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Hallberg ZF, Nicolas AM, Alvarez-Aponte ZI, Mok KC, Sieradzki ET, Pett-Ridge J, Banfield JF, Carlson HK, Firestone MK, Taga ME. Soil microbial community response to corrinoids is shaped by a natural reservoir of vitamin B 12. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.12.580003. [PMID: 38405713 PMCID: PMC10888822 DOI: 10.1101/2024.02.12.580003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Soil microbial communities perform critical ecosystem services through the collective metabolic activities of numerous individual organisms. Most microbes use corrinoids, a structurally diverse family of cofactors related to vitamin B12. Corrinoid structure influences the growth of individual microbes, yet how these growth responses scale to the community level remains unknown. Analysis of metagenome-assembled genomes suggests corrinoids are supplied to the community by members of the archaeal and bacterial phyla Thermoproteota, Actinobacteria, and Proteobacteria. Corrinoids were found largely adhered to the soil matrix in a grassland soil, at levels exceeding those required by cultured bacteria. Enrichment cultures and soil microcosms seeded with different corrinoids showed distinct shifts in bacterial community composition, supporting the hypothesis that corrinoid structure can shape communities. Environmental context influenced both community and taxon-specific responses to specific corrinoids. These results implicate corrinoids as key determinants of soil microbiome structure and suggest that environmental micronutrient reservoirs promote community stability.
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Affiliation(s)
- Zachary F. Hallberg
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, 94720 USA
| | - Alexa M. Nicolas
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, 94720 USA
| | - Zoila I. Alvarez-Aponte
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, 94720 USA
| | - Kenny C. Mok
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, 94720 USA
| | - Ella T. Sieradzki
- Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA, 94720 USA
| | - Jennifer Pett-Ridge
- Lawrence Livermore National Laboratory, Livermore, CA, 94550 USA
- Innovative Genomics Institute, Berkeley, CA, 94720 USA
| | - Jillian F. Banfield
- Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA, 94720 USA
- Innovative Genomics Institute, Berkeley, CA, 94720 USA
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720 USA
- Earth and Planetary Science, University of California, Berkeley, Berkeley, CA, 94720 USA
| | - Hans K. Carlson
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720 USA
| | - Mary K. Firestone
- Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA, 94720 USA
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720 USA
| | - Michiko E. Taga
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, 94720 USA
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2
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Liu M, Su X, Yuan J, Chen Y, Huang X, Yang X, Zheng J, Li Q, Xu J, He Y. Residual effects of chlorinated organic pollutants on microbial community and natural redox processes in coastal wetlands. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133364. [PMID: 38176260 DOI: 10.1016/j.jhazmat.2023.133364] [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: 11/03/2023] [Revised: 12/11/2023] [Accepted: 12/22/2023] [Indexed: 01/06/2024]
Abstract
Chlorinated organic pollutants (COPs) are common in flooded environments. To examine the residual status and effects of COPs on flooded environments, a survey of 7 coastal wetlands in Zhejiang, East China was conducted. Total COP concentrations detected from 95.69 to 412.76 ng g-1 dw. Gamma-HCH and o,p'-DDT posed the greatest risk with exceedance rates of 100% according to sediment quality guidelines. Samples with higher COP pollution had higher microbial diversity, more complex microbial networks, more deterministic community assembly processes and lower microbiome stability, indicating an improved soil function for balance cycle of substances, especially for COP degradation. Further analysis using quantitative real-time PCR suggested COP-dechlorination interacted with natural redox processes, especially sulfate reduction and methanogenesis. The positive correlation between CH4 and pentachlorobenzene indicated a potential increase in greenhouse gas emissions caused by COP pollution. Correlation between dsr gene and COPs demonstrated the ability of sulfate-reducing bacteria to degrade COPs. Particularly, facultative OHRB such as sulfate-reducing bacteria hold significant importance in the process of COP-dechlorination. This finding provides a reference for COP pollution remediation. Collectively, our study offers new insight into the residual effect of COPs in coastal wetlands and contributes to an improved understanding of bioremediation strategies for COP pollution.
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Affiliation(s)
- Meng Liu
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xin Su
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jing Yuan
- Department of Urban Studies and Planning, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yuxuan Chen
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xiaowei Huang
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Xueling Yang
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Jinjin Zheng
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Qinfen Li
- Environmental and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, Hainan, China
| | - Jianming Xu
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yan He
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, Hangzhou 310058, China.
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3
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Ng TL, Silver PA. Sustainable B 12-Dependent Dehalogenation of Organohalides in E. coli. ACS Chem Biol 2024; 19:380-391. [PMID: 38254247 DOI: 10.1021/acschembio.3c00585] [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: 01/24/2024]
Abstract
Microbial bioremediation can provide an environmentally friendly and scalable solution to treat contaminated soil and water. However, microbes have yet to optimize pathways for degrading persistent anthropogenic pollutants, in particular organohalides. In this work, we first expand our repertoire of enzymes useful for bioremediation. By screening a panel of cobalamin (B12)-dependent reductive dehalogenases, we identified previously unreported enzymes that dechlorinate perchloroethene and regioselectively deiodinate the thyroidal disruptor 2,4,6-triiodophenol. One deiodinase, encoded by the animal-associated anaerobe Clostridioides difficile, was demonstrated to dehalogenate the naturally occurring metabolites L-halotyrosines. In cells, several combinations of ferredoxin oxidoreductase and flavodoxin extract and transfer low-potential electrons from pyruvate to drive reductive dehalogenation without artificial reductants and mediators. This work provides new insights into a relatively understudied family of B12-dependent enzymes and sets the stage for engineering synthetic pathways for degrading unnatural small molecule pollutants.
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Affiliation(s)
- Tai L Ng
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Wyss Institute of Biologically-Inspired Engineering, Harvard University, Boston, Massachusetts 02115, United States
| | - Pamela A Silver
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, United States
- Wyss Institute of Biologically-Inspired Engineering, Harvard University, Boston, Massachusetts 02115, United States
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4
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Mok KC, Hallberg ZF, Procknow RR, Taga ME. Laboratory evolution of E. coli with a natural vitamin B 12 analog reveals roles for cobamide uptake and adenosylation in methionine synthase-dependent growth. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.04.574217. [PMID: 38260444 PMCID: PMC10802341 DOI: 10.1101/2024.01.04.574217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The majority of bacteria use cobamides as cofactors for methionine synthesis or other diverse metabolic processes. Cobamides are a structurally diverse family of cofactors related to vitamin B12 (cobalamin), and most bacteria studied to date grow most robustly with particular cobamides. Because different environments contain varying abundances of distinct cobamides, bacteria are likely to encounter cobamides that do not function efficiently for their metabolism. Here, we performed a laboratory evolution of a cobamide-dependent strain of Escherichia coli with pseudocobalamin (pCbl), a cobamide that E. coli uses less effectively than cobalamin for MetH-dependent methionine synthesis, to identify genetic adaptations that lead to improved growth with less-preferred cobamides. After propagating and sequencing nine independent lines and validating the results by constructing targeted mutations, we found that increasing expression of the outer membrane cobamide transporter BtuB is beneficial during growth under cobamide-limiting conditions. Unexpectedly, we also found that overexpression of the cobamide adenosyltransferase BtuR confers a specific growth advantage in pCbl. Characterization of this phenotype revealed that BtuR and adenosylated cobamides contribute to optimal MetH-dependent growth. Together, these findings improve our understanding of how bacteria expand their cobamide-dependent metabolic potential.
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Affiliation(s)
- Kenny C. Mok
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA U.S.A
| | - Zachary F. Hallberg
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA U.S.A
| | - Rebecca R. Procknow
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA U.S.A
| | - Michiko E. Taga
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA U.S.A
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5
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Chen JJ. Interfacial Electron Transfer in Chemical and Biological Transformation of Pollutants in Environmental Catalysis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:21540-21549. [PMID: 38086095 DOI: 10.1021/acs.est.3c05608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
Interfacial electron transfer (IET) is essential for chemical and biological transformation of pollutants, operative across diverse lengths and time scales. This Perspective presents an array of multiscale molecular simulation methodologies, supplemented by in situ monitoring and imaging techniques, serving as robust tools to decode IET enhancement mechanisms such as interface molecular modification, catalyst coordination mode, and atomic composition regulation. In addition, three IET-based pollutant transformation systems, an electrocatalytic oxidation system, a bioelectrochemical spatial coupling system, and an enzyme-inspired electrocatalytic system, were developed, demonstrating a high effect in transforming and degrading pollutants. To improve the effectiveness and scalability of IET-based strategies, the refinement of these systems is necessitated through rigorous research and theoretical exploration, particularly in the context of practical wastewater treatment scenarios. Future endeavors aim to elucidate the synergy between biological and chemical modules, edit the environmental functional microorganisms, and harness machine learning for designing advanced environmental catalysts to boost efficiency. This Perspective highlights the powerful potential of IET-focused environmental remediation strategies, emphasizing the critical role of interdisciplinary research in addressing the urgent global challenge of water pollution.
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Affiliation(s)
- Jie-Jie Chen
- CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, China
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6
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Sun Y, Wang C, May AL, Chen G, Yin Y, Xie Y, Lato AM, Im J, Löffler FE. Mn(III)-mediated bisphenol a degradation: Mechanisms and products. WATER RESEARCH 2023; 235:119787. [PMID: 36917870 DOI: 10.1016/j.watres.2023.119787] [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: 12/15/2022] [Revised: 02/20/2023] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
Bisphenol A (BPA) is a high production volume chemical with potential estrogenic effects susceptible to abiotic degradation by MnO2. BPA transformation products and reaction mechanisms with MnO2 have been investigated, but detailed process understanding of Mn(III)-mediated degradation has not been attained. Rapid consumption of BPA occurred in batch reaction vessels with 1 mM Mn(III) and 63.9 ± 0.7% of 1.76 ± 0.02 μmol BPA was degraded in 1 hour at circumneutral pH. BPA was consumed at 1.86 ± 0.09-fold higher rates in vessels with synthetic MnO2 comprising approximately 13 mol% surface-associated Mn(III) versus surface-Mn(III)-free MnO2, and 10-35% of BPA transformation could be attributed to Mn(III) during the initial 10-min reaction phase. High-resolution tandem mass spectrometry (HRMS/MS) analysis detected eight transformation intermediates in reactions with Mn(III), and quantum calculations proposed 14 BPA degradation products, nine of which had not been observed during MnO2-mediated BPA degradation, suggesting mechanistic differences between Mn(III)- versus MnO2-mediated BPA degradation. The findings demonstrate that both Mn(III) and Mn(IV) can effectively degrade BPA and indicate that surface-associated Mn(III) increases the reactivity of synthetic MnO2, offering opportunities for engineering more reactive oxidized Mn species for BPA removal.
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Affiliation(s)
- Yanchen Sun
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States; Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Chao Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Amanda L May
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Gao Chen
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States; Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Yongchao Yin
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States; Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Yongchao Xie
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States; Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Ashley M Lato
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Jeongdae Im
- Department of Civil Engineering, Kansas State University, Manhattan, Kansas 66506, United States
| | - Frank E Löffler
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States; Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States; Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States; Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, Tennessee 37996, United States; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
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7
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Marques HM. The inorganic chemistry of the cobalt corrinoids - an update. J Inorg Biochem 2023; 242:112154. [PMID: 36871417 DOI: 10.1016/j.jinorgbio.2023.112154] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 01/23/2023] [Accepted: 01/26/2023] [Indexed: 02/05/2023]
Abstract
The inorganic chemistry of the cobalt corrinoids, derivatives of vitamin B12, is reviewed, with particular emphasis on equilibrium constants for, and kinetics of, their axial ligand substitution reactions. The role the corrin ligand plays in controlling and modifying the properties of the metal ion is emphasised. Other aspects of the chemistry of these compounds, including their structure, corrinoid complexes with metals other than cobalt, the redox chemistry of the cobalt corrinoids and their chemical redox reactions, and their photochemistry are discussed. Their role as catalysts in non-biological reactions and aspects of their organometallic chemistry are briefly mentioned. Particular mention is made of the role that computational methods - and especially DFT calculations - have played in developing our understanding of the inorganic chemistry of these compounds. A brief overview of the biological chemistry of the B12-dependent enzymes is also given for the reader's convenience.
