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Zhou Y, He A, Xu B. Natural resources, quantification, microbial bioconversion, and bioactivities of vitamin B 12 for vegetarian diet. Food Chem 2024; 463:140849. [PMID: 39270609 DOI: 10.1016/j.foodchem.2024.140849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 08/07/2024] [Accepted: 08/10/2024] [Indexed: 09/15/2024]
Abstract
Vitamin B12 is a water-soluble vitamin with a complex chemical structure. It can participate in the synthesis and repair of DNA in the human body and plays an important role in regulating the nervous system. The deficiency of vitamin B12 will lead to megaloblastic anemia and neuropathy. Traditionally, animal foods have been the main dietary source of vitamin B12. However, this review points to certain plant sources (such as algae, mushrooms, fermented vegetables, and fermented beans) as viable vitamin B12 supplements for vegetarians. These sources validate our initial hypothesis that a plant-based diet can adequately provide essential nutrients previously thought to be available only through animal products. In terms of quantification, since the content of vitamin B12 in food samples is low and is easily interfered by impurities, highly sensitive and specific analytical methods are used for the quantification of vitamin B12. The findings from this review could be instrumental in developing fortified plant-based foods that could prevent B12 deficiency in vegetarians and vegans, thereby broadening the scope of nutritional options available to those on plant-based diets.
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Affiliation(s)
- Yixiao Zhou
- Food Science and Technology Program, Department of Life Sciences, BNU-HKBU United International College, Zhuhai, Guangdong 519087, China
| | - Aien He
- Food Science and Technology Program, Department of Life Sciences, BNU-HKBU United International College, Zhuhai, Guangdong 519087, China.; Department of Food Science and Technology, National University of Singapore, 119077, Singapore
| | - Baojun Xu
- Food Science and Technology Program, Department of Life Sciences, BNU-HKBU United International College, Zhuhai, Guangdong 519087, China..
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2
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Ruetz M, Mascarenhas R, Widner F, Kieninger C, Koutmos M, Kräutler B, Banerjee R. A Noble Metal Substitution Leads to B 12 Cofactor Mimicry by a Rhodibalamin. Biochemistry 2024; 63:1955-1962. [PMID: 39012171 DOI: 10.1021/acs.biochem.4c00216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/17/2024]
Abstract
In mammals, cobalamin is an essential cofactor that is delivered by a multitude of chaperones in an elaborate trafficking pathway to two client enzymes, methionine synthase and methylmalonyl-CoA mutase (MMUT). Rhodibalamins, the rhodium analogs of cobalamins, have been described as antimetabolites due to their ability to inhibit bacterial growth. In this study, we have examined the reactivity of adenosylrhodibalamin (AdoRhbl) with two key human chaperones, MMACHC (also known as CblC) and adenosyltransferase (MMAB, also known as ATR), and with the human and Mycobacterium tuberculosis MMUT. We demonstrate that while AdoRhbl binds tightly to all four proteins, the Rh-carbon bond is resistant to homolytic (on MMAB and MMUT) as well as heterolytic (on MMACHC) rupture. On the other hand, MMAB catalyzes Rh-carbon bond formation, converting rhodi(I)balamin in the presence of ATP to AdoRhbl. We report the first crystal structure of a rhodibalamin (AdoRhbl) bound to a B12 protein, i.e., MMAB, in the presence of triphosphate, which shows a weakened but intact Rh-carbon bond. The structure provides insights into how MMAB cleaves the corresponding Co-carbon bond in a sacrificial homolytic reaction that purportedly functions as a cofactor sequestration strategy. Collectively, the study demonstrates that while the noble metal substitution of cobalt by rhodium sets up structural mimicry, it compromises chemistry, which could be exploited for targeting human and bacterial B12 chaperones and enzymes.
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3
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Zhao W, Yang H, Cui H, Li W, Xing S, Han W. Elucidating the structural basis of vitamin B 12 derivatives as novel potent inhibitors of PTP1B: Insights from inhibitory mechanisms using Gaussian accelerated molecular dynamics (GaMD) and in vitro study. Int J Biol Macromol 2024; 268:131902. [PMID: 38692532 DOI: 10.1016/j.ijbiomac.2024.131902] [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: 11/01/2023] [Revised: 04/19/2024] [Accepted: 04/24/2024] [Indexed: 05/03/2024]
Abstract
Vitamin B12 is a group of biologically active cobalamin compounds. In this study, we investigated the inhibitory effects of methylcobalamin (MeCbl) and hydroxocobalamin acetate (OHCbl Acetate) on protein tyrosine phosphatase 1B (PTP1B). MeCbl and OHCbl Acetate exhibited an IC50 of approximately 58.390 ± 2.811 μM and 8.998 ± 0.587 μM, respectively. The Ki values of MeCbl and OHCbl Acetate were 25.01 μM and 4.04 μM respectively. To elucidate the inhibition mechanism, we conducted a 500 ns Gaussian accelerated molecular dynamics (GaMD) simulation. Utilizing PCA and tICA, we constructed Markov state models (MSM) to examine secondary structure changes during motion. Our findings revealed that the α-helix at residues 37-42 remained the most stable in the PTP1B-OHCbl Acetate system. Furthermore, upon binding of OHCbl Acetate or MeCbl, the WPD loop of PTP1B moved inward to the active pocket, forming a closed conformation and potentially obstructs substrate entry. Protein-ligand interaction analysis and MM-PBSA showed that OHCbl Acetate exhibited lower binding free energy and engaged in more residue interactions with PTP1B. In summary, our study confirmed the substantial inhibitory activity of OHCbl Acetate against PTP1B, with its inhibitory potency notably surpassing that of MeCbl. We demonstrated potential molecular mechanisms of OHCbl Acetate inhibiting PTP1B.
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Affiliation(s)
- Wencheng Zhao
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, Edmond H. Fischer Signal Transduction Laboratory, School of Life Sciences, Jilin University, 2699 Qianjin Street, Changchun 130012, China
| | - Hengzheng Yang
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, Edmond H. Fischer Signal Transduction Laboratory, School of Life Sciences, Jilin University, 2699 Qianjin Street, Changchun 130012, China
| | - Huizi Cui
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, Edmond H. Fischer Signal Transduction Laboratory, School of Life Sciences, Jilin University, 2699 Qianjin Street, Changchun 130012, China
| | - Wannan Li
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, Edmond H. Fischer Signal Transduction Laboratory, School of Life Sciences, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
| | - Shu Xing
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, Edmond H. Fischer Signal Transduction Laboratory, School of Life Sciences, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
| | - Weiwei Han
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, Edmond H. Fischer Signal Transduction Laboratory, School of Life Sciences, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
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4
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Stackpole BJ, Fredericksen JM, Brasch NE. Exploring the potential of the vitamin B 12 derivative azidocobalamin to undergo Huisgen 1,3-dipolar azide-alkyne cycloaddition reactions. J Inorg Biochem 2024; 254:112504. [PMID: 38412777 DOI: 10.1016/j.jinorgbio.2024.112504] [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: 12/20/2023] [Revised: 02/08/2024] [Accepted: 02/09/2024] [Indexed: 02/29/2024]
Abstract
There is considerable interest in using the metalloprotein cofactor vitamin B12 as a vehicle to deliver drugs and diagnostic agents into mammalian or bacterial cells by exploiting the B12-specific active uptake pathways. Conjugation of the cargo via the β-axial site or the 5'-OH of the ribose of the nucleotide are the most desirable sites, to maximise intracellular uptake. Herein we show the potential of conjugation at the beta-azido ligand of the vitamin B12 derivative azidocobalamin via a click-type azide-alkyne 1,3-dipolar cycloaddition (Huisgen cycloaddition) reaction. Reacting azidocobalamin with dimethyl acetylenedicarboxylate at 40 °C results in essentially stoichiometric conversion of azidocobalamin to the corresponding triazolato complex. The stability of the complex as a function of pH and in the presence of cyanide were investigated. The complex is stable in pD 7.0 phosphate buffer for 24 h. The rate of beta-axial ligand substitution was found to be one order of magnitude slower for the triazolatocobalamin complex compared with azidocobalamin.
