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Pavao A, Girinathan B, Peltier J, Altamirano Silva P, Dupuy B, Muti IH, Malloy C, Cheng LL, Bry L. Elucidating dynamic anaerobe metabolism with HRMAS 13C NMR and genome-scale modeling. Nat Chem Biol 2023; 19:556-564. [PMID: 36894723 PMCID: PMC10154198 DOI: 10.1038/s41589-023-01275-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 01/30/2023] [Indexed: 03/11/2023]
Abstract
Anaerobic microbial metabolism drives critical functions within global ecosystems, host-microbiota interactions, and industrial applications, yet remains ill-defined. Here we advance a versatile approach to elaborate cellular metabolism in obligate anaerobes using the pathogen Clostridioides difficile, an amino acid and carbohydrate-fermenting Clostridia. High-resolution magic angle spinning nuclear magnetic resonance (NMR) spectroscopy of C. difficile, grown with fermentable 13C substrates, informed dynamic flux balance analysis (dFBA) of the pathogen's genome-scale metabolism. Analyses identified dynamic recruitment of oxidative and supporting reductive pathways, with integration of high-flux amino acid and glycolytic metabolism at alanine's biosynthesis to support efficient energy generation, nitrogen handling and biomass generation. Model predictions informed an approach leveraging the sensitivity of 13C NMR spectroscopy to simultaneously track cellular carbon and nitrogen flow from [U-13C]glucose and [15N]leucine, confirming the formation of [13C,15N]alanine. Findings identify metabolic strategies used by C. difficile to support its rapid colonization and expansion in gut ecosystems.
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Affiliation(s)
- Aidan Pavao
- Massachusetts Host-Microbiome Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Brintha Girinathan
- Massachusetts Host-Microbiome Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
- Ginkgo Bioworks, The Innovation and Design Building, Boston, MA, USA
| | - Johann Peltier
- Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015, Institut Pasteur, Université Paris-Cité, UMR-CNRS 6047, Paris, France
- Institute for Integrative Biology of the Cell (I2BC), 91198, University of Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Pamela Altamirano Silva
- Centre for Investigations in Tropical Diseases, Faculty of Microbiology, University of Costa Rica, San José, Costa Rica
| | - Bruno Dupuy
- Laboratoire Pathogenèse des Bactéries Anaérobies, F-75015, Institut Pasteur, Université Paris-Cité, UMR-CNRS 6047, Paris, France
| | - Isabella H Muti
- Departments of Radiology and Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Craig Malloy
- Department of Radiology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Leo L Cheng
- Departments of Radiology and Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - Lynn Bry
- Massachusetts Host-Microbiome Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
- Clinical Microbiology Laboratory, Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
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2
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Bustin KA, Abbas A, Wang X, Abt MC, Zackular JP, Matthews ML. Characterizing metabolic drivers of Clostridioides difficile infection with activity-based hydrazine probes. Front Pharmacol 2023; 14:1074619. [PMID: 36778002 PMCID: PMC9908766 DOI: 10.3389/fphar.2023.1074619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 01/05/2023] [Indexed: 01/27/2023] Open
Abstract
Many enzymes require post-translational modifications or cofactor machinery for primary function. As these catalytically essential moieties are highly regulated, they act as dual sensors and chemical handles for context-dependent metabolic activity. Clostridioides difficile is a major nosocomial pathogen that infects the colon. Energy generating metabolism, particularly through amino acid Stickland fermentation, is central to colonization and persistence of this pathogen during infection. Here using activity-based protein profiling (ABPP), we revealed Stickland enzyme activity is a biomarker for C. difficile infection (CDI) and annotated two such cofactor-dependent Stickland reductases. We structurally characterized the cysteine-derived pyruvoyl cofactors of D-proline and glycine reductase in C. difficile cultures and showed through cofactor monitoring that their activity is regulated by their respective amino acid substrates. Proline reductase was consistently active in toxigenic C. difficile, confirming the enzyme to be a major metabolic driver of CDI. Further, activity-based hydrazine probes were shown to be active site-directed inhibitors of proline reductase. As such, this enzyme activity, via its druggable cofactor modality, is a promising therapeutic target that could allow for the repopulation of bacteria that compete with C. difficile for proline and therefore restore colonization resistance against C. difficile in the gut.
