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Saghaug CS, Gamlem AL, Hauge KB, Vahokoski J, Klotz C, Aebischer T, Langeland N, Hanevik K. Genetic diversity in the metronidazole metabolism genes nitroreductases and pyruvate ferredoxin oxidoreductases in susceptible and refractory clinical samples of Giardia lamblia. Int J Parasitol Drugs Drug Resist 2022; 21:51-60. [PMID: 36682328 PMCID: PMC9871439 DOI: 10.1016/j.ijpddr.2022.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 11/30/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022]
Abstract
The effectiveness of metronidazole against the tetraploid intestinal parasite Giardia lamblia is dependent on its activation/inactivation within the cytoplasm. There are several activating enzymes, including pyruvate ferredoxin reductase (PFOR) and nitroreductase (NR) 1 which metabolize metronidazole into toxic forms, while NR2 on the other hand inactivates it. Metronidazole treatment failures have been increasing rapidly over the last decade, indicating genetic resistance mechanisms. Analyzing genetic variation in the PFOR and NR genes in susceptible and refractory Giardia isolates may help identify potential markers of resistance. Full length PFOR1, PFOR2, NR1 and NR2 genes from clinical culturable isolates and non-cultured clinical Giardia assemblage B samples were cloned, sequenced and single nucleotide variants (SNVs) were analyzed to assess genetic diversity and alleles. A similar ratio of amino acid changing SNVs per gene length was found for the NRs; 4.2% for NR1 and 6.4% for NR2, while the PFOR1 and PFOR2 genes had less variability with a ratio of 1.1% and 1.6%, respectively. One of the samples from a refractory case had a nonsense mutation which caused a truncated NR1 gene in one out of six alleles. Further, we found three NR2 alleles with frameshift mutations, possibly causing a truncated protein in two susceptible isolates. One of these isolates was homozygous for the affected NR2 allele. Three nsSNVs with potential for affecting protein function were found in the ferredoxin domain of the PFOR2 gene. The considerable variation and discovery of mutations possibly causing dysfunctional NR proteins in clinical Giardia assemblage B isolates, reveal a potential for genetic link to metronidazole susceptibility and resistance.
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Affiliation(s)
- Christina S Saghaug
- Department of Clinical Science, University of Bergen, Bergen, Norway; Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway.
| | - Astrid L Gamlem
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Kirsti B Hauge
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Juha Vahokoski
- Department of Clinical Science, University of Bergen, Bergen, Norway; Department of Medicine, Haukeland University Hospital, Bergen, Norway
| | - Christian Klotz
- Department of Infectious Diseases, Unit 16 Mycotic and Parasitic Agents and Mycobacteria, Robert Koch-Institute, Berlin, Germany
| | - Toni Aebischer
- Department of Infectious Diseases, Unit 16 Mycotic and Parasitic Agents and Mycobacteria, Robert Koch-Institute, Berlin, Germany
| | - Nina Langeland
- Department of Clinical Science, University of Bergen, Bergen, Norway; Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway
| | - Kurt Hanevik
- Department of Clinical Science, University of Bergen, Bergen, Norway; Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway
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Bertsova YV, Kulik LV, Mamedov MD, Baykov AA, Bogachev AV. Flavodoxin with an air-stable flavin semiquinone in a green sulfur bacterium. Photosynth Res 2019; 142:127-136. [PMID: 31302833 DOI: 10.1007/s11120-019-00658-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 07/04/2019] [Indexed: 06/10/2023]
Abstract
Flavodoxins are small proteins with a non-covalently bound FMN that can accept two electrons and accordingly adopt three redox states: oxidized (quinone), one-electron reduced (semiquinone), and two-electron reduced (quinol). In iron-deficient cyanobacteria and algae, flavodoxin can substitute for ferredoxin as the electron carrier in the photosynthetic electron transport chain. Here, we demonstrate a similar function for flavodoxin from the green sulfur bacterium Chlorobium phaeovibrioides (cp-Fld). The expression of the cp-Fld gene, found in a close proximity with the genes for other proteins associated with iron transport and storage, increased in a low-iron medium. cp-Fld produced in Escherichia coli exhibited the optical, ERP, and electron-nuclear double resonance spectra that were similar to those of known flavodoxins. However, unlike all other flavodoxins, cp-Fld exhibited unprecedented stability of FMN semiquinone to oxidation by air and difference in midpoint redox potentials for the quinone-semiquinone and semiquinone-quinol couples (- 110 and - 530 mV, respectively). cp-Fld could be reduced by pyruvate:ferredoxin oxidoreductase found in the membrane-free extract of Chl. phaeovibrioides cells and photo-reduced by the photosynthetic reaction center found in membrane vesicles from these cells. The green sulfur bacterium Chl. phaeovibrioides appears thus to be a new type of the photosynthetic organisms that can use flavodoxin as an alternative electron carrier to cope with iron deficiency.
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Affiliation(s)
- Yulia V Bertsova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia, 119234
| | - Leonid V Kulik
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk, Russia, 630090
- Novosibirsk State University, Novosibirsk, Russia, 630090
| | - Mahir D Mamedov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia, 119234
| | - Alexander A Baykov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia, 119234
| | - Alexander V Bogachev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia, 119234.
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Abstract
The radioprotective effects of naturally occurring sulfur compounds and isothiocyanates such as diallyl sulfide (DAS), diallyl disulfide (DADS), allyl methyl sulfide (AMS), allyl isothiocyanate (AITC) and phenyl isothiocyanate (PITC) have been investigated in whole body irradiated Swiss albino mice. Administration of these sulfur compounds could reduce the serum content of alkaline phosphatase (ALP), which was elevated after irradiation (23.9 ± 1.82 KA units). The elevated liver content of glutamate pyruvate transaminase (GPT) in control animals (76.2 ± 2.2 U/mL) after irradiation was significantly reduced in DAS (58.93 ± 4 U/mL) and AMS (55.7 ± 2.2 U/mL) treated animals. Elevated levels of lipid peroxides in serum and liver of irradiated control animals were also significantly reduced by treatment with these sulfur compounds. The glutathione (GSH) content in liver and intestinal mucosa was drastically reduced after irradiation. All the sulfur compounds and isothiocyanates could effectively enhance the GSH content of intestinal mucosa and liver. Findings at histopathological analysis of the intestine proved to be correlated with the above results.