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Affiliation(s)
- Helder M Marques
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg 2050, South Africa.
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8
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Pang X, Huang J, Lin C, Zhang Y, Cheng N, Zi W, Sun ZZ, Yu Z, Zhao Z. Buried Interface Regulation by Bio-Functional Molecules for Efficient and Stable Planar Perovskite Solar Cells. Chemistry 2023; 29:e202202744. [PMID: 36446736 DOI: 10.1002/chem.202202744] [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: 09/07/2022] [Revised: 11/29/2022] [Accepted: 11/29/2022] [Indexed: 12/02/2022]
Abstract
Among the factors that lead to the reduction of the efficiency of perovskite solar cells (PSCs) the difficulty involved in realizing a high-quality film and the efficient charge transfer that takes place at the interface between electron-transport layer (ETL) and perovskite is worth mentioning. Here, a strategy for planar-type devices by natural bio-functional interfaces that uses a buried electron-transport layer made of cobalamin complexed tin oxide (SnO2 @B12 ) is demonstrated. Having systematically investigated the effects of SnO2 @B12 interfacial layer in perovskite solar cells, it can be concluded that cobalamin can chemically link the SnO2 layer and the perovskite layer, resulting in improved perovskite film quality and interfacial defect passivation. Utilizing SnO2 @B12 improves the efficiency of planar-type PSCs by 20.60 %. Furthermore, after 250 h of exposure to an ambient atmosphere, unsealed PSCs containing SnO2 @B12 degrade by 10 %. This research provides a viable method for developing bio-functional molecules that will increase the effectiveness and durability of planar-perovskite solar cells.
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Affiliation(s)
- Xuerui Pang
- Energy-Saving Building Materials Collaborative Innovation Center of Henan Province, Xinyang Normal University, Xinyang, 464000, P. R. China
| | - Jing Huang
- Energy-Saving Building Materials Collaborative Innovation Center of Henan Province, Xinyang Normal University, Xinyang, 464000, P. R. China
| | - Chunxia Lin
- Energy-Saving Building Materials Collaborative Innovation Center of Henan Province, Xinyang Normal University, Xinyang, 464000, P. R. China
| | - Yingfang Zhang
- Energy-Saving Building Materials Collaborative Innovation Center of Henan Province, Xinyang Normal University, Xinyang, 464000, P. R. China
| | - Nian Cheng
- Energy-Saving Building Materials Collaborative Innovation Center of Henan Province, Xinyang Normal University, Xinyang, 464000, P. R. China
| | - Wei Zi
- Energy-Saving Building Materials Collaborative Innovation Center of Henan Province, Xinyang Normal University, Xinyang, 464000, P. R. China
| | - Zhu-Zhu Sun
- Energy-Saving Building Materials Collaborative Innovation Center of Henan Province, Xinyang Normal University, Xinyang, 464000, P. R. China
| | - Zhen Yu
- Energy-Saving Building Materials Collaborative Innovation Center of Henan Province, Xinyang Normal University, Xinyang, 464000, P. R. China
| | - Zhiqiang Zhao
- Energy-Saving Building Materials Collaborative Innovation Center of Henan Province, Xinyang Normal University, Xinyang, 464000, P. R. China
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9
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Hallberg ZF, Seth EC, Thevasundaram K, Taga ME. Comparative Analysis of Corrinoid Profiles across Host-Associated and Environmental Samples. Biochemistry 2022; 61:2791-2796. [PMID: 36037062 DOI: 10.1021/acs.biochem.2c00367] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Vitamin B12 (the cyanated form of cobalamin cofactors) is best known for its essential role in human health. In addition to its function in human metabolism, cobalamin also plays important roles in microbial metabolism and can impact microbial community function. Cobalamin is a member of the structurally diverse family of cofactors known as cobamides that are produced exclusively by certain prokaryotes. Cobamides are considered shared nutrients in microbial communities because the majority of bacteria that possess cobamide-dependent enzymes cannot synthesize cobamides de novo. Furthermore, different microbes have evolved metabolic specificity for particular cobamides, and therefore, the availability of cobamides in the environment is important for cobamide-dependent microbes. Determining the cobamides present in an environment of interest is essential for understanding microbial metabolic interactions. By examining the abundances of different cobamides in diverse environments, including 10 obtained in this study, we find that, contrary to its preeminence in human metabolism, cobalamin is relatively rare in many microbial habitats. Comparison of cobamide profiles of mammalian gastrointestinal samples and wood-feeding insects reveals that host-associated cobamide abundances vary and that fecal cobamide profiles differ from those of their host gastrointestinal tracts. Environmental cobamide profiles obtained from aquatic, soil, and contaminated groundwater samples reveal that the cobamide compositions of environmental samples are highly variable. As the only commercially available cobamide, cobalamin is routinely supplied during microbial culturing efforts. However, these findings suggest that cobamides specific to a given microbiome may yield greater insight into nutrient utilization and physiological processes that occur in these habitats.
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Affiliation(s)
- Zachary F Hallberg
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, California 94720, United States
| | - Erica C Seth
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, California 94720, United States
| | - Kersh Thevasundaram
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, California 94720, United States
| | - Michiko E Taga
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, California 94720, United States
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10
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Cobalamin Riboswitches Are Broadly Sensitive to Corrinoid Cofactors to Enable an Efficient Gene Regulatory Strategy. mBio 2022; 13:e0112122. [PMID: 35993747 PMCID: PMC9600662 DOI: 10.1128/mbio.01121-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
In bacteria, many essential metabolic processes are controlled by riboswitches, gene regulatory RNAs that directly bind and detect metabolites. Highly specific effector binding enables riboswitches to respond to a single biologically relevant metabolite. Cobalamin riboswitches are a potential exception because over a dozen chemically similar but functionally distinct cobalamin variants (corrinoid cofactors) exist in nature. Here, we measured cobalamin riboswitch activity in vivo using a Bacillus subtilis fluorescent reporter system and found, among 38 tested riboswitches, a subset responded to corrinoids promiscuously, while others were semiselective. Analyses of chimeric riboswitches and structural models indicate, unlike other riboswitch classes, cobalamin riboswitches indirectly differentiate among corrinoids by sensing differences in their structural conformation. This regulatory strategy aligns riboswitch-corrinoid specificity with cellular corrinoid requirements in a B. subtilis model. Thus, bacteria can employ broadly sensitive riboswitches to cope with the chemical diversity of essential metabolites. IMPORTANCE Some bacterial mRNAs contain a region called a riboswitch which controls gene expression by binding to a metabolite in the cell. Typically, riboswitches sense and respond to a limited range of cellular metabolites, often just one type. In this work, we found the cobalamin (vitamin B12) riboswitch class is an exception, capable of sensing and responding to multiple variants of B12-collectively called corrinoids. We found cobalamin riboswitches vary in corrinoid specificity with some riboswitches responding to each of the corrinoids we tested, while others responding only to a subset of corrinoids. Our results suggest the latter class of riboswitches sense intrinsic conformational differences among corrinoids in order to support the corrinoid-specific needs of the cell. These findings provide insight into how bacteria sense and respond to an exceptionally diverse, often essential set of enzyme cofactors.
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11
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Qiao W, Liu G, Li M, Su X, Lu L, Ye S, Wu J, Edwards EA, Jiang J. Complete Reductive Dechlorination of 4-Hydroxy-chlorothalonil by Dehalogenimonas Populations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:12237-12246. [PMID: 35951369 DOI: 10.1021/acs.est.2c02574] [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: 06/15/2023]
Abstract
Chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile, TePN) is one of the most widely used fungicides all over the world. Its major environmental transformation product 4-hydroxy-chlorothalonil (4-hydroxy-2,5,6-trichloroisophthalonitrile, 4-OH-TPN) is more persistent, mobile, and toxic and is frequently detected at a higher concentration in various habitats compared to its parent compound TePN. Further microbial transformation of 4-OH-TPN has never been reported. In this study, we demonstrated that 4-OH-TPN underwent complete microbial reductive dehalogenation to 4-hydroxy-isophthalonitrile via 4-hydroxy-dichloroisophthalonitrile and 4-hydroxy-monochloroisophthalonitrile. 16S rRNA gene amplicon sequencing demonstrated that Dehalogenimonas species was enriched from 6% to 17-22% after reductive dechlorination of 77.24 μmol of 4-OH-TPN. Meanwhile, Dehalogenimonas copies increased by one order of magnitude and obtained a yield of 1.78 ± 1.47 × 108 cells per μmol Cl- released (N = 6), indicating that 4-OH-TPN served as the terminal electron acceptor for organohalide respiration of Dehalogenimonas species. A draft genome of Dehalogenimonas species was assembled through metagenomic sequencing, which harbors 30 putative reductive dehalogenase genes. Syntrophobacter, Acetobacterium, and Methanosarcina spp. were found to be the major non-dechlorinating populations in the microbial community, who might play important roles in the reductive dechlorination of 4-OH-TPN by the Dehalogenimonas species. This study first reports that Dehalogenimonas sp. can also respire on the seemingly dead-end product of TePN, paving the way to complete biotransformation of the widely present TePN and broadening the substrate spectrum of Dehalogenimonas sp. to polychlorinated hydroxy-benzonitrile.
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Affiliation(s)
- Wenjing Qiao
- Department of Microbiology, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Guiping Liu
- Department of Microbiology, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Mengya Li
- Department of Microbiology, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Xiaojing Su
- Department of Microbiology, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
| | - Lianghua Lu
- Jiangsu Provincial Academy of Environmental Science, Jiangsu Provincial Key Laboratory of Environmental Engineering, Nanjing 210036, China
| | - Shujun Ye
- Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
| | - Jichun Wu
- Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
| | - Elizabeth A Edwards
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto M5S 3E5, Canada
| | - Jiandong Jiang
- Department of Microbiology, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
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12
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Li X, Yang Y, Wang J, Jin H, Zhang Y, Cui Y, Song Y, Yan J. Organohalide Respiration with Diclofenac by Dehalogenimonas. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:11266-11276. [PMID: 35921385 DOI: 10.1021/acs.est.1c08824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Diclofenac (DCF) is a pharmaceutically active contaminant frequently found in aquatic ecosystems. The transformation pathways and microbiology involved in the biodegradation of DCF, particularly under anoxic conditions, remain poorly understood. Here, we demonstrated microbially mediated reductive dechlorination of DCF in anaerobic enrichment culture derived from contaminated river sediment. Over 90% of the initial 76.7 ± 3.6 μM DCF was dechlorinated at a maximum rate of 1.8 ± 0.3 μM day-1 during a 160 days' incubation. Mass spectrometric analysis confirmed that 2-(2-((2-chlorophenyl)amino)phenyl)acetic acid (2-CPA) and 2-anilinophenylacetic acid (2-APA) were formed as the monochlorinated and nonchlorinated DCF transformation products, respectively. A survey of microbial composition and Sanger sequencing revealed the enrichment and dominance of a new Dehalogenimonas population, designated as Dehalogenimonas sp. strain DCF, in the DCF-dechlorinating community. Following the stoichiometric conversion of DCF to 2-CPA (76.0 ± 2.1 μM) and 2-APA (3.7 ± 0.8 μM), strain DCF cell densities increased by 24.4 ± 4.4-fold with a growth yield of 9.0 ± 0.1 × 108 cells per μmol chloride released. Our findings expand the metabolic capability in the genus Dehalogenimonas and highlight the relevant roles of organohalide-respiring bacteria for the natural attenuation of halogenated contaminants of emerging concerns (e.g., DCF).