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Affiliation(s)
- Katelyn A. Bustin
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, United States
| | - Arwa Abbas
- Division of Protective Immunity, Children’s Hospital of Pennsylvania, Philadelphia, PA, United States
| | - Xie Wang
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, United States
| | - Michael C. Abt
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Joseph P. Zackular
- Division of Protective Immunity, Children’s Hospital of Pennsylvania, Philadelphia, PA, United States,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Megan L. Matthews
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, United States,*Correspondence: Megan L. Matthews,
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Marshall A, McGrath JW, Graham R, McMullan G. Food for thought-The link between Clostridioides difficile metabolism and pathogenesis. PLoS Pathog 2023; 19:e1011034. [PMID: 36602960 PMCID: PMC9815643 DOI: 10.1371/journal.ppat.1011034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Clostridioides difficile (C. difficile) is an opportunistic pathogen that leads to antibiotic-associated diarrhoea and is a leading cause of morbidity and mortality worldwide. Antibiotic usage is the main risk factor leading to C. difficile infection (CDI), as a dysbiotic gut environment allows colonisation and eventual pathology manifested by toxin production. Although colonisation resistance is mediated by the action of secondary bile acids inhibiting vegetative outgrowth, nutrient competition also plays a role in preventing CDI as the gut microbiota compete for nutrient niches inhibiting C. difficile growth. C. difficile is able to metabolise carbon dioxide, the amino acids proline, hydroxyproline, and ornithine, the cell membrane constituent ethanolamine, and the carbohydrates trehalose, cellobiose, sorbitol, and mucin degradation products as carbon and energy sources through multiple pathways. Zinc sequestration by the host response mediates metabolic adaptation of C. difficile by perhaps signalling an inflamed gut allowing it to acquire abundant nutrients. Persistence within the gut environment is also mediated by the by-products of metabolism through the production of p-cresol, which inhibit gut commensal species growth promoting dysbiosis. This review aims to explore and describe the various metabolic pathways of C. difficile, which facilitate its survival and pathogenesis within the colonised host gut.
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Affiliation(s)
- Andrew Marshall
- School of Biological Sciences, Queen’s University Belfast, Belfast, Northern Ireland, United Kingdom
- * E-mail:
| | - John W. McGrath
- School of Biological Sciences, Queen’s University Belfast, Belfast, Northern Ireland, United Kingdom
| | - Robert Graham
- School of Biological Sciences, Queen’s University Belfast, Belfast, Northern Ireland, United Kingdom
| | - Geoff McMullan
- School of Biological Sciences, Queen’s University Belfast, Belfast, Northern Ireland, United Kingdom
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4
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Schwanbeck J, Oehmig I, Groß U, Bohne W. Clostridioides difficile minimal nutrient requirements for flagellar motility. Front Microbiol 2023; 14:1172707. [PMID: 37065145 PMCID: PMC10098170 DOI: 10.3389/fmicb.2023.1172707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 03/15/2023] [Indexed: 04/18/2023] Open
Abstract
As many gastro-intestinal pathogens, the majority of Clostridioides difficile strains express flagella together with a complete chemotaxis system. The resulting swimming motility is likely contributing to the colonization success of this important pathogen. In contrast to the well investigated general energy metabolism of C. difficile, little is known about the metabolic requirements for maintaining the ion motive force across the membrane, which in turn powers the flagellar motor. We studied here systematically the effect of various amino acids and carbohydrates on the swimming velocity of C. difficile using video microscopy in conjunction with a software based quantification of the swimming speed. Removal of individual amino acids from the medium identified proline and cysteine as the most important amino acids that power swimming motility. Glycine, which is as proline one of the few amino acids that are reduced in Stickland reactions, was not critical for swimming motility. This suggests that the ion motive force that powers the flagellar motor, is critically depending on proline reduction. A maximal and stable swimming motility was achieved with only four compounds, including the amino acids proline, cysteine and isoleucine together with a single, but interchangeable carbohydrate source such as glucose, succinate, mannose, ribose, pyruvate, trehalose, or ethanolamine. We expect that the identified "minimal motility medium" will be useful in future investigations on the flagellar motility and chemotactic behavior in C. difficile, particularly for the unambiguous identification of chemoattractants.
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Affiliation(s)
- Julian Schwanbeck
- Institute for Medical Microbiology and Virology, University Medical Center, Göttingen, Germany
- Biotechnology Institute, University of Minnesota, Saint Paul, MN, United States
| | - Ines Oehmig
- Institute for Medical Microbiology and Virology, University Medical Center, Göttingen, Germany
| | - Uwe Groß
- Institute for Medical Microbiology and Virology, University Medical Center, Göttingen, Germany
- Uwe Groß,
| | - Wolfgang Bohne
- Institute for Medical Microbiology and Virology, University Medical Center, Göttingen, Germany
- *Correspondence: Wolfgang Bohne,
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5
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Liu Y, Chen H, Van Treuren W, Hou BH, Higginbottom SK, Dodd D. Clostridium sporogenes uses reductive Stickland metabolism in the gut to generate ATP and produce circulating metabolites. Nat Microbiol 2022; 7:695-706. [PMID: 35505245 PMCID: PMC9089323 DOI: 10.1038/s41564-022-01109-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 03/24/2022] [Indexed: 11/30/2022]
Abstract
Gut bacteria face a key problem in how they capture enough energy to sustain their growth and physiology. The gut bacterium Clostridium sporogenes obtains its energy by utilizing amino acids in pairs, coupling the oxidation of one to the reduction of another-the Stickland reaction. Oxidative pathways produce ATP via substrate-level phosphorylation, whereas reductive pathways are thought to balance redox. In the present study, we investigated whether these reductive pathways are also linked to energy generation and the production of microbial metabolites that may circulate and impact host physiology. Using metabolomics, we find that, during growth in vitro, C. sporogenes produces 15 metabolites, 13 of which are present in the gut of C. sporogenes-colonized mice. Four of these compounds are reductive Stickland metabolites that circulate in the blood of gnotobiotic mice and are also detected in plasma from healthy humans. Gene clusters for reductive Stickland pathways suggest involvement of electron transfer proteins, and experiments in vitro demonstrate that reductive metabolism is coupled to ATP formation and not just redox balance. Genetic analysis points to the broadly conserved Rnf complex as a key coupling site for energy transduction. Rnf complex mutants show aberrant amino acid metabolism in a defined medium and are attenuated for growth in the mouse gut, demonstrating a role of the Rnf complex in Stickland metabolism and gut colonization. Our findings reveal that the production of circulating metabolites by a commensal bacterium within the host gut is linked to an ATP-yielding redox process.
