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Antony P, Baby B, Ali A, Vijayan R, Al Jasmi F. Interaction of Glutathione with MMACHC Arginine-Rich Pocket Variants Associated with Cobalamin C Disease: Insights from Molecular Modeling. Biomedicines 2023; 11:3217. [PMID: 38137438 PMCID: PMC10740964 DOI: 10.3390/biomedicines11123217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 11/20/2023] [Accepted: 11/28/2023] [Indexed: 12/24/2023] Open
Abstract
Methylmalonic aciduria and homocystinuria type C protein (MMACHC) is required by the body to metabolize cobalamin (Cbl). Due to its complex structure and cofactor forms, Cbl passes through an extensive series of absorptive and processing steps before being delivered to mitochondrial methyl malonyl-CoA mutase and cytosolic methionine synthase. Depending on the cofactor attached, MMACHC performs either flavin-dependent reductive decyanation or glutathione (GSH)-dependent dealkylation. The alkyl groups of Cbl have to be removed in the presence of GSH to produce intermediates that can later be converted into active cofactor forms. Pathogenic mutations in the GSH binding site, such as R161Q, R161G, R206P, R206W, and R206Q, have been reported to cause Cbl diseases. The impact of these variations on MMACHC's structure and how it affects GSH and Cbl binding at the molecular level is poorly understood. To better understand the molecular basis of this interaction, mutant structures involving the MMACHC-MeCbl-GSH complex were generated using in silico site-directed point mutations and explored using molecular dynamics (MD) simulations. The results revealed that mutations in the key arginine residues disrupt GSH binding by breaking the interactions and reducing the free energy of binding of GSH. Specifically, variations at position 206 appeared to produce weaker GSH binding. The lowered binding affinity for GSH in the variant structures could impact metabolic pathways involving Cbl and its trafficking.
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Affiliation(s)
- Priya Antony
- Department of Biology, College of Science, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
| | - Bincy Baby
- Department of Biology, College of Science, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
| | - Amanat Ali
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
| | - Ranjit Vijayan
- Department of Biology, College of Science, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
- The Big Data Analytics Center, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
- Zayed Center for Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
| | - Fatma Al Jasmi
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
- Department of Pediatrics, Tawam Hospital, Al Ain P.O. Box 15258, United Arab Emirates
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Differences in the Formation of Reactive Oxygen Species and Their Cytotoxicity between Thiols Combined with Aqua- and Cyanocobalamins. Int J Mol Sci 2022; 23:ijms231911032. [PMID: 36232333 PMCID: PMC9569724 DOI: 10.3390/ijms231911032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/09/2022] [Accepted: 09/15/2022] [Indexed: 11/23/2022] Open
Abstract
Cobalamin is an essential nutrient required for the normal functioning of cells. Its deficiency can lead to various pathological states. Hydroxocobalamin (HOCbl) and cyanocobalamin (CNCbl) are the forms of vitamin B12 that are most commonly used for supplementation. There is substantial evidence indicating that cobalamins can both suppress and promote oxidative stress; however, the mechanisms underlying these effects are poorly understood. Here, it was shown that the oxidation of thiols catalyzed by HOCbl and CNCbl is accompanied by reactive oxygen species (ROS) production and induces, under certain conditions, oxidative stress and cell death. The form of vitamin B12 and the structure of thiol play a decisive role in these processes. It was found that the mechanisms and kinetics of thiol oxidation catalyzed by HOCbl and CNCbl differ substantially. HOCbl increased the rate of oxidation of thiols to a greater extent than CNCbl, but quenched ROS in combination with certain thiols. Oxidation catalyzed by CNCbl was generally slower. Yet, the absence of ROS quenching resulted in their higher accumulation. The aforementioned results might explain a more pronounced cytotoxicity induced by combinations of thiols with CNCbl. On the whole, the data obtained provide a new insight into the redox processes in which cobalamins are involved. Our results might also be helpful in developing new approaches to the treatment of some cobalamin-responsive disorders in which oxidative stress is an important component.
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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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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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Kiessling E, Peters F, Ebner LJ, Merolla L, Samardzija M, Baumgartner MR, Grimm C, Froese DS. HIF1 and DROSHA are involved in MMACHC repression in hypoxia. Biochim Biophys Acta Gen Subj 2022; 1866:130175. [DOI: 10.1016/j.bbagen.2022.130175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 05/03/2022] [Accepted: 05/23/2022] [Indexed: 11/25/2022]
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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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7
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Affiliation(s)
- Bernhard Kräutler
- Institute of Organic Chemistry and Centre of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria.
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Xu B, Zhang L, Chen Q, Wang Y, Peng Y, Tang H. Case Report: A Case of Late-Onset Combined Methylmalonic Acidemia and Hyperhomocysteinemia Induced by a Vegetarian Diet. Front Pediatr 2022; 10:896177. [PMID: 35903162 PMCID: PMC9315243 DOI: 10.3389/fped.2022.896177] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 06/21/2022] [Indexed: 11/13/2022] Open
Abstract
Methylmalonic acidemia is a rare autosomal recessive metabolic disease. However, because of the atypical clinical symptoms, the type of late-onset methylmalonic academia is often misdiagnosed. Especially when the blood vitamin B12 and folic acid levels are normal, it is not easy to think of this disease. Herein we report a 9-year-old girl who developed normally on a relatively balanced diet before 7 years of age. However, she presented with fatigue and attention deficit when she followed a vegetarian diet. Laboratory examination showed moderate macrocytic anemia, high levels of homocysteine, high level of propionylcarnitine/acetylcarnitine, urinary methylmalonic acid and methyl citrate. Gene mutation analysis showed c.609G > A and c.80A > G compound heterozygous mutations in the MMACHC gene, supported late-onset combined methylmalonic academia with homocysteinemia. Then treatment performed with add meat to the diet, vitamin B12, folic acid betaine and L-carnitine supplement. One week later, the child's clinical symptoms and the laboratory examinations were significantly improved.