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Affiliation(s)
- Xiuying Li
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Room 512 South Building, 72 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Yi Yang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Room 512 South Building, 72 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Jingjing Wang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Room 512 South Building, 72 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Huijuan Jin
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Room 512 South Building, 72 Wenhua Road, Shenyang, Liaoning 110016, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yaozhi Zhang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Room 512 South Building, 72 Wenhua Road, Shenyang, Liaoning 110016, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yiru Cui
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Room 512 South Building, 72 Wenhua Road, Shenyang, Liaoning 110016, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yufang Song
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Room 512 South Building, 72 Wenhua Road, Shenyang, Liaoning 110016, China
| | - Jun Yan
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Room 512 South Building, 72 Wenhua Road, Shenyang, Liaoning 110016, China
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13
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Hudari MSB, Richnow H, Vogt C, Nijenhuis I. Mini-review: effect of temperature on microbial reductive dehalogenation of chlorinated ethenes: a review. FEMS Microbiol Ecol 2022; 98:6638985. [PMID: 35810002 DOI: 10.1093/femsec/fiac081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 06/30/2022] [Accepted: 07/07/2022] [Indexed: 11/13/2022] Open
Abstract
Temperature is a key factor affecting microbial activity and ecology. An increase in temperature generally increases rates of microbial processes up to a certain threshold, above which rates decline rapidly. In the subsurface, temperature of groundwater is usually stable and related to the annual average temperature at the surface. However, anthropogenic activities related to the use of the subsurface, e.g. for thermal heat management, foremost heat storage, will affect the temperature of groundwater locally. This mini-review intends to summarize the current knowledge on reductive dehalogenation activities of the chlorinated ethenes, common urban groundwater contaminants, at different temperatures. This includes an overview of activity and dehalogenation extent at different temperatures in laboratory isolates and enrichment cultures, the effect of shifts in temperature in micro- and mesocosm studies as well as observed biotransformation at different natural and induced temperatures at contaminated field sites. Furthermore, we address indirect effects on biotransformation, e.g. changes in fermentation, methanogenesis and sulfate reduction as competing or synergetic microbial processes. Finally, we address the current gaps in knowledge regarding bioremediation of chlorinated ethenes, microbial community shifts and bottlenecks for active combination with thermal energy storage, and necessities for bioaugmentation and/or natural re-populations after exposure to high temperature.
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Affiliation(s)
- Mohammad Sufian Bin Hudari
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Hans Richnow
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Carsten Vogt
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Ivonne Nijenhuis
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
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14
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Mathur Y, Vartak AR, Hazra AB. Guardian of cobamide diversity: Probing the role of CobT in lower ligand activation in the biosynthesis of vitamin B 12 and other cobamide cofactors. Methods Enzymol 2022; 668:25-59. [PMID: 35589196 DOI: 10.1016/bs.mie.2022.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Enzymes catalyze a wide variety of reactions with exquisite precision under crowded conditions within cellular environments. When encountered with a choice of small molecules in their vicinity, even though most enzymes continue to be specific about the substrate they pick, some others are able to accept a range of substrates and subsequently produce a variety of products. The biosynthesis of Vitamin B12, an essential nutrient required by humans involves a multi-substrate α-phosphoribosyltransferase enzyme CobT that activates the lower ligand of B12. Vitamin B12 is a member of the cobamide family of cofactors which share a common tetrapyrrolic corrin scaffold with a centrally coordinated cobalt ion, and an upper and a lower ligand. The structural difference between B12 and other cobamides mainly arises from variations in the lower ligand, which is attached to the activated corrin ring by CobT and other downstream enzymes. In this chapter, we describe the steps involved in identifying and reconstituting the activity of new CobT homologs by deriving lessons from those previously characterized. We then highlight biochemical techniques to study the unique properties of these homologs. Finally, we describe a pairwise substrate competition assay to rank CobT substrate preference, a general method that can be applied for the study of other multi-substrate enzymes. Overall, the analysis with CobT provides insights into the range of cobamides that can be synthesized by an organism or a community, complementing efforts to predict cobamide diversity from complex metagenomic data.
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Affiliation(s)
- Yamini Mathur
- Department of Biology, Indian Institute of Science Education and Research Pune, Pune, India
| | - Aniket R Vartak
- Department of Biology, Indian Institute of Science Education and Research Pune, Pune, India
| | - Amrita B Hazra
- Department of Biology, Indian Institute of Science Education and Research Pune, Pune, India; Department of Chemistry, Indian Institute of Science Education and Research Pune, Pune, India.
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15
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Cimmino L, Schmid AW, Holliger C, Maillard J. Stoichiometry of the Gene Products From the Tetrachloroethene Reductive Dehalogenase Operon pceABCT. Front Microbiol 2022; 13:838026. [PMID: 35283847 PMCID: PMC8905343 DOI: 10.3389/fmicb.2022.838026] [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: 12/17/2021] [Accepted: 01/27/2022] [Indexed: 11/13/2022] Open
Abstract
Organohalide respiration (OHR) is a bacterial anaerobic process that uses halogenated compounds, e.g., tetrachloroethene (PCE), as terminal electron acceptors. Our model organisms are Dehalobacter restrictus strain PER-K23, an obligate OHR bacterium (OHRB), and Desulfitobacterium hafniense strain TCE1, a bacterium with a versatile metabolism. The key enzyme is the PCE reductive dehalogenase (PceA) that is encoded in the highly conserved gene cluster (pceABCT) in both above-mentioned strains, and in other Firmicutes OHRB. To date, the functions of PceA and PceT, a dedicated molecular chaperone for the maturation of PceA, are well defined. However, the role of PceB and PceC are still not elucidated. We present a multilevel study aiming at deciphering the stoichiometry of pceABCT individual gene products. The investigation was assessed at RNA level by reverse transcription and (quantitative) polymerase chain reaction, while at protein level, proteomic analyses based on parallel reaction monitoring were performed to quantify the Pce proteins in cell-free extracts as well as in soluble and membrane fractions of both strains using heavy-labeled reference peptides. At RNA level, our results confirmed the co-transcription of all pce genes, while the quantitative analysis revealed a relative stoichiometry of the gene transcripts of pceA, pceB, pceC, and pceT at ~ 1.0:3.0:0.1:0.1 in D. restrictus. This trend was not observed in D. hafniense strain TCE1, where no substantial difference was measured for the four genes. At proteomic level, an apparent 2:1 stoichiometry of PceA and PceB was obtained in the membrane fraction, and a low abundance of PceC in comparison to the other two proteins. In the soluble fraction, a 1:1 stoichiometry of PceA and PceT was identified. In summary, we show that the pce gene cluster is transcribed as an operon with, however, a level of transcription that differs for individual genes, an observation that could be explained by post-transcriptional events. Despite challenges in the quantification of integral membrane proteins such as PceB and PceC, the similar abundance of PceA and PceB invites to consider them as forming a membrane-bound PceA2B protein complex, which, in contrast to the proposed model, seems to be devoid of PceC.
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Affiliation(s)
- Lorenzo Cimmino
- Laboratory for Environmental Biotechnology, Institute for Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Adrien W Schmid
- Protein Core Facility, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Christof Holliger
- Laboratory for Environmental Biotechnology, Institute for Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Julien Maillard
- Laboratory for Environmental Biotechnology, Institute for Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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16
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Ma AT, Kantner DS, Beld J. Cobamide remodeling. VITAMINS AND HORMONES 2022; 119:43-63. [PMID: 35337629 DOI: 10.1016/bs.vh.2022.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cobamides are a family of structurally-diverse cofactors which includes vitamin B12 and over a dozen natural analogs. Within the nucleotide loop structure, cobamide analogs have variable lower ligands that fall into three categories: benzimidazoles, purines, and phenols. The range of cobamide analogs that can be utilized by an organism is dependent on the specificity of its cobamide-dependent enzymes, and most bacteria are able to utilize multiple analogs but not all. Some bacteria have pathways for cobamide remodeling, a process in which imported cobamides are converted into compatible analogs. Here we discuss cobamide analog diversity and three pathways for cobamide remodeling, mediated by amidohydrolase CbiZ, phosphodiesterase CbiR, and some homologs of cobamide synthase CobS. Remodeling proteins exhibit varying degrees of specificity for cobamide substrates, reflecting different strategies to ensure that imported cobamides can be utilized.
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Affiliation(s)
- Amy T Ma
- Department of Microbiology and Immunology, Center for Advanced Microbial Processing, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, United States.
| | - Daniel S Kantner
- Department of Microbiology and Immunology, Center for Advanced Microbial Processing, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Joris Beld
- Department of Microbiology and Immunology, Center for Advanced Microbial Processing, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, PA, United States
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17
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Elevated Levels of an Enzyme Involved in Coenzyme B 12 Biosynthesis Kills Escherichia coli. mBio 2022; 13:e0269721. [PMID: 35012330 PMCID: PMC8749415 DOI: 10.1128/mbio.02697-21] [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] [Indexed: 11/24/2022] Open
Abstract
Cobamides are cobalt-containing cyclic tetrapyrroles involved in the metabolism of organisms from all domains of life but produced de novo only by some bacteria and archaea. The pathway is thought to involve up to 30 enzymes, five of which comprise the so-called "late" steps of cobamide biosynthesis. Two of these reactions activate the corrin ring, one activates the nucleobase, a fourth one condenses activated precursors, and a phosphatase yields the final product of the pathway. The penultimate step is catalyzed by a polytopic integral membrane protein, namely, the cobamide (5'-phosphate) synthase, also known as cobamide synthase. At present, the reason for the association of all putative and bona fide cobamide synthases to cell membranes is unclear and intriguing. Here, we show that, in Escherichia coli, elevated levels of cobamide synthase kill the cell by dissipating the proton motive force and compromising membrane stability. We also show that overproduction of the phosphatase that catalyzes the last step of the pathway or phage shock protein A prevents cell death when the gene encoding cobamide synthase is overexpressed. We propose that in E. coli, and probably all cobamide producers, cobamide synthase anchors a multienzyme complex responsible for the assembly of vitamin B12 and other cobamides. IMPORTANCE E. coli is the best-studied prokaryote, and some strains of this bacterium are human pathogens. We show that when the level of the enzyme that catalyzes the penultimate step of vitamin B12 biosynthesis is elevated, the viability of E. coli decreases. These findings are of broad significance because the enzyme alluded to is an integral membrane protein in all cobamide-producing bacteria, many of which are human pathogens. Our results may provide new avenues for the development of antimicrobials, because none of the enzymes involved in vitamin B12 biosynthesis are present in mammalian cells.
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18
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Abstract
Cobamides are a family of enzyme cofactors that are required by organisms in all domains of life. Over a dozen cobamides exist in nature although only cobalamin (vitamin B12), the cobamide required by humans, has been studied extensively. Cobamides are exclusively produced by a subset of prokaryotes. Importantly, the bacteria and archaea that synthesize cobamides de novo typically produce a single type of cobamide, and furthermore, organisms that use cobamides are selective for certain cobamides. Therefore, a detailed understanding of the cobamide-dependent metabolism of an organism or microbial community of interest requires experiments performed with a variety of cobamides. A notable challenge is that cobalamin is the only cobamide that is commercially available at present. In this chapter, we describe methods to extract, purify, and quantify various cobamides from bacteria for use in laboratory experiments.
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Affiliation(s)
- Kenny C Mok
- Department of Plant & Microbial Biology, University of California, Berkeley, CA, United States
| | - Zachary F Hallberg
- Department of Plant & Microbial Biology, University of California, Berkeley, CA, United States
| | - Michiko E Taga
- Department of Plant & Microbial Biology, University of California, Berkeley, CA, United States.
