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Open Issues for Protein Function Assignment in Haloferax volcanii and Other Halophilic Archaea. Genes (Basel) 2021; 12:genes12070963. [PMID: 34202810 PMCID: PMC8305020 DOI: 10.3390/genes12070963] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 06/10/2021] [Accepted: 06/15/2021] [Indexed: 12/14/2022] Open
Abstract
Background: Annotation ambiguities and annotation errors are a general challenge in genomics. While a reliable protein function assignment can be obtained by experimental characterization, this is expensive and time-consuming, and the number of such Gold Standard Proteins (GSP) with experimental support remains very low compared to proteins annotated by sequence homology, usually through automated pipelines. Even a GSP may give a misleading assignment when used as a reference: the homolog may be close enough to support isofunctionality, but the substrate of the GSP is absent from the species being annotated. In such cases, the enzymes cannot be isofunctional. Here, we examined a variety of such issues in halophilic archaea (class Halobacteria), with a strong focus on the model haloarchaeon Haloferax volcanii. Results: Annotated proteins of Hfx. volcanii were identified for which public databases tend to assign a function that is probably incorrect. In some cases, an alternative, probably correct, function can be predicted or inferred from the available evidence, but this has not been adopted by public databases because experimental validation is lacking. In other cases, a probably invalid specific function is predicted by homology, and while there is evidence that this assigned function is unlikely, the true function remains elusive. We listed 50 of those cases, each with detailed background information, so that a conclusion about the most likely biological function can be drawn. For reasons of brevity and comprehension, only the key aspects are listed in the main text, with detailed information being provided in a corresponding section of the Supplementary Materials. Conclusions: Compiling, describing and summarizing these open annotation issues and functional predictions will benefit the scientific community in the general effort to improve the evaluation of protein function assignments and more thoroughly detail them. By highlighting the gaps and likely annotation errors currently in the databases, we hope this study will provide a framework for experimentalists to systematically confirm (or disprove) our function predictions or to uncover yet more unexpected functions.
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Hillman ET, Kozik AJ, Hooker CA, Burnett JL, Heo Y, Kiesel VA, Nevins CJ, Oshiro JM, Robins MM, Thakkar RD, Wu ST, Lindemann SR. Comparative genomics of the genus Roseburia reveals divergent biosynthetic pathways that may influence colonic competition among species. Microb Genom 2020; 6:mgen000399. [PMID: 32589566 PMCID: PMC7478625 DOI: 10.1099/mgen.0.000399] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 06/03/2020] [Indexed: 12/16/2022] Open
Abstract
Roseburia species are important denizens of the human gut microbiome that ferment complex polysaccharides to butyrate as a terminal fermentation product, which influences human physiology and serves as an energy source for colonocytes. Previous comparative genomics analyses of the genus Roseburia have examined polysaccharide degradation genes. Here, we characterize the core and pangenomes of the genus Roseburia with respect to central carbon and energy metabolism, as well as biosynthesis of amino acids and B vitamins using orthology-based methods, uncovering significant differences among species in their biosynthetic capacities. Variation in gene content among Roseburia species and strains was most significant for cofactor biosynthesis. Unlike all other species of Roseburia that we analysed, Roseburia inulinivorans strains lacked biosynthetic genes for riboflavin or pantothenate but possessed folate biosynthesis genes. Differences in gene content for B vitamin synthesis were matched with differences in putative salvage and synthesis strategies among species. For example, we observed extended biotin salvage capabilities in R. intestinalis strains, which further suggest that B vitamin acquisition strategies may impact fitness in the gut ecosystem. As differences in the functional potential to synthesize components of biomass (e.g. amino acids, vitamins) can drive interspecies interactions, variation in auxotrophies of the Roseburia spp. genomes may influence in vivo gut ecology. This study serves to advance our understanding of the potential metabolic interactions that influence the ecology of Roseburia spp. and, ultimately, may provide a basis for rational strategies to manipulate the abundances of these species.
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Affiliation(s)
- Ethan T. Hillman
- Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA
- Purdue University Interdisciplinary Life Science Program (PULSe), Purdue University, West Lafayette, IN 47907, USA
| | - Ariangela J. Kozik
- Purdue University Interdisciplinary Life Science Program (PULSe), Purdue University, West Lafayette, IN 47907, USA
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907, USA
- Present address: Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Casey A. Hooker
- Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - John L. Burnett
- Department of Food Science, Purdue University, West Lafayette, IN 47907, USA
| | - Yoojung Heo
- Department of Agronomy, Purdue University, West Lafayette, IN 47907, USA
| | - Violet A. Kiesel
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA
| | - Clayton J. Nevins
- Department of Agronomy, Purdue University, West Lafayette, IN 47907, USA
- Present address: Department of Soil and Water Sciences, University of Florida, Gainesville, FL 32603, USA
| | - Jordan M.K.I. Oshiro
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA
| | - Melissa M. Robins
- Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Riya D. Thakkar
- Department of Food Science, Purdue University, West Lafayette, IN 47907, USA
- Whistler Center for Carbohydrate Research, Purdue University, West Lafayette, IN 47907, USA
| | - Sophie Tongyu Wu
- Department of Food Science, Purdue University, West Lafayette, IN 47907, USA
| | - Stephen R. Lindemann
- Purdue University Interdisciplinary Life Science Program (PULSe), Purdue University, West Lafayette, IN 47907, USA
- Department of Food Science, Purdue University, West Lafayette, IN 47907, USA
- Whistler Center for Carbohydrate Research, Purdue University, West Lafayette, IN 47907, USA
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Abstract
Modified tetrapyrroles are large macrocyclic compounds, consisting of diverse conjugation and metal chelation systems and imparting an array of colors to the biological structures that contain them. Tetrapyrroles represent some of the most complex small molecules synthesized by cells and are involved in many essential processes that are fundamental to life on Earth, including photosynthesis, respiration, and catalysis. These molecules are all derived from a common template through a series of enzyme-mediated transformations that alter the oxidation state of the macrocycle and also modify its size, its side-chain composition, and the nature of the centrally chelated metal ion. The different modified tetrapyrroles include chlorophylls, hemes, siroheme, corrins (including vitamin B12), coenzyme F430, heme d1, and bilins. After nearly a century of study, almost all of the more than 90 different enzymes that synthesize this family of compounds are now known, and expression of reconstructed operons in heterologous hosts has confirmed that most pathways are complete. Aside from the highly diverse nature of the chemical reactions catalyzed, an interesting aspect of comparative biochemistry is to see how different enzymes and even entire pathways have evolved to perform alternative chemical reactions to produce the same end products in the presence and absence of oxygen. Although there is still much to learn, our current understanding of tetrapyrrole biogenesis represents a remarkable biochemical milestone that is summarized in this review.
