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Kraiselburd I, Brüls T, Heilmann G, Kaschani F, Kaiser M, Meckenstock RU. Metabolic reconstruction of the genome of candidate Desulfatiglans TRIP_1 and identification of key candidate enzymes for anaerobic phenanthrene degradation. Environ Microbiol 2019; 21:1267-1286. [PMID: 30680888 PMCID: PMC6849830 DOI: 10.1111/1462-2920.14527] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 12/12/2018] [Indexed: 11/30/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are widely distributed pollutants. As oxygen is rapidly depleted in water‐saturated PAH‐contaminated sites, anaerobic microorganisms are crucial for their consumption. Here, we report the metabolic pathway for anaerobic degradation of phenanthrene by a sulfate‐reducing enrichment culture (TRIP) obtained from a natural asphalt lake. The dominant organism of this culture belongs to the Desulfobacteraceae family of Deltaproteobacteria and genome‐resolved metagenomics led to the reconstruction of its genome along with a handful of genomes from lower abundance bacteria. Proteogenomic analyses confirmed metabolic capabilities for dissimilatory sulfate reduction and indicated the presence of the Embden‐Meyerhof‐Parnas pathway, a complete tricarboxylic acid cycle as well as a complete Wood‐Ljungdahl pathway. Genes encoding enzymes putatively involved in the degradation of phenanthrene were identified. This includes two gene clusters encoding a multisubunit carboxylase complex likely involved in the activation of phenanthrene, as well as genes encoding reductases potentially involved in subsequent ring dearomatization and reduction steps. The predicted metabolic pathways were corroborated by transcriptome and proteome analyses, and provide the first insights into the metabolic pathway responsible for the anaerobic degradation of three‐ringed PAHs.
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Affiliation(s)
- Ivana Kraiselburd
- Biofilm Centre, Aquatic Microbiology Department, Faculty of Chemistry, University Duisburg-Essen, Essen, Germany
| | - Thomas Brüls
- CEA, DRF, Institut Jacob, Genoscope, Evry, France.,CNRS-UMR8030, Université Paris-Saclay, Evry, France
| | - Geronimo Heilmann
- Centre of Medical Biotechnology, Chemical Biology Department, Faculty of Biology, University Duisburg-Essen, Essen, Germany
| | - Farnusch Kaschani
- Centre of Medical Biotechnology, Chemical Biology Department, Faculty of Biology, University Duisburg-Essen, Essen, Germany
| | - Markus Kaiser
- Centre of Medical Biotechnology, Chemical Biology Department, Faculty of Biology, University Duisburg-Essen, Essen, Germany
| | - Rainer U Meckenstock
- Biofilm Centre, Aquatic Microbiology Department, Faculty of Chemistry, University Duisburg-Essen, Essen, Germany
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2
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Yan Z, Maruyama A, Arakawa T, Fushinobu S, Wakagi T. Crystal structures of archaeal 2-oxoacid:ferredoxin oxidoreductases from Sulfolobus tokodaii. Sci Rep 2016; 6:33061. [PMID: 27619895 PMCID: PMC5020499 DOI: 10.1038/srep33061] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 08/16/2016] [Indexed: 11/22/2022] Open
Abstract
As the first three-dimensional structure of the two-subunit type 2-oxoacid:ferredoxin oxidoreductases (OFOR) from archaea, we solved the crystal structures of STK_23000/STK_22980 (StOFOR1) and STK_24350/STK_24330 (StOFOR2) from Sulfolobus tokodaii. They showed similar overall structures, consisting of two a- and b-subunit heterodimers containing thiamin pyrophosphate (TPP) cofactor and [4Fe-4S] cluster, but lack an intramolecular ferredoxin domain. Unlike other OFORs, StOFORs can utilize both pyruvate and 2-oxoglutarate, playing a key role in the central metabolism. In the structure of StOFOR2 in unreacted pyruvate complex form, carboxylate group of pyruvate is recognized by Arg344 and Thr257 from the a-subunit, which are conserved in pyruvate:ferredoxin oxidoreductase from Desulfovbrio africanus (DaPFOR). In the structure of StOFOR1 co-crystallized with 2-oxobutyrate, electron density corresponding to a 1-hydroxypropyl group (post-decarboxylation state) was observed at the thiazole ring of TPP. The binding pockets of the StOFORs surrounding the methyl or propyl group of the ligands are wider than that of DaPFOR. Mutational analyses indicated that several residues were responsible for the broad 2-oxoacid specificity of StOFORs. We also constructed a possible complex structural model by placing a Zn(2+)-containing dicluster ferredoxin of S. tokodaii into the large pocket of StOFOR2, providing insight into the electron transfer between the two redox proteins.