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Affiliation(s)
- Ben J Stackpole
- School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand; The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand; The Maurice Wilkins Centre for Molecular Biodiscovery, Private Bag 92019, Auckland 1142, New Zealand
| | - Jessica M Fredericksen
- School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand; The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand; The Maurice Wilkins Centre for Molecular Biodiscovery, Private Bag 92019, Auckland 1142, New Zealand
| | - Nicola E Brasch
- School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand; The Dodd-Walls Centre for Quantum and Photonic Technologies, Dunedin 9054, New Zealand; The Maurice Wilkins Centre for Molecular Biodiscovery, Private Bag 92019, Auckland 1142, New Zealand.
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5
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Chung T, McClain TP, Alonso-Mori R, Chollet M, Deb A, Garcia-Esparza AT, Huang Ze En J, Lamb RM, Michocki LB, Reinhard M, van Driel TB, Penner-Hahn JE, Sension RJ. Ultrafast X-ray Absorption Spectroscopy Reveals Excited-State Dynamics of B 12 Coenzymes Controlled by the Axial Base. J Phys Chem B 2024; 128:1428-1437. [PMID: 38301132 DOI: 10.1021/acs.jpcb.3c07779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
Polarized time-resolved X-ray absorption spectroscopy at the Co K-edge is used to probe the excited-state dynamics and photolysis of base-off methylcobalamin and the excited-state structure of base-off adenosylcobalamin. For both molecules, the final excited-state minimum shows evidence for an expansion of the cavity around the Co ion by ca. 0.04 to 0.05 Å. The 5-coordinate base-off cob(II)alamin that is formed following photodissociation has a structure similar to that of the 5-coordinate base-on cob(II)alamin, with a ring expansion of 0.03 to 0.04 Å and a contraction of the lower axial bond length relative to that in the 6-coordinate ground state. These data provide insights into the role of the lower axial ligand in modulating the reactivity of B12 coenzymes.
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Affiliation(s)
- Taewon Chung
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Taylor P McClain
- Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Roberto Alonso-Mori
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Matthieu Chollet
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Aniruddha Deb
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Angel T Garcia-Esparza
- Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025-7015, United States
| | - Joel Huang Ze En
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Ryan M Lamb
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Lindsay B Michocki
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
| | - Marco Reinhard
- Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025-7015, United States
| | - Tim B van Driel
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - James E Penner-Hahn
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
- Biophysics, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 48109-1055, United States
| | - Roseanne J Sension
- Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, Michigan 481091055, United States
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109-1040, United States
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6
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Sayer AP, Llavero-Pasquina M, Geisler K, Holzer A, Bunbury F, Mendoza-Ochoa GI, Lawrence AD, Warren MJ, Mehrshahi P, Smith AG. Conserved cobalamin acquisition protein 1 is essential for vitamin B12 uptake in both Chlamydomonas and Phaeodactylum. PLANT PHYSIOLOGY 2024; 194:698-714. [PMID: 37864825 PMCID: PMC10828217 DOI: 10.1093/plphys/kiad564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 08/01/2023] [Accepted: 08/18/2023] [Indexed: 10/23/2023]
Abstract
Microalgae play an essential role in global net primary productivity and global biogeochemical cycling. Despite their phototrophic lifestyle, over half of algal species depend for growth on acquiring an external supply of the corrinoid vitamin B12 (cobalamin), a micronutrient produced only by a subset of prokaryotic organisms. Previous studies have identified protein components involved in vitamin B12 uptake in bacterial species and humans. However, little is known about its uptake in algae. Here, we demonstrate the essential role of a protein, cobalamin acquisition protein 1 (CBA1), in B12 uptake in Phaeodactylum tricornutum using CRISPR-Cas9 to generate targeted knockouts and in Chlamydomonas reinhardtii by insertional mutagenesis. In both cases, CBA1 knockout lines could not take up exogenous vitamin B12. Complementation of the C. reinhardtii mutants with the wild-type CBA1 gene restored B12 uptake, and regulation of CBA1 expression via a riboswitch element enabled control of the phenotype. When visualized by confocal microscopy, a YFP-fusion with C. reinhardtii CBA1 showed association with membranes. Bioinformatics analysis found that CBA1-like sequences are present in all major eukaryotic phyla. In algal taxa, the majority that encoded CBA1 also had genes for B12-dependent enzymes, suggesting CBA1 plays a conserved role. Our results thus provide insight into the molecular basis of algal B12 acquisition, a process that likely underpins many interactions in aquatic microbial communities.
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Affiliation(s)
- Andrew P Sayer
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Marcel Llavero-Pasquina
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Katrin Geisler
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Andre Holzer
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Freddy Bunbury
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Gonzalo I Mendoza-Ochoa
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Andrew D Lawrence
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Martin J Warren
- School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UA, UK
| | - Payam Mehrshahi
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Alison G Smith
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
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7
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Fedosov SN, Nexo E, Heegaard CW. Kinetics of Cellular Cobalamin Uptake and Conversion: Comparison of Aquo/Hydroxocobalamin to Cyanocobalamin. Nutrients 2024; 16:378. [PMID: 38337663 PMCID: PMC10857013 DOI: 10.3390/nu16030378] [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: 12/22/2023] [Revised: 01/21/2024] [Accepted: 01/25/2024] [Indexed: 02/12/2024] Open
Abstract
Cyanocobalamin (CNCbl) and aquo/hydroxocobalamin (HOCbl) are the forms of vitamin B12 that are most commonly used for supplementation. They are both converted to methylcobalamin (MeCbl) and 5'-deoxyadenosylcobalamin (AdoCbl), which metabolize homocysteine and methylmalonic acid, respectively. Here, we compare the kinetics of uptake and the intracellular transformations of radiolabeled CNCbl vs. HOCbl in HeLa cells. More HOCbl was accumulated over 4-48 h, but further extrapolation indicated similar uptake (>90%) for both vitamin forms. The initially synthesized coenzyme was MeCbl, which noticeably exceeded AdoCbl during 48 h. Yet, the synthesis of AdoCbl accelerated, and the predicted final levels of Cbls were MeCbl ≈ AdoCbl ≈ 40% and HOCbl ≈ 20%. The designed kinetic model revealed the same patterns of the uptake and turnover for CNCbl and HOCbl, apart from two steps. First, the "activating" intracellular processing of the internalized HOCbl was six-fold faster. Second, the detachment rates from the cell surface (when the "excessive" Cbl-molecules were refluxed into the external medium) related as 4:1 for CNCbl vs. HOCbl. This gave a two-fold faster cellular accumulation and processing of HOCbl vs. CNCbl. In medical terms, our data suggest (i) an earlier response to the treatment of Cbl-deficiency with HOCbl, and (ii) the manifestation of a successful treatment initially as a decrease in homocysteine.
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Affiliation(s)
- Sergey N. Fedosov
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark;
- Department of Clinical Medicine/Clinical Biochemistry, Aarhus University Hospital, 8200 Aarhus N, Denmark;
| | - Ebba Nexo
- Department of Clinical Medicine/Clinical Biochemistry, Aarhus University Hospital, 8200 Aarhus N, Denmark;
| | - Christian W. Heegaard
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark;
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8
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Marciesky M, Aga DS, Bradley IM, Aich N, Ng C. Mechanisms and Opportunities for Rational In Silico Design of Enzymes to Degrade Per- and Polyfluoroalkyl Substances (PFAS). J Chem Inf Model 2023; 63:7299-7319. [PMID: 37981739 PMCID: PMC10716909 DOI: 10.1021/acs.jcim.3c01303] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/17/2023] [Accepted: 10/18/2023] [Indexed: 11/21/2023]
Abstract
Per and polyfluoroalkyl substances (PFAS) present a unique challenge to remediation techniques because their strong carbon-fluorine bonds make them difficult to degrade. This review explores the use of in silico enzymatic design as a potential PFAS degradation technique. The scope of the enzymes included is based on currently known PFAS degradation techniques, including chemical redox systems that have been studied for perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) defluorination, such as those that incorporate hydrated electrons, sulfate, peroxide, and metal catalysts. Bioremediation techniques are also discussed, namely the laccase and horseradish peroxidase systems. The redox potential of known reactants and enzymatic radicals/metal-complexes are then considered and compared to potential enzymes for degrading PFAS. The molecular structure and reaction cycle of prospective enzymes are explored. Current knowledge and techniques of enzyme design, particularly radical-generating enzymes, and application are also discussed. Finally, potential routes for bioengineering enzymes to enable or enhance PFAS remediation are considered as well as the future outlook for computational exploration of enzymatic in situ bioremediation routes for these highly persistent and globally distributed contaminants.