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Affiliation(s)
- Bei Xu
- Department of Pediatrics, Baoding No. 1 Central Hospital, Baoding, China
| | - Lihong Zhang
- Department of Pediatrics, Baoding No. 1 Central Hospital, Baoding, China
| | - Qiang Chen
- Department of Emergency, Baoding No. 1 Central Hospital, Baoding, China
| | - Yajuan Wang
- Department of Pediatrics, Baoding No. 1 Central Hospital, Baoding, China
| | - Yahong Peng
- Department of Pediatrics, Baoding No. 1 Central Hospital, Baoding, China
| | - Hui Tang
- Department of Pediatrics, Baoding No. 1 Central Hospital, Baoding, China
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9
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Peng C, Ren J, Li Y, Keqie Y, Zhou F, Zhang X, Zhu H, Hu T, Wang H, Chen X, Liu S. Preimplantation Genetic Testing for Rare Inherited Disease of MMA-CblC: an Unaffected Live Birth. Reprod Sci 2021; 28:3571-3578. [PMID: 34076870 DOI: 10.1007/s43032-021-00621-3] [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: 02/26/2021] [Accepted: 05/13/2021] [Indexed: 11/30/2022]
Abstract
Methylmalonic acidemia combined with homocysteinemia and cobalamin C type (MMA-CblC, MIM # 277400) is a rare inherited disease with cobalamin metabolic disorder, which are caused by deficiency in the MMACHC gene. A couple with a proband child carried with compound heterozygous mutations of MMACHC (c.609G>A and c.567 dup T, NM_015506) sought for assisted reproductive technology to avoid the transmission of pathogenic genetic variants and unnecessary induction of labor. Thus, in vitro fertilization (IVF), preimplantation genetic testing (PGT), and prenatal genetic diagnosis were applied to fulfill this clinical demand. In this study, seven embryos were biopsied and carried out whole-genome amplification using multiple annealing and looping-based amplification cycle (MALBAC) method. Sanger sequencing together with copy number variation (CNV) analysis and single-nucleotide polymorphism (SNP) haplotyping was conducted to detect the mutated alleles and chromosomal abnormalities simultaneously. Three embryos (E07, E06, and E02) were confirmed without CNVs and inherited mutations at MMACHC gene. Embryo E07 with the best embryo ranking of 5BB was selected preferentially to transfer which led to a successful pregnancy and an unaffected live birth. Prenatal genetic diagnosing with amniotic fluid cells, Sanger sequencing with cord blood cells, and neonate MMA screening further verified our successful application of PGT in preventing mutated allele transmission for this rare inherited disease.
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Affiliation(s)
- Cuiting Peng
- Center of Prenatal Diagnosis, Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, 17 South Renmin Road, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China
| | - Jun Ren
- Center of Prenatal Diagnosis, Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, 17 South Renmin Road, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China
| | - Yutong Li
- Center of Prenatal Diagnosis, Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, 17 South Renmin Road, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China
| | - Yuezhi Keqie
- Center of Prenatal Diagnosis, Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, 17 South Renmin Road, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China
| | - Fan Zhou
- Center of Prenatal Diagnosis, Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, 17 South Renmin Road, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China
| | - Xuemei Zhang
- Center of Prenatal Diagnosis, Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, 17 South Renmin Road, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China
| | - Hongmei Zhu
- Center of Prenatal Diagnosis, Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, 17 South Renmin Road, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China
| | - Ting Hu
- Center of Prenatal Diagnosis, Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, 17 South Renmin Road, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China
| | - He Wang
- Center of Prenatal Diagnosis, Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, 17 South Renmin Road, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China
| | - Xinlian Chen
- Center of Prenatal Diagnosis, Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, 17 South Renmin Road, Chengdu, China.
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China.
| | - Shanling Liu
- Center of Prenatal Diagnosis, Department of Obstetrics & Gynecology, West China Second University Hospital, Sichuan University, 17 South Renmin Road, Chengdu, China.
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University, Ministry of Education, Chengdu, China.
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Banerjee R, Gouda H, Pillay S. Redox-Linked Coordination Chemistry Directs Vitamin B 12 Trafficking. Acc Chem Res 2021; 54:2003-2013. [PMID: 33797888 DOI: 10.1021/acs.accounts.1c00083] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Metals are partners for an estimated one-third of the proteome and vary in complexity from mononuclear centers to organometallic cofactors. Vitamin B12 or cobalamin represents the epitome of this complexity and is the product of an assembly line comprising some 30 enzymes. Unable to biosynthesize cobalamin, mammals rely on dietary provision of this essential cofactor, which is needed by just two enzymes, one each in the cytoplasm (methionine synthase) and the mitochondrion (methylmalonyl-CoA mutase). Brilliant clinical genetics studies on patients with inborn errors of cobalamin metabolism spanning several decades had identified at least seven genetic loci in addition to the two encoding B12 enzymes. While cells are known to house a cadre of chaperones dedicated to metal trafficking pathways that contain metal reactivity and confer targeting specificity, the seemingly supernumerary chaperones in the B12 pathway had raised obvious questions as to the rationale for their existence.With the discovery of the genes underlying cobalamin disorders, our laboratory has been at the forefront of ascribing functions to B12 chaperones and elucidating the intricate redox-linked coordination chemistry and protein-linked cofactor conformational dynamics that orchestrate the processing and translocation of cargo along the trafficking pathway. These studies have uncovered novel chemistry that exploits the innate chemical versatility of alkylcobalamins, i.e., the ability to form and dismantle the cobalt-carbon bond using homolytic or heterolytic chemistry. In addition, they have revealed the practical utility of the dimethylbenzimidazole tail, an appendage unique to cobalamins and absent in the structural cousins, porphyrin, chlorin, and corphin, as an instrument for facilitating cofactor transfer between active sites.In this Account, we navigate the chemistry of the B12 trafficking pathway from its point of entry into cells, through lysosomes, and into the cytoplasm, where incoming cobalamin derivatives with a diversity of upper ligands are denuded by the β-ligand transferase activity of CblC to the common cob(II)alamin intermediate. The broad reaction and lax substrate specificity of CblC also enables conversion of cyanocobalamin (technically, vitamin B12, i.e., the form of the cofactor in one-a-day supplements), to cob(II)alamin. CblD then hitches up with CblC via a unique Co-sulfur bond to cob(II)alamin at a bifurcation point, leading to the cytoplasmic methylcobalamin or mitochondrial 5'-deoxyadenosylcobalamin branch. Mutations at loci upstream of the junction point typically affect both branches, leading to homocystinuria and methylmalonic aciduria, whereas mutations in downstream loci lead to one or the other disease. Elucidation of the biochemical penalties associated with individual mutations is providing molecular insights into the clinical data and, in some instances, identifying which cobalamin derivative(s) might be therapeutically beneficial.Our studies on B12 trafficking are revealing strategies for cofactor sequestration and mobilization from low- to high-affinity and low- to high-coordination-number sites, which in turn are regulated by protein dynamics that constructs ergonomic cofactor binding pockets. While these B12 lessons might be broadly relevant to other metal trafficking pathways, much remains to be learned. This Account concludes by identifying some of the major gaps and challenges that are needed to complete our understanding of B12 trafficking.
