, Kim JC, Carpenter EP, Rosenblatt DS, Coulton JW. Purification and interaction analyses of two human lysosomal vitamin B12transporters: LMBD1 and ABCD4. Mol Membr Biol 2014; 31:250-61. [DOI: 10.3109/09687688.2014.990998] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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21
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Jusufi J, Suormala T, Burda P, Fowler B, Froese DS, Baumgartner MR. Characterization of functional domains of the cblD (MMADHC) gene product. J Inherit Metab Dis 2014; 37:841-9. [PMID: 24722857 DOI: 10.1007/s10545-014-9709-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 03/14/2014] [Accepted: 03/17/2014] [Indexed: 12/01/2022]
Abstract
In humans vitamin B12 (cobalamin, Cbl) must be converted into two coenzyme forms, methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl), in order to maintain intracellular homeostasis of homocysteine and methylmalonic acid, respectively. Previously we have shown that in cblD patients three types of MMADHC mutations exist: 1) null mutations N-terminal to Met116 cause isolated methylmalonic aciduria (cblD-MMA) due to AdoCbl deficiency; 2) null mutations across the C-terminus (p.Y140-R250) cause combined methylmalonic aciduria and homocystinuria (cblD-MMA/HC) due to AdoCbl and MeCbl deficiency; 3) missense mutations in a conserved C-terminal region (p.D246-L259) cause isolated homocystinuria (cblD-HC) due to MeCbl deficiency. To better understand the domain boundaries related to MeCbl formation, we made selected point mutations and C-terminal truncations in MMADHC and tested rescue of MeCbl and AdoCbl synthesis in immortalized cblD-MMA/HC patient fibroblasts. Testing 20 mutations (15 missense and five C-terminal truncations) across p.P154-S287 revealed the presence of a region (p.R197-D226) responsible for MeCbl synthesis, which gave a similar cellular phenotype as cblD-HC. Further, mutation of the polypeptide stretch between the new and patient defined regions (p.D226-D246) and directly C-terminal to the patient region (p.L259-R266), gave cellular phenotypes intermediate to those of cblD-HC and cblD-MMA/HC. Finally, C-terminal truncation of more than 20 amino acids resulted in a cblD-MMA/HC like cellular phenotype, while truncation of between ten and 20 amino acids resulted in a cblD-HC like cellular phenotype. These data suggest that specific regions of MMADHC are involved in differential regulation of AdoCbl and MeCbl synthesis and help better define the boundaries of these regions.
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Affiliation(s)
- Jehona Jusufi
- Division for Metabolic Disorders and Children's Research Center, University Children's Hospital, Steinweisstrasse 75, 8032, Zurich, Switzerland
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22
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Moreno-Garcia MA, Pupavac M, Rosenblatt DS, Tremblay ML, Jerome-Majewska LA. The Mmachc gene is required for pre-implantation embryogenesis in the mouse. Mol Genet Metab 2014; 112:198-204. [PMID: 24889031 DOI: 10.1016/j.ymgme.2014.05.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 05/06/2014] [Accepted: 05/06/2014] [Indexed: 02/06/2023]
Abstract
Patients with mutations in MMACHC have the autosomal recessive disease of cobalamin metabolism known as cblC. These patients are unable to convert cobalamin into the two active forms, methylcobalamin and adenosylcobalamin and consequently have elevated homocysteine and methylmalonic acid in blood and urine. In addition, some cblC patients have structural abnormalities, including congenital heart defects. MMACHC is conserved in the mouse and shows tissue and stage-specific expression pattern in midgestation stage embryos. To create a mouse model of cblC we generated a line of mice with a gene-trap insertion in intron 1 of the Mmachc gene, (Mmachc(Gt(AZ0348)Wtsi)). Heterozygous mice show a 50% reduction of MMACHC protein, and have significantly higher levels of homocysteine and methylmalonic acid in their blood. The Mmachc(Gt) allele was inherited with a transmission ratio distortion in matings with heterozygous animals. Furthermore, homozygous Mmachc(Gt) embryos were not found after embryonic day 3.5 and these embryos were unable to generate giant cells in outgrowth assays. Our findings confirm that cblC is modeled in mice with reduced levels of Mmachc and suggest an early requirement for Mmachc in mouse development.