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Affiliation(s)
- Melissa Marciesky
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, United States
| | - Diana S Aga
- Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260, United States
| | - Ian M Bradley
- Department of Civil, Structural, and Environmental Engineering, State University of New York at Buffalo, Buffalo, New York 14228, United States
- Research and Education in Energy, Environmental and Water (RENEW) Institute, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Nirupam Aich
- Department of Civil and Environmental Engineering, University of Nebraska─Lincoln, Lincoln, Nebraska 68588-0531, United States
| | - Carla Ng
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, United States
- Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
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9
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Okeke ES, Nweze EJ, Ezike TC, Nwuche CO, Ezeorba TPC, Nwankwo CEI. Silicon-based nanoparticles for mitigating the effect of potentially toxic elements and plant stress in agroecosystems: A sustainable pathway towards food security. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 898:165446. [PMID: 37459984 DOI: 10.1016/j.scitotenv.2023.165446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 07/08/2023] [Accepted: 07/08/2023] [Indexed: 07/23/2023]
Abstract
Due to their size, flexibility, biocompatibility, large surface area, and variable functionality nanoparticles have enormous industrial, agricultural, pharmaceutical and biotechnological applications. This has led to their widespread use in various fields. The advancement of knowledge in this field of research has altered our way of life from medicine to agriculture. One of the rungs of this revolution, which has somewhat reduced the harmful consequences, is nanotechnology. A helpful ingredient for plants, silicon (Si), is well-known for its preventive properties under adverse environmental conditions. Several studies have shown how biogenic silica helps plants recover from biotic and abiotic stressors. The majority of research have demonstrated the benefits of silicon-based nanoparticles (Si-NPs) for plant growth and development, particularly under stressful environments. In order to minimize the release of brine, heavy metals, and radioactive chemicals into water, remove metals, non-metals, and radioactive components, and purify water, silica has also been used in environmental remediation. Potentially toxic elements (PTEs) have become a huge threat to food security through their negative impact on agroecosystem. Si-NPs have the potentials to remove PTEs from agroecosystem and promote food security via the promotion of plant growth and development. In this review, we have outlined the various sources and ecotoxicological consequences of PTEs in agroecosystems. The potentials of Si-NPs in mitigating PTEs were extensively discussed and other applications of Si-NPs in agriculture to foster food security were also highlighted.
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Affiliation(s)
- Emmanuel Sunday Okeke
- Institute of Environmental Health and Ecological Security, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, PR China; Natural Science Unit, School of General Studies, University of Nigeria, Nsukka, Enugu State 410001, Nigeria; Department of Biochemistry, Faculty of Biological Science University of Nigeria, Nsukka, Enugu State 410001, Nigeria
| | - Ekene John Nweze
- Department of Biochemistry, Faculty of Biological Science University of Nigeria, Nsukka, Enugu State 410001, Nigeria
| | - Tobechukwu Christian Ezike
- Department of Biochemistry, Faculty of Biological Science University of Nigeria, Nsukka, Enugu State 410001, Nigeria
| | - Charles Ogugua Nwuche
- Department of Microbiology, Faculty of Biological Science University of Nigeria, Nsukka, Enugu State 410001, Nigeria
| | - Timothy Prince Chidike Ezeorba
- Department of Biochemistry, Faculty of Biological Science University of Nigeria, Nsukka, Enugu State 410001, Nigeria; Department of Genetics and Biotechnology, Faculty of Biological Sciences, University of Nigeria, Nsukka 410001, Enugu State, Nigeria; Department of Environmental Health and Risk Management, College of Life and Environmental Sciences, University of Birmingham, B15 2TT Edgbaston, United Kingdom.
| | - Chidiebele Emmanuel Ikechukwu Nwankwo
- Natural Science Unit, School of General Studies, University of Nigeria, Nsukka, Enugu State 410001, Nigeria; Department of Microbiology, Faculty of Biological Science University of Nigeria, Nsukka, Enugu State 410001, Nigeria; Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China.
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10
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Mascarenhas R, Guha A, Li Z, Ruetz M, An S, Seravalli J, Banerjee R. Cobalt-Sulfur Coordination Chemistry Drives B 12 Loading onto Methionine Synthase. J Am Chem Soc 2023:10.1021/jacs.3c07941. [PMID: 37916782 PMCID: PMC11063128 DOI: 10.1021/jacs.3c07941] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
Cobalt-sulfur (Co-S) coordination is labile to both oxidation and reduction chemistry and is rarely seen in nature. Cobalamin (or vitamin B12) is an essential cobalt-containing organometallic cofactor in mammals and is escorted via an intricate network of chaperones to a single cytoplasmic target, methionine synthase. In this study, we report that the human cobalamin trafficking protein, MMADHC, exploits the chemical lability of Co-S coordination for cofactor off-loading onto methionine synthase. Cys-261 on MMADHC serves as the β-axial ligand to cobalamin. Complex formation between MMADHC and methionine synthase is signaled by loss of the lower axial nitrogen ligand, leading to five-coordinate thiolato-cobalamin. Nucleophilic displacement by the vicinal thiolate, Cys-262, completes cofactor transfer to methionine synthase and release of a cysteine disulfide-containing MMADHC. The physiological relevance of this mechanism is supported by clinical variants of MMADHC, which impair cofactor binding and off-loading, explaining the molecular basis of the associated homocystinuria.
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Affiliation(s)
- Romila Mascarenhas
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Arkajit Guha
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Zhu Li
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Markus Ruetz
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Sojin An
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Javier Seravalli
- Department of Biological Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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11
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Watson WP, Munter T, Golding BT. The effect of vitamin B 12 on DNA adduction by styrene oxide, a genotoxic xenobiotic. Chem Biol Interact 2023; 382:110591. [PMID: 37302460 DOI: 10.1016/j.cbi.2023.110591] [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: 04/13/2023] [Revised: 05/25/2023] [Accepted: 05/31/2023] [Indexed: 06/13/2023]
Abstract
Vitamin B12 (cyano- or hydroxo-cobalamin) acts, via its coenzymes, methyl- and adenosyl-cobalamin, as a partner for enzymatic reactions in humans catalysed by methionine synthase and methylmalonyl-CoA mutase. As well as its association with pernicious anaemia, human B12 deficiency may also be a risk factor for neurological illnesses, heart disease and cancer. In the present work the effect of vitamin B12 (hydroxocobalamin) on the formation of DNA adducts by the epoxide phenyloxirane (styrene oxide), a genotoxic metabolite of phenylethene (styrene), has been studied using an in vitro model system. Styrene was converted to its major metabolite styrene oxide as a mixture of enantiomers using a microsomal fraction from the livers of Sprague-Dawley rats with concomitant inhibition of epoxide hydrolase. However, microsomal oxidation of styrene in the presence of vitamin B12 gave diastereoisomeric 2-hydroxy-2-phenylcobalamins. The quantitative formation of styrene oxide-DNA adducts was investigated using 2-deoxyguanosine or calf thymus DNA in the presence or absence of vitamin B12. Microsomal incubations containing either deoxyguanosine or DNA in the absence of vitamin B12 gave 2-amino-7-(2-hydroxy-1-phenylethyl)-1,7-dihydro-6H-purin-6-one [N7-(2-hydroxy-1-phenylethyl)-guanine], and 2-amino-7-(2-hydroxy-2-phenylethyl)-1,7-dihydro-6H-purin-6-one [N7-(2-hydroxy-2-phenylethyl)guanine] as the principal adducts. With deoxyguanosine the level of formation of guanine adducts was ca. 150 adducts/106 unmodified nucleoside. With DNA the adduct level was 36 pmol/mg DNA (ca. 1 adduct/0.83 × 105 nucleotides). Styrene oxide adducts from deoxyguanosine or DNA were not detected in microsomal incubations of styrene in the presence of vitamin B12. These results suggest that vitamin B12 could protect DNA against genotoxicity due to styrene oxide and other xenobiotic metabolites. However, this potential defence mechanism requires that the 2-hydroxyalkylcobalamins derived from epoxides are not 'anti-vitamins' and ideally liberate, and therefore, recycle vitamin B12. Otherwise, depletion of vitamin B12 leading to human deficiency could increase the risk of carcinogenesis initiated by genotoxic epoxides.