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Affiliation(s)
- Ruma Banerjee
- Department of Biological Chemistry, Michigan Medicine, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Harsha Gouda
- Department of Biological Chemistry, Michigan Medicine, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Shubhadra Pillay
- Department of Biological Chemistry, Michigan Medicine, University of Michigan, Ann Arbor, Michigan 48109, United States
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Wingert V, Mukherjee S, Esser AJ, Behringer S, Tanimowo S, Klenzendorf M, Derevenkov IA, Makarov SV, Jacobsen DW, Spiekerkoetter U, Hannibal L. Thiolatocobalamins repair the activity of pathogenic variants of the human cobalamin processing enzyme CblC. Biochimie 2020; 183:108-125. [PMID: 33190793 DOI: 10.1016/j.biochi.2020.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/08/2020] [Accepted: 10/19/2020] [Indexed: 01/08/2023]
Abstract
Thiolatocobalamins are a class of cobalamins comprised of naturally occurring and synthetic ligands. Glutathionylcobalamin (GSCbl) occurs naturally in mammalian cells, and also as an intermediate in the glutathione-dependent dealkylation of methylcobalamin (MeCbl) to form cob(I)alamin by pure recombinant CblC from C. elegans. Glutathione-driven deglutathionylation of GSCbl was demonstrated both in mammalian as well as in C. elegans CblC. Dethiolation is orders of magnitude faster than dealkylation of Co-C bonded cobalamins, which motivated us to investigate two synthetic thiolatocobalamins as substrates to repair the enzymatic activity of pathogenic CblC variants in humans. We report the synthesis and kinetic characterization of cysteaminylcobalamin (CyaCbl) and 2-mercaptopropionylglycinocobalamin (MpgCbl). Both CyaCbl and MpgCbl were obtained in high purity (90-95%) and yield (78-85%). UV-visible spectral properties agreed with those reported for other thiolatocobalamins with absorbance maxima observed at 372 nm and 532 nm. Both CyaCbl and MpgCbl bound to wild type human recombinant CblC inducing spectral blue-shifts characteristic of the respective base-on to base-off transitions. Addition of excess glutathione (GSH) resulted in rapid elimination of the β-ligand to give aquacobalamin (H2OCbl) as the reaction product under aerobic conditions. Further, CyaCbl and MpgCbl underwent spontaneous dethiolation thereby repairing the loss of activity of pathogenic variants of human CblC, namely R161G and R161Q. We posit that thiolatocobalamins could be exploited therapeutically for the treatment of inborn errors of metabolism that impair processing of dietary and supplemental cobalamin forms. While these disorders are targets for newborn screening in some countries, there is currently no effective treatment available to patients.
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Affiliation(s)
- Victoria Wingert
- Laboratory of Clinical Biochemistry and Metabolism, Department of General Pediatrics, Adolescent Medicine and Neonatology, Faculty of Medicine, Medical Center - University of Freiburg, 79106, Freiburg, Germany
| | - Srijan Mukherjee
- Laboratory of Clinical Biochemistry and Metabolism, Department of General Pediatrics, Adolescent Medicine and Neonatology, Faculty of Medicine, Medical Center - University of Freiburg, 79106, Freiburg, Germany
| | - Anna J Esser
- Laboratory of Clinical Biochemistry and Metabolism, Department of General Pediatrics, Adolescent Medicine and Neonatology, Faculty of Medicine, Medical Center - University of Freiburg, 79106, Freiburg, Germany
| | - Sidney Behringer
- Laboratory of Clinical Biochemistry and Metabolism, Department of General Pediatrics, Adolescent Medicine and Neonatology, Faculty of Medicine, Medical Center - University of Freiburg, 79106, Freiburg, Germany
| | - Segun Tanimowo
- Laboratory of Clinical Biochemistry and Metabolism, Department of General Pediatrics, Adolescent Medicine and Neonatology, Faculty of Medicine, Medical Center - University of Freiburg, 79106, Freiburg, Germany
| | - Melissa Klenzendorf
- Laboratory of Clinical Biochemistry and Metabolism, Department of General Pediatrics, Adolescent Medicine and Neonatology, Faculty of Medicine, Medical Center - University of Freiburg, 79106, Freiburg, Germany; Faculty of Biology, University of Freiburg Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Ilia A Derevenkov
- Department of Food Chemistry, Ivanovo State University of Chemistry and Technology, Ivanovo, Russian Federation
| | - Sergei V Makarov
- Department of Food Chemistry, Ivanovo State University of Chemistry and Technology, Ivanovo, Russian Federation
| | - Donald W Jacobsen
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, USA
| | - Ute Spiekerkoetter
- Department of General Pediatrics, Adolescent Medicine and Neonatology, Faculty of Medicine, Medical Center - University of Freiburg, 79106, Freiburg, Germany
| | - Luciana Hannibal
- Laboratory of Clinical Biochemistry and Metabolism, Department of General Pediatrics, Adolescent Medicine and Neonatology, Faculty of Medicine, Medical Center - University of Freiburg, 79106, Freiburg, Germany.