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Affiliation(s)
- Yuanyuan Liu
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - Haoqing Chen
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - William Van Treuren
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Bi-Huei Hou
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - Steven K Higginbottom
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Dylan Dodd
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA.
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The Stickland Reaction Precursor trans-4-Hydroxy-l-Proline Differentially Impacts the Metabolism of Clostridioides difficile and Commensal Clostridia. mSphere 2022; 7:e0092621. [PMID: 35350846 PMCID: PMC9044972 DOI: 10.1128/msphere.00926-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
An intact gut microbiota confers colonization resistance against Clostridioides difficile through a variety of mechanisms, likely including competition for nutrients. Recently, proline was identified as an important environmental amino acid that C. difficile uses to support growth and cause significant disease. A posttranslationally modified form, trans-4-hydroxyproline, is highly abundant in collagen, which is degraded by host proteases in response to C. difficile toxin activity. The ability to dehydrate trans-4-hydroxyproline via the HypD glycyl radical enzyme is widespread among gut microbiota, including C. difficile and members of the commensal Clostridia, suggesting that this amino acid is an important nutrient in the host environment. Therefore, we constructed a C. difficile ΔhypD mutant and found that it was modestly impaired in fitness in a mouse model of infection, and was associated with an altered microbiota when compared to mice challenged with the wild-type strain. Changes in the microbiota between the two groups were largely driven by members of the Lachnospiraceae family and the Clostridium genus. We found that C. difficile and type strains of three commensal Clostridia had significant alterations to their metabolic gene expression in the presence of trans-4-hydroxyproline in vitro. The proline reductase (prd) genes were elevated in C. difficile, consistent with the hypothesis that trans-4-hydroxyproline is used by C. difficile to supply proline for energy metabolism. Similar transcripts were also elevated in some commensal Clostridia tested, although each strain responded differently. This suggests that the uptake and utilization of other nutrients by the commensal Clostridia may be affected by trans-4-hydroxyproline metabolism, highlighting how a common nutrient may be a signal to each organism to adapt to a unique niche. Further elucidation of the differences between them in the presence of hydroxyproline and other key nutrients will be important in determining their role in nutrient competition against C. difficile. IMPORTANCE Proline is an essential environmental amino acid that C. difficile uses to support growth and cause significant disease. A posttranslationally modified form, hydroxyproline, is highly abundant in collagen, which is degraded by host proteases in response to C. difficile toxin activity. The ability to dehydrate hydroxyproline via the HypD glycyl radical enzyme is widespread among gut microbiota, including C. difficile and members of the commensal Clostridia, suggesting that this amino acid is an important nutrient in the host environment. We found that C. difficile and three commensal Clostridia strains had significant, but different, alterations to their metabolic gene expression in the presence of hydroxyproline in vitro. This suggests that the uptake and utilization of other nutrients by the commensal Clostridia may be affected by hydroxyproline metabolism, highlighting how a common nutrient may be a signal to each organism to adapt to a unique niche. Further elucidation of the differences between them in the presence of hydroxyproline and other key nutrients will be important to determining their role in nutrient competition against C. difficile.
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7
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Neumann-Schaal M, Jahn D, Schmidt-Hohagen K. Metabolism the Difficile Way: The Key to the Success of the Pathogen Clostridioides difficile. Front Microbiol 2019; 10:219. [PMID: 30828322 PMCID: PMC6384274 DOI: 10.3389/fmicb.2019.00219] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 01/28/2019] [Indexed: 12/11/2022] Open
Abstract
Strains of Clostridioides difficile cause detrimental diarrheas with thousands of deaths worldwide. The infection process by the Gram-positive, strictly anaerobic gut bacterium is directly related to its unique metabolism, using multiple Stickland-type amino acid fermentation reactions coupled to Rnf complex-mediated sodium/proton gradient formation for ATP generation. Major pathways utilize phenylalanine, leucine, glycine and proline with the formation of 3-phenylproprionate, isocaproate, butyrate, 5-methylcaproate, valerate and 5-aminovalerate. In parallel a versatile sugar catabolism including pyruvate formate-lyase as a central enzyme and an incomplete tricarboxylic acid cycle to prevent unnecessary NADH formation completes the picture. However, a complex gene regulatory network that carefully mediates the continuous adaptation of this metabolism to changing environmental conditions is only partially elucidated. It involves the pleiotropic regulators CodY and SigH, the known carbon metabolism regulator CcpA, the proline regulator PrdR, the iron regulator Fur, the small regulatory RNA CsrA and potentially the NADH-responsive regulator Rex. Here, we describe the current knowledge of the metabolic principles of energy generation by C. difficile and the underlying gene regulatory scenarios.