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Heterologous expression of active Dehalobacter spp. respiratory reductive dehalogenases in Escherichia coli. Appl Environ Microbiol 2021; 88:e0199321. [PMID: 34851719 DOI: 10.1128/aem.01993-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Reductive dehalogenases (RDases) are a family of redox enzymes that are required for anaerobic organohalide respiration, a microbial process that is useful in bioremediation. Structural and mechanistic studies of these enzymes have been greatly impeded due to challenges in RDase heterologous expression, potentially because of their cobamide-dependence. There have been a few successful attempts at RDase production in unconventional heterologous hosts, but a robust method has yet to be developed. Here we outline a novel respiratory RDase expression system using Escherichia coli. The overexpression of E. coli's cobamide transport system, btu, and anaerobic expression conditions were found to be essential for production of active RDases from Dehalobacter - an obligate organohalide respiring bacterium. The expression system was validated on six enzymes with amino acid sequence identities as low as 28%. Dehalogenation activity was verified for each RDase by assaying cell-free extracts of small-scale expression cultures on various chlorinated substrates including chloroalkanes, chloroethenes, and hexachlorocyclohexanes. Two RDases, TmrA from Dehalobacter sp. UNSWDHB and HchA from Dehalobacter sp. HCH1, were purified by nickel affinity chromatography. Incorporation of the cobamide and iron-sulfur cluster cofactors was verified; though, the precise cobalamin incorporation could not be determined due to variance between methodologies, and the specific activity of TmrA was consistent with that of the native enzyme. The heterologous expression of respiratory RDases, particularly from obligate organohalide respiring bacteria, has been extremely challenging and unreliable. Here we present a relatively straightforward E. coli expression system that has performed well for a variety of Dehalobacter spp. RDases. IMPORTANCE Understanding microbial reductive dehalogenation is important to refine the global halogen cycle and to improve bioremediation of halogenated contaminants; however, studies of the family of enzymes responsible are limited. Characterization of reductive dehalogenase enzymes has largely eluded researchers due to the lack of a reliable and high-yielding production method. We are presenting an approach to express reductive dehalogenase enzymes from Dehalobacter, a key group of organisms used in bioremediation, in E. coli. This expression system will propel the study of reductive dehalogenases by facilitating their production and isolation, allowing researchers to pursue more in-depth questions about the activity and structure of these enzymes. This platform will also provide a starting point to improve the expression of reductive dehalogenases from many other organisms.
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Ultrastructure of organohalide-respiring Dehalococcoidia revealed by cryo-electron tomography. Appl Environ Microbiol 2021; 88:e0190621. [PMID: 34788060 DOI: 10.1128/aem.01906-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Dehalococcoides mccartyi (Dhc) and Dehalogenimonas spp. (Dhgm) are members of the class Dehalococcoidia, phylum Chloroflexi, characterized by streamlined genomes and a strict requirement for organohalogens as electron acceptors. Here, we used cryo-electron tomography to reveal morphological and ultrastructural features of Dhc strain BAV1 and 'Candidatus Dehalogenimonas etheniformans' strain GP cells at unprecedented resolution. Dhc cells were irregularly shaped discs (890 ± 110 nm long, 630 ± 110 nm wide and 130 ± 15 nm thick) with curved and straight sides that intersected at acute angles, whereas Dhgm cells appeared as slightly flattened cocci (760 ± 85 nm). The cell envelopes were composed of a cytoplasmic membrane (CM), a paracrystalline surface layer (S-layer) with hexagonal symmetry and ∼22 nm spacing between repeating units, and a layer of unknown composition separating the CM and the S-layer. Cell surface appendages were only detected in Dhc cells, whereas both cell types had bundled cytoskeletal filaments. Repetitive globular structures, ∼5 nm in diameter and ∼9 nm apart, were observed associated with the outer leaflet of the CM. We hypothesized that those represent organohalide respiration (OHR) complexes and estimated ∼30,000 copies per cell. In Dhgm cultures, extracellular lipid vesicles (20 - 110 nm in diameter) decorated with putative OHR complexes but lacking an S-layer were observed. The new findings expand our understanding of the unique cellular ultrastructure and biology of organohalide-respiring Dehalococcoidia. Importance: Dehalococcoidia respire organohalogen compounds and play relevant roles in bioremediation of groundwater, sediments and soils impacted with toxic chlorinated pollutants. Using advanced imaging tools, we have obtained 3-dimensional images at macromolecular resolution of whole Dehalococcoidia cells revealing their unique structural components. Our data detail the overall cellular shape, cell envelope architecture, cytoskeletal filaments, the likely localization of enzymatic complexes involved in reductive dehalogenation, and the structure of extracellular vesicles. The new findings expand our understanding of the cell structure-function relationship in Dehalococcoidia with implications for Dehalococcoidia biology and bioremediation.
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21
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Direct Cobamide Remodeling via Additional Function of Cobamide Biosynthesis Protein CobS from Vibrio cholerae. J Bacteriol 2021; 203:e0017221. [PMID: 34031037 DOI: 10.1128/jb.00172-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Vitamin B12 belongs to a family of structurally diverse cofactors with over a dozen natural analogs, collectively referred to as cobamides. Most bacteria encode cobamide-dependent enzymes, many of which can only utilize a subset of cobamide analogs. Some bacteria employ a mechanism called cobamide remodeling, a process in which cobamides are converted into other analogs to ensure that compatible cobamides are available in the cell. Here, we characterize an additional pathway for cobamide remodeling that is distinct from the previously characterized ones. Cobamide synthase (CobS) is an enzyme required for cobamide biosynthesis that attaches the lower ligand moiety in which the base varies between analogs. In a heterologous model system, we previously showed that Vibrio cholerae CobS (VcCobS) unexpectedly conferred remodeling activity in addition to performing the known cobamide biosynthesis reaction. Here, we show that additional Vibrio species perform the same remodeling reaction, and we further characterize VcCobS-mediated remodeling using bacterial genetics and in vitro assays. We demonstrate that VcCobS acts upon the cobamide pseudocobalamin directly to remodel it, a mechanism which differs from the known remodeling pathways in which cobamides are first cleaved into biosynthetic intermediates. This suggests that some CobS homologs have the additional function of cobamide remodeling, and we propose the term "direct remodeling" for this process. This characterization of yet another pathway for remodeling suggests that cobamide profiles are highly dynamic in polymicrobial environments, with remodeling pathways conferring a competitive advantage. IMPORTANCE Cobamides are widespread cofactors that mediate metabolic interactions in complex microbial communities. Few studies directly examine cobamide profiles, but several have shown that mammalian gastrointestinal tracts are rich in cobamide analogs. Studies of intestinal bacteria, including beneficial commensals and pathogens, show variation in the ability to produce and utilize different cobamides. Some bacteria can convert imported cobamides into compatible analogs in a process called remodeling. Recent discoveries of additional cobamide remodeling pathways, including this work, suggest that remodeling is an important factor in cobamide dynamics. Characterization of such pathways is critical in understanding cobamide flux and nutrient cross-feeding in polymicrobial communities, and it facilitates the establishment of microbiome manipulation strategies via modulation of cobamide profiles.
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Li Y, Zhao HP, Zhu L. Iron Sulfide Enhanced the Dechlorination of Trichloroethene by Dehalococcoides mccartyi Strain 195. Front Microbiol 2021; 12:665281. [PMID: 34140942 PMCID: PMC8203822 DOI: 10.3389/fmicb.2021.665281] [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: 02/07/2021] [Accepted: 04/06/2021] [Indexed: 12/04/2022] Open
Abstract
Iron sulfide (FeS) nanoparticles have great potential in environmental remediation. Using the representative species Dehalococcoides mccartyi strain 195 (Dhc 195), the effect of FeS on trichloroethene (TCE) dechlorination was studied with hydrogen and acetate as the electron donor and carbon source, respectively. With the addition of 0.2 mM Fe2+ and S2–, the dechlorination rate of TCE was enhanced from 25.46 ± 1.15 to 37.84 ± 1.89 μmol⋅L–1⋅day–1 by the in situ formed FeS nanoparticles, as revealed through X-ray diffraction. Comparing the tceA gene copy numbers between with FeS and without FeS, real-time polymerase chain reaction (PCR) indicated that the abundance of the tceA gene increased from (2.83 ± 0.13) × 107 to (4.27 ± 0.21) × 108 copies/ml on day 12. The transcriptional activity of key genes involved in the electron transport chain was upregulated after the addition of FeS, including those responsible for the iron–sulfur cluster assembly protein gene (DET1632) and transmembrane transport of iron (DET1503, DET0685), cobalamin (DET0685, DET1139), and molybdenum (DET1161) genes. Meanwhile, the reverse transcription of tceA was increased approximately five times on the 12th day. These upregulations together suggested that the electron transport of D. mccartyi strain 195 was enhanced by FeS for apparent TCE dechlorination. Overall, the present study provided an eco-friendly and effective method to achieve high remediation efficiency for organohalide-polluted groundwater and soil.
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Affiliation(s)
- Yaru Li
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China.,Key Laboratory of Organic Pollution Process and Control, Zhejiang University, Hangzhou, China
| | - He-Ping Zhao
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
| | - Lizhong Zhu
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China.,Key Laboratory of Organic Pollution Process and Control, Zhejiang University, Hangzhou, China
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Mattes TA, Malalasekara L, Escalante-Semerena JC. Functional Studies of α-Riboside Activation by the α-Ribazole Kinase (CblS) from Geobacillus kaustophilus. Biochemistry 2021; 60:2011-2021. [PMID: 34105957 DOI: 10.1021/acs.biochem.1c00119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report the initial characterization of the α-ribazole (α-R) kinase enzyme of Geobacillus kaustophilus (GkCblS), which converts α-R to α-R-phosphate (α-RP) during the synthesis of cobamides. We implemented a continuous spectrophotometric assay to obtain kinetic parameters for several potential substrates and to study the specificity of the enzyme for α-N-linked ribosides. The apparent Km values for α-R and ATP were 358 and 297 μM, respectively. We also report methods for synthesizing and quantifying non-commercially available α-ribosides and β-ribazole (β-R). Purified GkCblS activated α-R and other α-ribosides, including α-adenosine (α-Ado). GkCblS did not phosphorylate β-N-linked glycosides like β-adenosine or β-R. Expression of G. kaustophilus cblS+ in a Salmonella enterica subsp. enterica sv Typhimurium LT2 (S. enterica) strain lacking the nicotinate mononucleotide:5,6-dimethylbenzimidazole phosphoribosyl transferase (CobT) enzyme resulted in the activation of various benzimidazole α-ribosides, and the synthesis of benzimidazolyl cobamides to levels that supported robust growth. Notably, α-Ado did not support growth under similar conditions, in spite of the fact that GkCblS phosphorylated α-Ado in vitro. When α-Ado was provided at a very high concentration, growth was observed. This result suggested that in S. enterica α-Ado transport may be inefficient. We conclude that GkCblS has specificity for α-N-glycosidic bonds, but not for the base in α-ribosides.
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Affiliation(s)
- Theodoric A Mattes
- Department of Microbiology, University of Georgia, Athens, Georgia 30602, United States
| | - Lahiru Malalasekara
- Department of Microbiology, University of Georgia, Athens, Georgia 30602, United States
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Balabanova L, Averianova L, Marchenok M, Son O, Tekutyeva L. Microbial and Genetic Resources for Cobalamin (Vitamin B12) Biosynthesis: From Ecosystems to Industrial Biotechnology. Int J Mol Sci 2021; 22:ijms22094522. [PMID: 33926061 PMCID: PMC8123684 DOI: 10.3390/ijms22094522] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/23/2021] [Accepted: 04/23/2021] [Indexed: 12/12/2022] Open
Abstract
Many microbial producers of coenzyme B12 family cofactors together with their metabolically interdependent pathways are comprehensively studied and successfully used both in natural ecosystems dominated by auxotrophs, including bacteria and mammals, and in the safe industrial production of vitamin B12. Metabolic reconstruction for genomic and metagenomic data and functional genomics continue to mine the microbial and genetic resources for biosynthesis of the vital vitamin B12. Availability of metabolic engineering techniques and usage of affordable and renewable sources allowed improving bioprocess of vitamins, providing a positive impact on both economics and environment. The commercial production of vitamin B12 is mainly achieved through the use of the two major industrial strains, Propionobacterium shermanii and Pseudomonas denitrificans, that involves about 30 enzymatic steps in the biosynthesis of cobalamin and completely replaces chemical synthesis. However, there are still unresolved issues in cobalamin biosynthesis that need to be elucidated for future bioprocess improvements. In the present work, we review the current state of development and challenges for cobalamin (vitamin B12) biosynthesis, describing the major and novel prospective strains, and the studies of environmental factors and genetic tools effecting on the fermentation process are reported.