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Li Z, Greenhalgh ED, Twahir UT, Kallon A, Ruetz M, Warncke K, Brunold TC, Banerjee R. Chlorocob(II)alamin Formation Which Enhances the Thiol Oxidase Activity of the B 12-Trafficking Protein CblC. Inorg Chem 2020; 59:16065-16072. [PMID: 33074687 DOI: 10.1021/acs.inorgchem.0c02653] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
CblC is a chaperone that catalyzes removal of the β-axial ligand of cobalamin (or B12), generating cob(II)alamin in an early step in the cofactor trafficking pathway. Cob(II)alamin is subsequently partitioned to support cellular needs for the synthesis of active cobalamin cofactor derivatives. In addition to the β-ligand transferase activity, the Caenorhabdiitis elegans CblC (ceCblC) and clinical R161G/Q variants of the human protein exhibit robust thiol oxidase activity, converting glutathione to glutathione disulfide while concomitantly reducing O2 to H2O2. The chemical efficiency of the thiol oxidase side reaction during ceCblC-catalyzed dealkylation of alkylcobalamins is noteworthy in that it effectively scrubs ambient oxygen from the reaction mixture, leading to air stabilization of the highly reactive cob(I)alamin product. In this study, we report that the enhanced thiol oxidase activity of ceCblC requires the presence of KCl, which explains how the wasteful thiol oxidase activity is potentially curtailed inside cells where the chloride concentration is low. We have captured an unusual chlorocob(II)alamin intermediate that is formed in the presence of potassium chloride, a common component of the reaction buffer, and have characterized it by electron paramagnetic resonance, magnetic circular dichroism, and computational analyses. The ability to form a chlorocob(II)alamin intermediate could represent an evolutionary vestige in ceCblC, which is structurally related to bacterial B12-dependent reductive dehalogenases that have been proposed to form halogen cob(II)alamin intermediates in their catalytic cycle.
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Affiliation(s)
- Zhu Li
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
| | - Elizabeth D Greenhalgh
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, 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
| | - Markus Ruetz
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
| | - Kurt Warncke
- Department of Physics, Emory University, Atlanta, Georgia 30322-2430, United States
| | - Thomas C Brunold
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600, United States
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Chang KJ, Zhao Z, Shen HR, Bing Q, Li N, Guo X, Hu J. Adolescent/adult-onset homocysteine remethylation disorders characterized by gait disturbance with/without psychiatric symptoms and cognitive decline: a series of seven cases. Neurol Sci 2020; 42:1987-1993. [PMID: 33000330 DOI: 10.1007/s10072-020-04756-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 09/23/2020] [Indexed: 12/11/2022]
Abstract
Homocysteine remethylation disorders are rare inherited disorders caused by a deficient activity of the enzymes involved in the remethylation of homocysteine to methionine. The adolescent/adult-onset remethylation disorders are rarely reported. We analyzed the clinical and genetic characteristics of seven cases with adolescent/adult remethylation disorders, including 5 cases of the cobalamin C disease (cblC) and 2 cases of the methylenetetrahydrofolate reductase deficiency. The average onset age was 21.1 (range 14 to 40) years. All patients complained of gait disturbances. Other common symptoms included psychiatric symptoms (5/7) and cognitive decline (4/7). Acute encephalopathy, dysarthria, anorexia, vomiting, ketoacidosis, anemia, cataract, and hand tremor were also observed. The mean total homocysteine in serum when the patients were diagnosed was 94.6 (range 53.1-154.5) mol/L. Electrophysiological studies revealed neuropathy in the lower limbs (6/7). The brain MRI showed reversible altered signal from the dorsal portions of the cerebellar hemispheres (1/7), periventricular hyperintensity (2/7), and delayed/impaired myelination (2/7). The sural nerve biopsy performed in one case showed a modest loss of myelinated fibers. Five patients showed heterozygous mutations of the MMACHC gene, including c.482G>A (5/5), c.609G>A (2/5), and c.658-660delAAG (3/5). Two patients showed heterozygous mutations of the MTHFR gene, including c.698C>A (2/2), c.698C>G (1/2), and c.236+1G>A (1/2). The patients responded well to the treatments with significant improvements. Adolescent/adult-onset remethylation disorders are easily misdiagnosed. We recommend testing the serum homocysteine concentrations in young/adult patients with unexplained neuro-psychotic symptoms. Furthermore, individuals with significantly elevated serum homocysteine concentrations should be further tested by organic acid screening and genetic analysis.
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Affiliation(s)
- Kai-Jie Chang
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, No 139 Road Ziqiang, Shijiazhuang, 050051, People's Republic of China
| | - Zhe Zhao
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, No 139 Road Ziqiang, Shijiazhuang, 050051, People's Republic of China
| | - Hong-Rui Shen
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, No 139 Road Ziqiang, Shijiazhuang, 050051, People's Republic of China
| | - Qi Bing
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, No 139 Road Ziqiang, Shijiazhuang, 050051, People's Republic of China
| | - Nan Li
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, No 139 Road Ziqiang, Shijiazhuang, 050051, People's Republic of China
| | - Xuan Guo
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, No 139 Road Ziqiang, Shijiazhuang, 050051, People's Republic of China
| | - Jing Hu
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, No 139 Road Ziqiang, Shijiazhuang, 050051, People's Republic of China.