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Affiliation(s)
- Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Martin J Warren
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, United Kingdom
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, United Kingdom
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4
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Dudley QM, Nash CJ, Jewett MC. Cell-free biosynthesis of limonene using enzyme-enriched Escherichia coli lysates. Synth Biol (Oxf) 2019; 4:ysz003. [PMID: 30873438 PMCID: PMC6407499 DOI: 10.1093/synbio/ysz003] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 12/18/2018] [Accepted: 12/23/2018] [Indexed: 11/25/2022] Open
Abstract
Isoprenoids are an attractive class of metabolites for enzymatic synthesis from renewable substrates. However, metabolic engineering of microorganisms for monoterpenoid production is limited by the need for time-consuming, and often non-intuitive, combinatorial tuning of biosynthetic pathway variations to meet design criteria. Towards alleviating this limitation, the goal of this work was to build a modular, cell-free platform for construction and testing of monoterpenoid pathways, using the fragrance and flavoring molecule limonene as a model. In this platform, multiple Escherichia coli lysates, each enriched with a single overexpressed pathway enzyme, are mixed to construct the full biosynthetic pathway. First, we show the ability to synthesize limonene from six enriched lysates with mevalonate substrate, an adenosine triphosphate (ATP) source, and cofactors. Next, we extend the pathway to use glucose as a substrate, which relies on native metabolism in the extract to convert glucose to acetyl-CoA along with three additional enzymes to convert acetyl-CoA to mevalonate. We find that the native E. coli farnesyl diphosphate synthase (IspA) is active in the lysate and diverts flux from the pathway intermediate geranyl pyrophospahte to farnesyl pyrophsophate and the byproduct farnesol. By adjusting the relative levels of cofactors NAD+, ATP and CoA, the system can synthesize 0.66 mM (90.2 mg l-1) limonene over 24 h, a productivity of 3.8 mg l-1 h-1. Our results highlight the flexibility of crude lysates to sustain complex metabolism and, by activating a glucose-to-limonene pathway with 9 heterologous enzymes encompassing 20 biosynthetic steps, expands an approach of using enzyme-enriched lysates for constructing, characterizing and prototyping enzymatic pathways.
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Affiliation(s)
- Quentin M Dudley
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, USA
| | - Connor J Nash
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, USA
| | - Michael C Jewett
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, USA
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, USA
- Center for Synthetic Biology, Northwestern University, Evanston, IL, USA
- Robert H. Lurie Comprehensive Cancer Center, Simpson Querrey Institute Northwestern University, Chicago, IL, USA
- Simpson Querrey Institute Northwestern University, Chicago, IL, USA
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5
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Abstract
This review summarizes research performed over the last 23 years on the genetics, enzyme structures and functions, and regulation of the expression of the genes encoding functions involved in adenosylcobalamin (AdoCbl, or coenzyme B12) biosynthesis. It also discusses the role of coenzyme B12 in the physiology of Salmonella enterica serovar Typhimurium LT2 and Escherichia coli. John Roth's seminal contributions to the field of coenzyme B12 biosynthesis research brought the power of classical and molecular genetic, biochemical, and structural approaches to bear on the extremely challenging problem of dissecting the steps of what has turned out to be one of the most complex biosynthetic pathways known. In E. coli and serovar Typhimurium, uro'gen III represents the first branch point in the pathway, where the routes for cobalamin and siroheme synthesis diverge from that for heme synthesis. The cobalamin biosynthetic pathway in P. denitrificans was the first to be elucidated, but it was soon realized that there are at least two routes for cobalamin biosynthesis, representing aerobic and anaerobic variations. The expression of the AdoCbl biosynthetic operon is complex and is modulated at different levels. At the transcriptional level, a sensor response regulator protein activates the transcription of the operon in response to 1,2-Pdl in the environment. Serovar Typhimurium and E. coli use ethanolamine as a source of carbon, nitrogen, and energy. In addition, and unlike E. coli, serovar Typhimurium can also grow on 1,2-Pdl as the sole source of carbon and energy.
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6
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Elucidation of the anaerobic pathway for the corrin component of cobalamin (vitamin B12). Proc Natl Acad Sci U S A 2013; 110:14906-11. [PMID: 23922391 DOI: 10.1073/pnas.1308098110] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It has been known for the past 20 years that two pathways exist in nature for the de novo biosynthesis of the coenzyme form of vitamin B12, adenosylcobalamin, representing aerobic and anaerobic routes. In contrast to the aerobic pathway, the anaerobic route has remained enigmatic because many of its intermediates have proven technically challenging to isolate, because of their inherent instability. However, by studying the anaerobic cobalamin biosynthetic pathway in Bacillus megaterium and using homologously overproduced enzymes, it has been possible to isolate all of the intermediates between uroporphyrinogen III and cobyrinic acid. Consequently, it has been possible to detail the activities of purified cobinamide biosynthesis (Cbi) proteins CbiF, CbiG, CbiD, CbiJ, CbiET, and CbiC, as well as show the direct in vitro conversion of 5-aminolevulinic acid into cobyrinic acid using a mixture of 14 purified enzymes. This approach has resulted in the isolation of the long sought intermediates, cobalt-precorrin-6A and -6B and cobalt-precorrin-8. EPR, in particular, has proven an effective technique in following these transformations with the cobalt(II) paramagnetic electron in the dyz orbital, rather than the typical dz2. This result has allowed us to speculate that the metal ion plays an unexpected role in assisting the interconversion of pathway intermediates. By determining a function for all of the pathway enzymes, we complete the tool set for cobalamin biosynthesis and pave the way for not only enhancing cobalamin production, but also design of cobalamin derivatives through their combinatorial use and modification.
