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Acciarri G, Taborra ME, Gizzi FO, Blancato VS, Magni C. Insertion sequence IS6770 modulates potassium symporter kup transcription in Enterococcus faecalis JH2-2 under low pH conditions. Int J Food Microbiol 2024; 419:110736. [PMID: 38772216 DOI: 10.1016/j.ijfoodmicro.2024.110736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 04/05/2024] [Accepted: 05/05/2024] [Indexed: 05/23/2024]
Abstract
Enterococcus faecalis is a phylogenetically and industrially relevant microorganism associated with Lactic Acid Bacteria. Some strains of this bacterium are employed as probiotics in commercial applications, while others serve as the principal component in starter cultures for artisanal regional cheese production. However, over the last decade, this species has emerged as an opportunistic multiresistant pathogen, raising concerns about its impact on human health. Recently, we identified multiple potassium transporter systems in E. faecalis, including the Ktr systems (KtrAB and KtrAD), Kup, KimA and Kdp complex (KdpFABC). Nevertheless, the physiological significance of these proteins remains not fully understood. In this study, we observed that the kup gene promoter region in the JH2-2 strain was modified due to the insertion of a complete copy of the IS6770 insertion sequence. Consequently, we investigated the influence of IS6770 on the expression of the kup gene. To achieve this, we conducted a mapping of the promoter region of this gene in the E. faecalis JH2-2 strain, employing fluorescence gene reporters. In addition, a transcriptional analysis of the kup gene was executed in a strain derived from E. faecalis V583 that lacks the IS30-related insertion element, facilitating the identification of the transcriptional start site. Next, the expression of the kup gene was evaluated via RT-qPCR under different pH stressful conditions. A strong upregulation of the kup gene was observed at an initial pH of 5.0 in the strain derived from E. faecalis V583. However, the activation of transcription was not observed in the E. faecalis JH2-2 strain due to the hindrance caused by the presence of IS6770. Besides that, our computational analysis of E. faecalis genomes elucidates a plausible association between transposition and the regulation of the kup gene. Remarkably, the ubiquitous presence of IS6770 throughout the phylogenetic tree implies its ancient existence within E. faecalis. Moreover, the recurrent co-occurrence of IS6770 with the kup gene, observed in 30 % of IS6770-positive strains, alludes to the potential involvement of this genomic arrangement in the adaptive strategies of E. faecalis across diverse niches.
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Affiliation(s)
- Giuliana Acciarri
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Suipacha 590, Rosario, Argentina; Laboratorio de Biotecnología e Inocuidad de los Alimentos, Área de Biotecnología de los Alimentos (FBioyF, UNR- Municipalidad de Granadero Baigorria), Sede Suipacha 590, Rosario, Argentina
| | - Maria Eugenia Taborra
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Suipacha 590, Rosario, Argentina; Laboratorio de Biotecnología e Inocuidad de los Alimentos, Área de Biotecnología de los Alimentos (FBioyF, UNR- Municipalidad de Granadero Baigorria), Sede Suipacha 590, Rosario, Argentina
| | - Fernan O Gizzi
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Suipacha 590, Rosario, Argentina; Laboratorio de Biotecnología e Inocuidad de los Alimentos, Área de Biotecnología de los Alimentos (FBioyF, UNR- Municipalidad de Granadero Baigorria), Sede Suipacha 590, Rosario, Argentina
| | - Victor S Blancato
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Suipacha 590, Rosario, Argentina; Laboratorio de Biotecnología e Inocuidad de los Alimentos, Área de Biotecnología de los Alimentos (FBioyF, UNR- Municipalidad de Granadero Baigorria), Sede Suipacha 590, Rosario, Argentina
| | - Christian Magni
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Suipacha 590, Rosario, Argentina; Laboratorio de Biotecnología e Inocuidad de los Alimentos, Área de Biotecnología de los Alimentos (FBioyF, UNR- Municipalidad de Granadero Baigorria), Sede Suipacha 590, Rosario, Argentina.
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2
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Combret V, Rincé I, Budin-Verneuil A, Muller C, Deutscher J, Hartke A, Sauvageot N. Utilization of glycoprotein-derived N-acetylglucosamine-L-asparagine during Enterococcus faecalis infection depends on catabolic and transport enzymes of the glycosylasparaginase locus. Res Microbiol 2024; 175:104169. [PMID: 37977353 DOI: 10.1016/j.resmic.2023.104169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 10/30/2023] [Accepted: 11/09/2023] [Indexed: 11/19/2023]
Abstract
Enterococcus faecalis is a Gram-positive clinical pathogen causing severe infections. Its survival during infection depends on its ability to utilize host-derived metabolites, such as protein-deglycosylation products. We have identified in E. faecalis OG1RF a locus (ega) involved in the catabolism of the glycoamino acid N-acetylglucosamine-L-asparagine. This locus is separated into two transcription units, genes egaRP and egaGBCD1D2, respectively. RT-qPCR experiments revealed that the expression of the ega locus is regulated by the transcriptional repressor EgaR. Electromobility shift assays evidenced that N-acetylglucosamine-L-asparagine interacts directly with the EgaR protein, which leads to the transcription of the ega genes. Growth studies with egaG, egaB and egaC mutants confirmed that the encoded proteins are necessary for N-acetylglucosamine-L-asparagine catabolism. This glycoamino acid is transported and phosphorylated by a specific phosphotransferase system EIIABC components (OG1RF_10751, EgaB, EgaC) and subsequently hydrolyzed by the glycosylasparaginase EgaG, which generates aspartate and 6-P-N-acetyl-β-d-glucosaminylamine. The latter can be used as a fermentable carbon source by E. faecalis. Moreover, Galleria mellonella larvae had a significantly higher survival rate when infected with ega mutants compared to the wild-type strain, suggesting that the loss of N-acetylglucosamine-L-asparagine utilization affects enterococcal virulence.