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Affiliation(s)
- Zhen Yan
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Akane Maruyama
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takatoshi Arakawa
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Shinya Fushinobu
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takayoshi Wakagi
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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Klimchuk OI, Dibrova DV, Mulkidjanian AY. Phylogenomic analysis identifies a sodium-translocating decarboxylating oxidoreductase in thermotogae. BIOCHEMISTRY (MOSCOW) 2016; 81:481-90. [DOI: 10.1134/s0006297916050059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Li B, Elliott SJ. The Catalytic Bias of 2-Oxoacid:ferredoxin Oxidoreductase in CO2: evolution and reduction through a ferredoxin-mediated electrocatalytic assay. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.02.119] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Santos SG, Diniz CG, Silva VL, Lima FL, Andrade HM, Chapeaurouge DA, Perales J, Serufo JC, Carvalho MAR, Farias LM. Differentially regulated proteins in Prevotella intermedia after oxidative stress analyzed by 2D electrophoresis and mass spectrometry. Anaerobe 2012; 18:76-82. [DOI: 10.1016/j.anaerobe.2011.12.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 12/09/2011] [Accepted: 12/12/2011] [Indexed: 10/14/2022]
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Saini R, Kapoor R, Kumar R, Siddiqi TO, Kumar A. CO2 utilizing microbes — A comprehensive review. Biotechnol Adv 2011; 29:949-60. [PMID: 21856405 DOI: 10.1016/j.biotechadv.2011.08.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 08/04/2011] [Accepted: 08/05/2011] [Indexed: 11/30/2022]
Affiliation(s)
- Rashmi Saini
- Department of Botany, North Campus, University of Delhi, New Delhi-110007, India
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Baughn AD, Garforth SJ, Vilchèze C, Jacobs WR. An anaerobic-type alpha-ketoglutarate ferredoxin oxidoreductase completes the oxidative tricarboxylic acid cycle of Mycobacterium tuberculosis. PLoS Pathog 2009; 5:e1000662. [PMID: 19936047 PMCID: PMC2773412 DOI: 10.1371/journal.ppat.1000662] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 10/22/2009] [Indexed: 11/29/2022] Open
Abstract
Aerobic organisms have a tricarboxylic acid (TCA) cycle that is functionally distinct from those found in anaerobic organisms. Previous reports indicate that the aerobic pathogen Mycobacterium tuberculosis lacks detectable α-ketoglutarate (KG) dehydrogenase activity and drives a variant TCA cycle in which succinyl-CoA is replaced by succinic semialdehyde. Here, we show that M. tuberculosis expresses a CoA-dependent KG dehydrogenase activity, albeit one that is typically found in anaerobic bacteria. Unlike most enzymes of this family, the M. tuberculosis KG: ferredoxin oxidoreductase (KOR) is extremely stable under aerobic conditions. This activity is absent in a mutant strain deleted for genes encoding a previously uncharacterized oxidoreductase, and this strain is impaired for aerobic growth in the absence of sufficient amounts of CO2. Interestingly, inhibition of the glyoxylate shunt or exclusion of exogenous fatty acids alleviates this growth defect, indicating the presence of an alternate pathway that operates in the absence of β-oxidation. Simultaneous disruption of KOR and the first enzyme of the succinic semialdehyde pathway (KG decarboxylase; KGD) results in strict dependence upon the glyoxylate shunt for growth, demonstrating that KG decarboxylase is also functional in M. tuberculosis intermediary metabolism. These observations demonstrate that unlike most organisms M. tuberculosis utilizes two distinct TCA pathways from KG, one that functions concurrently with β-oxidation (KOR-dependent), and one that functions in the absence of β-oxidation (KGD-dependent). As these pathways are regulated by metabolic cues, we predict that their differential utilization provides an advantage for growth in different environments within the host. Knowledge of the basic biology of Mycobacterium tuberculosis is essential to identifying novel ways to combat the emerging threat of drug-resistant tuberculosis. Since the tricarboxylic acid (TCA) cycle is a cornerstone of metabolism and M. tuberculosis does not possess a “typical” TCA cycle enzyme set, much effort has been focused on elucidating the components of this pathway. Previous reports indicate that M. tuberculosis possesses a variant TCA cycle in which succinic semialdehyde replaces succinyl-CoA. Since this pathway does not conserve as much metabolic energy as the canonical pathway, we considered an alternative hypothesis: that M. tuberculosis might possess an anaerobic type α-ketoglutarate dehydrogenase. In this manuscript, we investigate this previously unknown activity for mycobacteria using a combination of genetic and biochemical approaches, and demonstrate that M. tuberculosis is capable of driving a conventional TCA cycle in an unconventional way. We also validate the existence of the previously described variant pathway and provide evidence that these two pathways are differentially utilized in response to a metabolic signal, fatty acid catabolism.