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Affiliation(s)
- Maira A Moreno-Garcia
- Department of Human Genetics, McGill University, 1205 Avenue Docteur Penfield, N5/13, Montreal, Quebec H3A 1B1, Canada
| | - Mihaela Pupavac
- Department of Human Genetics, McGill University, 1205 Avenue Docteur Penfield, N5/13, Montreal, Quebec H3A 1B1, Canada
| | - David S Rosenblatt
- Department of Human Genetics, McGill University, 1205 Avenue Docteur Penfield, N5/13, Montreal, Quebec H3A 1B1, Canada; Department of Pediatrics, McGill University, Research Institute, Place Toulon, 4060 Ste. Catherine West PT 420, Montreal Children's Hospital, Montreal, Quebec H3Z 2Z3, Canada
| | - Michel L Tremblay
- Department of Biochemistry, McGill University, Goodman Cancer Research Center, 1160 Avenue Pine, Montreal, Quebec, Canada
| | - Loydie A Jerome-Majewska
- Department of Human Genetics, McGill University, 1205 Avenue Docteur Penfield, N5/13, Montreal, Quebec H3A 1B1, Canada; Department of Pediatrics, McGill University, Research Institute, Place Toulon, 4060 Ste. Catherine West PT 420, Montreal Children's Hospital, Montreal, Quebec H3Z 2Z3, Canada; Department of Anatomy and Cell Biology, McGill University, Strathcona Anatomy and Dentistry Building, 3640 University Street, Montreal, Quebec H3A2B2, Canada.
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Moreno-Garcia MA, Rosenblatt DS, Jerome-Majewska LA. Vitamin B(12) metabolism during pregnancy and in embryonic mouse models. Nutrients 2013; 5:3531-50. [PMID: 24025485 PMCID: PMC3798919 DOI: 10.3390/nu5093531] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 08/10/2013] [Accepted: 08/23/2013] [Indexed: 11/16/2022] Open
Abstract
Vitamin B(12) (cobalamin, Cbl) is required for cellular metabolism. It is an essential coenzyme in mammals for two reactions: the conversion of homocysteine to methionine by the enzyme methionine synthase and the conversion of methylmalonyl-CoA to succinyl-CoA by the enzyme methylmalonyl-CoA mutase. Symptoms of Cbl deficiency are hematological, neurological and cognitive, including megaloblastic anaemia, tingling and numbness of the extremities, gait abnormalities, visual disturbances, memory loss and dementia. During pregnancy Cbl is essential, presumably because of its role in DNA synthesis and methionine synthesis; however, there are conflicting studies regarding an association between early pregnancy loss and Cbl deficiency. We here review the literature about the requirement for Cbl during pregnancy, and summarized what is known of the expression pattern and function of genes required for Cbl metabolism in embryonic mouse models.
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Affiliation(s)
- Maira A. Moreno-Garcia
- Department of Human Genetics, McGill University, 1205 Avenue Docteur Penfield, N5/13,Montreal, Quebec, Canada H3A 1B1; E-Mails: (M.A.M.-G.); (D.S.R.)
| | - David S. Rosenblatt
- Department of Human Genetics, McGill University, 1205 Avenue Docteur Penfield, N5/13,Montreal, Quebec, Canada H3A 1B1; E-Mails: (M.A.M.-G.); (D.S.R.)
- Department of Pediatrics, McGill University, Montreal, Quebec, Canada H3H 1P3
| | - Loydie A. Jerome-Majewska
- Department of Human Genetics, McGill University, 1205 Avenue Docteur Penfield, N5/13,Montreal, Quebec, Canada H3A 1B1; E-Mails: (M.A.M.-G.); (D.S.R.)