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Affiliation(s)
- Larissa Balabanova
- Department of Bioeconomy and Food Security, School of Economics and Management, Far Eastern Federal University, 690922 Vladivostok, Russia; (L.A.); (M.M.); (O.S.); (L.T.)
- Laboratory of Marine Biochemistry, G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, 690022 Vladivostok, Russia
- ARNIKA, Territory of PDA Nadezhdinskaya, 692481 Primorskiy Region, Russia
- Correspondence:
| | - Liudmila Averianova
- Department of Bioeconomy and Food Security, School of Economics and Management, Far Eastern Federal University, 690922 Vladivostok, Russia; (L.A.); (M.M.); (O.S.); (L.T.)
- ARNIKA, Territory of PDA Nadezhdinskaya, 692481 Primorskiy Region, Russia
| | - Maksim Marchenok
- Department of Bioeconomy and Food Security, School of Economics and Management, Far Eastern Federal University, 690922 Vladivostok, Russia; (L.A.); (M.M.); (O.S.); (L.T.)
- ARNIKA, Territory of PDA Nadezhdinskaya, 692481 Primorskiy Region, Russia
| | - Oksana Son
- Department of Bioeconomy and Food Security, School of Economics and Management, Far Eastern Federal University, 690922 Vladivostok, Russia; (L.A.); (M.M.); (O.S.); (L.T.)
- ARNIKA, Territory of PDA Nadezhdinskaya, 692481 Primorskiy Region, Russia
| | - Liudmila Tekutyeva
- Department of Bioeconomy and Food Security, School of Economics and Management, Far Eastern Federal University, 690922 Vladivostok, Russia; (L.A.); (M.M.); (O.S.); (L.T.)
- ARNIKA, Territory of PDA Nadezhdinskaya, 692481 Primorskiy Region, Russia
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Yan J, Wang J, Villalobos Solis MI, Jin H, Chourey K, Li X, Yang Y, Yin Y, Hettich RL, Löffler FE. Respiratory Vinyl Chloride Reductive Dechlorination to Ethene in TceA-Expressing Dehalococcoides mccartyi. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:4831-4841. [PMID: 33683880 DOI: 10.1021/acs.est.0c07354] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Bioremediation of chlorinated ethenes in anoxic aquifers hinges on organohalide-respiring Dehalococcoidia expressing vinyl chloride (VC) reductive dehalogenase (RDase). The tceA gene encoding the trichloroethene-dechlorinating RDase TceA is frequently detected in contaminated groundwater but not recognized as a biomarker for VC detoxification. We demonstrate that tceA-carrying Dehalococcoides mccartyi (Dhc) strains FL2 and 195 grow with VC as an electron acceptor when sufficient vitamin B12 (B12) is provided. Strain FL2 cultures that received 50 μg L-1 B12 completely dechlorinated VC to ethene at rates of 14.80 ± 1.30 μM day-1 and attained 1.64 ± 0.11 × 108 cells per μmol of VC consumed. Strain 195 attained similar growth yields of 1.80 ± 1.00 × 108 cells per μmol of VC consumed, and both strains could be consecutively transferred with VC as the electron acceptor. Proteomic analysis demonstrated TceA expression in VC-grown strain FL2 cultures. Resequencing of the strain FL2 and strain 195 tceA genes identified non-synonymous substitutions, although their consequences for TceA function are currently unknown. The finding that Dhc strains expressing TceA respire VC can explain ethene formation at chlorinated solvent sites, where quantitative polymerase chain reaction analysis indicates that tceA dominates the RDase gene pool.
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Affiliation(s)
- Jun Yan
- Key Laboratory of Pollution Control and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Jingjing Wang
- Key Laboratory of Pollution Control and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | | | - Huijuan Jin
- Key Laboratory of Pollution Control and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Karuna Chourey
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Xiuying Li
- Key Laboratory of Pollution Control and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
| | - Yi Yang
- Key Laboratory of Pollution Control and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
| | - Yongchao Yin
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Robert L Hettich
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Frank E Löffler
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Joint Institute for Biological Sciences (JIBS), Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
- Department of Biosystems Engineering & Soil Science, University of Tennessee, Knoxville, Tennessee 37996, United States
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Abstract
Salmonella is a human pathogen of worldwide importance, and coenzyme B12 is critical for the pathogenic lifestyle of this bacterium. The importance of the work reported here lies on the improvements to the methodology used to isolate cobamide synthase, a polytopic integral membrane protein that catalyzes the penultimate step of coenzyme B12 biosynthesis. Cobamides are cobalt-containing cyclic tetrapyrroles used by cells from all domains of life but only produced de novo by some bacteria and archaea. The “late steps” of the adenosylcobamide biosynthetic pathway are responsible for the assembly of the nucleotide loop and are required during de novo synthesis and precursor salvaging. These steps are characterized by activation of the corrin ring and lower ligand base, condensation of the activated precursors to adenosylcobamide phosphate, and removal of the phosphate, yielding a complete adenosylcobamide molecule. The condensation of the activated corrin ring and lower ligand base is performed by an integral membrane protein, cobamide (5′ phosphate) synthase (CobS), and represents an important convergence of two pathways necessary for nucleotide loop assembly. Interestingly, membrane association of this penultimate step is conserved among all cobamide producers, yet the physiological relevance of this association is not known. Here, we present the purification and biochemical characterization of the CobS enzyme of the enterobacterium Salmonella enterica subsp. enterica serovar Typhimurium strain LT2, investigate its association with liposomes, and quantify the effect of the lipid bilayer on its enzymatic activity and substrate affinity. We report a purification scheme that yields pure CobS protein, allowing in vitro functional analysis. Additionally, we report a method for liposome reconstitution of CobS, allowing for physiologically relevant studies of this inner membrane protein in a phospholipid bilayer. In vitro and in vivo data reported here expand our understanding of CobS and the implications of membrane-associated adenosylcobamide biosynthesis.
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Zhuge J, Jiang Z, Jiang W, Histand G, Lin D. Iodine-catalyzed oxidative functionalization of purines with (thio)ethers or methylarenes for the synthesis of purin-8-one analogues. Org Biomol Chem 2021; 19:5121-5126. [PMID: 34018534 DOI: 10.1039/d1ob00118c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An efficient oxidative functionalization of purine-like substrates with (thio)ethers or methylarenes under mild conditions is described. Using I2 as the catalyst, and TBHP as the oxidant, this protocol provides a valuable synthetic tool for the assembly of a wide range of 9-alkyl(benzyl)purin-8-one derivatives with high atom- and step-economy and exceptional functional group tolerance.
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Affiliation(s)
- Juanping Zhuge
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Ziyang Jiang
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Wei Jiang
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Gary Histand
- International School of Advanced Materials, South China University of Technology, Guangzhou 510640, China
| | - Dongen Lin
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China.
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Identification of a Novel Cobamide Remodeling Enzyme in the Beneficial Human Gut Bacterium Akkermansia muciniphila. mBio 2020; 11:mBio.02507-20. [PMID: 33293380 PMCID: PMC7733943 DOI: 10.1128/mbio.02507-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Cobamides, comprising the vitamin B12 family of cobalt-containing cofactors, are required for metabolism in all domains of life, including most bacteria. Cobamides have structural variability in the lower ligand, and selectivity for particular cobamides has been observed in most organisms studied to date. The beneficial human gut bacterium Akkermansia muciniphila provides metabolites to other members of the gut microbiota by breaking down host mucin, but most of its other metabolic functions have not been investigated. A. muciniphila strain MucT is known to use cobamides, the vitamin B12 family of cofactors with structural diversity in the lower ligand. However, A. muciniphila MucT is unable to synthesize cobamides de novo, and the specific forms that can be used by A. muciniphila have not been examined. We found that the levels of growth of A. muciniphila MucT were nearly identical with each of seven cobamides tested, in contrast to nearly all bacteria that had been studied previously. Unexpectedly, this promiscuity is due to cobamide remodeling—the removal and replacement of the lower ligand—despite the absence of the canonical remodeling enzyme CbiZ in A. muciniphila. We identified a novel enzyme, CbiR, that is capable of initiating the remodeling process by hydrolyzing the phosphoribosyl bond in the nucleotide loop of cobamides. CbiR does not share similarity with other cobamide remodeling enzymes or B12-binding domains and is instead a member of the apurinic/apyrimidinic (AP) endonuclease 2 enzyme superfamily. We speculate that CbiR enables bacteria to repurpose cobamides that they cannot otherwise use in order to grow under cobamide-requiring conditions; this function was confirmed by heterologous expression of cbiR in Escherichia coli. Homologs of CbiR are found in over 200 microbial taxa across 22 phyla, suggesting that many bacteria may use CbiR to gain access to the diverse cobamides present in their environment.
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29
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Xie Y, Chen G, May AL, Yan J, Brown LP, Powers JB, Campagna SR, Löffler FE. Pseudomonas sp. Strain 273 Degrades Fluorinated Alkanes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:14994-15003. [PMID: 33190477 DOI: 10.1021/acs.est.0c04029] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Fluorinated organic compounds have emerged as environmental constituents of concern. We demonstrate that the alkane degrader Pseudomonas sp. strain 273 utilizes terminally monofluorinated C7-C10 alkanes and 1,10-difluorodecane (DFD) as the sole carbon and energy sources in the presence of oxygen. Strain 273 degraded 1-fluorodecane (FD) (5.97 ± 0.22 mM, nominal) and DFD (5.62 ± 0.13 mM, nominal) within 7 days of incubation, and 92.7 ± 3.8 and 90.1 ± 1.9% of the theoretical maximum amounts of fluorine were recovered as inorganic fluoride, respectively. With n-decane, strain 273 attained (3.24 ± 0.14) × 107 cells per μmol of carbon consumed, while lower biomass yields of (2.48 ± 0.15) × 107 and (1.62 ± 0.23) × 107 cells were measured with FD or DFD as electron donors, respectively. The organism coupled decanol and decanoate oxidation to denitrification, but the utilization of (fluoro)alkanes was strictly oxygen-dependent, presumably because the initial attack on the terminal carbon requires oxygen. Fluorohexanoate was detected as an intermediate in cultures grown with FD or DFD, suggesting that the initial attack on the fluoroalkanes can occur on the terminal methyl or fluoromethyl groups. The findings indicate that specialized bacteria such as Pseudomonas sp. strain 273 can break carbon-fluorine bonds most likely with oxygenolytic enzyme systems and that terminally monofluorinated alkanes are susceptible to microbial degradation. The findings have implications for the fate of components associated with aqueous film-forming foam (AFFF) mixtures.
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Affiliation(s)
- Yongchao Xie
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Gao Chen
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Amanda L May
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Jun Yan
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, China
| | - Lindsay P Brown
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Joshua B Powers
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Shawn R Campagna
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
- Biological and Small Molecule Mass Spectrometry Core, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Frank E Löffler
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, Tennessee 37996, United States
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30
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Sokolovskaya OM, Shelton AN, Taga ME. Sharing vitamins: Cobamides unveil microbial interactions. Science 2020; 369:369/6499/eaba0165. [PMID: 32631870 DOI: 10.1126/science.aba0165] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Microbial communities are essential to fundamental processes on Earth. Underlying the compositions and functions of these communities are nutritional interdependencies among individual species. One class of nutrients, cobamides (the family of enzyme cofactors that includes vitamin B12), is widely used for a variety of microbial metabolic functions, but these structurally diverse cofactors are synthesized by only a subset of bacteria and archaea. Advances at different scales of study-from individual isolates, to synthetic consortia, to complex communities-have led to an improved understanding of cobamide sharing. Here, we discuss how cobamides affect microbes at each of these three scales and how integrating different approaches leads to a more complete understanding of microbial interactions.
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Affiliation(s)
- Olga M Sokolovskaya
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Amanda N Shelton
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Michiko E Taga
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, USA.