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Moore SJ, Biedendieck R, Lawrence AD, Deery E, Howard MJ, Rigby SEJ, Warren MJ. Characterization of the enzyme CbiH60 involved in anaerobic ring contraction of the cobalamin (vitamin B12) biosynthetic pathway. J Biol Chem 2013; 288:297-305. [PMID: 23155054 PMCID: PMC3537027 DOI: 10.1074/jbc.m112.422535] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 11/12/2012] [Indexed: 11/06/2022] Open
Abstract
The anaerobic pathway for the biosynthesis of cobalamin (vitamin B(12)) has remained poorly characterized because of the sensitivity of the pathway intermediates to oxygen and the low activity of enzymes. One of the major bottlenecks in the anaerobic pathway is the ring contraction step, which has not been observed previously with a purified enzyme system. The Gram-positive aerobic bacterium Bacillus megaterium has a complete anaerobic pathway that contains an unusual ring contraction enzyme, CbiH(60), that harbors a C-terminal extension with sequence similarity to the nitrite/sulfite reductase family. To improve solubility, the enzyme was homologously produced in the host B. megaterium DSM319. CbiH(60) was characterized by electron paramagnetic resonance and shown to contain a [4Fe-4S] center. Assays with purified recombinant CbiH(60) demonstrate that the enzyme converts both cobalt-precorrin-3 and cobalt factor III into the ring-contracted product cobalt-precorrin-4 in high yields, with the latter transformation dependent upon DTT and an intact Fe-S center. Furthermore, the ring contraction process was shown not to involve a change in the oxidation state of the central cobalt ion of the macrocycle.
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Affiliation(s)
- Simon J. Moore
- From the School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, United Kingdom
| | - Rebekka Biedendieck
- From the School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, United Kingdom
- the Institute of Microbiology, Technische Universität Braunschweig, Braunschweig D-38106, Germany, and
| | - Andrew D. Lawrence
- From the School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, United Kingdom
| | - Evelyne Deery
- From the School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, United Kingdom
| | - Mark J. Howard
- From the School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, United Kingdom
| | - Stephen E. J. Rigby
- the Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, Manchester M1 7DN, United Kingdom
| | - Martin J. Warren
- From the School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, United Kingdom
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8
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Systematic characterization of hypothetical proteins in Synechocystis sp. PCC 6803 reveals proteins functionally relevant to stress responses. Gene 2012; 512:6-15. [PMID: 23063937 DOI: 10.1016/j.gene.2012.10.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Revised: 10/03/2012] [Accepted: 10/05/2012] [Indexed: 11/22/2022]
Abstract
We described here a global detection and functional inference of hypothetical proteins involved in stress response in Synechocystis sp. PCC 6803. In the study, we first applied an iTRAQ-LC-MS/MS based quantitative proteomics to the Synechocystis cells grown under five stress conditions. The analysis detected a total of 807 hypothetical proteins with high confidence. Among them, 480 were differentially regulated. We then applied a Weighted Gene Co-expression Network Analysis approach to construct transcriptional networks for Synechocystis under nutrient limitation and osmotic stress conditions using transcriptome datasets. The analysis showed that 305 and 467 coding genes of hypothetical proteins were functionally relevant to nutrient limitation and osmotic stress, respectively. A comparison of responsive hypothetical proteins to all stress conditions allowed identification of 22 hypothetical proteins commonly responsive to all stresses, suggesting they may be part of the core stress responses in Synechocystis. Finally, functional inference of these core stress responsive proteins using both sequence similarity and non-similarity approaches was conducted. The study provided new insights into the stress response networks in Synechocystis, and also demonstrated that a combination of experimental "OMICS" and bioinformatics methodologies could improve functional annotation for hypothetical proteins.
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9
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Frank S, Deery E, Brindley AA, Leech HK, Lawrence A, Heathcote P, Schubert HL, Brocklehurst K, Rigby SEJ, Warren MJ, Pickersgill RW. Elucidation of substrate specificity in the cobalamin (vitamin B12) biosynthetic methyltransferases. Structure and function of the C20 methyltransferase (CbiL) from Methanothermobacter thermautotrophicus. J Biol Chem 2007; 282:23957-69. [PMID: 17567575 DOI: 10.1074/jbc.m703827200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ring contraction during cobalamin (vitamin B12) biosynthesis requires a seemingly futile methylation of the C20 position of the tetrapyrrole framework. Along the anaerobic route, this reaction is catalyzed by CbiL, which transfers a methyl group from S-adenosyl-L-methionine to cobalt factor II to generate cobalt factor III. CbiL belongs to the class III methyltransferases and displays similarity to other cobalamin biosynthetic methyltransferases that are responsible for the regiospecific methylation of a number of positions on the tetrapyrrole molecular canvas. In an attempt to understand how CbiL selectively methylates the C20 position, a detailed structure function analysis of the enzyme has been undertaken. In this paper, we demonstrate that the enzyme methylates the C20 position, that its preferred substrate is cobalt factor II, and that the metal ion does not undergo any oxidation change during the course of the reaction. The enzyme was crystallized, and its structure was determined by x-ray crystallography, revealing that the 26-kDa protein has a similar overall topology to other class III enzymes. This helped in the identification of some key amino acid residues (Asp(104), Lys(176), and Tyr(220)). Analysis of mutant variants of these groups has allowed us to suggest potential roles that these side chains may play in substrate binding and catalysis. EPR analysis of binary and ternary complexes indicate that the protein donates a fifth ligand to the cobalt ion via a gated mechanism to prevent transfer of the methyl group to water. The chemical logic underpinning the methylation is discussed.