- Department of Pediatrics, McGill University, Montreal, Quebec, Canada H3H 1P3
- McGill University Health Centre, 4060 Ste. Catherine West, PT 420, Montreal, Quebec, Canada H3Z 2Z3
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-514-412-4400 (ext. 23279); Fax: +1-514-412-4331
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24
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Fofou-Caillierez MB, Mrabet NT, Chéry C, Dreumont N, Flayac J, Pupavac M, Paoli J, Alberto JM, Coelho D, Camadro JM, Feillet F, Watkins D, Fowler B, Rosenblatt DS, Guéant JL. Interaction between methionine synthase isoforms and MMACHC: characterization in cblG-variant, cblG and cblC inherited causes of megaloblastic anaemia. Hum Mol Genet 2013; 22:4591-601. [DOI: 10.1093/hmg/ddt308] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Backe PH, Ytre-Arne M, Røhr AK, Brodtkorb E, Fowler B, Rootwelt H, Bjørås M, Mørkrid L. Novel Deletion Mutation Identified in a Patient with Late-Onset Combined Methylmalonic Acidemia and Homocystinuria, cblC Type. JIMD Rep 2013; 11:79-85. [PMID: 23580368 DOI: 10.1007/8904_2013_225] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Revised: 03/12/2013] [Accepted: 03/14/2013] [Indexed: 01/04/2023] Open
Abstract
Combined methylmalonic aciduria and homocystinuria, cblC type (MMACHC), is the most common inborn error of cellular vitamin B12 metabolism and is caused by mutations in the MMACHC gene. This metabolic disease results in impaired intracellular synthesis of adenosylcobalamin and methylcobalamin, coenzymes for the methylmalonyl-CoA mutase and methionine synthase enzymes, respectively. The inability to produce normal levels of these two coenzymes leads to increased concentrations of methylmalonic acid and homocysteine in plasma and urine, together with normal or decreased concentration of methionine in plasma. Here, we report a novel homozygous deletion mutation (NM_015506.2:c.392_394del) resulting in an in-frame deletion of amino acid Gln131 and late-onset disease in a 23-year-old male. The patient presented with sensory and motoric disabilities, urine and fecal incontinence, and light cognitive impairment. There was an excessive urinary excretion of methylmalonic acid and greatly elevated plasma homocysteine. The clinical symptoms and the laboratory abnormalities responded partly to treatment with hydroxycobalamin, folinic acid, methionine, and betaine. Studies on patient fibroblasts together with spectroscopic activity assays on recombinant MMACHC protein reveal that Gln131 is crucial in order to maintain enzyme activity. Furthermore, structural analyses show that Gln131 is one of only two residues making hydrogen bonds to the tail of cobalamin. Circular dichroism spectroscopy indicates that the 3D structure of the deletion mutant is folded but perturbed compared to the wild-type protein.
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Affiliation(s)
- Paul Hoff Backe
- Department of Microbiology, Oslo University Hospital and University of Oslo, 4950, 0424, Oslo, Nydalen, Norway,
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Gherasim C, Hannibal L, Rajagopalan D, Jacobsen DW, Banerjee R. The C-terminal domain of CblD interacts with CblC and influences intracellular cobalamin partitioning. Biochimie 2013; 95:1023-32. [PMID: 23415655 DOI: 10.1016/j.biochi.2013.02.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 02/01/2013] [Indexed: 11/15/2022]
Abstract
Mutations in cobalamin or B12 trafficking genes needed for cofactor assimilation and targeting lead to inborn errors of cobalamin metabolism. The gene corresponding to one of these loci, cblD, affects both the mitochondrial and cytoplasmic pathways for B12 processing. We have demonstrated that fibroblast cell lines from patients with mutations in CblD, can dealkylate exogenously supplied methylcobalamin (MeCbl), an activity catalyzed by the CblC protein, but show imbalanced intracellular partitioning of the cofactor into the MeCbl and 5'-deoxyadenosylcobalamin (AdoCbl) pools. These results confirm that CblD functions downstream of CblC in the cofactor assimilation pathway and that it plays an important role in controlling the traffic of the cofactor between the competing cytoplasmic and mitochondrial routes for MeCbl and AdoCbl synthesis, respectively. In this study, we report the interaction of CblC with four CblD protein variants with variable N-terminal start sites. We demonstrate that a complex between CblC and CblD can be isolated particularly under conditions that permit dealkylation of alkylcobalamin by CblC or in the presence of the corresponding dealkylated and oxidized product, hydroxocobalamin (HOCbl). A weak CblC·CblD complex is also seen in the presence of cyanocobalamin. Formation of the CblC·CblD complex is observed with all four CblD variants tested suggesting that the N-terminal 115 residues missing in the shortest variant are not essential for this interaction. Furthermore, limited proteolysis of the CblD variants indicates the presence of a stable C-terminal domain spanning residues ∼116-296. Our results are consistent with an adapter function for CblD, which in complex with CblC·HOCbl, or possibly the less oxidized CblC·cob(II)alamin, partitions the cofactor between AdoCbl and MeCbl assimilation pathways.