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31
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Sokolovskaya OM, Plessl T, Bailey H, Mackinnon S, Baumgartner MR, Yue WW, Froese DS, Taga ME. Naturally occurring cobalamin (B 12) analogs can function as cofactors for human methylmalonyl-CoA mutase. Biochimie 2020; 183:35-43. [PMID: 32659443 DOI: 10.1016/j.biochi.2020.06.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 06/26/2020] [Accepted: 06/30/2020] [Indexed: 12/20/2022]
Abstract
Cobalamin, commonly known as vitamin B12, is an essential micronutrient for humans because of its role as an enzyme cofactor. Cobalamin is one of over a dozen structurally related compounds - cobamides - that are found in certain foods and are produced by microorganisms in the human gut. Very little is known about how different cobamides affect B12-dependent metabolism in human cells. Here, we test in vitro how diverse cobamide cofactors affect the function of methylmalonyl-CoA mutase (MMUT), one of two cobalamin-dependent enzymes in humans. We find that, although cobalamin is the most effective cofactor for MMUT, multiple cobamides support MMUT function with differences in binding affinity (Kd), binding kinetics (kon), and concentration dependence during catalysis (KM, app). Additionally, we find that six disease-associated MMUT variants that cause cobalamin-responsive impairments in enzymatic activity also respond to other cobamides, with the extent of catalytic rescue dependent on the identity of the cobamide. Our studies challenge the exclusive focus on cobalamin in the context of human physiology, indicate that diverse cobamides can support the function of a human enzyme, and suggest future directions that will improve our understanding of the roles of different cobamides in human biology.
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Affiliation(s)
- Olga M Sokolovskaya
- Department of Plant & Microbial Biology, University of California, Berkeley, CA, USA; Department of Chemistry, University of California, Berkeley, CA, USA
| | - Tanja Plessl
- Division of Metabolism and Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Henry Bailey
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, UK
| | - Sabrina Mackinnon
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, UK
| | - Matthias R Baumgartner
- Division of Metabolism and Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Wyatt W Yue
- Structural Genomics Consortium, Nuffield Department of Clinical Medicine, University of Oxford, UK
| | - D Sean Froese
- Division of Metabolism and Children's Research Center, University Children's Hospital, Zurich, Switzerland
| | - Michiko E Taga
- Department of Plant & Microbial Biology, University of California, Berkeley, CA, USA.
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Heacock ML, Amolegbe SM, Skalla LA, Trottier BA, Carlin DJ, Henry HF, Lopez AR, Duncan CG, Lawler CP, Balshaw DM, Suk WA. Sharing SRP data to reduce environmentally associated disease and promote transdisciplinary research. REVIEWS ON ENVIRONMENTAL HEALTH 2020; 35:111-122. [PMID: 32126018 DOI: 10.1515/reveh-2019-0089] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 01/06/2020] [Indexed: 05/25/2023]
Abstract
The National Institute of Environmental Health Sciences (NIEHS) Superfund Basic Research and Training Program (SRP) funds a wide range of projects that span biomedical, environmental sciences, and engineering research and generate a wealth of data resulting from hypothesis-driven research projects. Combining or integrating these diverse data offers an opportunity to uncover new scientific connections that can be used to gain a more comprehensive understanding of the interplay between exposures and health. Integrating and reusing data generated from individual research projects within the program requires harmonization of data workflows, ensuring consistent and robust practices in data stewardship, and embracing data sharing from the onset of data collection and analysis. We describe opportunities to leverage data within the SRP and current SRP efforts to advance data sharing and reuse, including by developing an SRP dataset library and fostering data integration through Data Management and Analysis Cores. We also discuss opportunities to improve public health by identifying parallels in the data captured from health and engineering research, layering data streams for a more comprehensive picture of exposures and disease, and using existing SRP research infrastructure to facilitate and foster data sharing. Importantly, we point out that while the SRP is in a unique position to exploit these opportunities, they can be employed across environmental health research. SRP research teams, which comprise cross-disciplinary scientists focused on similar research questions, are well positioned to use data to leverage previous findings and accelerate the pace of research. Incorporating data streams from different disciplines addressing similar questions can provide a broader understanding and uncover the answers to complex and discrete research questions.
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Affiliation(s)
- Michelle L Heacock
- Superfund Research Program, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC, USA
| | | | | | - Brittany A Trottier
- Superfund Research Program, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC, USA
| | - Danielle J Carlin
- Superfund Research Program, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC, USA
| | - Heather F Henry
- Superfund Research Program, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC, USA
| | | | - Christopher G Duncan
- National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC, USA
| | - Cindy P Lawler
- National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC, USA
| | - David M Balshaw
- National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC, USA
| | - William A Suk
- Superfund Research Program, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC, USA
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33
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Flexible Cobamide Metabolism in Clostridioides ( Clostridium) difficile 630 Δ erm. J Bacteriol 2020; 202:JB.00584-19. [PMID: 31685533 DOI: 10.1128/jb.00584-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 10/26/2019] [Indexed: 01/05/2023] Open
Abstract
Clostridioides (Clostridium) difficile is an opportunistic pathogen known for its ability to colonize the human gut under conditions of dysbiosis. Several aspects of its carbon and amino acid metabolism have been investigated, but its cobamide (vitamin B12 and related cofactors) metabolism remains largely unexplored. C. difficile has seven predicted cobamide-dependent pathways encoded in its genome in addition to a nearly complete cobamide biosynthesis pathway and a cobamide uptake system. To address the importance of cobamides to C. difficile, we studied C. difficile 630 Δerm and mutant derivatives under cobamide-dependent conditions in vitro Our results show that C. difficile can use a surprisingly diverse array of cobamides for methionine and deoxyribonucleotide synthesis and can use alternative metabolites or enzymes, respectively, to bypass these cobamide-dependent processes. C. difficile 630 Δerm produces the cobamide pseudocobalamin when provided the early precursor 5-aminolevulinic acid or the late intermediate cobinamide (Cbi) and produces other cobamides if provided an alternative lower ligand. The ability of C. difficile 630 Δerm to take up cobamides and Cbi at micromolar or lower concentrations requires the transporter BtuFCD. Genomic analysis revealed genetic variations in the btuFCD loci of different C. difficile strains, which may result in differences in the ability to take up cobamides and Cbi. These results together demonstrate that, like other aspects of its physiology, cobamide metabolism in C. difficile is versatile.IMPORTANCE The ability of the opportunistic pathogen Clostridioides difficile to cause disease is closely linked to its propensity to adapt to conditions created by dysbiosis of the human gut microbiota. The cobamide (vitamin B12) metabolism of C. difficile has been underexplored, although it has seven metabolic pathways that are predicted to require cobamide-dependent enzymes. Here, we show that C. difficile cobamide metabolism is versatile, as it can use a surprisingly wide variety of cobamides and has alternative functions that can bypass some of its cobamide requirements. Furthermore, C. difficile does not synthesize cobamides de novo but produces them when given cobamide precursors. A better understanding of C. difficile cobamide metabolism may lead to new strategies to treat and prevent C. difficile-associated disease.
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Retroconversion of estrogens into androgens by bacteria via a cobalamin-mediated methylation. Proc Natl Acad Sci U S A 2019; 117:1395-1403. [PMID: 31848239 DOI: 10.1073/pnas.1914380117] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Steroid estrogens modulate physiology and development of vertebrates. Conversion of C19 androgens into C18 estrogens is thought to be an irreversible reaction. Here, we report a denitrifying Denitratisoma sp. strain DHT3 capable of catabolizing estrogens or androgens anaerobically. Strain DHT3 genome contains a polycistronic gene cluster, emtABCD, differentially transcribed under estrogen-fed conditions and predicted to encode a cobalamin-dependent methyltransferase system conserved among estrogen-utilizing anaerobes; an emtA-disrupted DHT3 derivative could catabolize androgens but not estrogens. These data, along with the observed androgen production in estrogen-fed strain DHT3 cultures, suggested the occurrence of a cobalamin-dependent estrogen methylation to form androgens. Consistently, the estrogen conversion into androgens in strain DHT3 cell extracts requires methylcobalamin and is inhibited by propyl iodide, a specific inhibitor of cobalamin-dependent enzymes. The identification of the cobalamin-dependent estrogen methylation thus represents an unprecedented metabolic link between cobalamin and steroid metabolism and suggests that retroconversion of estrogens into androgens occurs in the biosphere.
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35
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Li Y, Wen LL, Zhao HP, Zhu L. Addition of Shewanella oneidensis MR-1 to the Dehalococcoides-containing culture enhances the trichloroethene dechlorination. ENVIRONMENT INTERNATIONAL 2019; 133:105245. [PMID: 31683156 DOI: 10.1016/j.envint.2019.105245] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 09/28/2019] [Accepted: 10/04/2019] [Indexed: 06/10/2023]
Abstract
Dehalococcoides is able to completely dehalogenate tetrachloroethene (PCE) and trichloroethene (TCE) to ethene (ETH). However, the dechlorination efficiency of Dehalococcoides is low and result in the accumulation of toxic intermediates. In this study, Shewanella oneidensis MR-1 (S. oneidensis MR-1) was added to the Dehalococcoides-containing culture and the complete TCE to ETH dechlorination was shortened from 24 days to 16 days. Dehalococcoides-targeted 16S rRNA gene and two model reductive dehalogenase (RDase) genes (tceA and vcrA), responsible for dechlorinating TCE to vinyl chloride (VC) and VC to ETH respectively, were characterized. Results showed that S. oneidensis MR-1 has no effect on the cell growth while the RDase genes expression was up-regulated and the RDase activity of Dehalococcoides was elevated. The mRNA abundance of vcrA increased approximately tenfold along with the increased concentration of vitamin B12 (cyanocobalamin). Interestingly, the addition of S. oneidensis MR-1 increased the concentration of vitamin B12 by affecting the microbial community structure. Therefore, the addition of S. oneidensis MR-1 might have a positive effect on regulating the activity of RDase of functional microorganisms and uptake of vitamin B12, and further provided a practical vision of chloroethene dechlorination by the Dehalococcoides-containing culture.
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Affiliation(s)
- Yaru Li
- College of Environmental and Resource Science, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Organic Pollution Process and Control, Zhejiang Province, Zhejiang University, Hangzhou 310058, China
| | - Li-Lian Wen
- College of Environmental and Resource Science, Zhejiang University, Hangzhou 310058, China; College of Resource and Environmental Science, Hubei University, Wuhan 430062, China
| | - He-Ping Zhao
- College of Environmental and Resource Science, Zhejiang University, Hangzhou 310058, China
| | - Lizhong Zhu
- College of Environmental and Resource Science, Zhejiang University, Hangzhou 310058, China; Key Laboratory of Organic Pollution Process and Control, Zhejiang Province, Zhejiang University, Hangzhou 310058, China.
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Puentes Jácome LA, Wang PH, Molenda O, Li YXJJ, Islam MA, Edwards EA. Sustained Dechlorination of Vinyl Chloride to Ethene in Dehalococcoides-Enriched Cultures Grown without Addition of Exogenous Vitamins and at Low pH. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:11364-11374. [PMID: 31441646 DOI: 10.1021/acs.est.9b02339] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Trichloroethene (TCE) bioremediation has been demonstrated at field sites using microbial cultures harboring TCE-respiring Dehalococcoides whose growth is cobalamin (vitamin B12)-dependent. Bioaugmentation cultures grown ex situ with ample exogenous vitamins and at neutral pH may become vitamin-limited or inhibited by acidic pH once injected into field sites, resulting in incomplete TCE dechlorination and accumulation of vinyl chloride (VC). Here, we report growth of the Dehalococcoides-containing bioaugmentation culture KB-1 in a TCE-amended mineral medium devoid of vitamins and in a VC-amended mineral medium at low pH (6.0 and 5.5). In these cultures, Acetobacterium, which can synthesize 5,6-dimethylbenzimidazole (DMB), the lower ligand of cobalamin, and Sporomusa are dominant acetogens. At neutral pH, Acetobacterium supports complete TCE dechlorination by Dehalococcoides at millimolar levels with a substantial increase in cobalamin (∼20-fold). Sustained dechlorination of VC to ethene was achieved at pH as low as 5.5. Below pH 5.0, dechlorination was not stimulated by DMB supplementation but was restored by raising pH to neutral. Cell-extract assays revealed that vinyl chloride reductase activity declines significantly below pH 6.0 and is undetectable below pH 5.0. This study highlights the importance of cobamide-producing populations and pH in microbial dechlorinating communities for successful bioremediation at field sites.