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Affiliation(s)
- Stefanie Frank
- Protein Science Group, Department of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, United Kingdom
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10
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Holliday GL, Thornton JM, Marquet A, Smith AG, Rébeillé F, Mendel R, Schubert HL, Lawrence AD, Warren MJ. Evolution of enzymes and pathways for the biosynthesis of cofactors. Nat Prod Rep 2007; 24:972-87. [PMID: 17898893 DOI: 10.1039/b703107f] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The evolution of metabolic pathways is discussed with reference to the biosynthesis of a number of vitamins and cofactors. Retrograde and patchwork models are highlighted and their relevance to our knowledge of pathway processes and enzymes is examined. Pathway complexity is explained in terms of the acquisition of broad specificity enzymes.
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Affiliation(s)
- Gemma L Holliday
- European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, UK CB10 1SD.
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11
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Scott AI, Roessner CA. Recent discoveries in the pathways to cobalamin (coenzyme B12) achieved through chemistry and biology. PURE APPL CHEM 2007. [DOI: 10.1351/pac200779122179] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The genetic engineering of Escherichia coli for the over-expression of enzymes of the aerobic and anaerobic pathways to cobalamin has resulted in the in vivo and in vitro biosynthesis of new intermediates and other products that were isolated and characterized using a combination of bioorganic chemistry and high-resolution NMR. Analyses of these products were used to deduct the functions of the enzymes that catalyze their synthesis. CobZ, another enzyme for the synthesis of precorrin-3B of the aerobic pathway, has recently been described, as has been BluB, the enzyme responsible for the oxygen-dependent biosynthesis of dimethylbenzimidazole. In the anaerobic pathway, functions have recently been experimentally confirmed for or assigned to the CbiMNOQ cobalt transport complex, CbiA (a,c side chain amidation), CbiD (C-1 methylation), CbiF (C-11 methylation), CbiG (lactone opening, deacylation), CbiP (b,d,e,g side chain amidation), and CbiT (C-15 methylation, C-12 side chain decarboxylation). The dephosphorylation of adenosylcobalamin-phosphate, catalyzed by CobC, has been proposed as the final step in the biosynthesis of adenosylcobalamin.
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Affiliation(s)
- A. Ian Scott
- 1Center for Biological NMR, Department of Chemistry, Texas A and M University, College Station, TX 77843-3255, USA
| | - Charles A. Roessner
- 1Center for Biological NMR, Department of Chemistry, Texas A and M University, College Station, TX 77843-3255, USA
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12
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Roessner CA, Scott AI. Fine-tuning our knowledge of the anaerobic route to cobalamin (vitamin B12). J Bacteriol 2006; 188:7331-4. [PMID: 16936030 PMCID: PMC1636268 DOI: 10.1128/jb.00918-06] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Charles A Roessner
- Department of Chemistry, Center for Biological NMR, Texas A&M University, College Station, 77843-3255, USA.
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13
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Santander PJ, Kajiwara Y, Williams HJ, Scott AI. Structural characterization of novel cobalt corrinoids synthesized by enzymes of the vitamin B12 anaerobic pathway. Bioorg Med Chem 2005; 14:724-31. [PMID: 16198574 DOI: 10.1016/j.bmc.2005.08.062] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Accepted: 08/26/2005] [Indexed: 11/23/2022]
Abstract
Investigation on the use of the oxidized form (factor 3 (3a)) of the trimethylated intermediate (precorrin 3 (2)) as a substrate for the enzymes of the anaerobic pathway to vitamin B12 led to the synthesis of three pairs of novel cobalt corrinoids. The products were made with the aid of the Salmonella typhimurium enzymes CbiH, CbiF, CbiG, and CbiT, were synthesized in several 13C labeled versions, and were isolated as methylesters after esterification. Structures were determined by detailed NMR and MS analyses. Each set of products was obtained in the decarboxylated (RMe) and non-decarboxylated (R=CH2COOCH3) forms (at the C-12 position of the porphyrinoid).
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Affiliation(s)
- Patricio J Santander
- Center for Biological NMR, Department of Chemistry, Texas A&M University, PO Box 3255, College Station, TX 77843-3255, USA.
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14
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Frank S, Brindley AA, Deery E, Heathcote P, Lawrence AD, Leech HK, Pickersgill RW, Warren MJ. Anaerobic synthesis of vitamin B12: characterization of the early steps in the pathway. Biochem Soc Trans 2005; 33:811-4. [PMID: 16042604 DOI: 10.1042/bst0330811] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The anaerobic biosynthesis of vitamin B12 is slowly being unravelled. Recent work has shown that the first committed step along the anaerobic route involves the sirohydrochlorin (chelation of cobalt into factor II). The following enzyme in the pathway, CbiL, methylates cobalt-factor II to give cobalt-factor III. Recent progress on the molecular characterization of this enzyme has given a greater insight into its mode of action and specificity. Structural studies are being used to provide insights into how aspects of this highly complex biosynthetic pathway may have evolved. Between cobalt-factor III and cobyrinic acid, only one further intermediate has been identified. A combination of molecular genetics, recombinant DNA technology and bioorganic chemistry has led to some recent advances in assigning functions to the enzymes of the anaerobic pathway.
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Affiliation(s)
- S Frank
- School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK.
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15
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Roessner CA, Williams HJ, Scott AI. Genetically engineered production of 1-desmethylcobyrinic acid, 1-desmethylcobyrinic acid a,c-diamide, and cobyrinic acid a,c-diamide in Escherichia coli implies a role for CbiD in C-1 methylation in the anaerobic pathway to cobalamin. J Biol Chem 2005; 280:16748-53. [PMID: 15741157 DOI: 10.1074/jbc.m501805200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Co-expression of the cobA gene from Propionibacterium freudenreichii and the cbiA, -C, -D, -E, -T, -F, -G, -H, -J, -K, -L, and -P genes from Salmonella enterica serovar typhimurium in Escherichia coli resulted in the production of cobyrinic acid a,c-diamide. A cbiD deletion mutant of this strain produced 1-desmethylcobyrinic acid a,c-diamide, indicating that CbiD is involved in C-1 methylation in the anaerobic pathway to cobalamin. Strains that did not have the cbiP gene also produced 1-desmethylcobyrinic acid a,c-diamide, and strains that had neither cbiP nor cbiA synthesized 1-desmethylcobyrinic acid even in the presence of cbiD, suggesting that CbiA and CbiP are necessary for CbiD activity.