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Bartelt LA, Bolick DT, Kolling GL, Stebbins E, Huston CD, Guerrant RL, Hoffman PS. Amixicile Reduces Severity of Cryptosporidiosis but Does Not Have In Vitro Activity against Cryptosporidium. Antimicrob Agents Chemother 2018; 62:e00718-18. [PMID: 30297368 PMCID: PMC6256802 DOI: 10.1128/aac.00718-18] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 09/28/2018] [Indexed: 12/13/2022] Open
Abstract
Cryptosporidium species cause significant morbidity in malnourished children. Nitazoxanide (NTZ) is the only approved treatment for cryptosporidiosis, but NTZ has diminished effectiveness during malnutrition. Here, we show that amixicile, a highly selective water-soluble derivative of NTZ diminishes Cryptosporidium infection severity in a malnourished mouse model despite a lack of direct anticryptosporidial activity. We suggest that amixicile, by tamping down anaerobes associated with intestinal inflammation, reverses weight loss and indirectly mitigates infection-associated pathology.
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Affiliation(s)
- Luther A Bartelt
- Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Center for Gastrointestinal Biology and Disease, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - David T Bolick
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Glynis L Kolling
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Erin Stebbins
- Division of Infectious Diseases, Department of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Christopher D Huston
- Division of Infectious Diseases, Department of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Richard L Guerrant
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Paul S Hoffman
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
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Hädicke O, von Kamp A, Aydogan T, Klamt S. OptMDFpathway: Identification of metabolic pathways with maximal thermodynamic driving force and its application for analyzing the endogenous CO2 fixation potential of Escherichia coli. PLoS Comput Biol 2018; 14:e1006492. [PMID: 30248096 PMCID: PMC6171959 DOI: 10.1371/journal.pcbi.1006492] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 10/04/2018] [Accepted: 09/07/2018] [Indexed: 12/02/2022] Open
Abstract
Constraint-based modeling techniques have become a standard tool for the in silico analysis of metabolic networks. To further improve their accuracy, recent methodological developments focused on integration of thermodynamic information in metabolic models to assess the feasibility of flux distributions by thermodynamic driving forces. Here we present OptMDFpathway, a method that extends the recently proposed framework of Max-min Driving Force (MDF) for thermodynamic pathway analysis. Given a metabolic network model, OptMDFpathway identifies both the optimal MDF for a desired phenotypic behavior as well as the respective pathway itself that supports the optimal driving force. OptMDFpathway is formulated as a mixed-integer linear program and is applicable to genome-scale metabolic networks. As an important theoretical result, we also show that there exists always at least one elementary mode in the network that reaches the maximal MDF. We employed our new approach to systematically identify all substrate-product combinations in Escherichia coli where product synthesis allows for concomitant net CO2 assimilation via thermodynamically feasible pathways. Although biomass synthesis cannot be coupled to net CO2 fixation in E. coli we found that as many as 145 of the 949 cytosolic carbon metabolites contained in the genome-scale model iJO1366 enable net CO2 incorporation along thermodynamically feasible pathways with glycerol as substrate and 34 with glucose. The most promising products in terms of carbon assimilation yield and thermodynamic driving forces are orotate, aspartate and the C4-metabolites of the tricarboxylic acid cycle. We also identified thermodynamic bottlenecks frequently limiting the maximal driving force of the CO2-fixing pathways. Our results indicate that heterotrophic organisms like E. coli hold a possibly underestimated potential for CO2 assimilation which may complement existing biotechnological approaches for capturing CO2. Furthermore, we envision that the developed OptMDFpathway approach can be used for many other applications within the framework of constrained-based modeling and for rational design of metabolic networks. When analyzing metabolic networks, one often searches for metabolic pathways with certain (desired) properties, for example, conversion routes that maximize the yield of a product from a given substrate. While those problems can be solved with established methods of constraint-based modeling, no algorithm is currently available for genome-scale models to identify the pathway that has the highest possible thermodynamic driving force among all solutions with predefined stoichiometric properties. This gap is closed with our new approach OptMDFpathway which is based on the recently introduced concept of Max-min Driving Force (MDF). OptMDFpathway offers various applications, especially in the context of metabolic design of cell factories. To demonstrate the power and usefulness of OptMDFpathway, we employed it to analyze the endogenous CO2 fixation potential of Escherichia coli. While E. coli cannot assimilate CO2 into biomass, net CO2 fixation can take place along linear pathways from substrate to product and we show that thermodynamically feasible pathways with net CO2 assimilation exist for 145 (34) products when choosing glycerol (glucose) as substrate. Our results indicate that heterotrophic organisms like E. coli hold a possibly underestimated potential for CO2 assimilation which may complement existing biotechnological approaches for capturing CO2.
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Affiliation(s)
- Oliver Hädicke
- Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
- * E-mail: (OH); (SK)
| | - Axel von Kamp
- Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
| | - Timur Aydogan
- Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
| | - Steffen Klamt
- Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany
- * E-mail: (OH); (SK)
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Hutcherson JA, Sinclair KM, Belvin BR, Gui Q, Hoffman PS, Lewis JP. Amixicile, a novel strategy for targeting oral anaerobic pathogens. Sci Rep 2017; 7:10474. [PMID: 28874750 PMCID: PMC5585216 DOI: 10.1038/s41598-017-09616-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 07/24/2017] [Indexed: 01/27/2023] Open
Abstract
The oral microflora is composed of both health-promoting as well as disease-initiating bacteria. Many of the disease-initiating bacteria are anaerobic and include organisms such as Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, and Tannerella forsythia. Here we investigated a novel therapeutic, amixicile, that targets pyruvate:ferredoxin oxidoreductase (PFOR), a major metabolic enzyme involved in energy generation through oxidative decarboxylation of pyruvate. PFOR is present in these anaerobic pathogenic bacteria and thus we hypothesized that amixicile would effectively inhibit their growth. In general, PFOR is present in all obligate anaerobic bacteria, while oral commensal aerobes, including aerotolerant ones, such as Streptococcus gordonii, use pyruvate dehydrogenase to decarboxylate pyruvate. Accordingly, we observed that growth of the PFOR-containing anaerobic periodontal pathogens, grown in both monospecies as well as multispecies broth cultures was inhibited in a dose-dependent manner while that of S. gordonii was unaffected. Furthermore, we also show that amixicile is effective against these pathogens grown as monospecies and multispecies biofilms. Finally, amixicile is the first selective therapeutic agent active against bacteria internalized by host cells. Together, the results show that amixicile is an effective inhibitor of oral anaerobic bacteria and as such, is a good candidate for treatment of periodontal diseases.