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Affiliation(s)
- Victor Combret
- Normandie Université, UNICAEN, CBSA, F-14000 Caen, France
| | - Isabelle Rincé
- Normandie Université, UNICAEN, CBSA, F-14000 Caen, France
| | | | - Cécile Muller
- Normandie Université, UNICAEN, CBSA, F-14000 Caen, France
| | - Josef Deutscher
- Université Paris Saclay, INRAE, Micalis Institute, 78350 Jouy en Josas, France; CNRS, Institut de Biologie Physico-Chimique UMR8261, Expression Génétique Microbienne, 75005 Paris, France
| | - Axel Hartke
- Normandie Université, UNICAEN, CBSA, F-14000 Caen, France
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Eicher C, Coulon J, Favier M, Alexandre H, Reguant C, Grandvalet C. Citrate metabolism in lactic acid bacteria: is there a beneficial effect for Oenococcus oeni in wine? Front Microbiol 2024; 14:1283220. [PMID: 38249489 PMCID: PMC10798043 DOI: 10.3389/fmicb.2023.1283220] [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: 08/25/2023] [Accepted: 12/08/2023] [Indexed: 01/23/2024] Open
Abstract
Lactic acid bacteria (LAB) are Gram positive bacteria frequently used in the food industry for fermentation, mainly transformation of carbohydrates into lactic acid. In addition, these bacteria also have the capacity to metabolize citrate, an organic acid commonly found in food products. Its fermentation leads to the production of 4-carbon compounds such as diacetyl, resulting in a buttery flavor desired in dairy products. Citrate metabolism is known to have several beneficial effects on LAB physiology. Nevertheless, a controversial effect of citrate has been described on the acid tolerance of the wine bacterium Oenococcus oeni. This observation raises questions about the effect of citrate on the capacity of O. oeni to conduct malolactic fermentation in highly acidic wines. This review aims to summarize the current understanding of citrate metabolism in LAB, with a focus on the wine bacterium O. oeni. Metabolism with the related enzymes is detailed, as are the involved genes organized in cit loci. The known systems of cit locus expression regulation are also described. Finally, the beneficial effects of citrate catabolism on LAB physiology are reported and the negative impact observed in O. oeni is discussed.
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Affiliation(s)
- Camille Eicher
- UMR PAM, Université de Bourgogne Franche-Comté, Institut Agro, Université de Bourgogne, INRAE, Dijon, France
| | | | | | - Hervé Alexandre
- UMR PAM, Université de Bourgogne Franche-Comté, Institut Agro, Université de Bourgogne, INRAE, Dijon, France
| | - Cristina Reguant
- Universitat Rovira i Virgili, Grup de Biotecnologia Enològica, Departament de Bioquímica i Biotecnologia, Tarragona, Catalonia, Spain
| | - Cosette Grandvalet
- UMR PAM, Université de Bourgogne Franche-Comté, Institut Agro, Université de Bourgogne, INRAE, Dijon, France
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Marshall A, McGrath JW, Mitchell M, Fanning S, McMullan G. One size does not fit all - Trehalose metabolism by Clostridioides difficile is variable across the five phylogenetic lineages. Microb Genom 2023; 9:001110. [PMID: 37768179 PMCID: PMC10569727 DOI: 10.1099/mgen.0.001110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 09/19/2023] [Indexed: 09/29/2023] Open
Abstract
Clostridioides difficile, the leading cause of antibiotic-associated diarrhoea worldwide, is a genetically diverse species which can metabolise a number of nutrient sources upon colonising a dysbiotic gut environment. Trehalose, a disaccharide sugar consisting of two glucose molecules bonded by an α 1,1-glycosidic bond, has been hypothesised to be involved in the emergence of C. difficile hypervirulence due to its increased utilisation by the RT027 and RT078 strains. Here, growth in trehalose as the sole carbon source was shown to be non-uniform across representative C. difficile strains, even though the genes for its metabolism were induced. Growth in trehalose reduced the expression of genes associated with toxin production and sporulation in the C. difficile R20291 (RT027) and M120 (RT078) strains in vitro, suggesting an inhibitory effect on virulence factors. Interestingly, the R20291 TreR transcriptional regulatory protein appeared to possess an activator function as its DNA-binding ability was increased in the presence of its effector, trehalose-6-phosphate. Using RNA-sequencing analysis, we report the identification of a putative trehalose metabolism pathway which is induced during growth in trehalose: this has not been previously described within the C. difficile species. These data demonstrate the metabolic diversity exhibited by C. difficile which warrants further investigation to elucidate the molecular basis of trehalose metabolism within this important gut pathogen.