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Affiliation(s)
- William P Watson
- Syngenta Central Toxicology Laboratory, Alderley Park, Cheshire, SK10 4TJ, UK
| | - Tony Munter
- Syngenta Central Toxicology Laboratory, Alderley Park, Cheshire, SK10 4TJ, UK
| | - Bernard T Golding
- School of Natural and Environmental Sciences - Chemistry, Bedson Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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12
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Gouda H, Li Z, Ruetz M, Banerjee R. Coordination Chemistry Controls Coenzyme B 12 Synthesis by Human Adenosine Triphosphate:Cob(I)alamin Adenosyltransferase. Inorg Chem 2023; 62:12630-12633. [PMID: 37526260 PMCID: PMC10507449 DOI: 10.1021/acs.inorgchem.3c02163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
Cobalamin (or vitamin B12)-dependent enzymes and trafficking chaperones exploit redox-linked coordination chemistry to control the cofactor reactivity during catalysis and translocation. As the cobalt oxidation state decreases from 3+ to 1+, the preferred cobalamin geometry changes from six- to four-coordinate (4-c). In this study, we reveal the sizable thermodynamic gain that accrues for human adenosine triphosphate (ATP):cob(I)alamin adenosyltransferase (or MMAB) by enforcing an unfavorable 4-c cob(II)alamin geometry. MMAB-bound cob(II)alamin is reduced to the supernucleophilic cob(I)alamin intermediate during the synthesis of 5'-deoxyadenosylcobalamin. Herein, we report the first experimentally determined reduction potential for 4-c cob(II)alamin (-325 ± 9 mV), which is 180 mV more positive than for the five-coordinate (5-c) water-liganded species. The redox potential of MMAB-bound cob(II)alamin is within the range of adrenodoxin, which we demonstrate functions as an electron donor. We also show that stabilization of 5-c cob(II)alamin by a subset of MMAB patient variants compromises the reduction by adrenodoxin, explaining the underlying pathogenic mechanism.
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Affiliation(s)
- Harsha Gouda
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109 USA
| | - Zhu Li
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109 USA
| | - Markus Ruetz
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109 USA
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109 USA
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13
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Banerjee R. The structural basis of protein conformational switching revealed by experimental and AlphaFold2 analyses. Proc Natl Acad Sci U S A 2023; 120:e2309689120. [PMID: 37440570 PMCID: PMC10372629 DOI: 10.1073/pnas.2309689120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/15/2023] Open
Affiliation(s)
- Ruma Banerjee
- Department of Biological Chemistry, University of Michigan School of Medicine, Ann Arbor, MI48109
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14
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Mascarenhas R, Guha A, Li Z, Ruetz M, An S, Seravalli J, Banerjee R. Cobalt-sulfur coordination chemistry drives B 12 loading onto methionine synthase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.25.550549. [PMID: 37546824 PMCID: PMC10402061 DOI: 10.1101/2023.07.25.550549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Cobalt-sulfur (Co-S) coordination is labile to both oxidation and reduction chemistry and is rarely seen in Nature. Cobalamin (or vitamin B 12 ) is an essential cobalt-containing organometallic cofactor in mammals, and is escorted via an intricate network of chaperones to a single cytoplasmic target, methionine synthase. In this study, we report that the human cobalamin trafficking protein, MMADHC, exploits the chemical lability of Co-S coordination, for cofactor off-loading onto methionine synthase. Cys-261 on MMADHC serves as the β-axial ligand to cobalamin. Complex formation between MMADHC and methionine synthase is signaled by loss of the lower axial nitrogen ligand, leading to five-coordinate thiolato-cobalamin. Nucleophilic displacement by the vicinal thiolate, Cys-262, completes cofactor transfer to methionine synthase and release of a cysteine disulfide-containing MMADHC. The physiological relevance of this mechanism is supported by clinical variants of MMADHC, which impair cofactor binding and off-loading, explaining the molecular basis of the associated homocystinuria.
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15
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Mascarenhas R, Ruetz M, Gouda H, Heitman N, Yaw M, Banerjee R. Architecture of the human G-protein-methylmalonyl-CoA mutase nanoassembly for B 12 delivery and repair. Nat Commun 2023; 14:4332. [PMID: 37468522 PMCID: PMC10356863 DOI: 10.1038/s41467-023-40077-4] [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: 04/22/2023] [Accepted: 07/05/2023] [Indexed: 07/21/2023] Open
Abstract
G-proteins function as molecular switches to power cofactor translocation and confer fidelity in metal trafficking. The G-protein, MMAA, together with MMAB, an adenosyltransferase, orchestrate cofactor delivery and repair of B12-dependent human methylmalonyl-CoA mutase (MMUT). The mechanism by which the complex assembles and moves a >1300 Da cargo, or fails in disease, are poorly understood. Herein, we report the crystal structure of the human MMUT-MMAA nano-assembly, which reveals a dramatic 180° rotation of the B12 domain, exposing it to solvent. The complex, stabilized by MMAA wedging between two MMUT domains, leads to ordering of the switch I and III loops, revealing the molecular basis of mutase-dependent GTPase activation. The structure explains the biochemical penalties incurred by methylmalonic aciduria-causing mutations that reside at the MMAA-MMUT interfaces we identify here.
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Affiliation(s)
- Romila Mascarenhas
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Markus Ruetz
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Harsha Gouda
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Natalie Heitman
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Madeline Yaw
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA.
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Schleicher E, Didangelos T, Kotzakioulafi E, Cegan A, Peter A, Kantartzis K. Clinical Pathobiochemistry of Vitamin B 12 Deficiency: Improving Our Understanding by Exploring Novel Mechanisms with a Focus on Diabetic Neuropathy. Nutrients 2023; 15:nu15112597. [PMID: 37299560 DOI: 10.3390/nu15112597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 05/27/2023] [Accepted: 05/29/2023] [Indexed: 06/12/2023] Open
Abstract
Vitamin B12 (B12) is an essential cofactor of two important biochemical pathways, the degradation of methylmalonic acid and the synthesis of methionine from homocysteine. Methionine is an important donor of methyl groups for numerous biochemical reactions, including DNA synthesis and gene regulation. Besides hematological abnormalities (megaloblastic anemia or even pancytopenia), a deficiency in B12 may cause neurological symptoms, including symptoms resembling diabetic neuropathy. Although extensively studied, the underlining molecular mechanism for the development of diabetic peripheral neuropathy (DPN) is still unclear. Most studies have found a contribution of oxidative stress in the development of DPN. Detailed immunohistochemical investigations in sural nerve biopsies obtained from diabetic patients with DPN point to an activation of inflammatory pathways induced via elevated advanced glycation end products (AGE), ultimately resulting in increased oxidative stress. Similar results have been found in patients with B12 deficiency, indicating that the observed neural changes in patients with DPN might be caused by cellular B12 deficiency. Since novel results show that B12 exerts intrinsic antioxidative activity in vitro and in vivo, B12 may act as an intracellular, particularly as an intramitochondrial, antioxidant, independent from its classical, well-known cofactor function. These novel findings may provide a rationale for the use of B12 for the treatment of DPN, even in subclinical early states.