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Affiliation(s)
- Meina Neumann-Schaal
- Leibniz Institute DSMZ, German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany.,Integrated Centre of Systems Biology (BRICS), Braunschweig University of Technology, Braunschweig, Germany
| | - Dieter Jahn
- Integrated Centre of Systems Biology (BRICS), Braunschweig University of Technology, Braunschweig, Germany.,Institute of Microbiology, Braunschweig University of Technology, Braunschweig, Germany
| | - Kerstin Schmidt-Hohagen
- Integrated Centre of Systems Biology (BRICS), Braunschweig University of Technology, Braunschweig, Germany.,Department of Bioinformatics and Biochemistry, Braunschweig University of Technology, Braunschweig, Germany
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8
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Christgen SL, Becker DF. Role of Proline in Pathogen and Host Interactions. Antioxid Redox Signal 2019; 30:683-709. [PMID: 29241353 PMCID: PMC6338583 DOI: 10.1089/ars.2017.7335] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 10/26/2017] [Accepted: 11/14/2017] [Indexed: 01/20/2023]
Abstract
SIGNIFICANCE Proline metabolism has complex roles in a variety of biological processes, including cell signaling, stress protection, and energy production. Proline also contributes to the pathogenesis of various disease-causing organisms. Understanding the mechanisms of how pathogens utilize proline is important for developing new strategies against infectious diseases. Recent Advances: The ability of pathogens to acquire amino acids is critical during infection. Besides protein biosynthesis, some amino acids, such as proline, serve as a carbon, nitrogen, or energy source in bacterial and protozoa pathogens. The role of proline during infection depends on the physiology of the host/pathogen interactions. Some pathogens rely on proline as a critical respiratory substrate, whereas others exploit proline for stress protection. CRITICAL ISSUES Disruption of proline metabolism and uptake has been shown to significantly attenuate virulence of certain pathogens, whereas in other pathogens the importance of proline during infection is not known. Inhibiting proline metabolism and transport may be a useful therapeutic strategy against some pathogens. Developing specific inhibitors to avoid off-target effects in the host, however, will be challenging. Also, potential treatments that target proline metabolism should consider the impact on intracellular levels of Δ1-pyrroline-5-carboxylate, a metabolite intermediate that can have opposing effects on pathogenesis. FUTURE DIRECTIONS Further characterization of how proline metabolism is regulated during infection would provide new insights into the role of proline in pathogenesis. Biochemical and structural characterization of proline metabolic enzymes from different pathogens could lead to new tools for exploring proline metabolism during infection and possibly new therapeutic compounds.
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Affiliation(s)
- Shelbi L. Christgen
- Department of Biochemistry, Redox Biology Center, University of Nebraska−Lincoln, Lincoln, Nebraska
| | - Donald F. Becker
- Department of Biochemistry, Redox Biology Center, University of Nebraska−Lincoln, Lincoln, Nebraska
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9
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Berges M, Michel AM, Lassek C, Nuss AM, Beckstette M, Dersch P, Riedel K, Sievers S, Becher D, Otto A, Maaß S, Rohde M, Eckweiler D, Borrero-de Acuña JM, Jahn M, Neumann-Schaal M, Jahn D. Iron Regulation in Clostridioides difficile. Front Microbiol 2018; 9:3183. [PMID: 30619231 PMCID: PMC6311696 DOI: 10.3389/fmicb.2018.03183] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 12/10/2018] [Indexed: 12/13/2022] Open
Abstract
The response to iron limitation of several bacteria is regulated by the ferric uptake regulator (Fur). The Fur-regulated transcriptional, translational and metabolic networks of the Gram-positive, pathogen Clostridioides difficile were investigated by a combined RNA sequencing, proteomic, metabolomic and electron microscopy approach. At high iron conditions (15 μM) the C. difficile fur mutant displayed a growth deficiency compared to wild type C. difficile cells. Several iron and siderophore transporter genes were induced by Fur during low iron (0.2 μM) conditions. The major adaptation to low iron conditions was observed for the central energy metabolism. Most ferredoxin-dependent amino acid fermentations were significantly down regulated (had, etf, acd, grd, trx, bdc, hbd). The substrates of these pathways phenylalanine, leucine, glycine and some intermediates (phenylpyruvate, 2-oxo-isocaproate, 3-hydroxy-butyryl-CoA, crotonyl-CoA) accumulated, while end products like isocaproate and butyrate were found reduced. Flavodoxin (fldX) formation and riboflavin biosynthesis (rib) were enhanced, most likely to replace the missing ferredoxins. Proline reductase (prd), the corresponding ion pumping RNF complex (rnf) and the reaction product 5-aminovalerate were significantly enhanced. An ATP forming ATPase (atpCDGAHFEB) of the F0F1-type was induced while the formation of a ATP-consuming, proton-pumping V-type ATPase (atpDBAFCEKI) was decreased. The [Fe-S] enzyme-dependent pyruvate formate lyase (pfl), formate dehydrogenase (fdh) and hydrogenase (hyd) branch of glucose utilization and glycogen biosynthesis (glg) were significantly reduced, leading to an accumulation of glucose and pyruvate. The formation of [Fe-S] enzyme carbon monoxide dehydrogenase (coo) was inhibited. The fur mutant showed an increased sensitivity to vancomycin and polymyxin B. An intensive remodeling of the cell wall was observed, Polyamine biosynthesis (spe) was induced leading to an accumulation of spermine, spermidine, and putrescine. The fur mutant lost most of its flagella and motility. Finally, the CRISPR/Cas and a prophage encoding operon were downregulated. Fur binding sites were found upstream of around 20 of the regulated genes. Overall, adaptation to low iron conditions in C. difficile focused on an increase of iron import, a significant replacement of iron requiring metabolic pathways and the restructuring of the cell surface for protection during the complex adaptation phase and was only partly directly regulated by Fur.