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Affiliation(s)
- Andrew Marshall
- School of Biological Sciences, Queen’s University Belfast, 19 Chlorine Gardens, Belfast, BT9 5DL, UK
| | - John W. McGrath
- School of Biological Sciences, Queen’s University Belfast, 19 Chlorine Gardens, Belfast, BT9 5DL, UK
| | - Molly Mitchell
- University College Dublin-Centre for Food Safety University College Dublin, Dublin, Ireland
| | - Séamus Fanning
- University College Dublin-Centre for Food Safety University College Dublin, Dublin, Ireland
| | - Geoff McMullan
- School of Biological Sciences, Queen’s University Belfast, 19 Chlorine Gardens, Belfast, BT9 5DL, UK
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Li H, Ramia NE, Borges F, Revol-Junelles AM, Vogensen FK, Leisner JJ. Identification of Potential Citrate Metabolism Pathways in Carnobacterium maltaromaticum. Microorganisms 2021; 9:microorganisms9102169. [PMID: 34683489 PMCID: PMC8537297 DOI: 10.3390/microorganisms9102169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Revised: 10/13/2021] [Accepted: 10/15/2021] [Indexed: 11/16/2022] Open
Abstract
In the present study, we describe the identification of potential citrate metabolism pathways for the lactic acid bacterium (LAB) Carnobacterium maltaromaticum. A phenotypic assay indicated that four of six C. maltaromaticum strains showed weak (Cm 6-1 and ATCC 35586) or even delayed (Cm 3-1 and Cm 5-1) citrate utilization activity. The remaining two strains, Cm 4-1 and Cm 1-2 gave negative results. Additional analysis showed no or very limited utilization of citrate in media containing 1% glucose and 22 or 30 mM citrate and inoculated with Cm 6-1 or ATCC 35586. Two potential pathways of citrate metabolism were identified by bioinformatics analyses in C. maltaromaticum including either oxaloacetate (pathway 1) or tricarboxylic compounds such as isocitrate and α-ketoglutarate (pathway 2) as intermediates. Genes encoding pathway 1 were present in two out of six strains while pathway 2 included genes present in all six strains. The two potential citrate metabolism pathways in C. maltaromaticum may potentially affect the sensory profiles of milk and soft cheeses subjected to growth with this species.
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Affiliation(s)
- Heng Li
- Pasteurien College, Soochow University, Suzhou 215123, China;
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, Denmark
| | - Nancy E. Ramia
- Laboratoire d’Ingénierie des Biomolécules (LIBio), Ecole Nationale Supérieure d’Agronomie et des Industries Alimentaires (ENSAIA), Université de Lorraine, LIBio, F-54000 Nancy, France; (N.E.R.); (F.B.); (A.-M.R.-J.)
| | - Frédéric Borges
- Laboratoire d’Ingénierie des Biomolécules (LIBio), Ecole Nationale Supérieure d’Agronomie et des Industries Alimentaires (ENSAIA), Université de Lorraine, LIBio, F-54000 Nancy, France; (N.E.R.); (F.B.); (A.-M.R.-J.)
| | - Anne-Marie Revol-Junelles
- Laboratoire d’Ingénierie des Biomolécules (LIBio), Ecole Nationale Supérieure d’Agronomie et des Industries Alimentaires (ENSAIA), Université de Lorraine, LIBio, F-54000 Nancy, France; (N.E.R.); (F.B.); (A.-M.R.-J.)
| | - Finn Kvist Vogensen
- Department of Food Science, Faculty of Science, University of Copenhagen, DK-1958 Frederiksberg, Denmark;
| | - Jørgen J. Leisner
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, DK-1870 Frederiksberg, Denmark
- Correspondence:
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Terán LC, Mortera P, Tubio G, Alarcón SH, Blancato VS, Espariz M, Esteban L, Magni C. Genomic analysis revealed conserved acid tolerance mechanisms from native micro-organisms in fermented feed. J Appl Microbiol 2021; 132:1152-1165. [PMID: 34487594 DOI: 10.1111/jam.15292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 07/28/2021] [Accepted: 08/30/2021] [Indexed: 11/27/2022]
Abstract
AIMS Fermented feed is an agricultural practice used in many regions of the world to improve the growth performance of farm animals. This study aimed to identify and evaluate the lactic acid bacteria and yeast involved in the production of fermented feed. METHODS AND RESULTS We isolated and described two micro-organisms from autochthonous microbiota origin present in a regional feed product, Lactobacillus paracasei IBR07 (Lacticaseibacillus paracasei) and Kazachstania unispora IBR014 (Saccharomyces unisporum). Genome sequence analyses were performed to characterize both micro-organisms. Potential pathways involved in the acid response, tolerance and persistence were predicted in both genomes. Although L. paracasei and K. unispora are considered safe for animal feed, we analysed the presence of virulence factors, antibiotic resistance and pathogenicity islands. Furthermore, the Galleria mellonella model was used to support the safety of both isolates. CONCLUSIONS We conclude that IBR07 and IBR014 strains are good candidates to be used as starter cultures for feed fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY The data presented here will be helpful to explore other biotechnological aspects and constitute a starting point for further studies to establish the consumption benefit of fermented feed in farm animal production.