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Affiliation(s)
- Erwin Schleicher
- Institute for Clinical Chemistry and Pathobiochemistry, Department for Diagnostic Laboratory Medicine, University Hospital of Tübingen, 72076 Tübingen, Germany
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich, German Center for Diabetes Research (DZD), 72076 Tübingen, Germany
- German Center for Diabetes Research (DZD e.V.), 85764 Neuherberg, Germany
| | - Triantafyllos Didangelos
- Diabetes Center, 1st Propaedeutic Department of Internal Medicine, Medical School, "AHEPA" Hospital, Aristotle University of Thessaloniki, 54621 Thessaloniki, Greece
| | - Evangelia Kotzakioulafi
- Diabetes Center, 1st Propaedeutic Department of Internal Medicine, Medical School, "AHEPA" Hospital, Aristotle University of Thessaloniki, 54621 Thessaloniki, Greece
| | - Alexander Cegan
- Department of Biological and Biochemical Sciences, Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice, Czech Republic
| | - Andreas Peter
- Institute for Clinical Chemistry and Pathobiochemistry, Department for Diagnostic Laboratory Medicine, University Hospital of Tübingen, 72076 Tübingen, Germany
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich, German Center for Diabetes Research (DZD), 72076 Tübingen, Germany
- German Center for Diabetes Research (DZD e.V.), 85764 Neuherberg, Germany
| | - Konstantinos Kantartzis
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich, German Center for Diabetes Research (DZD), 72076 Tübingen, Germany
- German Center for Diabetes Research (DZD e.V.), 85764 Neuherberg, Germany
- Department of Internal Medicine IV, Division of Endocrinology, Diabetology and Nephrology, University of Tübingen, 72076 Tübingen, Germany
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17
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Du M, Wu S, Su C, Wang X, Li B, Lin Y, Yuan S, Chen Y, Zhu C, Wei H. Serum Vitamin B12 is a Promising Auxiliary Index for the Diagnosis of Methylmalonic Acidemia in Children: A Single Center Study in China. Clin Chim Acta 2023; 546:117409. [PMID: 37217112 DOI: 10.1016/j.cca.2023.117409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/25/2023] [Accepted: 05/19/2023] [Indexed: 05/24/2023]
Abstract
BACKGROUND AND AIMS Vitamin B12 (cobalamin, VitB12) is an essential coenzyme of methylmalonyl-CoA mutase and methionine synthase. Variations in VitB12 metabolism, absorption, transport, or intake may cause changes in methylmalonic acidemia (MMA) biomarkers. We aimed to investigate whether serum Vitamin B12 levels could be used in the early detection of MMA. MATERIALS AND METHODS We included 241 children with MMA and 241 healthy matched controls. We measured serum VitB12 levels by an enzyme immunoassay and investigated the relationship between abnormal VitB12 levels and hematologic parameters as potential risk factors for MMA symptoms. RESULTS Compared with controls, the serum levels of VitB12 were increased in the MMA group (p < 0.001). Serum VitB12 distinguished patients with MMA from healthy children (p < 0.001). Serum VitB12 combined with homocysteine and ammonia identified cblC and mut type MMA, respectively (p < 0.001). Homocysteine, folate, ammonia, NLR, and red blood cells contributed to serum VitB12 in cblC type MMA (p < 0.001); homocysteine, ammonia, and red blood cells, contributed in mut type MMA (p < 0.001); and elevated VitB12 was an independent predictor of MMA clinical onset (p < 0.001). CONCLUSION Serum VitB12 can be used as an early diagnostic biomarker for MMA in children.
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Affiliation(s)
- Mengmeng Du
- Children's Hospital Affiliated to Zhengzhou University, Department of Endocrinology, Genetics and Metabolism, Henan Children's Hospital, Zhengz- hou Children's Hospital, Zhengzhou, China; Henan Key Laboratory of Child Brain Injury and Henan Pediatric Clinical Research Center, Third Affiliated Hospital and Institute of Neuroscience, Zhengzhou University, Zhengzhou, China.
| | - Shengnan Wu
- Children's Hospital Affiliated to Zhengzhou University, Department of Endocrinology, Genetics and Metabolism, Henan Children's Hospital, Zhengz- hou Children's Hospital, Zhengzhou, China.
| | - Chang Su
- Department of Endocrinology, Genetic and Metabolism, Beijing Children's Hospital, Capital Medical University, Beijing, China.
| | - Xiaohong Wang
- Children's Hospital Affiliated to Zhengzhou University, Department of Endocrinology, Genetics and Metabolism, Henan Children's Hospital, Zhengz- hou Children's Hospital, Zhengzhou, China.
| | - Bingbing Li
- Henan Key Laboratory of Child Brain Injury and Henan Pediatric Clinical Research Center, Third Affiliated Hospital and Institute of Neuroscience, Zhengzhou University, Zhengzhou, China.
| | - Yifan Lin
- Children's Hospital Affiliated to Zhengzhou University, Department of Endocrinology, Genetics and Metabolism, Henan Children's Hospital, Zhengz- hou Children's Hospital, Zhengzhou, China.
| | - Shuxian Yuan
- Children's Hospital Affiliated to Zhengzhou University, Department of Endocrinology, Genetics and Metabolism, Henan Children's Hospital, Zhengz- hou Children's Hospital, Zhengzhou, China.
| | - Yongxing Chen
- Children's Hospital Affiliated to Zhengzhou University, Department of Endocrinology, Genetics and Metabolism, Henan Children's Hospital, Zhengz- hou Children's Hospital, Zhengzhou, China.
| | - Changlian Zhu
- Children's Hospital Affiliated to Zhengzhou University, Department of Endocrinology, Genetics and Metabolism, Henan Children's Hospital, Zhengz- hou Children's Hospital, Zhengzhou, China; Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, University of Gothenburg, Sweden.
| | - Haiyan Wei
- Children's Hospital Affiliated to Zhengzhou University, Department of Endocrinology, Genetics and Metabolism, Henan Children's Hospital, Zhengz- hou Children's Hospital, Zhengzhou, China.
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18
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Fedosov SN, Nexo E, Heegaard CW. Low methylcobalamin in liver tissues is an artifact as shown by a revised extraction procedure. Biochim Biophys Acta Gen Subj 2023; 1867:130315. [PMID: 36739999 DOI: 10.1016/j.bbagen.2023.130315] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 01/10/2023] [Accepted: 01/23/2023] [Indexed: 02/05/2023]
Abstract
BACKGROUND Vitamin B12 (cobalamin, Cbl) is represented by several molecular variants distinguished by the exchangeable ligand X coordinated to cobalt ion (XCbl). The most typical XCbl-forms are cyanocobalamin (CNCbl), hydroxocobalamin (HOCbl), methylcobalamin (MeCbl) and 5'-deoxydeoxyadenosylcobalamin (AdoCbl). Cells convert the "inactive" vitamins CNCbl and HOCbl to the two critically important coenzymes AdoCbl or MeCbl. Surprisingly, little or no MeCbl is usually uncovered in the tissue samples, as compared to AdoCbl and HOCbl. We hypothesized that a low level of MeCbl is an artifact of "harsh" extractions, leading to degradation of MeCbl and/or its conversion to other XCbl-forms. METHODS We designed a "mild" extraction protocol, including homogenization of rat liver in ammonium acetate (pH 4.6), dilution with EtOH (final 60%) and heating for 10 min at 70 °C. The XCbls were separated by HPLC and quantified by isotope dilution assays. RESULTS A "mild" extraction revealed the following composition of Cbls: 37% AdoCbl, 35% MeCbl, 15% HOCbl and 13% CNCbl. The usual "harsh" protocol (pH 7, 20 min at 80 °C) changed this balance to 33%, 5%, 43% and 17%, respectively. A model assay revealed that MeCbl underwent demethylation and conversion to HOCbl at pH 3 and pH > 7, when heated with thiols. Other changes included decyanation of CNCbl and destruction of HOCbl. CONCLUSIONS Our procedure reveals a high content of MeCbl in rat liver. GENERAL SIGNIFICANCE This result challenges previous data and pinpoints the need for new studies to characterize the endogenous Cbl-forms in health and disease.