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Affiliation(s)
- Mareike Berges
- Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany
| | - Annika-Marisa Michel
- Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany
| | - Christian Lassek
- Center for Functional Genomics of Microbes (CFGM), Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Aaron M Nuss
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Michael Beckstette
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Petra Dersch
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Katharina Riedel
- Center for Functional Genomics of Microbes (CFGM), Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Susanne Sievers
- Center for Functional Genomics of Microbes (CFGM), Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Dörte Becher
- Center for Functional Genomics of Microbes (CFGM), Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Andreas Otto
- Center for Functional Genomics of Microbes (CFGM), Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Sandra Maaß
- Center for Functional Genomics of Microbes (CFGM), Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Manfred Rohde
- Central Facility for Microscopy, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany
| | - Denitsa Eckweiler
- Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany
| | | | - Martina Jahn
- Institute of Microbiology, Technische Universität Braunschweig, Braunschweig, Germany
| | - Meina Neumann-Schaal
- Leibniz-Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Dieter Jahn
- Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany.,Institute of Microbiology, Technische Universität Braunschweig, Braunschweig, Germany
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10
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Bassi D, Cappa F, Cocconcelli PS. Array-based transcriptional analysis of Clostridium sporogenes UC9000 during germination, cell outgrowth and vegetative life. Food Microbiol 2012; 33:11-23. [PMID: 23122496 DOI: 10.1016/j.fm.2012.08.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 07/04/2012] [Accepted: 08/05/2012] [Indexed: 01/22/2023]
Abstract
The members of the genus Clostridium, including the spore-forming anaerobic bacteria, have a complex and strictly regulated life cycle, but very little is known about the genetic pathways involved in the different stages of their life cycle. Clostridium sporogenes, a Gram-positive bacterium usually involved in food spoilage and frequently isolated from late blowing cheese, is genetically indistinguishable from the proteolytic Clostridium botulinum. As the non-neurotoxic counterpart, it is often used as an exemplar for the toxic subtypes. In this work, we performed a microscopic study combined with a custom array-based analysis of the C. sporogenes cycle, from dormant spores to the early stationary phase. We identified a total of 211 transcripts in spores, validating the hypothesis that mRNAs are abundant in spores and the pattern of mRNA expression is strikingly different from that present in growing cells. The spore transcripts included genes responsible for different life-sustaining functions, suggesting there was transcript entrapment or basic poly-functional gene activation for future steps. In addition, 3 h after the beginning of the germination process, 20% of the total up-regulated genes were temporally expressed in germinating spores. The vegetative condition appeared to be more active in terms of gene transcription and protein synthesis than the spore, and genes coding for germination and sporulation factors seemed to be expressed at this point. These results suggest that spores are not silent entities, and a broader knowledge of the genetic pathways involved in the Clostridium life cycle could provide a better understanding of pathogenic clostridia types.
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Affiliation(s)
- Daniela Bassi
- Istituto di Microbiologia, Università Cattolica del Sacro Cuore, Via Emilia Parmense 84, 29122 Piacenza/Via Milano 24, 26100 Cremona, Italy.
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11
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Fischbach MA, Sonnenburg JL. Eating for two: how metabolism establishes interspecies interactions in the gut. Cell Host Microbe 2011; 10:336-47. [PMID: 22018234 PMCID: PMC3225337 DOI: 10.1016/j.chom.2011.10.002] [Citation(s) in RCA: 323] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In bacterial communities, "tight economic times" are the norm. Of the many challenges bacteria face in making a living, perhaps none are more important than generating energy, maintaining redox balance, and acquiring carbon and nitrogen to synthesize primary metabolites. The ability of bacteria to meet these challenges depends heavily on the rest of their community. Indeed, the most fundamental way in which bacteria communicate is by importing the substrates for metabolism and exporting metabolic end products. As an illustration of this principle, we will travel down a carbohydrate catabolic pathway common to many species of Bacteroides, highlighting the interspecies interactions established (often inevitably) at its key steps. We also discuss the metabolic considerations in maintaining the stability of host-associated microbial communities.
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Affiliation(s)
- Michael A Fischbach
- Department of Bioengineering and Therapeutic Sciences and California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, CA 94158, USA.