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14
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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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Sloan JL, Achilly NP, Arnold ML, Catlett JL, Blake T, Bishop K, Jones M, Harper U, English MA, Anderson S, Trivedi NS, Elkahloun A, Hoffmann V, Brooks BP, Sood R, Venditti CP. The vitamin B12 processing enzyme, mmachc, is essential for zebrafish survival, growth and retinal morphology. Hum Mol Genet 2020; 29:2109-2123. [PMID: 32186706 PMCID: PMC7399538 DOI: 10.1093/hmg/ddaa044] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/10/2020] [Accepted: 03/11/2020] [Indexed: 12/16/2022] Open
Abstract
Cobalamin C (cblC) deficiency, the most common inborn error of intracellular cobalamin metabolism, is caused by mutations in MMACHC, a gene responsible for the processing and intracellular trafficking of vitamin B12. This recessive disorder is characterized by a failure to metabolize cobalamin into adenosyl- and methylcobalamin, which results in the biochemical perturbations of methylmalonic acidemia, hyperhomocysteinemia and hypomethioninemia caused by the impaired activity of the downstream enzymes, methylmalonyl-CoA mutase and methionine synthase. Cobalamin C deficiency can be accompanied by a wide spectrum of clinical manifestations, including progressive blindness, and, in mice, manifests with very early embryonic lethality. Because zebrafish harbor a full complement of cobalamin metabolic enzymes, we used genome editing to study the loss of mmachc function and to develop the first viable animal model of cblC deficiency. mmachc mutants survived the embryonic period but perished in early juvenile life. The mutants displayed the metabolic and clinical features of cblC deficiency including methylmalonic acidemia, severe growth retardation and lethality. Morphologic and metabolic parameters improved when the mutants were raised in water supplemented with small molecules used to treat patients, including hydroxocobalamin, methylcobalamin, methionine and betaine. Furthermore, mmachc mutants bred to express rod and/or cone fluorescent reporters, manifested a retinopathy and thin optic nerves (ON). Expression analysis using whole eye mRNA revealed the dysregulation of genes involved in phototransduction and cholesterol metabolism. Zebrafish with mmachc deficiency recapitulate the several of the phenotypic and biochemical features of the human disorder, including ocular pathology, and show a response to established treatments.
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Affiliation(s)
- Jennifer L Sloan
- Organic Acid Research Section, Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, 20892 USA
| | - Nathan P Achilly
- Organic Acid Research Section, Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, 20892 USA
| | - Madeline L Arnold
- Organic Acid Research Section, Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, 20892 USA
| | - Jerrel L Catlett
- Organic Acid Research Section, Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, 20892 USA
| | - Trevor Blake
- Zebrafish Core Facility, Translational and Functional Genomics Branch, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Kevin Bishop
- Zebrafish Core Facility, Translational and Functional Genomics Branch, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Marypat Jones
- Genomics Core, Cancer Genetics and Comparative Genomics Branch, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Ursula Harper
- Genomics Core, Cancer Genetics and Comparative Genomics Branch, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Milton A English
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, Bethesda, MD, 20892 USA
| | - Stacie Anderson
- Flow Cytometry, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Niraj S Trivedi
- Social Behavioral Research Branch, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Abdel Elkahloun
- Microarray Core, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Victoria Hoffmann
- Diagnostic and Research Services Branch, Division of Veterinary Resources, Office of the Director, National Institutes of Health, Bethesda, MD, 20892 USA
| | - Brian P Brooks
- Office of the Clinical Director, National Eye Institute, Bethesda, MD, 20892 USA
| | - Raman Sood
- Zebrafish Core Facility, Translational and Functional Genomics Branch, National Human Genome Research Institute, Bethesda, MD, 20892 USA
| | - Charles P Venditti
- Organic Acid Research Section, Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, NIH, Bethesda, MD, 20892 USA
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16
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Mascarenhas R, Li Z, Gherasim C, Ruetz M, Banerjee R. The human B 12 trafficking protein CblC processes nitrocobalamin. J Biol Chem 2020; 295:9630-9640. [PMID: 32457044 DOI: 10.1074/jbc.ra120.014094] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/22/2020] [Indexed: 01/12/2023] Open
Abstract
In humans, cobalamin or vitamin B12 is delivered to two target enzymes via a complex intracellular trafficking pathway comprising transporters and chaperones. CblC (or MMACHC) is a processing chaperone that catalyzes an early step in this trafficking pathway. CblC removes the upper axial ligand of cobalamin derivatives, forming an intermediate in the pathway that is subsequently converted to the active cofactor derivatives. Mutations in the cblC gene lead to methylmalonic aciduria and homocystinuria. Here, we report that nitrosylcobalamin (NOCbl), which was developed as an antiproliferative reagent, and is purported to cause cell death by virtue of releasing nitric oxide, is highly unstable in air and is rapidly oxidized to nitrocobalamin (NO2Cbl). We demonstrate that CblC catalyzes the GSH-dependent denitration of NO2Cbl forming 5-coordinate cob(II)alamin, which had one of two fates. It could be oxidized to aquo-cob(III)alamin or enter a futile thiol oxidase cycle forming GSH disulfide. Arg-161 in the active site of CblC suppressed the NO2Cbl-dependent thiol oxidase activity, whereas the disease-associated R161G variant stabilized cob(II)alamin and promoted futile cycling. We also report that CblC exhibits nitrite reductase activity, converting cob(I)alamin and nitrite to NOCbl. Finally, the denitration activity of CblC supported cell proliferation in the presence of NO2Cbl, which can serve as a cobalamin source. The newly described nitrite reductase and denitration activities of CblC extend its catalytic versatility, adding to its known decyanation and dealkylation activities. In summary, upon exposure to air, NOCbl is rapidly converted to NO2Cbl, which is a substrate for the B12 trafficking enzyme CblC.
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Affiliation(s)
- Romila Mascarenhas
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan, USA
| | - Zhu Li
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan, USA
| | - Carmen Gherasim
- Department of Pathology, University of Michigan Medical Center, Ann Arbor, Michigan, USA
| | - Markus Ruetz
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan, USA
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan, USA
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17
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Huemer M, Baumgartner MR. The clinical presentation of cobalamin-related disorders: From acquired deficiencies to inborn errors of absorption and intracellular pathways. J Inherit Metab Dis 2019; 42:686-705. [PMID: 30761552 DOI: 10.1002/jimd.12012] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 09/25/2018] [Accepted: 09/27/2018] [Indexed: 12/11/2022]
Abstract
This review gives an overview of clinical characteristics, treatment and outcome of nutritional and acquired cobalamin (Cbl; synonym: vitamin B12) deficiencies, inborn errors of Cbl absorption and intracellular trafficking, as well as methylenetetrahydrofolate dehydrogenase (MTHFD1) and methylene tetrahydrofolate reductase (MTHFR) deficiencies, which impair Cbl-dependent remethylation. Acquired and inborn Cbl-related disorders and MTHFR deficiency cause multisystem, often severe disease. Failure to thrive, neurocognitive or psychiatric symptoms, eye disease, bone marrow alterations, microangiopathy and thromboembolic events are characteristic. The recently identified MTHFD1 defect additionally presents with severe immune deficiency. Deficient Cbl-dependent enzymes cause reduced methylation capacity and metabolite toxicity. Further net-effects of perturbed Cbl function or reduced Cbl supply causing oxidative stress, altered cytokine regulation or immune functions are discussed.