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Affiliation(s)
- Sergey N Fedosov
- Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, 8000 Aarhus C, Denmark; Department of Clinical Biochemistry, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark.
| | - Ebba Nexo
- Department of Clinical Biochemistry, Aarhus University Hospital, Palle Juul-Jensens Boulevard 99, 8200 Aarhus N, Denmark.
| | - Christian W Heegaard
- Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, 8000 Aarhus C, Denmark.
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19
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Mascarenhas R, Ruetz M, Gouda H, Heitman N, Yaw M, Banerjee R. Architecture of the human G-protein-methylmalonyl-CoA mutase nanoassembly for B 12 delivery and repair. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.23.533963. [PMID: 36993209 PMCID: PMC10055420 DOI: 10.1101/2023.03.23.533963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
G-proteins function as molecular switches to power cofactor translocation and confer fidelity in metal trafficking. MMAA, a G-protein motor, together with MMAB, an adenosyltransferase, orchestrate cofactor delivery and repair of B 12 -dependent human methylmalonyl-CoA mutase (MMUT). The mechanism by which the motor assembles and moves a >1300 Da cargo, or fails in disease, are poorly understood. Herein, we report the crystal structure of the human MMUT-MMAA nanomotor assembly, which reveals a dramatic 180° rotation of the B 12 domain, exposing it to solvent. The nanomotor complex, stabilized by MMAA wedging between two MMUT domains, leads to ordering of the switch I and III loops, revealing the molecular basis of mutase-dependent GTPase activation. The structure explains the biochemical penalties incurred by methylmalonic aciduria-causing mutations that reside at the newly identified MMAA-MMUT interfaces.
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20
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Gouda H, Mascarenhas R, Ruetz M, Yaw M, Banerjee R. Bivalent molecular mimicry by ADP protects metal redox state and promotes coenzyme B 12 repair. Proc Natl Acad Sci U S A 2023; 120:e2220677120. [PMID: 36888659 PMCID: PMC10243129 DOI: 10.1073/pnas.2220677120] [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: 12/05/2022] [Accepted: 02/07/2023] [Indexed: 03/09/2023] Open
Abstract
Control over transition metal redox state is essential for metalloprotein function and can be achieved via coordination chemistry and/or sequestration from bulk solvent. Human methylmalonyl-Coenzyme A (CoA) mutase (MCM) catalyzes the isomerization of methylmalonyl-CoA to succinyl-CoA using 5'-deoxyadenosylcobalamin (AdoCbl) as a metallocofactor. During catalysis, the occasional escape of the 5'-deoxyadenosine (dAdo) moiety leaves the cob(II)alamin intermediate stranded and prone to hyperoxidation to hydroxocobalamin, which is recalcitrant to repair. In this study, we have identified the use of bivalent molecular mimicry by ADP, coopting the 5'-deoxyadenosine and diphosphate moieties in the cofactor and substrate, respectively, to protect against cob(II)alamin overoxidation on MCM. Crystallographic and electron paramagnetic resonance (EPR) data reveal that ADP exerts control over the metal oxidation state by inducing a conformational change that seals off solvent access, rather than by switching five-coordinate cob(II)alamin to the more air stable four-coordinate state. Subsequent binding of methylmalonyl-CoA (or CoA) promotes cob(II)alamin off-loading from MCM to adenosyltransferase for repair. This study identifies an unconventional strategy for controlling metal redox state by an abundant metabolite to plug active site access, which is key to preserving and recycling a rare, but essential, metal cofactor.
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Affiliation(s)
- Harsha Gouda
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI48109
| | - Romila Mascarenhas
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI48109
| | - Markus Ruetz
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI48109
| | - Madeline Yaw
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI48109
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI48109
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21
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Liu A, Cai C, Wang Z, Wang B, He J, Xie Y, Deng H, Liu S, Zeng S, Yin Z, Wang M. Inductively coupled plasma mass spectrometry based urine metallome to construct clinical decision models for autism spectrum disorder. METALLOMICS : INTEGRATED BIOMETAL SCIENCE 2022; 14:6849992. [PMID: 36442146 DOI: 10.1093/mtomcs/mfac091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND The global prevalence of autism spectrum disorder (ASD) is on the rise, and high levels of exposure to toxic heavy metals may be associated with this increase. Urine analysis is a noninvasive method for investigating the accumulation and excretion of heavy metals. The aim of this study was to identify ASD-associated urinary metal markers. METHODS Overall, 70 children with ASD and 71 children with typical development (TD) were enrolled in this retrospective case-control study. In this metallomics investigation, inductively coupled plasma mass spectrometry was performed to obtain the urine profile of 27 metals. RESULTS Children with ASD could be distinguished from children with TD based on the urine metal profile, with ASD children showing an increased urine metal Shannon diversity. A metallome-wide association analysis was used to identify seven ASD-related metals in urine, with cobalt, aluminum, selenium, and lithium significantly higher, and manganese, mercury, and titanium significantly lower in the urine of children with ASD than in children with TD. The least absolute shrinkage and selection operator (LASSO) machine learning method was used to rank the seven urine metals in terms of their effect on ASD. On the basis of these seven urine metals, we constructed a LASSO regression model for ASD classification and found an area under the receiver operating characteristic curve of 0.913. We also constructed a clinical prediction model for ASD based on the seven metals that were different in the urine of children with ASD and found that the model would be useful for the clinical prediction of ASD risk. CONCLUSIONS The study findings suggest that altered urine metal concentrations may be an important risk factor for ASD, and we recommend further exploration of the mechanisms and clinical treatment measures for such alterations.
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Affiliation(s)
- Aiping Liu
- T he department of Laboratory, Baoan Public Health Service Center of Shenzhen, Baoan District, Shenzhen, 518108, China
| | - Chunquan Cai
- Tianjin Pediatric Research Institute, Tianjin Key Laboratory of Birth Defects for Prevention and Treatment, Tianjin Children's Hospital (Children's Hospital of Tianjin University), Tianjin 300134, China
| | - Zhangxing Wang
- Division of Neonatology, Shenzhen Longhua People's Hospital, Guangdong 518109, China
| | - Bin Wang
- The department of Dermatology, The University of Hong Kong-Shenzhen Hospital, Shenzhen 518053, China
| | - Juntao He
- Shenzhen Prevention and Treatment Center for Occupational Diseases (Physical Testing & Chemical Analysis Department), Shenzhen 518020, China
| | - Yanhong Xie
- T he department of Laboratory, Baoan Public Health Service Center of Shenzhen, Baoan District, Shenzhen, 518108, China
| | - Honglian Deng
- T he department of Laboratory, Baoan Public Health Service Center of Shenzhen, Baoan District, Shenzhen, 518108, China
| | - Shaozhi Liu
- T he department of Laboratory, Baoan Public Health Service Center of Shenzhen, Baoan District, Shenzhen, 518108, China
| | - Shujuan Zeng
- Division of Neonatology, Longgang District Central Hospital of Shenzhen, Guangdong 518116, China
| | - Zhaoqing Yin
- Division of Pediatrics, The People's Hospital of Dehong Autonomous Prefecture, Dehong Hospital of Kunming Medical University, Mangshi, Yunnan 678400, China
| | - Mingbang Wang
- Microbiome Therapy Center, South China Hospital, Health Science Center, Shenzhen University, Shenzhen 518116, China.,Shanghai Key Laboratory of Birth Defects, Division of Neonatology, Children's Hospital of Fudan University, National Center for Children's Health, Shanghai 201102, China
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22
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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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Marelli C, Fouilhoux A, Benoist J, De Lonlay P, Guffon‐Fouilhoux N, Brassier A, Cano A, Chabrol B, Pennisi A, Schiff M, Acquaviva C, Murphy E, Servais A, Lachmann R. Very long-term outcomes in 23 patients with cblA type methylmalonic acidemia. J Inherit Metab Dis 2022; 45:937-951. [PMID: 35618652 PMCID: PMC9540587 DOI: 10.1002/jimd.12525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 05/16/2022] [Accepted: 05/23/2022] [Indexed: 11/10/2022]
Abstract
OBJECTIVES To present the very long-term follow up of patients with cobalamin A (cblA) deficiency. METHODS A retrospective case series of adult (>16 years) patients with molecular or enzymatic diagnosis of cblA deficiency. RESULTS We included 23 patients (mean age: 27 ± 7.6 years; mean follow-up: 24.9 ± 7.6 years). Disease onset was mostly pediatric (78% < 1 year, median = 4 months) with acute neurologic deterioration (65%). Eight patients presented with chronic symptoms, and one had an adult-onset mild cblA deficiency. Most of the patients (61%) were initially classified as vitamin B12-unresponsive methylmalonic aciduria (MMA); in vitro B12 responsiveness was subsequently found in all the tested patients (n = 13). Initial management consisted of protein restriction (57%), B12 (17%), or both (26%). The main long-term problems were intellectual disability (39%) and renal failure (30%). However, 56.5% of the patients were living independently. Intellectual disability was equally distributed among the initial treatment groups, while renal failure (moderate and beginning at the age of 38 years) was present in only one out of seven patients initially treated with B12. CONCLUSIONS We provide a detailed picture of the long-term outcome of a series of adult cblA patients, mostly diagnosed before the enzymatic and molecular era. We confirm that about 35% of the patients do not present acutely, underlining the importance of measuring MMA in any case of unexplained chronic renal failure, intellectual disability, or growth delay. In addition, we describe a patient with a milder adult-onset form. Early B12 supplementation seems to protect from severe renal insufficiency.