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Affiliation(s)
- Lucrecia C Terán
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Rosario, Argentina.,Laboratorio de Biotecnología e Inocuidad de los Alimentos, Área de Biotecnología de los alimentos, FBioyF, UNR-Municipalidad de Granadero Baigorria, Rosario, Argentina.,Centro de Referencia para Lactobacilos, CERELA-CONICET, San Miguel de Tucuman, Tucumán, Argentina
| | - Pablo Mortera
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Rosario, Argentina.,Laboratorio de Biotecnología e Inocuidad de los Alimentos, Área de Biotecnología de los alimentos, FBioyF, UNR-Municipalidad de Granadero Baigorria, Rosario, Argentina
| | - Gisela Tubio
- Instituto de Procesos Biotecnológicos y Químicos Rosario, IPROByQ (CONICET-UNR), Rosario, Argentina
| | - Sergio H Alarcón
- Laboratorio de Biotecnología e Inocuidad de los Alimentos, Área de Biotecnología de los alimentos, FBioyF, UNR-Municipalidad de Granadero Baigorria, Rosario, Argentina.,Instituto de Química de Rosario, IQUIR (CONICET-UNR), Rosario, Argentina
| | - Victor S Blancato
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Rosario, Argentina.,Laboratorio de Biotecnología e Inocuidad de los Alimentos, Área de Biotecnología de los alimentos, FBioyF, UNR-Municipalidad de Granadero Baigorria, Rosario, Argentina
| | - Martín Espariz
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Rosario, Argentina.,Laboratorio de Biotecnología e Inocuidad de los Alimentos, Área de Biotecnología de los alimentos, FBioyF, UNR-Municipalidad de Granadero Baigorria, Rosario, Argentina.,Área Estadística y Procesamiento de Datos, Departamento de Matemática y Estadística, FBioyF-UNR, Rosario, Argentina
| | - Luis Esteban
- Química Biológica, Facultad de Ciencias Médicas, UNR, Rosario, Argentina
| | - Christian Magni
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Rosario, Argentina.,Laboratorio de Biotecnología e Inocuidad de los Alimentos, Área de Biotecnología de los alimentos, FBioyF, UNR-Municipalidad de Granadero Baigorria, Rosario, Argentina
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Horne CR, Venugopal H, Panjikar S, Wood DM, Henrickson A, Brookes E, North RA, Murphy JM, Friemann R, Griffin MDW, Ramm G, Demeler B, Dobson RCJ. Mechanism of NanR gene repression and allosteric induction of bacterial sialic acid metabolism. Nat Commun 2021; 12:1988. [PMID: 33790291 PMCID: PMC8012715 DOI: 10.1038/s41467-021-22253-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 03/03/2021] [Indexed: 12/20/2022] Open
Abstract
Bacteria respond to environmental changes by inducing transcription of some genes and repressing others. Sialic acids, which coat human cell surfaces, are a nutrient source for pathogenic and commensal bacteria. The Escherichia coli GntR-type transcriptional repressor, NanR, regulates sialic acid metabolism, but the mechanism is unclear. Here, we demonstrate that three NanR dimers bind a (GGTATA)3-repeat operator cooperatively and with high affinity. Single-particle cryo-electron microscopy structures reveal the DNA-binding domain is reorganized to engage DNA, while three dimers assemble in close proximity across the (GGTATA)3-repeat operator. Such an interaction allows cooperative protein-protein interactions between NanR dimers via their N-terminal extensions. The effector, N-acetylneuraminate, binds NanR and attenuates the NanR-DNA interaction. The crystal structure of NanR in complex with N-acetylneuraminate reveals a domain rearrangement upon N-acetylneuraminate binding to lock NanR in a conformation that weakens DNA binding. Our data provide a molecular basis for the regulation of bacterial sialic acid metabolism. The GntR superfamily is one of the largest families of transcription factors in prokaryotes. Here the authors combine biophysical analysis and structural biology to dissect the mechanism by which NanR — a GntR-family regulator — binds to its promoter to repress the transcription of genes necessary for sialic acid metabolism.
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Affiliation(s)
- Christopher R Horne
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Hariprasad Venugopal
- Clive and Vera Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Clayton, VIC, Australia
| | - Santosh Panjikar
- Australian Synchrotron, ANSTO, Clayton, VIC, Australia.,Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
| | - David M Wood
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Amy Henrickson
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada
| | - Emre Brookes
- Department of Chemistry, University of Montana, Missoula, MT, USA
| | - Rachel A North
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - James M Murphy
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Rosmarie Friemann
- Department of Clinical Microbiology, Sahlgrenska University Hospital, Gothenburg, Sweden.,Centre for Antibiotic Resistance Research (CARe), University of Gothenburg, Gothenburg, Sweden
| | - Michael D W Griffin
- Bio21 Molecular Science and Biotechnology Institute, Department of Biochemistry and Pharmacology, University of Melbourne, Parkville, VIC, Australia
| | - Georg Ramm
- Clive and Vera Ramaciotti Centre for Cryo-Electron Microscopy, Monash University, Clayton, VIC, Australia.,Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
| | - Borries Demeler
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada.,Department of Chemistry, University of Montana, Missoula, MT, USA
| | - Renwick C J Dobson
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand. .,Bio21 Molecular Science and Biotechnology Institute, Department of Biochemistry and Pharmacology, University of Melbourne, Parkville, VIC, Australia.
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8
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Arya G, Pal M, Sharma M, Singh B, Singh S, Agrawal V, Chaba R. Molecular insights into effector binding by DgoR, a GntR/FadR family transcriptional repressor of D-galactonate metabolism in Escherichia coli. Mol Microbiol 2020; 115:591-609. [PMID: 33068046 DOI: 10.1111/mmi.14625] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 10/06/2020] [Accepted: 10/09/2020] [Indexed: 01/23/2023]
Abstract
Several GntR/FadR transcriptional regulators govern sugar acid metabolism in bacteria. Although effectors have been identified for a few sugar acid regulators, the mode of effector binding is unknown. Even in the overall FadR subfamily, there are limited details on effector-regulator interactions. Here, we identified the effector-binding cavity in Escherichia coli DgoR, a FadR subfamily transcriptional repressor of D-galactonate metabolism that employs D-galactonate as its effector. Using a genetic screen, we isolated several dgoR superrepressor alleles. Blind docking suggested eight amino acids corresponding to these alleles to form a part of the effector-binding cavity. In vivo and in vitro assays showed that these mutations compromise the inducibility of DgoR without affecting its oligomeric status or affinity for target DNA. Taking Bacillus subtilis GntR as a representative, we demonstrated that the effector-binding cavity is similar among FadR subfamily sugar acid regulators. Finally, a comparison of sugar acid regulators with other FadR members suggested conserved features of effector-regulator recognition within the FadR subfamily. Sugar acid metabolism is widely implicated in bacterial colonization and virulence. The present study sets the basis to investigate the influence of natural genetic variations in FadR subfamily regulators on their sensitivity to sugar acids and ultimately on host-bacterial interactions.