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Affiliation(s)
- Martina Huemer
- Division of Metabolism and Children's Research Center, University Children's Hospital Zürich, Zürich, Switzerland
- Department of Paediatrics, Landeskrankenhaus Bregenz, Bregenz, Austria
| | - Matthias R Baumgartner
- Division of Metabolism and Children's Research Center, University Children's Hospital Zürich, Zürich, Switzerland
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18
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Wang X, Yang Y, Li X, Li C, Wang C. Distinct clinical, neuroimaging and genetic profiles of late-onset cobalamin C defects (cb1C): a report of 16 Chinese cases. Orphanet J Rare Dis 2019; 14:109. [PMID: 31092259 PMCID: PMC6521494 DOI: 10.1186/s13023-019-1058-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Accepted: 04/08/2019] [Indexed: 02/08/2023] Open
Abstract
Objective The importance of late-onset cobalamin C (cblC) disorder is underestimated in adults. Improved awareness on its clinical and neuroimaging features helps timely diagnosis and appropriate treatment. Methods Totally 16 late-onset cblC cases were diagnosed based on clinical, biochemical findings and MMAHC gene mutation analysis. Clinical presentations, neuroimaging features and mutational spectrum were reviewed. Results The case series included 10 males and 6 females, with average age of 22 (range 13–40) years. All the 16 patients displayed bilateral pyramidal tract signs, and most of the cases (13) had cognitive impairment. Other symptoms included psychiatric symptoms (6), epilepsy (6), peripheral nerve damage (5), ocular symptoms (4) and lower-limb thrombosis (1). The neuroimaging findings were dominated by cerebral atrophy (11/16), followed by white matter lesions (4), cerebellar lesions/atrophy (2) and spinal cord lesions (1). There were also 2 patients with normal imaging. All the MMACHC mutations were compound heterozygous, of which the most and second frequent was c.482G > A (p.R161Q; 15/16 case; allele frequency: 46.88%) and c.609G > A(p.W203X; 6/16 case; allele frequency: 18.75%). In addition, patients carrying frameshift mutations (deletion/duplication) presented more frequently with psychiatric symptoms (57.1%) and optic nerve damages (42.9%) than those carrying point mutations (22.2 and 11.1%, respectively). In contrast, peripheral nerve (44.4%) and white matter lesions (33.3%) were more frequently identified in point mutation- carriers. However, the differences did not achieve statistical significance (all p > 0.05). Conclusion Compared to the early-onset form, late-onset cblC displayed some clinical, neuroimaging and mutational profiles, which warrants particular attention in adult neurologic practice. These findings not only broaden our insights into the genotypes and phenotypes of the disease, but highlight the importance of early diagnosis and initiation of appropriate treatments. Electronic supplementary material The online version of this article (10.1186/s13023-019-1058-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xianling Wang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, 45 Changchun Street, Xicheng District, Beijing, 100053, People's Republic of China
| | - Yanhui Yang
- Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Xuying Li
- Department of Neurobiology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Cunjiang Li
- Department of Neurology, Xuanwu Hospital, Capital Medical University, 45 Changchun Street, Xicheng District, Beijing, 100053, People's Republic of China.
| | - Chaodong Wang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, 45 Changchun Street, Xicheng District, Beijing, 100053, People's Republic of China.
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Jarman PJ, Noakes F, Fairbanks S, Smitten K, Griffiths IK, Saeed HK, Thomas JA, Smythe C. Exploring the Cytotoxicity, Uptake, Cellular Response, and Proteomics of Mono- and Dinuclear DNA Light-Switch Complexes. J Am Chem Soc 2018; 141:2925-2937. [DOI: 10.1021/jacs.8b09999] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Paul J. Jarman
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, U.K
| | - Felicity Noakes
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, U.K
- Department of Chemistry, University of Sheffield, Sheffield S10 2TN, U.K
| | - Simon Fairbanks
- Department of Chemistry, University of Sheffield, Sheffield S10 2TN, U.K
| | - Kirsty Smitten
- Department of Chemistry, University of Sheffield, Sheffield S10 2TN, U.K
| | | | - Hiwa K. Saeed
- Department of Chemistry, University of Sheffield, Sheffield S10 2TN, U.K
| | - Jim A. Thomas
- Department of Chemistry, University of Sheffield, Sheffield S10 2TN, U.K
| | - Carl Smythe
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, U.K
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20
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Altered Redox Homeostasis in Branched-Chain Amino Acid Disorders, Organic Acidurias, and Homocystinuria. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:1246069. [PMID: 29743968 PMCID: PMC5884027 DOI: 10.1155/2018/1246069] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 12/26/2017] [Accepted: 01/16/2018] [Indexed: 02/06/2023]
Abstract
Inborn errors of metabolism (IEMs) are a group of monogenic disorders characterized by dysregulation of the metabolic networks that underlie development and homeostasis. Emerging evidence points to oxidative stress and mitochondrial dysfunction as major contributors to the multiorgan alterations observed in several IEMs. The accumulation of toxic metabolites in organic acidurias, respiratory chain, and fatty acid oxidation disorders inhibits mitochondrial enzymes and processes resulting in elevated levels of reactive oxygen species (ROS). In other IEMs, as in homocystinuria, different sources of ROS have been proposed. In patients' samples, as well as in cellular and animal models, several studies have identified significant increases in ROS levels along with decreases in antioxidant defences, correlating with oxidative damage to proteins, lipids, and DNA. Elevated ROS disturb redox-signaling pathways regulating biological processes such as cell growth, differentiation, or cell death; however, there are few studies investigating these processes in IEMs. In this review, we describe the published data on mitochondrial dysfunction, oxidative stress, and impaired redox signaling in branched-chain amino acid disorders, other organic acidurias, and homocystinuria, along with recent studies exploring the efficiency of antioxidants and mitochondria-targeted therapies as therapeutic compounds in these diseases.