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Affiliation(s)
- Justin A Hutcherson
- Philips Institute of Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Kathryn M Sinclair
- Philips Institute of Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Benjamin R Belvin
- Philips Institute of Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA
- Department of Biochemistry, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Qin Gui
- Philips Institute of Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Paul S Hoffman
- Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia, USA
| | - Janina P Lewis
- Philips Institute of Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA.
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, USA.
- Department of Biochemistry, Virginia Commonwealth University, Richmond, Virginia, USA.
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7
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Lehning CE, Siedler S, Ellabaan MMH, Sommer MOA. Assessing glycolytic flux alterations resulting from genetic perturbations in E. coli using a biosensor. Metab Eng 2017; 42:194-202. [PMID: 28709932 PMCID: PMC5555440 DOI: 10.1016/j.ymben.2017.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 07/11/2017] [Indexed: 11/19/2022]
Abstract
We describe the development of an optimized glycolytic flux biosensor and its application in detecting altered flux in a production strain and in a mutant library. The glycolytic flux biosensor is based on the Cra-regulated ppsA promoter of E. coli controlling fluorescent protein synthesis. We validated the glycolytic flux dependency of the biosensor in a range of different carbon sources in six different E. coli strains and during mevalonate production. Furthermore, we studied the flux-altering effects of genome-wide single gene knock-outs in E. coli in a multiplex FlowSeq experiment. From a library consisting of 2126 knock-out mutants, we identified 3 mutants with high-flux and 95 mutants with low-flux phenotypes that did not have severe growth defects. This approach can improve our understanding of glycolytic flux regulation improving metabolic models and engineering efforts.
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Affiliation(s)
- Christina E Lehning
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet Building 220, 2800 Lyngby, Denmark
| | - Solvej Siedler
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet Building 220, 2800 Lyngby, Denmark
| | - Mostafa M H Ellabaan
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet Building 220, 2800 Lyngby, Denmark
| | - Morten O A Sommer
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet Building 220, 2800 Lyngby, Denmark.
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Takenaka M, Yoon KS, Matsumoto T, Ogo S. Acetyl-CoA production by encapsulated pyruvate ferredoxin oxidoreductase in alginate hydrogels. Bioresour Technol 2017; 227:279-285. [PMID: 28040649 DOI: 10.1016/j.biortech.2016.12.051] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 12/10/2016] [Accepted: 12/12/2016] [Indexed: 05/08/2023]
Abstract
Pyruvate ferredoxin oxidoreductase from Citrobacter sp. S-77 (PFORS77) was purified in order to develop a method for acetyl-CoA production. Although the purified PFORS77 showed high O2-sensitivity, the activity could be remarkably stabilized in anaerobic conditions. PFORS77 was effectively immobilized on ceramic hydroxyapatite (PFORS77-HA) with an efficiency of more than 96%, however, after encapsulation of PFORS77-HA in alginate, the rate of catalytic acetyl-CoA production was highly reduced to 36% when compared to that of the free enzyme. However, the operational stability of the PFORS77-HA in alginate hydrogels was remarkable, retaining over 68% initial activity even after ten repeated cycles. The results suggested that the PFORS77-HA hydrogels have a high potential for biotechnological application.
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Affiliation(s)
- Makoto Takenaka
- International Institute for Carbon-Neutral Energy Research (WPI-I(2)CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan; Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Ki-Seok Yoon
- International Institute for Carbon-Neutral Energy Research (WPI-I(2)CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan; Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan; Centre for Small Molecule Energy, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Takahiro Matsumoto
- International Institute for Carbon-Neutral Energy Research (WPI-I(2)CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan; Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan; Centre for Small Molecule Energy, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Seiji Ogo
- International Institute for Carbon-Neutral Energy Research (WPI-I(2)CNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan; Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan; Centre for Small Molecule Energy, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan.
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Ramel F, Brasseur G, Pieulle L, Valette O, Hirschler-Réa A, Fardeau ML, Dolla A. Growth of the obligate anaerobe Desulfovibrio vulgaris Hildenborough under continuous low oxygen concentration sparging: impact of the membrane-bound oxygen reductases. PLoS One 2015; 10:e0123455. [PMID: 25837676 PMCID: PMC4383621 DOI: 10.1371/journal.pone.0123455] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 03/04/2015] [Indexed: 11/18/2022] Open
Abstract
Although obligate anaerobe, the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough (DvH) exhibits high aerotolerance that involves several enzymatic systems, including two membrane-bound oxygen reductases, a bd-quinol oxidase and a cc(b/o)o3 cytochrome oxidase. Effect of constant low oxygen concentration on growth and morphology of the wild-type, single (Δbd, Δcox) and double deletion (Δcoxbd) mutant strains of the genes encoding these oxygen reductases was studied. When both wild-type and deletion mutant strains were cultured in lactate/sulfate medium under constant 0.02% O2 sparging, they were able to grow but the final biomasses and the growth yield were lower than that obtained under anaerobic conditions. At the end of the growth, lactate was not completely consumed and when conditions were then switched to anaerobic, growth resumed. Time-lapse microscopy revealed that a large majority of the cells were then able to divide (over 97%) but the time to recover a complete division event was longer for single deletion mutant Δbd than for the three other strains. Determination of the molar growth yields on lactate suggested that a part of the energy gained from lactate oxidation was derived toward cells protection/repairing against oxidative conditions rather than biosynthesis, and that this part was higher in the single deletion mutant Δbd and, to a lesser extent, Δcox strains. Our data show that when DvH encounters oxidative conditions, it is able to stop growing and to rapidly resume growing when conditions are switched to anaerobic, suggesting that it enters active dormancy sate under oxidative conditions. We propose that the pyruvate-ferredoxin oxidoreductase (PFOR) plays a central role in this phenomenon by reversibly switching from an oxidative-sensitive fully active state to an oxidative-insensitive inactive state. The oxygen reductases, and especially the bd-quinol oxidase, would have a crucial function by maintaining reducing conditions that permit PFOR to stay in its active state.