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Affiliation(s)
- Garima Arya
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
| | - Mohinder Pal
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
| | - Monika Sharma
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, India
| | - Bhupinder Singh
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
| | - Swati Singh
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
| | - Vishal Agrawal
- Department of Biochemistry, Panjab University, Chandigarh, India
| | - Rachna Chaba
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
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Ogura M, Shindo K, Kanesaki Y. Bacillus subtilis Nucleoid-Associated Protein YlxR Is Involved in Bimodal Expression of the Fructoselysine Utilization Operon ( frlBONMD-yurJ) Promoter. Front Microbiol 2020; 11:2024. [PMID: 32983026 PMCID: PMC7475707 DOI: 10.3389/fmicb.2020.02024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 07/30/2020] [Indexed: 11/13/2022] Open
Abstract
Bacteria must survive harsh environmental fluctuations at times and have evolved several strategies. “Collective” behaviors have been identified due to recent progress in single-cell analysis. Since most bacteria exist as single cells, bacterial populations are often considered clonal. However, accumulated evidence suggests this is not the case. Gene expression and protein expression are often not homogeneous, resulting in phenotypic heterogeneity. In extreme cases, this leads to bistability, the existence of two stable states. In many cases, expression of key master regulators is bimodal via positive feedback loops causing bimodal expression of the target genes. We observed bimodal expression of metabolic genes for alternative carbon sources. Expression profiles of the frlBONMD-yurJ operon driven by the frlB promoter (PfrlB), which encodes degradation enzymes and a transporter for amino sugars including fructoselysine, were investigated using transcriptional lacZ and gfp, and translational fluorescence reporter mCherry fusions. Disruption effects of genes encoding CodY, FrlR, RNaseY, and nucleoid-associated protein YlxR, four known regulatory factors for PfrlB, were examined for expression of each fusion construct. Expression of PfrlB-gfp and PfrlB-mCherry, which were located at amyE and its original locus, respectively, was bimodal; and disruption of ylxR resulted in the disappearance of the clear bimodal expression pattern in flow cytometric analyses. This suggested a role for YlxR on the bimodal expression of PfrlB. The data indicated that YlxR acted on the bimodal expression of PfrlB through both transcription and translation. YlxR regulates many genes, including those related to translation, supporting the above notion. Depletion of RNaseY abolished heterogenous expression of transcriptional PfrlB-gfp but not bimodal expression of translational PfrlB-mCherry, suggesting the role of RNaseY in regulation of the operon through mRNA stability control and regulatory mechanism for PfrlB-mCherry at the translational level. Based on these results, we discuss the meaning and possible cause of bimodal PfrlB expression.
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Affiliation(s)
- Mitsuo Ogura
- Institute of Oceanic Research and Development, Tokai University, Shizuoka, Japan
| | - Kazutoshi Shindo
- Department of Food and Nutrition, Japan Women's University, Tokyo, Japan
| | - Yu Kanesaki
- Research Institute of Green Science and Technology, Shizuoka University, Shizuoka, Japan
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D'Angelo M, Martino GP, Blancato VS, Espariz M, Hartke A, Sauvageot N, Benachour A, Alarcón SH, Magni C. Diversity of volatile organic compound production from leucine and citrate in Enterococcus faecium. Appl Microbiol Biotechnol 2019; 104:1175-1186. [PMID: 31828406 DOI: 10.1007/s00253-019-10277-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 11/14/2019] [Accepted: 11/23/2019] [Indexed: 01/22/2023]
Abstract
Enterococcus faecium is frequently isolated from fermented food; in particular, they positively contribute to the aroma compound generation in traditional cheese. Citrate fermentation is a desirable property in these bacteria, but this feature is not uniformly distributed among E. faecium strains. In the present study, three selected E. faecium strains, IQ110 (cit-), GM70 (cit+ type I), and Com12 (cit+ type II), were analyzed in their production of aroma compounds in milk. End products and volatile organic compounds (VOCs) were determined by solid-phase micro-extraction combined with gas chromatography mass spectrometry (SPME-GC-MS). Principal component analysis (PCA) of aroma compound profiles revealed a different VOC composition for the three strains. In addition, resting cell experiments of E. faecium performed in the presence of leucine, citrate, or pyruvate as aroma compound precursors allowed us to determine metabolic differences between the studied strains. GM70 (cit+ type I) showed an active citrate metabolism, with increased levels of diacetyl and acetoin generation relative to Com12 or to citrate defective IQ110 strains. In addition, in the experimental conditions tested, a defective citrate-fermenting phenotype for the Com12 strain was found, while its leucine degradation and pyruvate metabolism were conserved. In conclusion, rational selection of E. faecium strains could be performed based on genotypic and phenotypic analyses. This would result in a performing strain, such as GM70, that could positively contribute to flavor, with typical notes of diacetyl, acetoin, 3-methyl butanal, and 3-methyl butanol in an adjuvant culture.