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Affiliation(s)
- Carmen Gherasim
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, MI 48109-0600, USA
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27
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Watkins D, Rosenblatt DS. Lessons in biology from patients with inborn errors of vitamin B12 metabolism. Biochimie 2013; 95:1019-22. [PMID: 23402785 DOI: 10.1016/j.biochi.2013.01.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 01/28/2013] [Indexed: 01/14/2023]
Abstract
BACKGROUND Since 1975 cells lines from patients with suspected inborn errors of vitamin B12 metabolism have been referred to our laboratory because of elevations of homocysteine, methylmalonic acid, or both. DESIGN Cultured fibroblasts from patients were subjected to a battery of tests: incorporation of labelled propionate and methyltetrahydrofolate into cellular macromolecules, to test the functional integrity of methylmalonyl-CoA mutase and methionine synthase, respectively; uptake of labelled cyanocobalamin and synthesis of adenosylcobalamin and methylcobalamin; and, where applicable, complementation analysis. RESULTS This approach has allowed for the discovery of novel steps in the cellular transport and metabolism of vitamin B12, including those involving cellular uptake, the efflux of vitamin B12 from lysosomes, and the synthesis of adenosylcobalamin and methylcobalamin. For all of these disorders, the responsible genes have been discovered. CONCLUSION The study of highly selected patients with suspected inborn errors of metabolism has consistently resulted in the discovery of previously unknown metabolic steps and has provided new lessons in biology.
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Affiliation(s)
- David Watkins
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
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28
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Mah W, Deme JC, Watkins D, Fung S, Janer A, Shoubridge EA, Rosenblatt DS, Coulton JW. Subcellular location of MMACHC and MMADHC, two human proteins central to intracellular vitamin B(12) metabolism. Mol Genet Metab 2013; 108:112-8. [PMID: 23270877 DOI: 10.1016/j.ymgme.2012.11.284] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 11/29/2012] [Accepted: 11/29/2012] [Indexed: 11/22/2022]
Abstract
MMACHC and MMADHC are the genes responsible for cblC and cblD defects of vitamin B(12) metabolism, respectively. Patients with cblC and cblD defects present with various combinations of methylmalonic aciduria (MMA) and homocystinuria (HC). Those with cblC mutations have both MMA and HC whereas cblD patients can present with one of three distinct biochemical phenotypes: isolated MMA, isolated HC, or combined MMA and HC. Based on the subcellular localization of these enzymatic pathways it is thought that MMACHC functions in the cytoplasm while MMADHC functions downstream of MMACHC in both the cytoplasm and the mitochondrion. In this study we determined the subcellular location of MMACHC and MMADHC by immunofluorescence and subcellular fractionation. We show that MMACHC is cytoplasmic while MMADHC is both mitochondrial and cytoplasmic, consistent with the proposal that MMADHC acts as a branch point for vitamin B(12) delivery to the cytoplasm and mitochondria. The factors that determine the distribution of MMADHC between the cytoplasm and mitochondria remain unknown. Functional complementation experiments showed that retroviral expression of the GFP tagged constructs rescued all biochemical defects in cblC and cblD fibroblasts except propionate incorporation in cblD-MMA cells, suggesting that the endogenous mutant protein interferes with the function of the transduced wild type construct.