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Affiliation(s)
- Fanny Ramel
- Aix-Marseille Université, CNRS, LCB-UMR7283, Marseille, France
| | - Gael Brasseur
- Aix-Marseille Université, CNRS, LCB-UMR7283, Marseille, France
| | | | - Odile Valette
- Aix-Marseille Université, CNRS, LCB-UMR7283, Marseille, France
| | - Agnès Hirschler-Réa
- Aix-Marseille Université, Université de Toulon, CNRS, IRD, MIO, UM110, 13288 Marseille, Cedex 09, France
| | - Marie Laure Fardeau
- Aix-Marseille Université, Université de Toulon, CNRS, IRD, MIO, UM110, 13288 Marseille, Cedex 09, France
| | - Alain Dolla
- Aix-Marseille Université, CNRS, LCB-UMR7283, Marseille, France
- * E-mail:
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Kushkevych IV. Kinetic Properties of Pyruvate Ferredoxin Oxidoreductase of Intestinal Sulfate-Reducing Bacteria Desulfovibrio piger Vib-7 and Desulfomicrobium sp. Rod-9. Pol J Microbiol 2015; 64:107-114. [PMID: 26373169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023] Open
Abstract
Intestinal sulfate-reducing bacteria reduce sulfate ions to hydrogen sulfide causing inflammatory bowel diseases of humans and animals. The bacteria consume lactate as electron donor which is oxidized to acetate via pyruvate in process of the dissimilatory sulfate reduction. Pyruvate-ferredoxin oxidoreductase activity and the kinetic properties of the enzyme from intestinal sulfate-reducing bacteria Desulfovibrio piger and Desulfomicrobium sp. have never been well-characterized and have not been yet studied. In this paper we present for the first time the specific activity of pyruvate-ferredoxin oxidoreductase and the kinetic properties of the enzyme in cell-free extracts of both D. piger Vib-7 and Desulfomicrobium sp. Rod-9 intestinal bacterial strains. Microbiological, biochemical, biophysical and statistical methods were used in this work. The optimal temperature (+35°C) and pH 8.5 for enzyme reaction were determined. The spectral analysis of the puri- fied pyruvate-ferredoxin oxidoreductase from the cell-free extracts was demonstrated. Analysis of the kinetic properties of the studied enzyme was carried out. Initial (instantaneous) reaction velocity (V0), maximum amount of the product of reaction (Pmax), the reaction time (half saturation period) and maximum velocity of the pyruvate-ferredoxin oxidoreductase reaction (V ) were defined. Michaelis constants (Km) of the enzyme reaction were calculated for both intestinal bacterial strains. The studies of the kinetic enzyme properties in the intestinal sulfate-reducing bacteria strains in detail can be prospects for clarifying the etiological role of these bacteria in the development of inflammatory bowel diseases.
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van Lis R, Baffert C, Couté Y, Nitschke W, Atteia A. Chlamydomonas reinhardtii chloroplasts contain a homodimeric pyruvate:ferredoxin oxidoreductase that functions with FDX1. Plant Physiol 2013; 161:57-71. [PMID: 23154536 PMCID: PMC3532286 DOI: 10.1104/pp.112.208181] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 11/11/2012] [Indexed: 05/24/2023]
Abstract
Eukaryotic algae have long been known to live in anoxic environments, but interest in their anaerobic energy metabolism has only recently gained momentum, largely due to their utility in biofuel production. Chlamydomonas reinhardtii figures remarkably in this respect, because it efficiently produces hydrogen and its genome harbors many genes for anaerobic metabolic routes. Central to anaerobic energy metabolism in many unicellular eukaryotes (protists) is pyruvate:ferredoxin oxidoreductase (PFO), which decarboxylates pyruvate and forms acetyl-coenzyme A with concomitant reduction of low-potential ferredoxins or flavodoxins. Here, we report the biochemical properties of the homodimeric PFO of C. reinhardtii expressed in Escherichia coli. Electron paramagnetic resonance spectroscopy of the recombinant enzyme (Cr-rPFO) showed three distinct [4Fe-4S] iron-sulfur clusters and a thiamine pyrophosphate radical upon reduction by pyruvate. Purified Cr-rPFO exhibits a specific decarboxylase activity of 12 µmol pyruvate min⁻¹ mg⁻¹ protein using benzyl viologen as electron acceptor. Despite the fact that the enzyme is very oxygen sensitive, it localizes to the chloroplast. Among the six known chloroplast ferredoxins (FDX1-FDX6) in C. reinhardtii, FDX1 and FDX2 were the most efficient electron acceptors from Cr-rPFO, with comparable apparent K(m) values of approximately 4 µm. As revealed by immunoblotting, anaerobic conditions that lead to the induction of CrPFO did not increase levels of either FDX1 or FDX2. FDX1, being by far the most abundant ferredoxin, is thus likely the partner of PFO in C. reinhardtii. This finding postulates a direct link between CrPFO and hydrogenase and provides new opportunities to better study and engineer hydrogen production in this protist.
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Magneschi L, Catalanotti C, Subramanian V, Dubini A, Yang W, Mus F, Posewitz MC, Seibert M, Perata P, Grossman AR. A mutant in the ADH1 gene of Chlamydomonas reinhardtii elicits metabolic restructuring during anaerobiosis. Plant Physiol 2012; 158:1293-305. [PMID: 22271746 PMCID: PMC3291268 DOI: 10.1104/pp.111.191569] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 01/21/2012] [Indexed: 05/20/2023]
Abstract
The green alga Chlamydomonas reinhardtii has numerous genes encoding enzymes that function in fermentative pathways. Among these, the bifunctional alcohol/acetaldehyde dehydrogenase (ADH1), highly homologous to the Escherichia coli AdhE enzyme, is proposed to be a key component of fermentative metabolism. To investigate the physiological role of ADH1 in dark anoxic metabolism, a Chlamydomonas adh1 mutant was generated. We detected no ethanol synthesis in this mutant when it was placed under anoxia; the two other ADH homologs encoded on the Chlamydomonas genome do not appear to participate in ethanol production under our experimental conditions. Pyruvate formate lyase, acetate kinase, and hydrogenase protein levels were similar in wild-type cells and the adh1 mutant, while the mutant had significantly more pyruvate:ferredoxin oxidoreductase. Furthermore, a marked change in metabolite levels (in addition to ethanol) synthesized by the mutant under anoxic conditions was observed; formate levels were reduced, acetate levels were elevated, and the production of CO(2) was significantly reduced, but fermentative H(2) production was unchanged relative to wild-type cells. Of particular interest is the finding that the mutant accumulates high levels of extracellular glycerol, which requires NADH as a substrate for its synthesis. Lactate production is also increased slightly in the mutant relative to the control strain. These findings demonstrate a restructuring of fermentative metabolism in the adh1 mutant in a way that sustains the recycling (oxidation) of NADH and the survival of the mutant (similar to wild-type cell survival) during dark anoxic growth.