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Affiliation(s)
- Matilde D'Angelo
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Suipacha 590, Rosario, Argentina
- Instituto de Química de Rosario (IQUIR), FBioyF, UNR-CONICET, Suipacha 570, Rosario, Argentina
| | - Gabriela P Martino
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Suipacha 590, Rosario, Argentina
- Laboratorio de Biotecnología e Inocuidad de los Alimentos, FBioyF, UNR-Municipalidad de Granadero Baigorria, Sede Suipacha 590, Rosario, Argentina
| | - Victor S Blancato
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Suipacha 590, Rosario, Argentina
- Laboratorio de Biotecnología e Inocuidad de los Alimentos, FBioyF, UNR-Municipalidad de Granadero Baigorria, Sede Suipacha 590, Rosario, Argentina
- U2RM Stress/Virulence, Normandie Univ, UNICAEN, 14000, Caen, France
| | - Martín Espariz
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Suipacha 590, Rosario, Argentina
- Laboratorio de Biotecnología e Inocuidad de los Alimentos, FBioyF, UNR-Municipalidad de Granadero Baigorria, Sede Suipacha 590, Rosario, Argentina
- U2RM Stress/Virulence, Normandie Univ, UNICAEN, 14000, Caen, France
| | - Axel Hartke
- U2RM Stress/Virulence, Normandie Univ, UNICAEN, 14000, Caen, France
| | | | | | - Sergio H Alarcón
- Instituto de Química de Rosario (IQUIR), FBioyF, UNR-CONICET, Suipacha 570, Rosario, Argentina
- Laboratorio de Biotecnología e Inocuidad de los Alimentos, FBioyF, UNR-Municipalidad de Granadero Baigorria, Sede Suipacha 590, Rosario, Argentina
| | - Christian Magni
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular y Celular de Rosario (IBR), sede Facultad de Ciencias Bioquímicas y Farmacéuticas (FBioyF), Universidad Nacional de Rosario (UNR), Consejo Nacional de Ciencia y Tecnología (CONICET), Suipacha 590, Rosario, Argentina.
- Laboratorio de Biotecnología e Inocuidad de los Alimentos, FBioyF, UNR-Municipalidad de Granadero Baigorria, Sede Suipacha 590, Rosario, Argentina.
- U2RM Stress/Virulence, Normandie Univ, UNICAEN, 14000, Caen, France.
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11
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Kotowska M, Świat M, Zarȩba-Pasławska J, Jaworski P, Pawlik K. A GntR-Like Transcription Factor HypR Regulates Expression of Genes Associated With L-Hydroxyproline Utilization in Streptomyces coelicolor A3(2). Front Microbiol 2019; 10:1451. [PMID: 31297104 PMCID: PMC6608401 DOI: 10.3389/fmicb.2019.01451] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 06/11/2019] [Indexed: 11/13/2022] Open
Abstract
Bacteria from the genus Streptomyces have been long exploited as the most prolific producers of antibiotics, other secondary metabolites and enzymes. They are important members of soil microbial communities that can adapt to changing conditions thank to the fine regulation of gene expression in response to environmental signals. Streptomyces coelicolor A3(2) is a model organism for molecular studies with the most deeply recognized interactions within the complex metabolic and regulatory network. However, details about molecular signals recognized by specialized regulatory proteins as well as their direct targets are often missing. We describe here a zinc-binding protein HypR (SCO6294) which belongs to FadR subfamily of GntR-like regulators. The DNA sequence 5'-TACAATGTCAC-3' recognized by the HypR protein in its own promoter region was identified by DNase I footprinting. Binding of six DNA fragments containing similar sequences located in other promoter regions were confirmed by the electrophoretic mobility shift assay (EMSA). The sequences of 7 in vitro-determined binding sites were assembled to generate a logo of the HypR binding motif, 5'-CTNTGC(A/C)ATGTCAC-3'. Comparison of luciferase reporter genes expression under the control of cloned promoter regions in S. coelicolor A3(2) wild type and deletion mutant strains revealed, that the HypR protein acts as a repressor of its target genes. Genes belonging to the regulon of HypR code for enzymes putatively involved in collagen degradation and utilization of L-hydroxyproline (L-Hyp) as concluded from predicted structure and conserved domains. Their transcription is induced in the wild type strain by the addition of L-Hyp to the culture medium. Moreover, knockout of one of the genes from the predicted L-Hyp utilization operon abolished the ability of the strain to grow on L-Hyp as a sole source of carbon. To our knowledge, this work is the first indication of the existence of the pathway of L-hydroxyproline catabolism in Streptomycetes.
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Affiliation(s)
- Magdalena Kotowska
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland
| | | | | | | | - Krzysztof Pawlik
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland
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12
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Implications of the expression of Enterococcus faecalis citrate fermentation genes during infection. PLoS One 2018; 13:e0205787. [PMID: 30335810 PMCID: PMC6193673 DOI: 10.1371/journal.pone.0205787] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 10/02/2018] [Indexed: 12/05/2022] Open
Abstract
Citrate is an ubiquitous compound in nature. However, citrate fermentation is present only in a few pathogenic or nonpathogenic microorganisms. The citrate fermentation pathway includes a citrate transporter, a citrate lyase complex, an oxaloacetate decarboxylase and a regulatory system. Enterococcus faecalis is commonly present in the gastro-intestinal microbiota of warm-blooded animals and insect guts. These bacteria can also cause infection and disease in immunocompromised individuals. In the present study, we performed whole genome analysis in Enterococcus strains finding that the complete citrate pathway is present in all of the E. faecalis strains isolated from such diverse habitats as animals, hospitals, water, milk, plants, insects, cheese, etc. These results indicate the importance of this metabolic preservation for persistence and growth of E. faecalis in different niches. We also analyzed the role of citrate metabolism in the E. faecalis pathogenicity. We found that an E. faecalis citrate fermentation-deficient strain was less pathogenic for Galleria mellonella larvae than the wild type. Furthermore, strains with deletions in the oxaloacetate decarboxylase subunits or in the α-acetolactate synthase resulted also less virulent than the wild type strain. We also observed that citrate promoters are induced in blood, urine and also in the hemolymph of G. mellonella. In addition, we showed that citrate fermentation allows E. faecalis to grow better in blood, urine and G. mellonella. The results presented here clearly indicate that citrate fermentation plays an important role in E. faecalis opportunistic pathogenic behavior.