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Affiliation(s)
- Wayne Mah
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
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29
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Noncompaction of the ventricular myocardium and hydrops fetalis in cobalamin C disease. JIMD Rep 2012; 10:33-8. [PMID: 23430797 DOI: 10.1007/8904_2012_197] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 10/17/2012] [Accepted: 10/30/2012] [Indexed: 01/11/2023] Open
Abstract
Cobalamin C disease (cblC), a form of combined methylmalonic acidemia and hyperhomocysteinemia caused by mutations in the MMACHC gene, may be the most common inborn error of intracellular cobalamin metabolism. The clinical manifestations of cblC disease are diverse and range from intrauterine growth retardation to adult onset neurological disease. The occurrence of structural heart defects appears to be increased in cblC patients and may be related to the function of the MMACHC enzyme during cardiac embryogenesis, a concept supported by the observation that Mmachc is expressed in the bulbis cordis of the developing mouse heart. Here we report an infant who presented with hydrops fetalis, ventricular dysfunction, and echocardiographic evidence of LVNC, a rare congenital cardiomyopathy. Metabolic evaluations, complementation studies, and mutation analysis confirmed the diagnosis of cblC disease. These findings highlight an intrauterine cardiac phenotype that can be displayed in cblC disease in association with nonimmune hydrops.
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30
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Deme JC, Miousse IR, Plesa M, Kim JC, Hancock MA, Mah W, Rosenblatt DS, Coulton JW. Structural features of recombinant MMADHC isoforms and their interactions with MMACHC, proteins of mammalian vitamin B12 metabolism. Mol Genet Metab 2012; 107:352-62. [PMID: 22832074 DOI: 10.1016/j.ymgme.2012.07.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 07/01/2012] [Indexed: 12/17/2022]
Abstract
The genes MMACHC and MMADHC encode critical proteins involved in the intracellular metabolism of cobalamin. Two clinical features, homocystinuria and methylmalonic aciduria, define inborn errors of these genes. Based on disease phenotypes, MMADHC acts at a branch point for cobalamin delivery, apparently exerting its function through interaction with MMACHC that demonstrates dealkylase and decyanase activities. Here we present biophysical analyses of MMADHC to identify structural features and to further characterize its interaction with MMACHC. Two recombinant tag-less isoforms of MMADHC (MMADHCΔ1-12 and MMADHCΔ1-61) were expressed and purified. Full length MMACHC and full length MMADHC were detected in whole cell lysates of human cells; by Western blotting, their molecular masses corresponded to purified recombinant proteins. By clear-native PAGE and by dynamic light scattering, recombinant MMADHCs were stable and monodisperse. Both species were monomeric, adopting extended conformations in solution. Circular dichroism and secondary structure predictions correlated with significant regions of disorder within the N-terminal domain of MMADHC. We found no evidence that MMADHC binds cobalamin. Phage panning against MMADHC predicted four binding regions on MMACHC, two of which overlap with predicted sites on MMACHC at which it may self-associate. Specific, concentration-dependent responses were observed for MMACHC binding to itself and to both MMADHC constructs. As estimated in the sub-micromolar range, the binding of MMACHC to itself was weaker compared to its interaction with either of the MMADHC isoforms. We propose that the function of MMADHC is exerted through its structured C-terminal domain via interactions with MMACHC.
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Affiliation(s)
- Justin C Deme
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
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31
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Froese DS, Krojer T, Wu X, Shrestha R, Kiyani W, von Delft F, Gravel RA, Oppermann U, Yue WW. Structure of MMACHC Reveals an Arginine-Rich Pocket and a Domain-Swapped Dimer for Its B12 Processing Function. Biochemistry 2012; 51:5083-90. [DOI: 10.1021/bi300150y] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | - Xuchu Wu
- Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Canada
| | | | | | | | - Roy A. Gravel
- Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, Canada
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32
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Carrillo-Carrasco N, Chandler RJ, Venditti CP. Combined methylmalonic acidemia and homocystinuria, cblC type. I. Clinical presentations, diagnosis and management. J Inherit Metab Dis 2012; 35:91-102. [PMID: 21748409 PMCID: PMC4219318 DOI: 10.1007/s10545-011-9364-y] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 05/27/2011] [Accepted: 06/09/2011] [Indexed: 11/25/2022]
Abstract
Combined methylmalonic acidemia and homocystinuria, cblC type, is an inborn error of intracellular cobalamin metabolism with a wide spectrum of clinical manifestations that is stated to be the most common inherited disorder of cobalamin metabolism. This metabolic disease is caused by mutations in the MMACHC gene and results in impaired intracellular synthesis of adenosylcobalamin and methylcobalamin, cofactors for the methylmalonyl-CoA mutase and methionine synthase enzymes. Elevated methylmalonic acid and homocysteine with decreased methionine production are the biochemical hallmarks of this disorder. Awareness of the diverse clinical presentations associated with cblC disease is necessary to provide a timely diagnosis, to guide management of affected individuals and to establish a framework for the future treatment of individuals detected through expanded newborn screening. This article reviews the biochemistry, clinical presentations, genotype-phenotype correlations, diagnosis and management of cblC disease.