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Affiliation(s)
- Leonardo Magneschi
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, USA.
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Hopkins RC, Sun J, Jenney FE, Chandrayan SK, McTernan PM, Adams MWW. Homologous expression of a subcomplex of Pyrococcus furiosus hydrogenase that interacts with pyruvate ferredoxin oxidoreductase. PLoS One 2011; 6:e26569. [PMID: 22039508 PMCID: PMC3200332 DOI: 10.1371/journal.pone.0026569] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 09/29/2011] [Indexed: 11/18/2022] Open
Abstract
Hydrogen gas is an attractive alternative fuel as it is carbon neutral and has higher energy content per unit mass than fossil fuels. The biological enzyme responsible for utilizing molecular hydrogen is hydrogenase, a heteromeric metalloenzyme requiring a complex maturation process to assemble its O(2)-sensitive dinuclear-catalytic site containing nickel and iron atoms. To facilitate their utility in applied processes, it is essential that tools are available to engineer hydrogenases to tailor catalytic activity and electron carrier specificity, and decrease oxygen sensitivity using standard molecular biology techniques. As a model system we are using hydrogen-producing Pyrococcus furiosus, which grows optimally at 100°C. We have taken advantage of a recently developed genetic system that allows markerless chromosomal integrations via homologous recombination. We have combined a new gene marker system with a highly-expressed constitutive promoter to enable high-level homologous expression of an engineered form of the cytoplasmic NADP-dependent hydrogenase (SHI) of P. furiosus. In a step towards obtaining 'minimal' hydrogenases, we have successfully produced the heterodimeric form of SHI that contains only two of the four subunits found in the native heterotetrameric enzyme. The heterodimeric form is highly active (150 units mg(-1) in H(2) production using the artificial electron donor methyl viologen) and thermostable (t(1/2) ∼0.5 hour at 90°C). Moreover, the heterodimer does not use NADPH and instead can directly utilize reductant supplied by pyruvate ferredoxin oxidoreductase from P. furiosus. The SHI heterodimer and POR therefore represent a two-enzyme system that oxidizes pyruvate and produces H(2) in vitro without the need for an intermediate electron carrier.
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Affiliation(s)
- R. Christopher Hopkins
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Junsong Sun
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Francis E. Jenney
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Sanjeev K. Chandrayan
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Patrick M. McTernan
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Michael W. W. Adams
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, United States of America
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St Maurice M, Cremades N, Croxen MA, Sisson G, Sancho J, Hoffman PS. Flavodoxin:quinone reductase (FqrB): a redox partner of pyruvate:ferredoxin oxidoreductase that reversibly couples pyruvate oxidation to NADPH production in Helicobacter pylori and Campylobacter jejuni. J Bacteriol 2007; 189:4764-73. [PMID: 17468253 PMCID: PMC1913460 DOI: 10.1128/jb.00287-07] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Pyruvate-dependent reduction of NADP has been demonstrated in cell extracts of the human gastric pathogen Helicobacter pylori. However, NADP is not a substrate of purified pyruvate:ferredoxin oxidoreductase (PFOR), suggesting that other redox active enzymes mediate this reaction. Here we show that fqrB (HP1164), which is essential and highly conserved among the epsilonproteobacteria, exhibits NADPH oxidoreductase activity. FqrB was purified by nickel interaction chromatography following overexpression in Escherichia coli. The protein contained flavin adenine dinucleotide and exhibited NADPH quinone reductase activity with menadione or benzoquinone and weak activity with cytochrome c, molecular oxygen, and 5,5'-dithio-bis-2-nitrobenzoic acid (DTNB). FqrB exhibited a ping-pong catalytic mechanism, a k(cat) of 122 s(-1), and an apparent K(m) of 14 muM for menadione and 26 muM for NADPH. FqrB also reduced flavodoxin (FldA), the electron carrier of PFOR. In coupled enzyme assays with purified PFOR and FldA, FqrB reduced NADP in a pyruvate- and reduced coenzyme A (CoA)-dependent manner. Moreover, in the presence of NADPH, CO(2), and acetyl-CoA, the PFOR:FldA:FqrB complex generated pyruvate via CO(2) fixation. PFOR was the rate-limiting enzyme in the complex, and nitazoxanide, a specific inhibitor of PFOR of H. pylori and Campylobacter jejuni, also inhibited NADP reduction in cell-free lysates. These capnophilic (CO(2)-requiring) organisms contain gaps in pathways of central metabolism that would benefit substantially from pyruvate formation via CO(2) fixation. Thus, FqrB provides a novel function in pyruvate metabolism and, together with production of superoxide anions via quinone reduction under high oxygen tensions, contributes to the unique microaerobic lifestyle that defines the epsilonproteobacterial group.
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Affiliation(s)
- Martin St Maurice
- Department of Medicine, Division of Infectious Diseases, University of Virginia Health Systems, 409 Lane Road, Charlottesville, VA 22908, USA
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Jahn U, Huber H, Eisenreich W, Hügler M, Fuchs G. Insights into the autotrophic CO2 fixation pathway of the archaeon Ignicoccus hospitalis: comprehensive analysis of the central carbon metabolism. J Bacteriol 2007; 189:4108-19. [PMID: 17400748 PMCID: PMC1913412 DOI: 10.1128/jb.00047-07] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Ignicoccus hospitalis is an autotrophic hyperthermophilic archaeon that serves as a host for another parasitic/symbiotic archaeon, Nanoarchaeum equitans. In this study, the biosynthetic pathways of I. hospitalis were investigated by in vitro enzymatic analyses, in vivo (13)C-labeling experiments, and genomic analyses. Our results suggest the operation of a so far unknown pathway of autotrophic CO(2) fixation that starts from acetyl-coenzyme A (CoA). The cyclic regeneration of acetyl-CoA, the primary CO(2) acceptor molecule, has not been clarified yet. In essence, acetyl-CoA is converted into pyruvate via reductive carboxylation by pyruvate-ferredoxin oxidoreductase. Pyruvate-water dikinase converts pyruvate into phosphoenolpyruvate (PEP), which is carboxylated to oxaloacetate by PEP carboxylase. An incomplete citric acid cycle is operating: citrate is synthesized from oxaloacetate and acetyl-CoA by a (re)-specific citrate synthase, whereas a 2-oxoglutarate-oxidizing enzyme is lacking. Further investigations revealed that several special biosynthetic pathways that have recently been described for various archaea are operating. Isoleucine is synthesized via the uncommon citramalate pathway and lysine via the alpha-aminoadipate pathway. Gluconeogenesis is achieved via a reverse Embden-Meyerhof pathway using a novel type of fructose 1,6-bisphosphate aldolase. Pentosephosphates are formed from hexosephosphates via the suggested ribulose-monophosphate pathway, whereby formaldehyde is released from C-1 of hexose. The organism may not contain any sugar-metabolizing pathway. This comprehensive analysis of the central carbon metabolism of I. hospitalis revealed further evidence for the unexpected and unexplored diversity of metabolic pathways within the (hyperthermophilic) archaea.