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Affiliation(s)
- Cecilia Marelli
- Expert Centre for Neurogenetic Diseases and Adult Mitochondrial and Metabolic DiseasesUniversity Hospital of MontpellierMontpellierFrance
- MMDNUniversity of Montpellier, Ecole Pratique des Hautes Etudes, InsermMontpellierFrance
| | - Alain Fouilhoux
- Reference Center for Inborn Error of MetabolismHôpital Femme Mère Enfant, Hospices Civils de LyonBronFrance
| | - Jean‐Francois Benoist
- Inserm UMR_S1163Institut ImagineParisFrance
- Biochemistry DepartmentHôpital Necker Enfants Malades, Assistance Publique – Hôpitaux de ParisParisFrance
| | - Pascale De Lonlay
- Necker Hospital, Assistance Publique – Hôpitaux de Paris, Reference Center for Inborn Error of Metabolism and Filière G2M, Pediatrics DepartmentUniversity of ParisParisFrance
| | - Nathalie Guffon‐Fouilhoux
- Reference Center for Inborn Error of MetabolismHôpital Femme Mère Enfant, Hospices Civils de LyonBronFrance
| | - Anais Brassier
- Necker Hospital, Assistance Publique – Hôpitaux de Paris, Reference Center for Inborn Error of Metabolism and Filière G2M, Pediatrics DepartmentUniversity of ParisParisFrance
| | - Aline Cano
- Reference Center for Inherited Metabolic Disorders, Assistance Publique Hôpitaux de MarseilleCentre Hospitalier Universitaire de La Timone EnfantsMarseilleFrance
| | - Brigitte Chabrol
- Reference Center for Inherited Metabolic Disorders, Assistance Publique Hôpitaux de MarseilleCentre Hospitalier Universitaire de La Timone EnfantsMarseilleFrance
| | - Alessandra Pennisi
- Necker Hospital, Assistance Publique – Hôpitaux de Paris, Reference Center for Inborn Error of Metabolism and Filière G2M, Pediatrics DepartmentUniversity of ParisParisFrance
| | - Manuel Schiff
- Inserm UMR_S1163Institut ImagineParisFrance
- Necker Hospital, Assistance Publique – Hôpitaux de Paris, Reference Center for Inborn Error of Metabolism and Filière G2M, Pediatrics DepartmentUniversity of ParisParisFrance
| | - Cecile Acquaviva
- Center for Inherited Metabolic Disorders and Neonatal Screening, Est Biology and Pathology Department, Groupement Hospitalier Est (GHE)Hospices Civils de LyonBronFrance
| | - Elaine Murphy
- C. Dent Adult Metabolic UnitNational Hospital for Neurology and NeurosurgeryLondonUK
| | - Aude Servais
- Necker Hospital, Assistance Publique – Hôpitaux de Paris, Reference Center for Inborn Error of Metabolism and Filière G2M, Pediatrics DepartmentUniversity of ParisParisFrance
- Adult Nephrology and Transplantation DepartmentHôpital Necker Enfants Malades, APHPParisFrance
| | - Robin Lachmann
- C. Dent Adult Metabolic UnitNational Hospital for Neurology and NeurosurgeryLondonUK
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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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25
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Padmanabhan S, Pérez-Castaño R, Osete-Alcaraz L, Polanco MC, Elías-Arnanz M. Vitamin B 12 photoreceptors. VITAMINS AND HORMONES 2022; 119:149-184. [PMID: 35337618 DOI: 10.1016/bs.vh.2022.01.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Photoreceptor proteins enable living organisms to sense light and transduce this signal into biochemical outputs to elicit appropriate cellular responses. Their light sensing is typically mediated by covalently or noncovalently bound molecules called chromophores, which absorb light of specific wavelengths and modulate protein structure and biological activity. Known photoreceptors have been classified into about ten families based on the chromophore and its associated photosensory domain in the protein. One widespread photoreceptor family uses coenzyme B12 or 5'-deoxyadenosylcobalamin, a biological form of vitamin B12, to sense ultraviolet, blue, or green light, and its discovery revealed both a new type of photoreceptor and a novel functional facet of this vitamin, best known as an enzyme cofactor. Large strides have been made in our understanding of how these B12-based photoreceptors function, high-resolution structural descriptions of their functional states are available, as are details of their unusual photochemistry. Additionally, they have inspired notable applications in optogenetics/optobiochemistry and synthetic biology. Here, we provide an overview of what is currently known about these B12-based photoreceptors, their discovery, distribution, molecular mechanism of action, and the structural and photochemical basis of how they orchestrate signal transduction and gene regulation, and how they have been used to engineer optogenetic control of protein activities in living cells.
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Affiliation(s)
- S Padmanabhan
- Instituto de Química Física "Rocasolano", Consejo Superior de Investigaciones Científicas, Madrid, Spain.
| | - Ricardo Pérez-Castaño
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - Lucía Osete-Alcaraz
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - María Carmen Polanco
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, Murcia, Spain
| | - Montserrat Elías-Arnanz
- Departamento de Genética y Microbiología, Área de Genética (Unidad Asociada al IQFR-CSIC), Facultad de Biología, Universidad de Murcia, Murcia, Spain.
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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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27
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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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28
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Ruetz M, Koutmos M, Kräutler B. Antivitamins B 12: Synthesis and application as inhibitory ligand of the B 12-tailoring enzyme CblC. Methods Enzymol 2022; 668:157-178. [PMID: 35589193 DOI: 10.1016/bs.mie.2021.12.016] [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] [Indexed: 10/19/2022]
Abstract
Antivitamins B12 are non-natural corrinoids that have been designed to counteract the metabolic effects of vitamin B12 and related cobalamins (Cbls) in humans and other mammals. A basic structure- and reactivity-based concept typifies antivitamins B12 as close structural mimics of vitamin B12 that are not transformed by the cellular metabolism into organometallic B12-cofactors. Antivitamins B12 have the correct structure for efficient take-up and transport via the natural mammalian pathway for cobalamin assimilation. Thus they can be delivered to every cell in the body, where they are proposed to target and inhibit the Cbl tailoring enzyme CblC. Antivitamins B12 may be specifically inert Cbls or isostructural Cbl-analogues that carry a metal centre other than a cobalt-ion. The syntheses of two antivitamins B12 are detailed here, as are biochemical and crystallographic studies that provide insights into the crucial binding interactions of Cbl-based antivitamins B12 with the human B12-tailoring enzyme CblC. This key enzyme binds genuine antivitamins B12 as inert substrate mimics and enzyme inhibitors, effectively repressing the metabolic generation of the B12-cofactors. Hence, antivitamins B12 induce the diagnostic symptoms of (functional) B12-deficiency, as observed in healthy laboratory mice.