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13
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Kim SH, Kwon CT, Song G, Koh HJ, An G, Paek NC. The rice zebra3 (z3) mutation disrupts citrate distribution and produces transverse dark-green/green variegation in mature leaves. RICE (NEW YORK, N.Y.) 2018; 11:1. [PMID: 29305728 PMCID: PMC5756232 DOI: 10.1186/s12284-017-0196-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 12/27/2017] [Indexed: 05/22/2023]
Abstract
BACKGROUND Rice zebra mutants are leaf variegation mutants that exhibit transverse sectors of green/yellow or green/white in developing or mature leaves. In most cases, leaf variegation is caused by defects in chloroplast biogenesis pathways, leading to an accumulation of reactive oxygen species in a transverse pattern in the leaves. Here, we examine a new type of leaf variegation mutant in rice, zebra3 (z3), which exhibits transverse dark-green/green sectors in mature leaves and lacks the typical yellow or white sectors. RESULTS Map-based cloning revealed that the Z3 locus encodes a putative citrate transporter that belongs to the citrate-metal hydrogen symport (CitMHS) family. CitMHS family members have been extensively studied in bacteria and function as secondary transporters that can transport metal-citrate complexes, but whether CitMHS family transporters exist in eukaryotes remains unknown. To investigate whether Z3 acts as a citrate transporter in rice, we measured citrate levels in wild-type leaves and in the dark-green and green sectors of the leaves of z3 mutants. The results showed that citrates accumulated to high levels in the dark-green sectors of z3 mutant leaves, but not in the green sectors as compared with the wild-type leaves. CONCLUSIONS These results suggest that leaf variegation in the z3 mutant is caused by an unbalanced accumulation of citrate in a transverse pattern in the leaves. Taking these results together, we propose that Z3 plays an important role in citrate transport and distribution during leaf development and is a possible candidate for a CitMHS family member in plants.
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Affiliation(s)
- Suk-Hwan Kim
- Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Republic of Korea
| | - Choon-Tak Kwon
- Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Republic of Korea
- Present address: Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 11724, USA
| | - Giha Song
- Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Republic of Korea
| | - Hee-Jong Koh
- Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Republic of Korea
| | - Gynheung An
- Crop Biotech Institute and Graduate School of Biotechnology, Kyung Hee University, Yongin, 17104, Republic of Korea
| | - Nam-Chon Paek
- Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Republic of Korea.
- Crop Biotechnology Institute, Institutes of Green Bio Science and Technology, Seoul National University, Pyeongchang, 25354, Republic of Korea.
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14
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Lo R, Ho VTT, Bansal N, Turner MS. The genetic basis underlying variation in production of the flavour compound diacetyl by Lactobacillus rhamnosus strains in milk. Int J Food Microbiol 2018; 265:30-39. [DOI: 10.1016/j.ijfoodmicro.2017.10.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 08/01/2017] [Accepted: 10/28/2017] [Indexed: 01/16/2023]
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15
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Zuljan FA, Mortera P, Alarcón SH, Blancato VS, Espariz M, Magni C. Lactic acid bacteria decarboxylation reactions in cheese. Int Dairy J 2016. [DOI: 10.1016/j.idairyj.2016.07.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Blancato VS, Pagliai FA, Magni C, Gonzalez CF, Lorca GL. Functional Analysis of the Citrate Activator CitO from Enterococcus faecalis Implicates a Divalent Metal in Ligand Binding. Front Microbiol 2016; 7:101. [PMID: 26903980 PMCID: PMC4746285 DOI: 10.3389/fmicb.2016.00101] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 01/19/2016] [Indexed: 02/04/2023] Open
Abstract
The regulator of citrate metabolism, CitO, from Enterococcus faecalis belongs to the FCD family within the GntR superfamily. In the presence of citrate, CitO binds to cis-acting sequences located upstream of the cit promoters inducing the expression of genes involved in citrate utilization. The quantification of the molecular binding affinities, performed by isothermal titration calorimetry (ITC), indicated that CitO has a high affinity for citrate (KD = 1.2 ± 0.2 μM), while it did not recognize other metabolic intermediates. Based on a structural model of CitO where a putative small molecule and a metal binding site were identified, it was hypothesized that the metal ion is required for citrate binding. In agreement with this model, citrate binding to CitO sharply decreased when the protein was incubated with EDTA. This effect was reverted by the addition of Ni2+, and Zn2+ to a lesser extent. Structure-based site-directed mutagenesis was conducted and it was found that changes to alanine in residues Arg97 and His191 resulted in decreased binding affinities for citrate, as determined by EMSA and ITC. Further assays using lacZ fusions confirmed that these residues in CitO are involved in sensing citrate in vivo. These results indicate that the molecular modifications induced by a ligand and a metal binding in the C-terminal domain of CitO are required for optimal DNA binding activity, and consequently, transcriptional activation.