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Affiliation(s)
- Ulrike Jahn
- Lehrstuhl Mikrobiologie und Archaeenzentrum, Universität Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
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Kim YS, Song HO, Choi IH, Park SJ, Ryu JS. Hydrogenosomal activity of Trichomonas vaginalis cultivated under different iron conditions. Korean J Parasitol 2007; 44:373-8. [PMID: 17170580 PMCID: PMC2559125 DOI: 10.3347/kjp.2006.44.4.373] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
To evaluate whether iron concentration in TYM medium influence on hydrogenosomal enzyme gene expression and hydrogenosomal membrane potential of Trichomonas vaginalis, trophozoites were cultivated in irondepleted, normal and iron-supplemented TYM media. The mRNA of hydrogenosomal enzymes, such as pyruvate ferredoxin oxidoreductase (PFOR), hydrogenase, ferredoxin and malic enzyme, was increased with iron concentrations in T. vaginalis culture media, measured by RT-PCR. Hydrogenosomal membrane potentials measured with DiOC6 also showed similar tendency, e.g. T. vaginalis cultivated in iron-depleted and iron-supplemented media for 3 days showed a significantly reduced and enhanced hydrogenosomal membrane potential compared with that of normal TYM media, respectively. Therefore, it is suggested that iron may regulate hydrogenosomal activity through hydrogenosomal enzyme expression and hydrogenosomal membrane potential.
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Affiliation(s)
- Yong-Seok Kim
- Department of Biochemistry and Molecular Biology, Hanyang University College of Medicine, Seoul, Korea
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Hu Y, Holden JF. Citric acid cycle in the hyperthermophilic archaeon Pyrobaculum islandicum grown autotrophically, heterotrophically, and mixotrophically with acetate. J Bacteriol 2006; 188:4350-5. [PMID: 16740941 PMCID: PMC1482950 DOI: 10.1128/jb.00138-06] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The hyperthermophilic archaeon Pyrobaculum islandicum uses the citric acid cycle in the oxidative and reductive directions for heterotrophic and autotrophic growth, respectively, but the control of carbon flow is poorly understood. P. islandicum was grown at 95 degrees C autotrophically, heterotrophically, and mixotrophically with acetate, H2, and small amounts of yeast extract and with thiosulfate as the terminal electron acceptor. The autotrophic growth rates and maximum concentrations of cells were significantly lower than those in other media. The growth rates on H2 and 0.001% yeast extract with and without 0.05% acetate were the same, but the maximum concentration of cells was fourfold higher with acetate. There was no growth with acetate if 0.001% yeast extract was not present, and addition of H2 to acetate-containing medium greatly increased the growth rates and maximum concentrations of cells. P. islandicum cultures assimilated 14C-labeled acetate in the presence of H2 and yeast extract with an efficiency of 55%. The activities of 11 of 19 enzymes involved in the central metabolism of P. islandicum were regulated under the three different growth conditions. Pyruvate synthase and acetate:coenzyme A (CoA) ligase (ADP-forming) activities were detected only in heterotrophically grown cultures. Citrate synthase activity decreased in autotrophic and acetate-containing cultures compared to the activity in heterotrophic cultures. Acetylated citrate lyase, acetate:CoA ligase (AMP forming), and phosphoenolpyruvate carboxylase activities increased in autotrophic and acetate-containing cultures. Citrate lyase activity was higher than ATP citrate synthase activity in autotrophic cultures. These data suggest that citrate lyase and AMP-forming acetate:CoA ligase, but not ATP citrate synthase, work opposite citrate synthase to control the direction of carbon flow in the citric acid cycle.
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Affiliation(s)
- Yajing Hu
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA
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18
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Astashkin AV, Seravalli J, Mansoorabadi SO, Reed GH, Ragsdale SW. Pulsed electron paramagnetic resonance experiments identify the paramagnetic intermediates in the pyruvate ferredoxin oxidoreductase catalytic cycle. J Am Chem Soc 2006; 128:3888-9. [PMID: 16551078 PMCID: PMC3119504 DOI: 10.1021/ja0585275] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pyruvate ferredoxin oxidoreductase (PFOR) is central to the anaerobic metabolism of many bacteria and amitochondriate eukaryotes. PFOR contains thiamine pyrophosphate (TPP) and three [4Fe-4S] clusters, which link pyruvate oxidation to reduction of ferredoxin. In the PFOR reaction, TPP reacts with pyruvate to form lactyl-TPP, which undergoes decarboxylation to form a hydroxyethyl-TPP (HE-TPP) intermediate. One electron is then transferred from HE-TPP to one of the three [4Fe-4S] clusters to form an HE-TPP radical and a [4Fe-4S]1+ intermediate. Pulsed EPR methods have been used to measure the distance between the HE-TPP radical and the [4Fe-4S]1+ cluster to which it is coupled. Computational analysis including the PFOR crystal structure and the spin distribution in the HE-TPP radical and in the reduced [4Fe-4S] cluster demonstrates that the distance between the HE-TPP radical and the medial cluster B matches the experimentally determined dipolar interaction, while one of the other two clusters is too close and the other is too far away. These results clearly demonstrate that it is the medial cluster (cluster B) that is reduced. Thus, rapid electron transfer occurs through the electron-transfer chain, which leaves an oxidized proximal cluster poised to accept an electron from the HE-TPP radical in the subsequent reaction step.