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Affiliation(s)
- Charles A Roessner
- Center for Biological NMR, Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, USA.
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16
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Woodson JD, Escalante-Semerena JC. CbiZ, an amidohydrolase enzyme required for salvaging the coenzyme B12 precursor cobinamide in archaea. Proc Natl Acad Sci U S A 2004; 101:3591-6. [PMID: 14990804 PMCID: PMC373507 DOI: 10.1073/pnas.0305939101] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2003] [Indexed: 11/18/2022] Open
Abstract
The existence of a pathway for salvaging the coenzyme B(12) precursor dicyanocobinamide (Cbi) from the environment was established by genetic and biochemical means. The pathway requires the function of a previously unidentified amidohydrolase enzyme that converts adenosylcobinamide to adenosylcobyric acid, a bona fide intermediate of the de novo coenzyme B(12) biosynthetic route. The cbiZ gene of the methanogenic archaeon Methanosarcina mazei strain Göl was cloned, was overproduced in Escherichia coli, and the recombinant protein was isolated to homogeneity. HPLC, UV-visible spectroscopy, MS, and bioassay data established adenosylcobyric as the corrinoid product of the CbiZ-catalyzed reaction. Inactivation of the cbiZ gene in the extremely halophilic archaeon Halobacterium sp. strain NRC-1 blocked the ability of this archaeon to salvage Cbi. cbiZ function restored Cbi salvaging in a strain of the bacterium Salmonella enterica, whose Cbi-salvaging pathway was blocked. The salvaging of Cbi through the CbiZ enzyme appears to be an archaeal strategy because all of the genomes of B(12)-producing archaea have a cbiZ ortholog. Reasons for the evolution of two distinct pathways for Cbi salvaging in prokaryotes are discussed.
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Affiliation(s)
- Jesse D Woodson
- Department of Bacteriology, University of Wisconsin, Madison, WI 53726-4087, USA
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17
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Woodson JD, Zayas CL, Escalante-Semerena JC. A new pathway for salvaging the coenzyme B12 precursor cobinamide in archaea requires cobinamide-phosphate synthase (CbiB) enzyme activity. J Bacteriol 2004; 185:7193-201. [PMID: 14645280 PMCID: PMC296239 DOI: 10.1128/jb.185.24.7193-7201.2003] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ability of archaea to salvage cobinamide has been under question because archaeal genomes lack orthologs to the bacterial nucleoside triphosphate:5'-deoxycobinamide kinase enzyme (cobU in Salmonella enterica). The latter activity is required for cobinamide salvaging in bacteria. This paper reports evidence that archaea salvage cobinamide from the environment by using a pathway different from the one used by bacteria. These studies demanded the functional characterization of two genes whose putative function had been annotated based solely on their homology to the bacterial genes encoding adenosylcobyric acid and adenosylcobinamide-phosphate synthases (cbiP and cbiB, respectively) of S. enterica. A cbiP mutant strain of the archaeon Halobacterium sp. strain NRC-1 was auxotrophic for adenosylcobyric acid, a known intermediate of the de novo cobamide biosynthesis pathway, but efficiently salvaged cobinamide from the environment, suggesting the existence of a salvaging pathway in this archaeon. A cbiB mutant strain of Halobacterium was auxotrophic for adenosylcobinamide-GDP, a known de novo intermediate, and did not salvage cobinamide. The results of the nutritional analyses of the cbiP and cbiB mutants suggested that the entry point for cobinamide salvaging is adenosylcobyric acid. The data are consistent with a salvaging pathway for cobinamide in which an amidohydrolase enzyme cleaves off the aminopropanol moiety of adenosylcobinamide to yield adenosylcobyric acid, which is converted by the adenosylcobinamide-phosphate synthase enzyme to adenosylcobinamide-phosphate, a known intermediate of the de novo biosynthetic pathway. The existence of an adenosylcobinamide amidohydrolase enzyme would explain the lack of an adenosylcobinamide kinase in archaea.
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Affiliation(s)
- Jesse D Woodson
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin 53726, USA
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18
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Abstract
The chronology of the discoveries along the pathway of vitamin B(12) biosynthesis is reviewed from a personal perspective, including discussion of the most recent finding that two pathways to B(12) exist-one aerobic and one anaerobic-which differ mainly in the ring contraction mechanisms that convert porphyrin to corrin.
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Affiliation(s)
- A Ian Scott
- Center for Biological NMR, Chemistry Department, Texas A&M University, 3255 TAMU, College Station, Texas 77843-3255, USA.
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19
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Raux E, Leech HK, Beck R, Schubert HL, Santander PJ, Roessner CA, Scott AI, Martens JH, Jahn D, Thermes C, Rambach A, Warren MJ. Identification and functional analysis of enzymes required for precorrin-2 dehydrogenation and metal ion insertion in the biosynthesis of sirohaem and cobalamin in Bacillus megaterium. Biochem J 2003; 370:505-16. [PMID: 12408752 PMCID: PMC1223173 DOI: 10.1042/bj20021443] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2002] [Revised: 10/21/2002] [Accepted: 10/31/2002] [Indexed: 11/17/2022]
Abstract
In Bacillus megaterium, the hemAXBCDL genes were isolated and were found to be highly similar to the genes from Bacillus subtilis that are required for the conversion of glutamyl-tRNA into uroporphyrinogen III. Overproduction and purification of HemC (porphobilinogen deaminase) and -D (uroporphyrinogen III synthase) allowed these enzymes to be used for the in vitro synthesis of uroporphyrinogen III from porphobilinogen. A second smaller cluster of three genes (termed sirABC) was also isolated and found to encode the enzymes that catalyse the transformation of uroporphyrinogen III into sirohaem on the basis of their ability to complement a defined Escherichia coli (cysG) mutant. The functions of SirC and -B were investigated by direct enzyme assay, where SirC was found to act as a precorrin-2 dehydrogenase, generating sirohydrochlorin, and SirB was found to act as a ferrochelatase responsible for the final step in sirohaem synthesis. CbiX, a protein found encoded within the main B. megaterium cobalamin biosynthetic operon, shares a high degree of similarity with SirB and acts as the cobaltochelatase associated with cobalamin biosynthesis by inserting cobalt into sirohydrochlorin. CbiX contains an unusual histidine-rich region in the C-terminal portion of the protein, which was not found to be essential in the chelation process. Sequence alignments suggest that SirB and CbiX share a similar active site to the cobaltochelatase, CbiK, from Salmonella enterica.