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Affiliation(s)
- Markus Ruetz
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Markos Koutmos
- Department of Chemistry, Program in Biophysics, Program in Chemical Biology, University of Michigan, Ann Arbor, MI, United States.
| | - Bernhard Kräutler
- Institute of Organic Chemistry and Center of Molecular Biosciences, University of Innsbruck, Innsbruck, Austria.
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Li Z, Gouda H, Pillay S, Yaw M, Ruetz M, Banerjee R. The human B 12 trafficking chaperones: CblA, ATR, CblC and CblD. Methods Enzymol 2022; 668:137-156. [PMID: 35589192 PMCID: PMC9418966 DOI: 10.1016/bs.mie.2021.12.009] [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] [Indexed: 11/29/2022]
Abstract
Mammals rely on an elaborate intracellular trafficking pathway for processing and delivering vitamin B12 to two client enzymes. CblC (also known as MMACHC) is postulated to receive the cofactor as it enters the cytoplasm and converts varied B12 derivatives to a common cob(II)alamin intermediate. CblD (or MMADHC) reacts with CblC-bound cob(II)alamin forming an interprotein thiolato-cobalt coordination complex and, by a mechanism that remains to be elucidated, transfers the cofactor to methionine synthase. In the mitochondrion, CblB (also known as MMAB or adenosyltransferase) synthesizes AdoCbl from cob(II)alamin and ATP in the presence of an electron donor. CblA (or MMAA), a GTPase, gates cofactor loading from CblB to methylmalonyl-CoA mutase and off-loading of cob(II)alamin in the reverse direction. This chapter focuses on assays for measuring the activities of the four B12 chaperones CblA-D.
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Affiliation(s)
- Zhu Li
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Harsha Gouda
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Shubhadra Pillay
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Madeline Yaw
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Markus Ruetz
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, United States
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30
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Mascarenhas R, Gouda H, Ruetz M, Banerjee R. Human B 12-dependent enzymes: Methionine synthase and Methylmalonyl-CoA mutase. Methods Enzymol 2022; 668:309-326. [PMID: 35589199 PMCID: PMC9420401 DOI: 10.1016/bs.mie.2021.12.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Humans have only two known cobalamin or B12-dependent enzymes: cytoplasmic methionine synthase and mitochondrial methylmalonyl-CoA mutase. A complex intracellular B12 trafficking pathway, comprising a multitude of chaperones, process and deliver cobalamin to the two target enzymes. Methionine synthase catalyzes the transfer of a methyl group from N5-methytetrahydrofolate to homocysteine, generating tetrahydrofolate and methionine. Cobalamin serves as an intermediate methyl group carrier and cycles between methylcobalamin and cob(I)alamin. Methylmalonyl-CoA mutase uses the 5'-deoxyadenosylcobalamin form of the cofactor and catalyzes the 1,2 rearrangement of methylmalonyl-CoA to succinyl-CoA. Two chaperones, CblA (or MMAA) and CblB (or MMAB, also known as adenosyltransferase), serve the mutase and ensure that the fidelity of the cofactor loading and unloading processes is maintained. This chapter focuses on assays for purifying and measuring the activities of methionine synthase and methylmalonyl-CoA mutase.
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31
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Gouda H, Mascarenhas R, Pillay S, Ruetz M, Koutmos M, Banerjee R. Patient mutations in human ATP:cob(I)alamin adenosyltransferase differentially affect its catalytic versus chaperone functions. J Biol Chem 2021; 297:101373. [PMID: 34757128 PMCID: PMC8633584 DOI: 10.1016/j.jbc.2021.101373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/25/2021] [Accepted: 10/27/2021] [Indexed: 11/26/2022] Open
Abstract
Human ATP:cob(I)alamin adenosyltransferase (ATR) is a mitochondrial enzyme that catalyzes an adenosyl transfer to cob(I)alamin, synthesizing 5′-deoxyadenosylcobalamin (AdoCbl) or coenzyme B12. ATR is also a chaperone that escorts AdoCbl, transferring it to methylmalonyl-CoA mutase, which is important in propionate metabolism. Mutations in ATR lead to methylmalonic aciduria type B, an inborn error of B12 metabolism. Our previous studies have furnished insights into how ATR protein dynamics influence redox-linked cobalt coordination chemistry, controlling its catalytic versus chaperone functions. In this study, we have characterized three patient mutations at two conserved active site residues in human ATR, R190C/H, and E193K and obtained crystal structures of R190C and E193K variants, which display only subtle structural changes. All three mutations were found to weaken affinities for the cob(II)alamin substrate and the AdoCbl product and increase KM(ATP). 31P NMR studies show that binding of the triphosphate product, formed during the adenosylation reaction, is also weakened. However, although the kcat of this reaction is significantly diminished for the R190C/H mutants, it is comparable with the WT enzyme for the E193K variant, revealing the catalytic importance of Arg-190. Furthermore, although the E193K mutation selectively impairs the chaperone function by promoting product release into solution, its catalytic function might be unaffected at physiological ATP concentrations. In contrast, the R190C/H mutations affect both the catalytic and chaperoning activities of ATR. Because the E193K mutation spares the catalytic activity of ATR, our data suggest that the patients carrying this mutation are more likely to be responsive to cobalamin therapy.
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Affiliation(s)
- Harsha Gouda
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Romila Mascarenhas
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Shubhadra Pillay
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Markus Ruetz
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Markos Koutmos
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA; Department of Biophysics, University of Michigan, Ann Arbor, Michigan, USA
| | - Ruma Banerjee
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
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32
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Edmonds KA, Jordan MR, Giedroc DP. COG0523 proteins: a functionally diverse family of transition metal-regulated G3E P-loop GTP hydrolases from bacteria to man. Metallomics 2021; 13:6327566. [PMID: 34302342 PMCID: PMC8360895 DOI: 10.1093/mtomcs/mfab046] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 07/15/2021] [Indexed: 01/13/2023]
Abstract
Transition metal homeostasis ensures that cells and organisms obtain sufficient metal to meet cellular demand while dispensing with any excess so as to avoid toxicity. In bacteria, zinc restriction induces the expression of one or more Zur (zinc-uptake repressor)-regulated Cluster of Orthologous Groups (COG) COG0523 proteins. COG0523 proteins encompass a poorly understood sub-family of G3E P-loop small GTPases, others of which are known to function as metallochaperones in the maturation of cobalamin (CoII) and NiII cofactor-containing metalloenzymes. Here, we use genomic enzymology tools to functionally analyse over 80 000 sequences that are evolutionarily related to Acinetobacter baumannii ZigA (Zur-inducible GTPase), a COG0523 protein and candidate zinc metallochaperone. These sequences segregate into distinct sequence similarity network (SSN) clusters, exemplified by the ZnII-Zur-regulated and FeIII-nitrile hydratase activator CxCC (C, Cys; X, any amino acid)-containing COG0523 proteins (SSN cluster 1), NiII-UreG (clusters 2, 8), CoII-CobW (cluster 4), and NiII-HypB (cluster 5). A total of five large clusters that comprise ≈ 25% of all sequences, including cluster 3 which harbors the only structurally characterized COG0523 protein, Escherichia coli YjiA, and many uncharacterized eukaryotic COG0523 proteins. We also establish that mycobacterial-specific protein Y (Mpy) recruitment factor (Mrf), which promotes ribosome hibernation in actinomycetes under conditions of ZnII starvation, segregates into a fifth SSN cluster (cluster 17). Mrf is a COG0523 paralog that lacks all GTP-binding determinants as well as the ZnII-coordinating Cys found in CxCC-containing COG0523 proteins. On the basis of this analysis, we discuss new perspectives on the COG0523 proteins as cellular reporters of widespread nutrient stress induced by ZnII limitation.
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Affiliation(s)
- Katherine A Edmonds
- Department of Chemistry, Indiana University, Bloomington, IN 47405-7102, USA
| | - Matthew R Jordan
- Department of Chemistry, Indiana University, Bloomington, IN 47405-7102, USA.,Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - David P Giedroc
- Department of Chemistry, Indiana University, Bloomington, IN 47405-7102, USA.,Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
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