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Affiliation(s)
- Andrei V Astashkin
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721-0041, USA
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Porat I, Kim W, Hendrickson EL, Xia Q, Zhang Y, Wang T, Taub F, Moore BC, Anderson IJ, Hackett M, Leigh JA, Whitman WB. Disruption of the operon encoding Ehb hydrogenase limits anabolic CO2 assimilation in the archaeon Methanococcus maripaludis. J Bacteriol 2006; 188:1373-80. [PMID: 16452419 PMCID: PMC1367223 DOI: 10.1128/jb.188.4.1373-1380.2006] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Methanococcus maripaludis is a mesophilic archaeon that reduces CO2 to methane with H2 or formate as an energy source. It contains two membrane-bound energy-conserving hydrogenases, Eha and Ehb. To determine the role of Ehb, a deletion in the ehb operon was constructed to yield the mutant, strain S40. Growth of S40 was severely impaired in minimal medium. Both acetate and yeast extract were necessary to restore growth to nearly wild-type levels, suggesting that Ehb was involved in multiple steps in carbon assimilation. However, no differences in the total hydrogenase specific activities were found between the wild type and mutant in either cell extracts or membrane-purified fractions. Methanogenesis by resting cells with pyruvate as the electron donor was also reduced by 30% in S40, suggesting a defect in pyruvate oxidation. CO dehydrogenase/acetyl coenzyme A (CoA) synthase and pyruvate oxidoreductase had higher specific activities in the mutant, and genes encoding these enzymes, as well as AMP-forming acetyl-CoA synthetase, were expressed at increased levels. These observations support a role for Ehb in anabolic CO2 assimilation in methanococci.
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Affiliation(s)
- Iris Porat
- Department of Microbiology, University of Georgia, Athens, Georgia 30602-2605, USA
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Park YJ, Yoo CB, Choi SY, Lee HB. Purifications and characterizations of a ferredoxin and its related 2-oxoacid:ferredoxin oxidoreductase from the hyperthermophilic archaeon, Sulfolobus solfataricus P1. BMB Rep 2006; 39:46-54. [PMID: 16466637 DOI: 10.5483/bmbrep.2006.39.1.046] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The coenzyme A-acylating 2-oxoacid:ferredoxin oxidoreductase and ferredoxin (an effective electron acceptor) were purified from the hyperthermophilic archaeon, Sulfolobus solfataricus P1 (DSM1616). The purified ferredoxin is a monomeric protein with an apparent molecular mass of approximately 11 kDa by SDS-PAGE and of 11,180+/-50 Da by MALDI-TOF mass spectrometry. Ferredoxin was identified to be a dicluster, [3Fe-4S][4Fe-4S], type ferredoxin by spectrophotometric and EPR studies, and appeared to be zinc-containing based on the shared homology of its N-terminal sequence with those of known zinc-containing ferredoxins. On the other hand, the purified 2-oxoacid: ferredoxin oxidoreductase was found to be a heterodimeric enzyme consisting of 69 kDa alpha and 34 kDa beta subunits by SDS-PAGE and MALDI-TOF mass spectrometry. The purified enzyme showed a specific activity of 52.6 units/mg for the reduction of cytochrome c with 2-oxoglutarate as substrate at 55 degrees C, pH 7.0. Maximum activity was observed at 70 degrees C and the optimum pH for enzymatic activity was 7.0 -8.0. The enzyme displays broad substrate specificity toward 2-oxoacids, such as pyruvate, 2-oxobutyrate, and 2-oxoglutarate. Among the 2-oxoacids tested (pyruvate, 2-oxobutyrate, and 2-oxoglutarate), 2-oxoglutarate was found to be the best substrate with Km and kcat values of 163 microM and 452 min(-1), respectively. These results provide useful information for structural studies on these two proteins and for studies on the mechanism of electron transfer between the two.
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Affiliation(s)
- Young-Jun Park
- Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon, 200-701, Korea
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Collet C, Girbal L, Péringer P, Schwitzguébel JP, Soucaille P. Metabolism of lactose by Clostridium thermolacticum growing in continuous culture. Arch Microbiol 2006; 185:331-9. [PMID: 16508746 DOI: 10.1007/s00203-006-0098-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2005] [Revised: 01/18/2006] [Accepted: 02/07/2006] [Indexed: 11/24/2022]
Abstract
The objective of the present study was to characterize the metabolism of Clostridium thermolacticum, a thermophilic anaerobic bacterium, growing continuously on lactose (10 g l(-1)) and to determine the enzymes involved in the pathways leading to the formation of the fermentation products. Biomass and metabolites concentration were measured at steady-state for different dilution rates, from 0.013 to 0.19 h(-1). Acetate, ethanol, hydrogen and carbon dioxide were produced at all dilution rates, whereas lactate was detected only for dilution rates below 0.06 h(-1). The presence of several key enzymes involved in lactose metabolism, including beta-galactosidase, glyceraldehyde-3-phosphate dehydrogenase, pyruvate:ferredoxin oxidoreductase, acetate kinase, ethanol dehydrogenase and lactate dehydrogenase, was demonstrated. Finally, the intracellular level of NADH, NAD+, ATP and ADP was also measured for different dilution rates. The production of ethanol and lactate appeared to be linked with the re-oxidation of NADH produced during glycolysis, whereas hydrogen produced should come from reduced ferredoxin generated during pyruvate decarboxylation. To produce more hydrogen or more acetate from lactose, it thus appears that an efficient H2 removal system should be used, based on a physical (membrane) or a biological approach, respectively, by cultivating C. thermolacticum with efficient H2 scavenging and acetate producing microorganisms.