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Affiliation(s)
- Evelyne Raux
- School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK
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20
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Woodson JD, Peck RF, Krebs MP, Escalante-Semerena JC. The cobY gene of the archaeon Halobacterium sp. strain NRC-1 is required for de novo cobamide synthesis. J Bacteriol 2003; 185:311-6. [PMID: 12486068 PMCID: PMC141819 DOI: 10.1128/jb.185.1.311-316.2003] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Genetic and nutritional analyses of mutants of the extremely halophilic archaeon Halobacterium sp. strain NRC-1 showed that open reading frame (ORF) Vng1581C encodes a protein with nucleoside triphosphate:adenosylcobinamide-phosphate nucleotidyltransferase enzyme activity. This activity was previously associated with the cobY gene of the methanogenic archaeon Methanobacterium thermoautotrophicum strain DeltaH, but no evidence was obtained to demonstrate the direct involvement of this protein in cobamide biosynthesis in archaea. Computer analysis of the Halobacterium sp. strain NRC-1 ORF Vng1581C gene and the cobY gene of M. thermoautotrophicum strain DeltaH showed the primary amino acid sequence of the proteins encoded by these two genes to be 35% identical and 48% similar. A strain of Halobacterium sp. strain NRC-1 carrying a null allele of the cobY gene was auxotrophic for cobinamide-GDP, a known intermediate of the late steps of cobamide biosynthesis. The auxotrophic requirement for cobinamide-GDP was corrected when a wild-type allele of cobY was introduced into the mutant strain, demonstrating that the lack of cobY function was solely responsible for the observed block in cobamide biosynthesis in this archaeon. The data also show that Halobacterium sp. strain NRC-1 possesses a high-affinity transport system for corrinoids and that this archaeon can synthesize cobamides de novo under aerobic growth conditions. To the best of our knowledge this is the first genetic and nutritional analysis of cobalamin biosynthetic mutants in archaea.
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Affiliation(s)
- J D Woodson
- Biomolecular Chemistry Department, School of Medicine, University of Wisconsin-Madison, 1740 University Avenue, Madison, WI 53726-4087, USA
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21
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Keller JP, Smith PM, Benach J, Christendat D, deTitta GT, Hunt JF. The crystal structure of MT0146/CbiT suggests that the putative precorrin-8w decarboxylase is a methyltransferase. Structure 2002; 10:1475-87. [PMID: 12429089 DOI: 10.1016/s0969-2126(02)00876-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The CbiT and CbiE enzymes participate in the biosynthesis of vitamin B12. They are fused together in some organisms to form a protein called CobL, which catalyzes two methylations and one decarboxylation on a precorrin intermediate. Because CbiE has sequence homology to canonical precorrin methyltransferases, CbiT was hypothesized to catalyze the decarboxylation. We herein present the crystal structure of MT0146, the CbiT homolog from Methanobacterium thermoautotrophicum. The protein shows structural similarity to Rossmann-like S-adenosyl-methionine-dependent methyltransferases, and our 1.9 A cocrystal structure shows that it binds S-adenosyl-methionine in standard geometry near a binding pocket that could accommodate a precorrin substrate. Therefore, MT0146/CbiT probably functions as a precorrin methyltransferase and represents the first enzyme identified with this activity that does not have the canonical precorrin methyltransferase fold.
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Affiliation(s)
- Jacob P Keller
- Department of Biological Sciences, 702A Fairchild Center, MC2434, Columbia University, New York, NY 10027, USA
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22
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Roessner CA, Huang KX, Warren MJ, Raux E, Scott AI. Isolation and characterization of 14 additional genes specifying the anaerobic biosynthesis of cobalamin (vitamin B12) in Propionibacterium freudenreichii (P. shermanii). MICROBIOLOGY (READING, ENGLAND) 2002; 148:1845-1853. [PMID: 12055304 DOI: 10.1099/00221287-148-6-1845] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A search for genes encoding enzymes involved in cobalamin (vitamin B12) production in the commercially important organism Propionibacterium freudenreichii (P. shermanii) has resulted in the isolation of an additional 14 genes encoding enzymes responsible for 17 steps of the anaerobic B12 pathway in this organism. All of the genes believed to be necessary for the biosynthesis of adenosylcobinamide from uroporphyrinogen III have now been isolated except two (cbiA and an as yet unidentified gene encoding cobalt reductase). Most of the genes are contained in two divergent operons, one of which, in turn, is closely linked to the operon encoding the B12-dependent enzyme methylmalonyl-CoA mutase. The close linkage of the three genes encoding the subunits of transcarboxylase to the hemYHBXRL gene cluster is reported. The functions of the P. freudenreichii B12 pathway genes are discussed, and a mechanism for the regulation of cobalamin and propionic acid production by oxygen in this organism is proposed.
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Affiliation(s)
- Charles A Roessner
- Center for Biological NMR, Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA1
| | - Ke-Xue Huang
- Center for Biological NMR, Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA1
| | - Martin J Warren
- School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK2
| | - Evelyne Raux
- School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK2
| | - A Ian Scott
- Center for Biological NMR, Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA1
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23
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Abstract
The chronology of the discoveries along the pathway of vitamin B12 biosynthesis is reviewed from a personal perspective, including discussion of the most recent finding that two pathways to B12 exist--one aerobic and one anaerobic--which differ mainly in the ring contraction mechanisms which convert porphyrin to corrin.
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Affiliation(s)
- A I Scott
- Center for Biological NMR, Chemistry Department, Texas A&M University, College Station 77843-3255, USA.