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Affiliation(s)
- Anthony D. Baughn
- Howard Hughes Medical Institute, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Scott J. Garforth
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Catherine Vilchèze
- Howard Hughes Medical Institute, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - William R. Jacobs
- Howard Hughes Medical Institute, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, United States of America
- * E-mail:
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Yamamoto M, Ikeda T, Arai H, Ishii M, Igarashi Y. Carboxylation reaction catalyzed by 2-oxoglutarate:ferredoxin oxidoreductases from Hydrogenobacter thermophilus. Extremophiles 2009; 14:79-85. [PMID: 19894084 DOI: 10.1007/s00792-009-0289-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Accepted: 10/19/2009] [Indexed: 11/29/2022]
Abstract
Hydrogenobacter thermophilus TK-6 is a thermophilic, chemolithoautotrophic, hydrogen-oxidizing bacterium that fixes carbon dioxide via the reductive tricarboxylic acid (rTCA) cycle. 2-Oxoglutarate:ferredoxin oxidoreductase (OGOR) is the key enzyme in this cycle that fixes carbon dioxide. The genome of strain TK-6 encodes at least two distinct OGOR enzymes, termed For and Kor. We report here a method for measuring the carboxylation of succinyl-CoA catalyzed by OGORs. The method involves the in vitro coupling of OGOR with ferredoxin and pyruvate:ferredoxin oxidoreductase from strain TK-6, and glutamate dehydrogenase from Sulfolobus tokodaii. Using this method, we determined both the apparent maximum velocities and the K (m) values of For and Kor for the carboxylation of succinyl-CoA. This is the first reported kinetic analysis of carbon fixation catalyzed by OGOR enzymes from the rTCA cycle.
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Affiliation(s)
- Masahiro Yamamoto
- Department of Biotechnology, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
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Podar M, Anderson I, Makarova KS, Elkins JG, Ivanova N, Wall MA, Lykidis A, Mavromatis K, Sun H, Hudson ME, Chen W, Deciu C, Hutchison D, Eads JR, Anderson A, Fernandes F, Szeto E, Lapidus A, Kyrpides NC, Saier MH, Richardson PM, Rachel R, Huber H, Eisen JA, Koonin EV, Keller M, Stetter KO. A genomic analysis of the archaeal system Ignicoccus hospitalis-Nanoarchaeum equitans. Genome Biol 2008; 9:R158. [PMID: 19000309 PMCID: PMC2614490 DOI: 10.1186/gb-2008-9-11-r158] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 10/21/2008] [Accepted: 11/10/2008] [Indexed: 01/03/2023] Open
Abstract
Sequencing of the complete genome of Ignicoccus hospitalis gives insight into its association with another species of Archaea, Nanoarchaeum equitans. Background The relationship between the hyperthermophiles Ignicoccus hospitalis and Nanoarchaeum equitans is the only known example of a specific association between two species of Archaea. Little is known about the mechanisms that enable this relationship. Results We sequenced the complete genome of I. hospitalis and found it to be the smallest among independent, free-living organisms. A comparative genomic reconstruction suggests that the I. hospitalis lineage has lost most of the genes associated with a heterotrophic metabolism that is characteristic of most of the Crenarchaeota. A streamlined genome is also suggested by a low frequency of paralogs and fragmentation of many operons. However, this process appears to be partially balanced by lateral gene transfer from archaeal and bacterial sources. Conclusions A combination of genomic and cellular features suggests highly efficient adaptation to the low energy yield of sulfur-hydrogen respiration and efficient inorganic carbon and nitrogen assimilation. Evidence of lateral gene exchange between N. equitans and I. hospitalis indicates that the relationship has impacted both genomes. This association is the simplest symbiotic system known to date and a unique model for studying mechanisms of interspecific relationships at the genomic and metabolic levels.