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Affiliation(s)
- Christophe Collet
- Laboratory for Environmental Biotechnology (LBE), Swiss Federal Institute of Technology Lausanne (EPFL), Station 6, 1015, Lausanne, Switzerland
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22
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Atteia A, van Lis R, Gelius-Dietrich G, Adrait A, Garin J, Joyard J, Rolland N, Martin W. Pyruvate formate-lyase and a novel route of eukaryotic ATP synthesis in Chlamydomonas mitochondria. J Biol Chem 2006; 281:9909-18. [PMID: 16452484 DOI: 10.1074/jbc.m507862200] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pyruvate formate-lyase (PFL) catalyzes the non-oxidative conversion of pyruvate to formate and acetyl-CoA. PFL and its activating enzyme (PFL-AE) are common among strict anaerobic and microaerophilic prokaryotes but are very rare among eukaryotes. In a proteome survey of isolated Chlamydomonas reinhardtii mitochondria, we found several PFL-specific peptides leading to the identification of cDNAs for PFL and PFL-AE, establishing the existence of a PFL system in this photosynthetic algae. Anaerobiosis and darkness led to increased PFL transcripts but had little effect on protein levels, as determined with antiserum raised against C. reinhardtii PFL. Protein blots revealed the occurrence of PFL in both chloroplast and mitochondria purified from aerobically grown cells. Mass spectrometry sequencing of C. reinhardtii mitochondrial proteins, furthermore, identified peptides for phosphotransacetylase and acetate kinase. The phosphotransacetylase-acetate kinase pathway is a common route of ATP synthesis or acetate assimilation among prokaryotes but is novel among eukaryotes. In addition to PFL and pyruvate dehydrogenase, the algae also expresses pyruvate:ferredoxin oxidoreductase and bifunctional aldehyde/alcohol dehydrogenase. Among eukaryotes, the oxygen producer C. reinhardtii has the broadest repertoire of pyruvate-, ethanol-, and acetate-metabolizing enzymes described to date, many of which were previously viewed as specific to anaerobic eukaryotic lineages.
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Affiliation(s)
- Ariane Atteia
- Institute of Botany, University of Düsseldorf, 40225 Düsseldorf, Germany.
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Schreiner ME, Riedel C, Holátko J, Pátek M, Eikmanns BJ. Pyruvate:quinone oxidoreductase in Corynebacterium glutamicum: molecular analysis of the pqo gene, significance of the enzyme, and phylogenetic aspects. J Bacteriol 2006; 188:1341-50. [PMID: 16452416 PMCID: PMC1367228 DOI: 10.1128/jb.188.4.1341-1350.2006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Accepted: 10/17/2005] [Indexed: 11/20/2022] Open
Abstract
Corynebacterium glutamicum recently has been shown to possess pyruvate:quinone oxidoreductase (PQO), catalyzing the oxidative decarboxylation of pyruvate to acetate and CO2 with a quinone as the electron acceptor. Here, we analyze the expression of the C. glutamicum pqo gene, investigate the relevance of the PQO enzyme for growth and amino acid production, and perform phylogenetic studies. Expression analyses revealed that transcription of pqo is initiated 45 bp upstream of the translational start site and that it is organized in an operon together with genes encoding a putative metal-activated pyridoxal enzyme and a putative activator protein. Inactivation of the chromosomal pqo gene led to the absence of PQO activity; however, growth and amino acid production were not affected under either condition tested. Introduction of plasmid-bound pqo into a pyruvate dehydrogenase complex-negative C. glutamicum strain partially relieved the growth phenotype of this mutant, indicating that high PQO activity can compensate for the function of the pyruvate dehydrogenase complex. To investigate the distribution of PQO enzymes in prokaryotes and to clarify the relationship between PQO, pyruvate oxidase (POX), and acetohydroxy acid synthase enzymes, we compiled and analyzed the phylogeny of respective proteins deposited in public databases. The analyses revealed a wide distribution of PQOs among prokaryotes, corroborated the hypothesis of a common ancestry of the three enzymes, and led us to propose that the POX enzymes of Lactobacillales were derived from a PQO.
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Affiliation(s)
- Mark E Schreiner
- Department of Microbiology and Biotechnology, University of Ulm, 89069 Ulm, Germany
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Li YH, Liu Y, Wang SC, Tong ZY, Xu QS. [Co-expressions of phosphoenolpyruvate synthetase A (ppsA) and transketolase A (tktA) genes of Escherichia coli]. Sheng Wu Gong Cheng Xue Bao 2003; 19:301-6. [PMID: 15969011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Metabolic engineering is the analysis of metabolic pathway and designing rational genetic modification to optimize cellular properties by using principle of molecular biology. Aromatic metabolites such as tryptophan, phenylalanine, and tyrosine are essential amino acids for human and animals. In addition, phenylalanine is used in aspartame production. Escherichia coli and many other microoganism synthesize aromatic amino acids through the condensation reaction between phospho-enolpyruvate (PEP) and erythrose-4-phosphate(E4P) to form 3-deoxy-D-arabinoheptulosonate 7-phosphate(DAHP). But many enzymes compete for intracellular PEP, especially the phosphotransferase system which is responsible for glucose transport in E. coli. This system uses PEP as a phosphate donor and converts it to pyruvate, which is less likely to recycle back to PEP. To channel more carbon flux into the aromatic pathway, one has to overcome pathways competing for PEP. ppsA and tktA are the key genes in central metabolism of aromatic amino acids biosynthesis. ppsA encoding phosphoenolpyrucate synthetase A (PpsA) which catalyzes pyruvate into PEP; tktA encoding transketolase A which plays a major role in erythrose-4-phosphate (E4P) production of pentose pathway. We amplified ppsA and tktA from E. coli K-12 by PCR and constructed recombinant plasmids of them in pBV220 vector containing P(R)P(L) promoter. Because of each gene carrying P(L) promoter, four productions of ligation were obtained. The monoclonal host containing recombinant plasmids was routinely grown in Luria-Bertani (LB) medium added Ampicillin at 37 degrees C overnight, and then inoculated in LB (Apr) medium by 3%-5% in flasks on a rotary shaker at 30 degres C, induced at 42 degrees C for 4.5 hours when OD600 = 0.4, cells were obtained by centrifugation at 10,000 r/min at 4 degrees C. The results of SDS-PAGE demonstrated that the bands at 84kD and 73kD were more intensive than the same ones of the controls. The specific activity of PpsA in crude extracts was increased by 10.8-fold, and TktA, by 3.9-fold. When both genes were co-expressed in E. coli, the activity of PpsA varied from 2.1-9.1 fold comparing to control, but the activity of TktA was relatively stable(3.9-4.5 fold). Whatever the two genes were expressed respectively or cooperatively, both could promote the production of DAHP, the first intermediate of the common aromatic pathway, but co-expression was more effective on forming DAHP. The results demonstrate that co-expression of ppsA and tktA can improve the production of DAHP to near theoretical yield. This report details a different strategy based on co-expression of two genes in one vector in vivo to release the burden and paves the way for construction of genetic engineering bacteria for further research.
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Affiliation(s)
- Yong-Hui Li
- Institute of Radiation Medicine, Academy of Military Medicine Science, Beijing 100850, China
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