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Fonknechten N, Chaussonnerie S, Tricot S, Lajus A, Andreesen JR, Perchat N, Pelletier E, Gouyvenoux M, Barbe V, Salanoubat M, Le Paslier D, Weissenbach J, Cohen GN, Kreimeyer A. Clostridium sticklandii, a specialist in amino acid degradation:revisiting its metabolism through its genome sequence. BMC Genomics 2010; 11:555. [PMID: 20937090 PMCID: PMC3091704 DOI: 10.1186/1471-2164-11-555] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Accepted: 10/11/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Clostridium sticklandii belongs to a cluster of non-pathogenic proteolytic clostridia which utilize amino acids as carbon and energy sources. Isolated by T.C. Stadtman in 1954, it has been generally regarded as a "gold mine" for novel biochemical reactions and is used as a model organism for studying metabolic aspects such as the Stickland reaction, coenzyme-B12- and selenium-dependent reactions of amino acids. With the goal of revisiting its carbon, nitrogen, and energy metabolism, and comparing studies with other clostridia, its genome has been sequenced and analyzed. RESULTS C. sticklandii is one of the best biochemically studied proteolytic clostridial species. Useful additional information has been obtained from the sequencing and annotation of its genome, which is presented in this paper. Besides, experimental procedures reveal that C. sticklandii degrades amino acids in a preferential and sequential way. The organism prefers threonine, arginine, serine, cysteine, proline, and glycine, whereas glutamate, aspartate and alanine are excreted. Energy conservation is primarily obtained by substrate-level phosphorylation in fermentative pathways. The reactions catalyzed by different ferredoxin oxidoreductases and the exergonic NADH-dependent reduction of crotonyl-CoA point to a possible chemiosmotic energy conservation via the Rnf complex. C. sticklandii possesses both the F-type and V-type ATPases. The discovery of an as yet unrecognized selenoprotein in the D-proline reductase operon suggests a more detailed mechanism for NADH-dependent D-proline reduction. A rather unusual metabolic feature is the presence of genes for all the enzymes involved in two different CO2-fixation pathways: C. sticklandii harbours both the glycine synthase/glycine reductase and the Wood-Ljungdahl pathways. This unusual pathway combination has retrospectively been observed in only four other sequenced microorganisms. CONCLUSIONS Analysis of the C. sticklandii genome and additional experimental procedures have improved our understanding of anaerobic amino acid degradation. Several specific metabolic features have been detected, some of which are very unusual for anaerobic fermenting bacteria. Comparative genomics has provided the opportunity to study the lifestyle of pathogenic and non-pathogenic clostridial species as well as to elucidate the difference in metabolic features between clostridia and other anaerobes.
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Affiliation(s)
- Nuria Fonknechten
- Institut de Génomique, Genoscope, 2 Rue Gaston Crémieux, F-91057 Evry, France
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Jackson-Rosario S, Cowart D, Myers A, Tarrien R, Levine RL, Scott RA, Self WT. Auranofin disrupts selenium metabolism in Clostridium difficile by forming a stable Au-Se adduct. J Biol Inorg Chem 2009; 14:507-19. [PMID: 19165513 DOI: 10.1007/s00775-009-0466-z] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Accepted: 01/02/2009] [Indexed: 12/18/2022]
Abstract
Clostridium difficile is a nosocomial pathogen whose incidence and importance are on the rise. Previous work in our laboratory characterized the central role of selenoenzyme-dependent Stickland reactions in C. difficile metabolism. In this work we have identified, using mass spectrometry, a stable complex formed upon reaction of auranofin (a gold-containing drug) with selenide in vitro. X-ray absorption spectroscopy supports the structure that we proposed on the basis of mass-spectrometric data. Auranofin potently inhibits the growth of C. difficile but does not similarly affect other clostridia that do not utilize selenoproteins to obtain energy. Moreover, auranofin inhibits the incorporation of radioisotope selenium ((75)Se) in selenoproteins in both Escherichia coli, the prokaryotic model for selenoprotein synthesis, and C. difficile without impacting total protein synthesis. Auranofin blocks the uptake of selenium and results in the accumulation of the auranofin-selenide adduct in the culture medium. Addition of selenium in the form of selenite or L-selenocysteine to the growth medium significantly reduces the inhibitory action of auranofin on the growth of C. difficile. On the basis of these results, we propose that formation of this complex and the subsequent deficiency in available selenium for selenoprotein synthesis is the mechanism by which auranofin inhibits C. difficile growth. This study demonstrates that targeting selenium metabolism provides a new avenue for antimicrobial development against C. difficile and other selenium-dependent pathogens.