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21
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Almannai M, Marom R, Divin K, Scaglia F, Sutton VR, Craigen WJ, Lee B, Burrage LC, Graham BH. Milder clinical and biochemical phenotypes associated with the c.482G>A (p.Arg161Gln) pathogenic variant in cobalamin C disease: Implications for management and screening. Mol Genet Metab 2017; 122:60-66. [PMID: 28693988 PMCID: PMC5612879 DOI: 10.1016/j.ymgme.2017.06.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 06/24/2017] [Accepted: 06/25/2017] [Indexed: 02/08/2023]
Abstract
INTRODUCTION Cobalamin C disease is a multisystemic disease with variable manifestations and age of onset. Genotype-phenotype correlations are well-recognized in this disorder. Here, we present a large cohort of individuals with cobalamin C disease, several of whom are heterozygous for the c.482G>A pathogenic variant (p.Arg161Gln). We compared clinical characteristics of individuals with this pathogenic variant to those who do not have this variant. To our knowledge, this study represents the largest single cohort of individuals with the c.482G>A (p.Arg161Gln) pathogenic variant. METHODS A retrospective chart review of 27 individuals from 21 families with cobalamin C disease who are followed at our facility was conducted. RESULTS 13 individuals (48%) are compound heterozygous with the c.482G>A (p.Arg161Gln) on one allele and a second pathogenic variant on the other allele. Individuals with the c.482G>A (p.Arg161Gln) pathogenic variant had later onset of symptoms and easier metabolic control. Moreover, they had milder biochemical abnormalities at presentation which likely contributed to the observation that 4 individuals (31%) in this group were missed by newborn screening. CONCLUSION The c.482G>A (p.Arg161Gln) pathogenic variant is associated with milder disease. These individuals may not receive a timely diagnosis as they may not be identified on newborn screening or because of unrecognized, late onset symptoms. Despite the milder presentation, significant complications can occur, especially if treatment is delayed.
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Affiliation(s)
- Mohammed Almannai
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Department of Molecular and Human Genetics, Texas Children's Hospital, Houston, TX, USA
| | - Ronit Marom
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Department of Molecular and Human Genetics, Texas Children's Hospital, Houston, TX, USA
| | - Kristian Divin
- Department of Molecular and Human Genetics, Texas Children's Hospital, Houston, TX, USA
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Department of Molecular and Human Genetics, Texas Children's Hospital, Houston, TX, USA
| | - V Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Department of Molecular and Human Genetics, Texas Children's Hospital, Houston, TX, USA
| | - William J Craigen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Department of Molecular and Human Genetics, Texas Children's Hospital, Houston, TX, USA
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Department of Molecular and Human Genetics, Texas Children's Hospital, Houston, TX, USA
| | - Lindsay C Burrage
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Department of Molecular and Human Genetics, Texas Children's Hospital, Houston, TX, USA.
| | - Brett H Graham
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Department of Molecular and Human Genetics, Texas Children's Hospital, Houston, TX, USA.
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22
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Pitsawong W, Haynes CA, Koder RL, Rodgers DW, Miller AF. Mechanism-Informed Refinement Reveals Altered Substrate-Binding Mode for Catalytically Competent Nitroreductase. Structure 2017; 25:978-987.e4. [PMID: 28578873 DOI: 10.1016/j.str.2017.05.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 04/02/2017] [Accepted: 05/05/2017] [Indexed: 01/25/2023]
Abstract
Nitroreductase (NR) from Enterobacter cloacae reduces diverse nitroaromatics including herbicides, explosives, and prodrugs, and holds promise for bioremediation, prodrug activation, and enzyme-assisted synthesis. We solved crystal structures of NR complexes with bound substrate or analog for each of its two half-reactions. We complemented these with kinetic isotope effect (KIE) measurements elucidating H-transfer steps essential to each half-reaction. KIEs indicate hydride transfer from NADH to the flavin consistent with our structure of NR with the NADH analog nicotinic acid adenine dinucleotide (NAAD). The KIE on reduction of p-nitrobenzoic acid (p-NBA) also indicates hydride transfer, and requires revision of prior computational mechanisms. Our mechanistic information provided a structural restraint for the orientation of bound substrate, placing the nitro group closer to the flavin N5 in the pocket that binds the amide of NADH. KIEs show that solvent provides a proton, enabling accommodation of different nitro group placements, consistent with the broad repertoire of NR.
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Affiliation(s)
- Warintra Pitsawong
- Department of Chemistry, University of Kentucky, 505 Rose Street, Lexington, KY 40506-0055, USA
| | - Chad A Haynes
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, 741 South Limestone Street, Lexington, KY 40536-0509, USA
| | - Ronald L Koder
- Department of Chemistry, University of Kentucky, 505 Rose Street, Lexington, KY 40506-0055, USA
| | - David W Rodgers
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, 741 South Limestone Street, Lexington, KY 40536-0509, USA.
| | - Anne-Frances Miller
- Department of Chemistry, University of Kentucky, 505 Rose Street, Lexington, KY 40506-0055, USA; Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, 741 South Limestone Street, Lexington, KY 40536-0509, USA.