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Affiliation(s)
- Mircea Podar
- Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831, USA.
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10
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Ikeda T, Ochiai T, Morita S, Nishiyama A, Yamada E, Arai H, Ishii M, Igarashi Y. Anabolic five subunit-type pyruvate:ferredoxin oxidoreductase from Hydrogenobacter thermophilus TK-6. Biochem Biophys Res Commun 2006; 340:76-82. [PMID: 16343420 DOI: 10.1016/j.bbrc.2005.11.155] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Accepted: 11/30/2005] [Indexed: 10/25/2022]
Abstract
The thermophilic, obligately chemolithoautotrophic hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus TK-6, assimilates carbon dioxide via the reductive tricarboxylic acid cycle. A gene cluster, porEDABG, encoding pyruvate:ferredoxin oxidoreductase (POR), which plays a key role in this cycle, was cloned and sequenced. The nucleotide sequence and the gene organization were similar to those of the five subunit-type 2-oxoglutarate:ferredoxin oxidoreductase from this strain, although the anabolic POR had been previously reported to consist of four subunits. A small protein (8 kDa) encoded by porE, which had not been detected in the previous work, was identified in the purified recombinant POR expressed in Escherichia coli, indicating that the enzyme is also a five-subunit type. Incorporation of PorE in the wild-type POR enzyme was confirmed by immunological analysis. PorA, PorB, PorG, and PorE were similar to the alpha, beta, gamma, and delta subunits of the four subunit-type 2-oxoacid oxidoreductases, respectively, and had conserved specific motifs. PorD had no specific motifs but was essential for the expression of the active enzyme.
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Affiliation(s)
- Takeshi Ikeda
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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11
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Atomi H. Microbial enzymes involved in carbon dioxide fixation. J Biosci Bioeng 2005; 94:497-505. [PMID: 16233341 DOI: 10.1016/s1389-1723(02)80186-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2002] [Accepted: 09/17/2002] [Indexed: 11/26/2022]
Abstract
This review focuses on the enzymes involved in two microbial carbon dioxide fixation pathways, the Calvin-Benson-Bassham cycle and the reductive tricarboxylic acid cycle. The function, structural features, and gene regulation of microbial ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), a key enzyme of the Calvin-Benson-Bassham cycle, is described. Some recent findings on Rubisco from archaea and Rubisco-like proteins are also outlined. In the final section, biochemical features of the key enzymes in the reductive tricarboxylic acid cycle are reviewed.
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Affiliation(s)
- Haruyuki Atomi
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan.
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Yamamoto M, Arai H, Ishii M, Igarashi Y. Characterization of two different 2-oxoglutarate:ferredoxin oxidoreductases from Hydrogenobacter thermophilus TK-6. Biochem Biophys Res Commun 2003; 312:1297-302. [PMID: 14652015 DOI: 10.1016/j.bbrc.2003.11.078] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
A thermophilic, chemolithoautotrophic hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus TK-6, fixes carbon dioxide via the reductive TCA cycle. 2-Oxoglutarate:ferredoxin oxidoreductase (OGOR) is one of the key enzymes of this cycle. Strain TK-6 has two distinct OGOR enzymes termed For and Kor. These enzymes were purified and characterized following heterologous expression in Escherichia coli. The specific activity of For was approximately one-tenth of that of Kor. Additionally, For showed higher thermo-stability than Kor under both aerobic and anaerobic conditions. Western blot analysis showed that both of For and Kor were expressed when strain TK-6 was grown under aerobic conditions. In contrast, only Kor was expressed when the strain was grown under anaerobic conditions using nitrate as a terminal electron acceptor. These results indicate that For supports the optimal growth of strain TK-6 in the presence of oxygen.