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Affiliation(s)
- Sarah Jackson-Rosario
- Burnett School of Biomedical Science, College of Medicine, University of Central Florida, Orlando, FL 32816-2364, USA
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Kell DB. Iron behaving badly: inappropriate iron chelation as a major contributor to the aetiology of vascular and other progressive inflammatory and degenerative diseases. BMC Med Genomics 2009; 2:2. [PMID: 19133145 PMCID: PMC2672098 DOI: 10.1186/1755-8794-2-2] [Citation(s) in RCA: 359] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Accepted: 01/08/2009] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular 'reactive oxygen species' (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. REVIEW We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation).The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible.This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, since in some circumstances (especially the presence of poorly liganded iron) molecules that are nominally antioxidants can actually act as pro-oxidants. The reduction of redox stress thus requires suitable levels of both antioxidants and effective iron chelators. Some polyphenolic antioxidants may serve both roles.Understanding the exact speciation and liganding of iron in all its states is thus crucial to separating its various pro- and anti-inflammatory activities. Redox stress, innate immunity and pro- (and some anti-)inflammatory cytokines are linked in particular via signalling pathways involving NF-kappaB and p38, with the oxidative roles of iron here seemingly involved upstream of the IkappaB kinase (IKK) reaction. In a number of cases it is possible to identify mechanisms by which ROSs and poorly liganded iron act synergistically and autocatalytically, leading to 'runaway' reactions that are hard to control unless one tackles multiple sites of action simultaneously. Some molecules such as statins and erythropoietin, not traditionally associated with anti-inflammatory activity, do indeed have 'pleiotropic' anti-inflammatory effects that may be of benefit here. CONCLUSION Overall we argue, by synthesising a widely dispersed literature, that the role of poorly liganded iron has been rather underappreciated in the past, and that in combination with peroxide and superoxide its activity underpins the behaviour of a great many physiological processes that degrade over time. Understanding these requires an integrative, systems-level approach that may lead to novel therapeutic targets.
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Affiliation(s)
- Douglas B Kell
- School of Chemistry and Manchester Interdisciplinary Biocentre, The University of Manchester, 131 Princess St, Manchester, M1 7DN, UK.
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Dixon NM, Lovitt RW, Kell DB, Morris JG. Effects ofpCO2on the growth and metabolism ofClostridium sporogenesNCIB 8053 in defined media. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1365-2672.1987.tb02700.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Jackson S, Calos M, Myers A, Self WT. Analysis of proline reduction in the nosocomial pathogen Clostridium difficile. J Bacteriol 2006; 188:8487-95. [PMID: 17041035 PMCID: PMC1698225 DOI: 10.1128/jb.01370-06] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Clostridium difficile, a proteolytic strict anaerobe, has emerged as a clinically significant nosocomial pathogen in recent years. Pathogenesis is due to the production of lethal toxins, A and B, members of the large clostridial cytotoxin family. Although it has been established that alterations in the amino acid content of the growth medium affect toxin production, the molecular mechanism for this observed effect is not yet known. Since there is a paucity of information on the amino acid fermentation pathways used by this pathogen, we investigated whether Stickland reactions might be at the heart of its bioenergetic pathways. Growth of C. difficile on Stickland pairs yielded large increases in cell density in a limiting basal medium, demonstrating that these reactions are tied to ATP production. Selenium supplementation was required for this increase in cell yield. Analysis of genome sequence data reveals genes encoding the protein components of two key selenoenzyme reductases, glycine reductase and d-proline reductase (PR). These selenoenzymes were expressed upon the addition of the corresponding Stickland acceptor (glycine, proline, or hydroxyproline). Purification of the selenoenzyme d-proline reductase revealed a mixed complex of PrdA and PrdB (SeCys-containing) proteins. PR utilized only d-proline but not l-hydroxyproline, even in the presence of an expressed and purified proline racemase. PR was found to be independent of divalent cations, and zinc was a potent inhibitor of PR. These results show that Stickland reactions are key to the growth of C. difficile and that the mechanism of PR may differ significantly from that of previously studied PR from nonpathogenic species.
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Affiliation(s)
- Sarah Jackson
- Department of Molecular Biology and Microbiology, Burnett College of Biomedical Science, University of Central Florida, Orlando, FL 32816-2364, USA
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Kabisch UC, Gräntzdörffer A, Schierhorn A, Rücknagel KP, Andreesen JR, Pich A. Identification of D-proline reductase from Clostridium sticklandii as a selenoenzyme and indications for a catalytically active pyruvoyl group derived from a cysteine residue by cleavage of a proprotein. J Biol Chem 1999; 274:8445-54. [PMID: 10085076 DOI: 10.1074/jbc.274.13.8445] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Highly active D-proline reductase was obtained from Clostridium sticklandii by a modified purification scheme. The cytoplasmic enzyme had a molecular mass of about 870 kDa and was composed of three subunits with molecular masses of 23, 26, and 45 kDa. The 23-kDa subunit contained a carbonyl group at its N terminus, which could either be labeled with fluorescein thiosemicarbazide or removed by o-phenylenediamine; thus, N-terminal sequencing became feasible for this subunit. L-[14C]proline was covalently bound to the 23-kDa subunit if proline racemase and NaBH4 were added. Selenocysteine was detected in the 26-kDa subunit, which correlated with an observed selenium content of 10.6 g-atoms in D-proline reductase. No other non-proteinaceous cofactor was identified in the enzyme. A 4.8-kilobase pair (kb) EcoRI fragment was isolated and sequenced containing the two genes prdA and prdB. prdA coding for a 68-kDa protein was most likely translated as a proprotein that was posttranslationally cleaved at a threonine-cysteine site to give the 45-kDa subunit and most probably a pyruvoyl-containing 23-kDa subunit. The gene prdB encoded the 26-kDa subunit and contained an in frame UGA codon for selenocysteine insertion. prdA and prdB were transcribed together on a transcript of 4.5 kb; prdB was additionally transcribed as indicated by a 0.8-kb mRNA species.