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23
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Ruetz M, Shanmuganathan A, Gherasim C, Karasik A, Salchner R, Kieninger C, Wurst K, Banerjee R, Koutmos M, Kräutler B. Inhibierung des humanen B12-verarbeitenden Enzyms CblC durch Antivitamine B12- Kristallstruktur des inaktiven ternären Komplexes mit dem Kosubstrat Glutathion. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201701583] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Markus Ruetz
- Institut für Organische Chemie und Zentrum für Molekulare, Biowissenschaften; Universität Innsbruck; 6020 Innsbruck Österreich
- University of Michigan Medical School; Ann Arbor MI 48109-0600 USA
| | | | - Carmen Gherasim
- University of Michigan Medical School; Ann Arbor MI 48109-0600 USA
- Department of Pathology; University of Utah School of Medicine; Salt Lake City UT USA
| | - Agnes Karasik
- Department of Biochemistry; Uniformed Services University of the Health Sciences; Bethesda MD 28104 USA
| | - Robert Salchner
- Institut für Organische Chemie und Zentrum für Molekulare, Biowissenschaften; Universität Innsbruck; 6020 Innsbruck Österreich
- Watercryst GmbH & Co; Kematen Österreich
| | - Christoph Kieninger
- Institut für Organische Chemie und Zentrum für Molekulare, Biowissenschaften; Universität Innsbruck; 6020 Innsbruck Österreich
| | - Klaus Wurst
- Institut für Allgemeine, Anorganische Chemie und Theoretische Chemie; Universität Innsbruck; Österreich
| | - Ruma Banerjee
- University of Michigan Medical School; Ann Arbor MI 48109-0600 USA
| | - Markos Koutmos
- Department of Biochemistry; Uniformed Services University of the Health Sciences; Bethesda MD 28104 USA
| | - Bernhard Kräutler
- Institut für Organische Chemie und Zentrum für Molekulare, Biowissenschaften; Universität Innsbruck; 6020 Innsbruck Österreich
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24
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Ruetz M, Shanmuganathan A, Gherasim C, Karasik A, Salchner R, Kieninger C, Wurst K, Banerjee R, Koutmos M, Kräutler B. Antivitamin B 12 Inhibition of the Human B 12 -Processing Enzyme CblC: Crystal Structure of an Inactive Ternary Complex with Glutathione as the Cosubstrate. Angew Chem Int Ed Engl 2017; 56:7387-7392. [PMID: 28544088 DOI: 10.1002/anie.201701583] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Indexed: 02/06/2023]
Abstract
B12 antivitamins are important and robust tools for investigating the biological roles of vitamin B12 . Here, the potential antivitamin B12 2,4-difluorophenylethynylcobalamin (F2PhEtyCbl) was prepared, and its 3D structure was studied in solution and in the crystal. Chemically inert F2PhEtyCbl resisted thermolysis of its Co-C bond at 100 °C, was stable in bright daylight, and also remained intact upon prolonged storage in aqueous solution at room temperature. It binds to the human B12 -processing enzyme CblC with high affinity (KD =130 nm) in the presence of the cosubstrate glutathione (GSH). F2PhEtyCbl withstood tailoring by CblC, and it also stabilized the ternary complex with GSH. The crystal structure of this inactivated assembly provides first insight into the binding interactions between an antivitamin B12 and CblC, as well as into the organization of GSH and a base-off cobalamin in the active site of this enzyme.
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Affiliation(s)
- Markus Ruetz
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria.,University of Michigan Medical School, Ann Arbor, USA
| | | | - Carmen Gherasim
- University of Michigan Medical School, Ann Arbor, USA.,Current address: Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Agnes Karasik
- Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, USA
| | - Robert Salchner
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria.,Current address: Watercryst GmbH & Co, Kematen, Austria
| | - Christoph Kieninger
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
| | - Klaus Wurst
- Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Austria
| | - Ruma Banerjee
- University of Michigan Medical School, Ann Arbor, USA
| | - Markos Koutmos
- Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, USA
| | - Bernhard Kräutler
- Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria
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25
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Li Z, Shanmuganathan A, Ruetz M, Yamada K, Lesniak NA, Kräutler B, Brunold TC, Koutmos M, Banerjee R. Coordination chemistry controls the thiol oxidase activity of the B 12-trafficking protein CblC. J Biol Chem 2017; 292:9733-9744. [PMID: 28442570 DOI: 10.1074/jbc.m117.788554] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 04/20/2017] [Indexed: 01/20/2023] Open
Abstract
The cobalamin or B12 cofactor supports sulfur and one-carbon metabolism and the catabolism of odd-chain fatty acids, branched-chain amino acids, and cholesterol. CblC is a B12-processing enzyme involved in an early cytoplasmic step in the cofactor-trafficking pathway. It catalyzes the glutathione (GSH)-dependent dealkylation of alkylcobalamins and the reductive decyanation of cyanocobalamin. CblC from Caenorhabditis elegans (ceCblC) also exhibits a robust thiol oxidase activity, converting reduced GSH to oxidized GSSG with concomitant scrubbing of ambient dissolved O2 The mechanism of thiol oxidation catalyzed by ceCblC is not known. In this study, we demonstrate that novel coordination chemistry accessible to ceCblC-bound cobalamin supports its thiol oxidase activity via a glutathionyl-cobalamin intermediate. Deglutathionylation of glutathionyl-cobalamin by a second molecule of GSH yields GSSG. The crystal structure of ceCblC provides insights into how architectural differences at the α- and β-faces of cobalamin promote the thiol oxidase activity of ceCblC but mute it in wild-type human CblC. The R161G and R161Q mutations in human CblC unmask its latent thiol oxidase activity and are correlated with increased cellular oxidative stress disease. In summary, we have uncovered key architectural features in the cobalamin-binding pocket that support unusual cob(II)alamin coordination chemistry and enable the thiol oxidase activity of ceCblC.
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Affiliation(s)
- Zhu Li
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600
| | - Aranganathan Shanmuganathan
- the Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814
| | - Markus Ruetz
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600
| | - Kazuhiro Yamada
- the Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814
| | - Nicholas A Lesniak
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600
| | - Bernhard Kräutler
- the Institute of Organic Chemistry and Centre of Molecular Biosciences, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria, and
| | - Thomas C Brunold
- the Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Markos Koutmos
- the Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814
| | - Ruma Banerjee
- From the Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0600,
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26
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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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