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Affiliation(s)
- Nuria Carrillo-Carrasco
- Organic Acid Research Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Building 49, Room 4A18, Bethesda, MD 20892, USA
| | - Randy J. Chandler
- Organic Acid Research Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Building 49, Room 4A18, Bethesda, MD 20892, USA
- Institute for Biomedical Sciences, The George Washington University, Washington, DC, USA
| | - Charles P. Venditti
- Organic Acid Research Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Building 49, Room 4A18, Bethesda, MD 20892, USA
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33
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Investigation on the pH-dependent binding of vitamin B12 and lysozyme by fluorescence and absorbance. J Mol Struct 2012. [DOI: 10.1016/j.molstruc.2011.10.028] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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34
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Stucki M, Coelho D, Suormala T, Burda P, Fowler B, Baumgartner MR. Molecular mechanisms leading to three different phenotypes in the cblD defect of intracellular cobalamin metabolism. Hum Mol Genet 2011; 21:1410-8. [DOI: 10.1093/hmg/ddr579] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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35
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Pupavac M, Garcia MAM, Rosenblatt DS, Jerome-Majewska LA. Expression of Mmachc and Mmadhc during mouse organogenesis. Mol Genet Metab 2011; 103:401-5. [PMID: 21536470 DOI: 10.1016/j.ymgme.2011.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 04/12/2011] [Accepted: 04/12/2011] [Indexed: 01/14/2023]
Abstract
To examine whether Mmachc and Mmadhc, two genes involved in vitamin B(12) (cobalamin) metabolism, show tissue-specific expression during mouse embryogenesis, we determined their sites of expression at 11.5days post conception by in situ hybridization. There was ubiquitous expression of Mmadhc, but tissue and cell type-specific expression of Mmachc in the developing lung, heart, cardiovascular and nervous system. This suggests that during organogenesis Mmachc and Mmadhc may interact in only a subset of cells.
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Affiliation(s)
- Mihaela Pupavac
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada H3A 1B1
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36
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Glutathione increases the binding affinity of a bovine B₁₂ trafficking chaperone bCblC for vitamin B₁₂. Biochem Biophys Res Commun 2011; 412:360-5. [PMID: 21821010 DOI: 10.1016/j.bbrc.2011.07.103] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 07/22/2011] [Indexed: 11/20/2022]
Abstract
Intracellular B(12) metabolism involves a B(12) trafficking chaperone CblC that is well conserved in mammals including human. The protein CblC is known to bind cyanocobalamin (CNCbl, vitamin B(12)) inducing the base-off transition and convert it into an intermediate that can be used in enzyme cofactor synthesis. The binding affinity of human CblC for CNCbl was determined to be K(d)=≈6-16 μM, which is relatively low considering sub-micromolar B(12) concentrations (0.03-0.7 μM) in normal cells. In the current study, we discovered that the base-off transition of CNCbl upon binding to bCblC, a bovine homolog of human CblC, is facilitated in the presence of reduced form of glutathione (GSH). In addition, GSH dramatically increases the binding affinity for CNCbl lowering the K(d) from 27.1 ± 0.2-0.24 ± 0.09 μM. The effect of GSH is due to conformational change of bCblC upon binding with GSH, which was indicated by limited proteolysis and urea-induced equilibrium denaturation of the protein. The results of this study suggest that GSH positively modulates bCblC by increasing the binding affinity for CNCbl, which would enhance functional efficiency of the protein.
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