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Affiliation(s)
- Luz A Puentes Jácome
- Department of Chemical Engineering and Applied Chemistry , University of Toronto , Toronto , Ontario M5S 3E5 , Canada
| | - Po-Hsiang Wang
- Department of Chemical Engineering and Applied Chemistry , University of Toronto , Toronto , Ontario M5S 3E5 , Canada
| | - Olivia Molenda
- Department of Chemical Engineering and Applied Chemistry , University of Toronto , Toronto , Ontario M5S 3E5 , Canada
| | - Yi Xuan Jine-Jine Li
- Department of Chemical Engineering and Applied Chemistry , University of Toronto , Toronto , Ontario M5S 3E5 , Canada
| | - M Ahsanul Islam
- Department of Chemical Engineering and Applied Chemistry , University of Toronto , Toronto , Ontario M5S 3E5 , Canada
| | - Elizabeth A Edwards
- Department of Chemical Engineering and Applied Chemistry , University of Toronto , Toronto , Ontario M5S 3E5 , Canada
- Department of Cell and Systems Biology , University of Toronto , Toronto , Ontario M5S 3G5 , Canada
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37
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Sokolovskaya OM, Mok KC, Park JD, Tran JLA, Quanstrom KA, Taga ME. Cofactor Selectivity in Methylmalonyl Coenzyme A Mutase, a Model Cobamide-Dependent Enzyme. mBio 2019; 10:e01303-19. [PMID: 31551329 PMCID: PMC6759758 DOI: 10.1128/mbio.01303-19] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 08/23/2019] [Indexed: 12/25/2022] Open
Abstract
Cobamides, a uniquely diverse family of enzyme cofactors related to vitamin B12, are produced exclusively by bacteria and archaea but used in all domains of life. While it is widely accepted that cobamide-dependent organisms require specific cobamides for their metabolism, the biochemical mechanisms that make cobamides functionally distinct are largely unknown. Here, we examine the effects of cobamide structural variation on a model cobamide-dependent enzyme, methylmalonyl coenzyme A (CoA) mutase (MCM). The in vitro binding affinity of MCM for cobamides can be dramatically influenced by small changes in the structure of the lower ligand of the cobamide, and binding selectivity differs between bacterial orthologs of MCM. In contrast, variations in the lower ligand have minor effects on MCM catalysis. Bacterial growth assays demonstrate that cobamide requirements of MCM in vitro largely correlate with in vivo cobamide dependence. This result underscores the importance of enzyme selectivity in the cobamide-dependent physiology of bacteria.IMPORTANCE Cobamides, including vitamin B12, are enzyme cofactors used by organisms in all domains of life. Cobamides are structurally diverse, and microbial growth and metabolism vary based on cobamide structure. Understanding cobamide preference in microorganisms is important given that cobamides are widely used and appear to mediate microbial interactions in host-associated and aquatic environments. Until now, the biochemical basis for cobamide preferences was largely unknown. In this study, we analyzed the effects of the structural diversity of cobamides on a model cobamide-dependent enzyme, methylmalonyl-CoA mutase (MCM). We found that very small changes in cobamide structure could dramatically affect the binding affinity of cobamides to MCM. Strikingly, cobamide-dependent growth of a model bacterium, Sinorhizobium meliloti, largely correlated with the cofactor binding selectivity of S. meliloti MCM, emphasizing the importance of cobamide-dependent enzyme selectivity in bacterial growth and cobamide-mediated microbial interactions.
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Affiliation(s)
- Olga M Sokolovskaya
- Department of Plant & Microbial Biology, University of California Berkeley, Berkeley, California, USA
- Department of Chemistry, University of California Berkeley, Berkeley, California, USA
| | - Kenny C Mok
- Department of Plant & Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Jong Duk Park
- Department of Plant & Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Jennifer L A Tran
- Department of Plant & Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Kathryn A Quanstrom
- Department of Plant & Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Michiko E Taga
- Department of Plant & Microbial Biology, University of California Berkeley, Berkeley, California, USA
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Complete Genome Sequence of Dehalococcoides mccartyi Strain FL2, a Trichloroethene-Respiring Anaerobe Isolated from Pristine Freshwater Sediment. Microbiol Resour Announc 2019; 8:8/33/e00558-19. [PMID: 31416865 PMCID: PMC6696640 DOI: 10.1128/mra.00558-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Dehalococcoides mccartyi strain FL2 couples growth to hydrogen oxidation and reductive dechlorination of trichloroethene and cis- and trans-1,2-dichloroethenes. Strain FL2 has a 1.42-Mb genome with a G+C content of 47.0% and carries 1,465 protein-coding sequences, including 24 reductive dehalogenase genes.
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Schubert T, von Reuß SH, Kunze C, Paetz C, Kruse S, Brand‐Schön P, Nelly AM, Nüske J, Diekert G. Guided cobamide biosynthesis for heterologous production of reductive dehalogenases. Microb Biotechnol 2019; 12:346-359. [PMID: 30549216 PMCID: PMC6389850 DOI: 10.1111/1751-7915.13339] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 10/23/2018] [Accepted: 10/30/2018] [Indexed: 12/01/2022] Open
Abstract
Cobamides (Cbas) are essential cofactors of reductive dehalogenases (RDases) in organohalide-respiring bacteria (OHRB). Changes in the Cba structure can influence RDase function. Here, we report on the cofactor versatility or selectivity of Desulfitobacterium RDases produced either in the native organism or heterologously. The susceptibility of Desulfitobacterium hafniense strain DCB-2 to guided Cba biosynthesis (i.e. incorporation of exogenous Cba lower ligand base precursors) was analysed. Exogenous benzimidazoles, azabenzimidazoles and 4,5-dimethylimidazole were incorporated by the organism into Cbas. When the type of Cba changed, no effect on the turnover rate of the 3-chloro-4-hydroxy-phenylacetate-converting enzyme RdhA6 and the 3,5-dichlorophenol-dehalogenating enzyme RdhA3 was observed. The impact of the amendment of Cba lower ligand precursors on RDase function was also investigated in Shimwellia blattae, the Cba producer used for the heterologous production of Desulfitobacterium RDases. The recombinant tetrachloroethene RDase (PceAY51 ) appeared to be non-selective towards different Cbas. However, the functional production of the 1,2-dichloroethane-dihaloeliminating enzyme (DcaA) of Desulfitobacterium dichloroeliminans was completely prevented in cells producing 5,6-dimethylbenzimidazolyl-Cba, but substantially enhanced in cells that incorporated 5-methoxybenzimidazole into the Cba cofactor. The results of the study indicate the utilization of a range of different Cbas by Desulfitobacterium RDases with selected representatives apparently preferring distinct Cbas.
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Affiliation(s)
- Torsten Schubert
- Department of Applied and Ecological MicrobiologyInstitute of MicrobiologyFriedrich Schiller UniversityPhilosophenweg 12D‐07743JenaGermany
| | - Stephan H. von Reuß
- Department of Bioorganic ChemistryMax Planck Institute for Chemical EcologyHans‐Knöll‐Straße 8D‐07745JenaGermany
- Present address:
Laboratory for Bioanalytical ChemistryInstitute of ChemistryUniversity of NeuchâtelAvenue de Bellevaux 512000NeuchâtelSwitzerland
| | - Cindy Kunze
- Department of Applied and Ecological MicrobiologyInstitute of MicrobiologyFriedrich Schiller UniversityPhilosophenweg 12D‐07743JenaGermany
- Present address:
DECHEMA‐ForschungsinstitutTheodor‐Heuss‐Allee 25D‐60486Frankfurt am MainGermany
| | - Christian Paetz
- Research Group Biosynthesis/NMRMax Planck Institute for Chemical EcologyHans‐Knöll‐Straße 8D‐07745JenaGermany
| | - Stefan Kruse
- Department of Applied and Ecological MicrobiologyInstitute of MicrobiologyFriedrich Schiller UniversityPhilosophenweg 12D‐07743JenaGermany
| | - Peggy Brand‐Schön
- Department of Applied and Ecological MicrobiologyInstitute of MicrobiologyFriedrich Schiller UniversityPhilosophenweg 12D‐07743JenaGermany
| | - Anita Mac Nelly
- Department of Applied and Ecological MicrobiologyInstitute of MicrobiologyFriedrich Schiller UniversityPhilosophenweg 12D‐07743JenaGermany
| | - Jörg Nüske
- Department of Applied and Ecological MicrobiologyInstitute of MicrobiologyFriedrich Schiller UniversityPhilosophenweg 12D‐07743JenaGermany
| | - Gabriele Diekert
- Department of Applied and Ecological MicrobiologyInstitute of MicrobiologyFriedrich Schiller UniversityPhilosophenweg 12D‐07743JenaGermany
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40
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Türkowsky D, Jehmlich N, Diekert G, Adrian L, von Bergen M, Goris T. An integrative overview of genomic, transcriptomic and proteomic analyses in organohalide respiration research. FEMS Microbiol Ecol 2019; 94:4830072. [PMID: 29390082 DOI: 10.1093/femsec/fiy013] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 01/24/2018] [Indexed: 02/06/2023] Open
Abstract
Organohalide respiration (OHR) is a crucial process in the global halogen cycle and of interest for bioremediation. However, investigations on OHR are hampered by the restricted genetic accessibility and the poor growth yields of many organohalide-respiring bacteria (OHRB). Therefore, genomics, transcriptomics and proteomics are often used to investigate OHRB. In general, these gene expression studies are more useful when the data of the different 'omics' approaches are integrated and compared among a wide range of cultivation conditions and ideally involve several closely related OHRB. Despite the availability of a couple of proteomic and transcriptomic datasets dealing with OHRB, such approaches are currently not covered in reviews. Therefore, we here present an integrative and comparative overview of omics studies performed with the OHRB Sulfurospirillum multivorans, Dehalococcoides mccartyi, Desulfitobacterium spp. and Dehalobacter restrictus. Genes, transcripts, proteins and the regulatory and biochemical processes involved in OHR are discussed, and a comprehensive view on the unusual metabolism of D. mccartyi, which is one of the few bacteria possibly using a quinone-independent respiratory chain, is provided. Several 'omics'-derived theories on OHRB, e.g. the organohalide-respiratory chain, hydrogen metabolism, corrinoid biosynthesis or one-carbon metabolism are critically discussed on the basis of this integrative approach.