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24
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Anderson PJ, Entsch B, McKay DB. A gene, cobA + hemD, from Selenomonas ruminantium encodes a bifunctional enzyme involved in the synthesis of vitamin B12. Gene 2001; 281:63-70. [PMID: 11750128 DOI: 10.1016/s0378-1119(01)00820-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Coenzymes derived from vitamin B12 (cyanocobalamin) are particularly important for core metabolism in ruminant animals. Selenomonas ruminantium, a Gram-positive obligate anaerobe isolated from cattle, is the main contributor of vitamin B12 to such ruminant animals. In nature, there are both aerobic and anaerobic pathways for B12 synthesis - the latter is only partly elucidated. Until now, there has been no investigation of B12 synthesis in S. ruminantium, which must use an anaerobic pathway. This paper reports the cloning of the chromosomal operon from S. ruminantium which is responsible for the first committed steps in corrinoid synthesis. Five open reading frames were found in the cloned fragment. All deduced amino acid sequences had similarity to defined proteins in the databases that are involved in porphyrin and corrin synthesis. Of particular interest is the gene designated cobA + hemD, which encodes a single polypeptide possessing two catalytic functions - uroporphyrinogen III synthase and uroporphyrinogen III 2,7-methyltransferase. This enzyme converts hydroxymethylbilane to precorrin-2. The functions of the protein coded by cobA + hemD were established by heterologous expression in Escherichia coli. The CobA activity has been demonstrated for three distinct types of proteins - monofunctional, bifunctional with siroheme formation and, this report, bifunctional with uroporphyrinogen III synthesis. The type found in S. ruminantium (cobA + hemD) is probably restricted to obligately anaerobic fermentative bacteria.
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Affiliation(s)
- P J Anderson
- Molecular and Cellular Biology, School of Biological Sciences, University of New England, Armidale, NSW 2351, Australia
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25
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Fonseca MV, Escalante-Semerena JC. An in vitro reducing system for the enzymic conversion of cobalamin to adenosylcobalamin. J Biol Chem 2001; 276:32101-8. [PMID: 11408479 DOI: 10.1074/jbc.m102510200] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Homogeneous ferredoxin (flavodoxin):NADP(+) reductase and flavodoxin A proteins served as electron donors for the reduction of co(III)rrinoids to co(I)rrinoids in vitro. The resulting co(I)rrinoids served as substrates for the ATP:co(I)rrinoid adenosyltransferase (CobA) enzyme of Salmonella enterica serovar Typhimurium LT2 and were converted to their respective adenosylated derivatives. The reaction products were isolated by reverse phase high performance liquid chromatography, and their identities were confirmed by UV-visible spectroscopy, mass spectrometry, and in vivo biological activity assays. Adenosylcobalamin generated by this system supported the activity of 1,2-propanediol dehydratase as effectively as authentic adenosylcobalamin. This is the first report of a protein system that can be coupled to the adenosyltransferase CobA enzyme for the conversion of co(III)rrinoids to their adenosylated derivatives.
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Affiliation(s)
- M V Fonseca
- Department of Bacteriology, University of Wisconsin, Madison, Wisconsin 53706, USA
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26
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Roessner CA, Santander PJ, Scott AI. Multiple biosynthetic pathways for vitamin B12: variations on a central theme. VITAMINS AND HORMONES 2001; 61:267-97. [PMID: 11153269 DOI: 10.1016/s0083-6729(01)61009-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The manner in which vitamin B12 is synthesized is detailed with emphasis on the different mechanisms for ring contraction encountered in aerobic and anaerobic organisms. The aerobic process utilizes two enzymes and is dependent on molecular oxygen, in stark contrast to the anaerobic mechanism which is controlled by cobalt and requires only one enzyme.
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Affiliation(s)
- C A Roessner
- Center for Biological NMR, Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
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27
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Roper JM, Raux E, Brindley AA, Schubert HL, Gharbia SE, Shah HN, Warren MJ. The enigma of cobalamin (Vitamin B12) biosynthesis in Porphyromonas gingivalis. Identification and characterization of a functional corrin pathway. J Biol Chem 2000; 275:40316-23. [PMID: 11007789 DOI: 10.1074/jbc.m007146200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ability of Porphyromonas gingivalis to biosynthesize tetrapyrroles de novo has been investigated. Extracts of the bacterium do not possess activity for 5- aminolevulinic-acid dehydratase or porphobilinogen deaminase, two key enzymes involved in the synthesis of uroporphyrinogen III. Similarly, it was not possible to detect any genetic evidence for these early enzymes with the use of degenerate polymerase chain reaction. However, the bacterium does appear to harbor some of the enzymes for cobalamin biosynthesis since cobyric acid, a pathway intermediate, was converted into cobinamide. Furthermore, degenerate polymerase chain reaction with primers to cbiP, which encodes cobyric-acid synthase, produced a fragment with a high degree of identity to Salmonella typhimurium cbiP. Indeed, the recently released genome sequence data confirmed the presence of cbiP together with 14 other genes of the cobalamin pathway. A number of these genes were cloned and functionally characterized. Although P. gingivalis harbors all the genes necessary to convert precorrin-2 into cobalamin, it is missing the genes for the synthesis of precorrin-2. Either the organism has a novel pathway for the synthesis of precorrin-2, or more likely, it has lost this early part of the pathway. The remainder of the pathway may be being maintained to act as a salvage route for corrin synthesis.