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Affiliation(s)
- Masahiro Yamamoto
- Department of Biotechnology, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, 113-8657, Tokyo, Japan
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Ebenau-Jehle C, Boll M, Fuchs G. 2-Oxoglutarate:NADP(+) oxidoreductase in Azoarcus evansii: properties and function in electron transfer reactions in aromatic ring reduction. J Bacteriol 2003; 185:6119-29. [PMID: 14526024 PMCID: PMC225024 DOI: 10.1128/jb.185.20.6119-6129.2003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The conversion of [(14)C]benzoyl-coenzyme A (CoA) to nonaromatic products in the denitrifying beta-proteobacterium Azoarcus evansii grown anaerobically on benzoate was investigated. With cell extracts and 2-oxoglutarate as the electron donor, benzoyl-CoA reduction occurred at a rate of 10 to 15 nmol min(-1) mg(-1). 2-Oxoglutarate could be replaced by dithionite (200% rate) and by NADPH ( approximately 10% rate); in contrast NADH did not serve as an electron donor. Anaerobic growth on aromatic compounds induced 2-oxoglutarate:acceptor oxidoreductase (KGOR), which specifically reduced NADP(+), and NADPH:acceptor oxidoreductase. KGOR was purified by a 76-fold enrichment. The enzyme had a molecular mass of 290 +/- 20 kDa and was composed of three subunits of 63 (gamma), 62 (alpha), and 37 (beta) kDa in a 1:1:1 ratio, suggesting an (alphabetagamma)(2) composition. The native enzyme contained Fe (24 mol/mol of enzyme), S (23 mol/mol), flavin adenine dinucleotide (FAD; 1.4 mol/mol), and thiamine diphosphate (0.95 mol/mol). KGOR from A. evansii was highly specific for 2-oxoglutarate as the electron donor and accepted both NADP(+) and oxidized viologens as electron acceptors; in contrast NAD(+) was not reduced. These results suggest that benzoyl-CoA reduction is coupled to the complete oxidation of the intermediate acetyl-CoA in the tricarboxylic acid cycle. Electrons generated by KGOR can be transferred to both oxidized ferredoxin and NADP(+), depending on the cellular needs. N-terminal amino acid sequence analysis revealed that the open reading frames for the three subunits of KGOR are similar to three adjacently located open reading frames in Bradyrhizobium japonicum. We suggest that these genes code for a very similar three-subunit KGOR, which may play a role in nitrogen fixation. The alpha-subunit is supposed to harbor one FAD molecule, two [4Fe-4S] clusters, and the NADPH binding site; the beta-subunit is supposed to harbor one thiamine diphosphate molecule and one further [4Fe-4S] cluster; and the gamma-subunit is supposed to harbor the CoA binding site. This is the first study of an NADP(+)-specific KGOR. A similar NADP(+)-specific pyruvate oxidoreductase, which contains all domains in one large subunit, has been reported for the mitochondrion of the protist Euglena gracilis and the apicomplexan Cryptosporidium parvum.
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Affiliation(s)
- Christa Ebenau-Jehle
- Mikrobiologie, Institut für Biologie II, Universität Freiburg, Freiburg, Germany
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Yun NR, Yamamoto M, Arai H, Ishii M, Igarashi Y. A novel five-subunit-type 2-oxoglutalate:ferredoxin oxidoreductases from Hydrogenobacter thermophilus TK-6. Biochem Biophys Res Commun 2002; 292:280-6. [PMID: 11890705 DOI: 10.1006/bbrc.2002.6651] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A thermophilic, chemolithoautotrophic hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus TK-6, fixes carbon dioxide via the reductive TCA cycle. 2-Oxoglutarate:ferredoxin oxidoreductase (OGOR) of this strain is one of the key enzymes of the pathway. OGOR of strain TK-6 has been reported to be a two-subunit-type OGOR and encoded by korAB. A gene cluster, forDABGEF, encoding another OGOR was found 148 bp upstream of korAB in the opposite orientation. Five of the for genes (forDABGE) were required for the expression of the active recombinant enzyme in Escherichia coli. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme showed five polypeptides corresponding to the forDABGE gene products, suggesting that the enzyme had a novel five-subunit structure. The recombinant enzyme had high substrate specificity toward 2-oxoglutarate as in the case of the gene products of korAB. Primer extension analysis showed that the korA and forD genes were transcribed from one and two transcriptional initiation sites, respectively. The results also suggested that both gene clusters were expressed in the cells of strain TK-6.
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Affiliation(s)
- Na-Rae Yun
- Department of Biotechnology, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
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