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Affiliation(s)
- U C Kabisch
- Institut für Mikrobiologie, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Strasse 3, D-6099 Halle, Germany
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Andreesen JR, Wagner M, Sonntag D, Kohlstock M, Harms C, Gursinsky T, Jäger J, Parther T, Kabisch U, Gräntzdörffer A, Pich A, Söhling B. Various functions of selenols and thiols in anaerobic gram-positive, amino acids-utilizing bacteria. Biofactors 1999; 10:263-70. [PMID: 10609892 DOI: 10.1002/biof.5520100226] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Electron transfer reactions for the reduction of glycine in Eubacterium acidaminophilum involve many selenocysteine (U)- and thiol-containing proteins, as shown by biochemical and molecular analysis. These include an unusual thioredoxin system (-CXXC-), protein A (-CXXU-) and the substrate-specific protein B of glycine reductase (-UXXCXXC-). Most probably a selenoether is formed at protein B by splitting the C-N-bond after binding of the substrate. The carboxymethyl group is then transferred to the selenocysteine of protein A containing a conserved motif. The latter protein acts as a carbon and electron donor by giving rise to a protein C-bound acetyl-thioester and a mixed selenide-sulfide bond at protein A that will be reduced by the thioredoxin system. The dithiothreitol-dependent D-proline reductase of Clostridium sticklandii exhibits many similarities to protein B of glycine reductase including the motif containing selenocysteine. In both cases proprotein processing at a cysteine residue gives rise to a blocked N-terminus, most probably a pyruvoyl group. Formate dehydrogenase and some other proteins from E. acidaminophilum contain selenocysteine, e.g., a 22 kDa protein showing an extensive homology to peroxiredoxins involved in the detoxification of peroxides.
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Affiliation(s)
- J R Andreesen
- Institut für Mikrobiologie, Martin-Luther Universität Halle-Wittenberg, Germany.
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Patterson-Curtis SI, Johnson EA. Roles of arginine in growth of Clostridium botulinum Okra B. Appl Environ Microbiol 1992; 58:2334-7. [PMID: 1637170 PMCID: PMC195778 DOI: 10.1128/aem.58.7.2334-2337.1992] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Group I strains of Clostridium botulinum are known to degrade arginine by the arginine deiminase pathway. We have found that C. botulinum Okra B consumed a level of arginine (20 g/liter) higher than the basal requirement for growth (3 g/liter). Arginine was probably the preferred source of nitrogen for biosynthesis but did not serve as a major source of energy. Citrulline and proline were produced as major fermentation products in media containing high levels of arginine, but in media with basal amounts of arginine these products were produced in lower quantities during growth and were later reassimilated. The results indicate that C. botulinum Okra B changes its metabolism during consumption of surplus arginine, and this change is associated with toxin repression, formation of citrulline and proline as end products, and possibly resistance to environmental stresses such as increased acidity and osmolarity.
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Affiliation(s)
- S I Patterson-Curtis
- Department of Food Microbiology and Toxicology, University of Wisconsin, Madison 53706
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Reductive cleavage of sarcosine and betaine by Eubacterium acidaminophilum via enzyme systems different from glycine reductase. Arch Microbiol 1989. [DOI: 10.1007/bf00277541] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Dixon NM, James EW, Lovitt RW, Kell DB. Electromicrobial transformations using the pyruvate synthase system of Clostridium sporogenes. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/0302-4598(89)85004-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Dixon NM, James EW, Lovitt RW, Kell DB. Electromicrobial transformations using the pyruvate synthase system of Clostridium sporogenes. J Electroanal Chem (Lausanne) 1989. [DOI: 10.1016/0022-0728(89)87226-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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James EW, Kell DB, Lovitt RW, Gareth Morris J. Electrosynthesis and electroanalysis using Clostridium sporogenes. J Electroanal Chem (Lausanne) 1988. [DOI: 10.1016/0022-0728(80)80331-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Lovitt RW, Kell DB, Morris JG. The physiology of Clostridium sporogenes NCIB 8053 growing in defined media. THE JOURNAL OF APPLIED BACTERIOLOGY 1987; 62:81-92. [PMID: 3571035 DOI: 10.1111/j.1365-2672.1987.tb02383.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The physiology of Clostridium sporogenes was investigated in defined, minimal media. In batch culture, the major end products of glucose dissimilation were acetate, ethanol and formate. When L-proline was present as an electron acceptor, acetate production was strongly enhanced at the expense of ethanol. As judged by assay of the relevant enzymes, glucose was metabolized via the Embden-Meyerhof-Parnas pathway. The growth energetics of Cl. sporogenes were investigated in glucose- or L-valine-limited chemostat cultures. In the former case, the addition of L-proline to the medium caused a significant increase in the molar growth yield (as calculated by extrapolation to infinite dilution rate). This finding adds weight to the view that the reduction of L-proline by Cl. sporogenes is coupled to the conservation of free energy.
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