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Affiliation(s)
- Dominique Türkowsky
- Department of Molecular Systems Biology, Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Nico Jehmlich
- Department of Molecular Systems Biology, Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany
| | - Gabriele Diekert
- Department of Applied and Ecological Microbiology, Institute of Microbiology, Friedrich Schiller University, Philosophenweg 12, 07743 Jena, Germany
| | - Lorenz Adrian
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany.,Chair of Geobiotechnology, Technische Universität Berlin, Ackerstraße 76, 13355 Berlin
| | - Martin von Bergen
- Department of Molecular Systems Biology, Helmholtz Centre for Environmental Research - UFZ, Permoserstraße 15, 04318 Leipzig, Germany.,Institute of Biochemistry, Faculty of Life Sciences, University of Leipzig, Brüderstraße 34, Germany
| | - Tobias Goris
- Department of Applied and Ecological Microbiology, Institute of Microbiology, Friedrich Schiller University, Philosophenweg 12, 07743 Jena, Germany
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Jeter VL, Mattes TA, Beattie NR, Escalante-Semerena JC. A New Class of Phosphoribosyltransferases Involved in Cobamide Biosynthesis Is Found in Methanogenic Archaea and Cyanobacteria. Biochemistry 2019; 58:951-964. [PMID: 30640434 DOI: 10.1021/acs.biochem.8b01253] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Cobamides are coenzymes used by cells from all domains of life but made de novo by only some bacteria and archaea. The last steps of the cobamide biosynthetic pathway activate the corrin ring and the lower ligand base, condense the activated intermediates, and dephosphorylate the product prior to the release of the biologically active coenzyme. In bacteria, a phosphoribosyltransferase (PRTase) enyzme activates the base into its α-mononucleotide. The enzyme from Salmonella enterica ( SeCobT) has been extensively biochemically and structurally characterized. The crystal structure of the putative PRTase from the archaeum Methanocaldococcus jannaschii ( MjCobT) is known, but its function has not been validated. Here we report the in vivo and in vitro characterization of MjCobT. In vivo, in vitro, and phylogenetic data reported here show that MjCobT belongs to a new class of NaMN-dependent PRTases. We also show that the Synechococcus sp. WH7803 CobT protein has PRTase activity in vivo. Lastly, results of isothermal titration calorimetry and analytical ultracentrifugation analysis show that the biologically active form of MjCobT is a dimer, not a trimer, as suggested by its crystal structure.
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42
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Yin Y, Yan J, Chen G, Murdoch FK, Pfisterer N, Löffler FE. Nitrous Oxide Is a Potent Inhibitor of Bacterial Reductive Dechlorination. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:692-701. [PMID: 30558413 PMCID: PMC6944068 DOI: 10.1021/acs.est.8b05871] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Organohalide-respiring bacteria are key players for the turnover of organohalogens. At sites impacted with chlorinated ethenes, bioremediation promotes reductive dechlorination; however, stoichiometric conversion to environmentally benign ethene is not always achieved. We demonstrate that nitrous oxide (N2O), a compound commonly present in groundwater, inhibits organohalide respiration. N2O concentrations in the low micromolar range decreased dechlorination rates and resulted in incomplete dechlorination of tetrachloroethene (PCE) in Geobacter lovleyi strain SZ and of cis-1,2-dichloroethene ( cDCE) and vinyl chloride (VC) in Dehalococcoides mccartyi strain BAV1 axenic cultures. Presumably, N2O interferes with reductive dechlorination by reacting with super-reduced Co(I)-corrinoids of reductive dehalogenases, which is supported by the finding that N2O did not inhibit corrinoid-independent fumarate-to-succinate reduction in strain SZ. Kinetic analyses revealed a best fit to the noncompetitive Michaelis-Menten inhibition model and determined N2O inhibitory constants, KI, for PCE and cDCE dechlorination of 40.8 ± 3.8 and 21.2 ± 3.5 μM in strain SZ and strain BAV1, respectively. The lowest KI value of 9.6 ± 0.4 μM was determined for VC to ethene reductive dechlorination in strain BAV1, suggesting that this crucial dechlorination step for achieving detoxification is most susceptible to N2O inhibition. Groundwater N2O concentrations exceeding 100 μM are not uncommon, especially in watersheds impacted by nitrate runoff from agricultural sources. Thus, dissolved N2O measurements can inform about cDCE and VC stalls at sites impacted with chlorinated ethenes.
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Affiliation(s)
- Yongchao Yin
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Jun Yan
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Liaoning 110016, People’s Republic of China
| | - Gao Chen
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Fadime Kara Murdoch
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Nina Pfisterer
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Frank E. Löffler
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States
- Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
- Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, Tennessee 37996, United States
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Corresponding Author: Phone: (865) 974-4933.
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Uneven distribution of cobamide biosynthesis and dependence in bacteria predicted by comparative genomics. ISME JOURNAL 2018; 13:789-804. [PMID: 30429574 PMCID: PMC6461909 DOI: 10.1038/s41396-018-0304-9] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 09/14/2018] [Accepted: 10/04/2018] [Indexed: 11/08/2022]
Abstract
The vitamin B12 family of cofactors known as cobamides are essential for a variety of microbial metabolisms. We used comparative genomics of 11,000 bacterial species to analyze the extent and distribution of cobamide production and use across bacteria. We find that 86% of bacteria in this data set have at least one of 15 cobamide-dependent enzyme families, but only 37% are predicted to synthesize cobamides de novo. The distribution of cobamide biosynthesis and use vary at the phylum level. While 57% of Actinobacteria are predicted to biosynthesize cobamides, only 0.6% of Bacteroidetes have the complete pathway, yet 96% of species in this phylum have cobamide-dependent enzymes. The form of cobamide produced by the bacteria could be predicted for 58% of cobamide-producing species, based on the presence of signature lower ligand biosynthesis and attachment genes. Our predictions also revealed that 17% of bacteria have partial biosynthetic pathways, yet have the potential to salvage cobamide precursors. Bacteria with a partial cobamide biosynthesis pathway include those in a newly defined, experimentally verified category of bacteria lacking the first step in the biosynthesis pathway. These predictions highlight the importance of cobamide and cobamide precursor salvaging as examples of nutritional dependencies in bacteria.
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Microbial Functional Responses to Cholesterol Catabolism in Denitrifying Sludge. mSystems 2018; 3:mSystems00113-18. [PMID: 30417110 PMCID: PMC6208644 DOI: 10.1128/msystems.00113-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/11/2018] [Indexed: 01/08/2023] Open
Abstract
Steroids are ubiquitous and abundant natural compounds that display recalcitrance. Biodegradation via sludge communities in wastewater treatment plants is the primary removal process for steroids. To date, compared to studies for aerobic steroid degradation, the knowledge of anaerobic degradation of steroids has been based on only a few model organisms. Due to the increase of anthropogenic impacts, steroid inputs may affect microbial diversity and functioning in ecosystems. Here, we first investigated microbial functional responses to cholesterol, the most abundant steroid in sludge, at the community level. Our metagenomic and metatranscriptomic analyses revealed that the capacities for cholesterol approach, uptake, and degradation are unique traits of certain low-abundance betaproteobacteria, indicating the importance of the rare biosphere in bioremediation. Apparent expression of genes involved in cofactor de novo synthesis and salvage pathways suggests that these micronutrients play important roles for cholesterol degradation in sludge communities. The 2,3-seco pathway, the pathway for anaerobic cholesterol degradation, has been established in the denitrifying betaproteobacterium Sterolibacterium denitrificans. However, knowledge of how microorganisms respond to cholesterol at the community level is elusive. Here, we applied mesocosm incubation and 16S rRNA sequencing to reveal that, in denitrifying sludge communities, three betaproteobacterial operational taxonomic units (OTUs) with low (94% to 95%) 16S rRNA sequence similarity to Stl. denitrificans are cholesterol degraders and members of the rare biosphere. Metatranscriptomic and metabolite analyses show that these degraders adopt the 2,3-seco pathway to sequentially catalyze the side chain and sterane of cholesterol and that two molybdoenzymes—steroid C25 dehydrogenase and 1-testosterone dehydrogenase/hydratase—are crucial for these bioprocesses, respectively. The metatranscriptome further suggests that these betaproteobacterial degraders display chemotaxis and motility toward cholesterol and that FadL-like transporters may be the key components for substrate uptake. Also, these betaproteobacteria are capable of transporting micronutrients and synthesizing cofactors essential for cellular metabolism and cholesterol degradation; however, the required cobalamin is possibly provided by cobalamin-de novo-synthesizing gamma-, delta-, and betaproteobacteria via the salvage pathway. Overall, our results indicate that the ability to degrade cholesterol in sludge communities is reserved for certain rare biosphere members and that C25 dehydrogenase can serve as a biomarker for sterol degradation in anoxic environments. IMPORTANCE Steroids are ubiquitous and abundant natural compounds that display recalcitrance. Biodegradation via sludge communities in wastewater treatment plants is the primary removal process for steroids. To date, compared to studies for aerobic steroid degradation, the knowledge of anaerobic degradation of steroids has been based on only a few model organisms. Due to the increase of anthropogenic impacts, steroid inputs may affect microbial diversity and functioning in ecosystems. Here, we first investigated microbial functional responses to cholesterol, the most abundant steroid in sludge, at the community level. Our metagenomic and metatranscriptomic analyses revealed that the capacities for cholesterol approach, uptake, and degradation are unique traits of certain low-abundance betaproteobacteria, indicating the importance of the rare biosphere in bioremediation. Apparent expression of genes involved in cofactor de novo synthesis and salvage pathways suggests that these micronutrients play important roles for cholesterol degradation in sludge communities.
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45
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Schubert T, Adrian L, Sawers RG, Diekert G. Organohalide respiratory chains: composition, topology and key enzymes. FEMS Microbiol Ecol 2018; 94:4923014. [DOI: 10.1093/femsec/fiy035] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 02/28/2018] [Indexed: 02/07/2023] Open
Affiliation(s)
- Torsten Schubert
- Department of Applied and Ecological Microbiology, Institute of Microbiology, Friedrich Schiller University, Philosophenweg 12, D-07743 Jena, Germany
| | - Lorenz Adrian
- Department Isotope Biogeochemistry, Helmholtz Centre for Environmental Research-UFZ, Permoserstraße 15, D-04318 Leipzig, Germany
- Department of Geobiotechnology, Technische Universität Berlin, Ackerstraße 74, D-13355 Berlin, Germany
| | - R Gary Sawers
- Institute of Biology/Microbiology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3, D-06120 Halle (Saale), Germany
| | - Gabriele Diekert
- Department of Applied and Ecological Microbiology, Institute of Microbiology, Friedrich Schiller University, Philosophenweg 12, D-07743 Jena, Germany
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46
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Walworth NG, Lee MD, Suffridge C, Qu P, Fu FX, Saito MA, Webb EA, Sañudo-Wilhelmy SA, Hutchins DA. Functional Genomics and Phylogenetic Evidence Suggest Genus-Wide Cobalamin Production by the Globally Distributed Marine Nitrogen Fixer Trichodesmium. Front Microbiol 2018; 9:189. [PMID: 29487583 PMCID: PMC5816740 DOI: 10.3389/fmicb.2018.00189] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Accepted: 01/26/2018] [Indexed: 11/17/2022] Open
Abstract
Only select prokaryotes can biosynthesize vitamin B12 (i.e., cobalamins), but these organic co-enzymes are required by all microbial life and can be vanishingly scarce across extensive ocean biomes. Although global ocean genome data suggest cyanobacteria to be a major euphotic source of cobalamins, recent studies have highlighted that >95% of cyanobacteria can only produce a cobalamin analog, pseudo-B12, due to the absence of the BluB protein that synthesizes the α ligand 5,6-dimethylbenzimidizole (DMB) required to biosynthesize cobalamins. Pseudo-B12 is substantially less bioavailable to eukaryotic algae, as only certain taxa can intracellularly remodel it to one of the cobalamins. Here we present phylogenetic, metagenomic, transcriptomic, proteomic, and chemical analyses providing multiple lines of evidence that the nitrogen-fixing cyanobacterium Trichodesmium transcribes and translates the biosynthetic, cobalamin-requiring BluB enzyme. Phylogenetic evidence suggests that the Trichodesmium DMB biosynthesis gene, bluB, is of ancient origin, which could have aided in its ecological differentiation from other nitrogen-fixing cyanobacteria. Additionally, orthologue analyses reveal two genes encoding iron-dependent B12 biosynthetic enzymes (cbiX and isiB), suggesting that iron availability may be linked not only to new nitrogen supplies from nitrogen fixation, but also to B12 inputs by Trichodesmium. These analyses suggest that Trichodesmium contains the genus-wide genomic potential for a previously unrecognized role as a source of cobalamins, which may prove to considerably impact marine biogeochemical cycles.
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Affiliation(s)
- Nathan G Walworth
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - Michael D Lee
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - Christopher Suffridge
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - Pingping Qu
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - Fei-Xue Fu
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - Mak A Saito
- Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Eric A Webb
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - Sergio A Sañudo-Wilhelmy
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| | - David A Hutchins
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
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