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Affiliation(s)
- J M Roper
- School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom
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28
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Thomas MG, Escalante-Semerena JC. Identification of an alternative nucleoside triphosphate: 5'-deoxyadenosylcobinamide phosphate nucleotidyltransferase in Methanobacterium thermoautotrophicum delta H. J Bacteriol 2000; 182:4227-33. [PMID: 10894731 PMCID: PMC101920 DOI: 10.1128/jb.182.15.4227-4233.2000] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Computer analysis of the archaeal genome databases failed to identify orthologues of all of the bacterial cobamide biosynthetic enzymes. Of particular interest was the lack of an orthologue of the bifunctional nucleoside triphosphate (NTP):5'-deoxyadenosylcobinamide kinase/GTP:adenosylcobinamide-phosphate guanylyltransferase enzyme (CobU in Salmonella enterica). This paper reports the identification of an archaeal gene encoding a new nucleotidyltransferase, which is proposed to be the nonorthologous replacement of the S. enterica cobU gene. The gene encoding this nucleotidyltransferase was identified using comparative genome analysis of the sequenced archaeal genomes. Orthologues of the gene encoding this activity are limited at present to members of the domain Archaea. The corresponding ORF open reading frame from Methanobacterium thermoautotrophicum Delta H (MTH1152; referred to as cobY) was amplified and cloned, and the CobY protein was expressed and purified from Escherichia coli as a hexahistidine-tagged fusion protein. This enzyme had GTP:adenosylcobinamide-phosphate guanylyltransferase activity but did not have the NTP:AdoCbi kinase activity associated with the CobU enzyme of S. enterica. NTP:adenosylcobinamide kinase activity was not detected in M. thermoautotrophicum Delta H cell extract, suggesting that this organism may not have this activity. The cobY gene complemented a cobU mutant of S. enterica grown under anaerobic conditions where growth of the cell depended on de novo adenosylcobalamin biosynthesis. cobY, however, failed to restore adenosylcobalamin biosynthesis in cobU mutants grown under aerobic conditions where de novo synthesis of this coenzyme was blocked, and growth of the cell depended on the assimilation of exogenous cobinamide. These data strongly support the proposal that the relevant cobinamide intermediates during de novo adenosylcobalamin biosynthesis are adenosylcobinamide-phosphate and adenosylcobinamide-GDP, not adenosylcobinamide. Therefore, NTP:adenosylcobinamide kinase activity is not required for de novo cobamide biosynthesis.
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Affiliation(s)
- M G Thomas
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin 53706-1567, USA
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29
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Koyama M, Katayama S, Kaji M, Taniguchi Y, Matsushita O, Minami J, Morita S, Okabe A. A Clostridium perfringens hem gene cluster contains a cysG(B) homologue that is involved in cobalamin biosynthesis. Microbiol Immunol 2000; 43:947-57. [PMID: 10585141 DOI: 10.1111/j.1348-0421.1999.tb03355.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The hem gene cluster, which consists of hemA, cysG(B), hemC, hemD, hemB, and hemL genes, and encodes enzymes involved in the biosynthetic pathway from glutamyl-tRNA to uroporphyrinogen III, has been identified by the cloning and sequencing of two overlapping DNA fragments from Clostridium perfringens NCTC8237. The deduced amino acid sequence of the N-terminal region of C. perfringens HemD is homologous to those reported for the C-terminal region of Salmonella typhimurium CysG and Clostridium josui HemD. C. perfringens CysG(B) is a predicted 220-residue protein which shows homology to the N-terminal region of S. typhimurium CysG. Disruption of the cysG(B) gene in C. perfringens strain 13 by homologous recombination reduced cobalamin (vitamin B12) levels by a factor of 200. When grown in vitamin B12-deficient medium, the mutant strain showed a four-fold increase in its doubling time compared with that of the wild-type strain, and this effect was counteracted by supplementing the medium with vitamin B12. These results suggest that C. perfringens CysG(B) is involved in the chelation of cobalt to precorrin II as suggested for the CysG(B) domain of S. typhimurium CysG, enabling the synthesis of cobalamin.
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Affiliation(s)
- M Koyama
- Department of Pharmacy, Kagawa Medical University, Kita-gun, Japan
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30
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Shearer N, Hinsley AP, Van Spanning RJ, Spiro S. Anaerobic growth of Paracoccus denitrificans requires cobalamin: characterization of cobK and cobJ genes. J Bacteriol 1999; 181:6907-13. [PMID: 10559155 PMCID: PMC94164 DOI: 10.1128/jb.181.22.6907-6913.1999] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A pleiotropic mutant of Paracoccus denitrificans, which has a severe defect that affects its anaerobic growth when either nitrate, nitrite, or nitrous oxide is used as the terminal electron acceptor and which is also unable to use ethanolamine as a carbon and energy source for aerobic growth, was isolated. This phenotype of the mutant is expressed only during growth on minimal media and can be reversed by addition of cobalamin (vitamin B(12)) or cobinamide to the media or by growth on rich media. Sequence analysis revealed the mutation causing this phenotype to be in a gene homologous to cobK of Pseudomonas denitrificans, which encodes precorrin-6x reductase of the cobalamin biosynthesis pathway. Convergently transcribed with cobK is a gene homologous to cobJ of Pseudomonas denitrificans, which encodes precorrin-3b methyltransferase. The inability of the cobalamin auxotroph to grow aerobically on ethanolamine implies that wild-type P. denitrificans (which can grow on ethanolamine) expresses a cobalamin-dependent ethanolamine ammonia lyase and that this organism synthesizes cobalamin under both aerobic and anaerobic growth conditions. Comparison of the cobK and cobJ genes with their orthologues suggests that P. denitrificans uses the aerobic pathway for cobalamin synthesis. It is paradoxical that under anaerobic growth conditions, P. denitrificans appears to use the aerobic (oxygen-requiring) pathway for cobalamin synthesis. Anaerobic growth of the cobalamin auxotroph could be restored by the addition of deoxyribonucleosides to minimal media. These observations provide evidence that P. denitrificans expresses a cobalamin-dependent ribonucleotide reductase, which is essential for growth only under anaerobic conditions.
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Affiliation(s)
- N Shearer
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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31
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Santander PJ, Stolowich NJ, Scott AI. Chemoenzymatic synthesis of an unnatural tetramethyl cobalt corphinoid. Bioorg Med Chem 1999; 7:789-94. [PMID: 10400331 DOI: 10.1016/s0968-0896(99)00014-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The chemoenzymatic synthesis and structural characterization by 13C NMR of a tetramethyl cobalt-corphinoid produced by methylation of cobalt-precorrin-3 using CbiF are described.
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Affiliation(s)
- P J Santander
- Department of Chemistry, Texas A&M University, College Station 77842-3012, USA
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32
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Raux E, Schubert HL, Roper JM, Wilson KS, Warren MJ. Vitamin B12: Insights into Biosynthesis's Mount Improbable. Bioorg Chem 1999. [DOI: 10.1006/bioo.1998.1125] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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