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Affiliation(s)
- Víctor S Blancato
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular de Rosario, Consejo Nacional de Investigaciones Científicas y TécnicasRosario, Argentina; Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Science, University of FloridaGainesville, FL, USA
| | - Fernando A Pagliai
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Science, University of Florida Gainesville, FL, USA
| | - Christian Magni
- Laboratorio de Fisiología y Genética de Bacterias Lácticas, Instituto de Biología Molecular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas Rosario, Argentina
| | - Claudio F Gonzalez
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Science, University of Florida Gainesville, FL, USA
| | - Graciela L Lorca
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Science, University of Florida Gainesville, FL, USA
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Aroma compounds generation in citrate metabolism of Enterococcus faecium: Genetic characterization of type I citrate gene cluster. Int J Food Microbiol 2016; 218:27-37. [DOI: 10.1016/j.ijfoodmicro.2015.11.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 09/24/2015] [Accepted: 11/11/2015] [Indexed: 01/02/2023]
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18
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Ruiz-Cruz S, Espinosa M, Goldmann O, Bravo A. Global Regulation of Gene Expression by the MafR Protein of Enterococcus faecalis. Front Microbiol 2016; 6:1521. [PMID: 26793169 PMCID: PMC4707282 DOI: 10.3389/fmicb.2015.01521] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 12/17/2015] [Indexed: 12/27/2022] Open
Abstract
Enterococcus faecalis is a natural inhabitant of the human gastrointestinal tract. However, as an opportunistic pathogen, it is able to colonize other host niches and cause life-threatening infections. Its adaptation to new environments involves global changes in gene expression. The EF3013 gene (here named mafR) of E. faecalis strain V583 encodes a protein (MafR, 482 residues) that has sequence similarity to global response regulators of the Mga/AtxA family. The enterococcal OG1RF genome also encodes the MafR protein (gene OG1RF_12293). In this work, we have identified the promoter of the mafR gene using several in vivo approaches. Moreover, we show that MafR influences positively the transcription of many genes on a genome-wide scale. The most significant target genes encode components of PTS-type membrane transporters, components of ABC-type membrane transporters, and proteins involved in the metabolism of carbon sources. Some of these genes were previously reported to be up-regulated during the growth of E. faecalis in blood and/or in human urine. Furthermore, we show that a mafR deletion mutant strain induces a significant lower degree of inflammation in the peritoneal cavity of mice, suggesting that enterococcal cells deficient in MafR are less virulent. Our work indicates that MafR is a global transcriptional regulator. It might facilitate the adaptation of E. faecalis to particular host niches and, therefore, contribute to its potential virulence.
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Affiliation(s)
- Sofía Ruiz-Cruz
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Oliver Goldmann
- Infection Immunology Research Group, Helmholtz Centre for Infection Research Braunschweig, Germany
| | - Alicia Bravo
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas Madrid, Spain
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Hu J, Zhao L, Yang M. A GntR family transcription factor positively regulates mycobacterial isoniazid resistance by controlling the expression of a putative permease. BMC Microbiol 2015; 15:214. [PMID: 26474554 PMCID: PMC4609117 DOI: 10.1186/s12866-015-0556-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 10/08/2015] [Indexed: 01/13/2023] Open
Abstract
Background Bacteria use transcriptional regulation to respond to environmental stresses. Specifically, exposure to antibacterial drugs is deemed to be an atypical stress, and altering transcriptional regulation in response to such stress can increase bacterial drug resistance. However, only a few transcription factors that regulate drug resistance have been reported. Results In the present study, a GntR family transcription factor, encoded by the MSMEG_0535 (Ms0535) gene, was shown to be an isoniazid (INH) resistance regulator in Mycobacterium smegmatis. When the Ms0535 gene was overexpressed, cells showed a significant increase in INH resistance. First, the interaction between Ms0535 and its own promoter was determined, and a conserved 26-bp palindromic DNA binding motif was identified using electrophoretic mobility shift and DNaseI footprinting assays. Second, quantitative reverse transcription-PCR assays showed that Ms0535 acted as a transcriptional activator, and positively regulated its own expression, as well as that of a permease encoded by the MSMEG_0534 (Ms0534) gene. Similar to the case for the Ms0535 gene, a recombinant Ms0534-overexpressing strain also exhibited increased INH resistance compared with the wild-type strain. Furthermore, we showed that Ms0535 and Ms0534 deletion strains were more sensitive to INH than the wild-type strain. Interestingly, overexpressing Ms0534 in the Ms0535 deletion strain enhanced its INH resistance. In contrast, the Ms0534 deletion strain was still sensitive to INH even when Ms0535 was overexpressed. These findings suggest that Ms0534 is an effector protein that affects INH resistance in M. smegmatis. Conclusions In summary, the GntR transcriptional regulator Ms0535 positively regulates INH resistance by transcriptionally regulating the expression of the Ms0534 permease in M. smegmatis. These results improve our understanding of the role of transcriptional regulation in INH drug resistance in mycobacteria. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0556-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jialing Hu
- National Key Laboratory of Agricultural Microbiology, Center for Proteomics Research, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Lei Zhao
- National Key Laboratory of Agricultural Microbiology, Center for Proteomics Research, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Min Yang
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
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20
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Kaur B, Kaur R. Isolation, identification and genetic organization of the ADI operon in Enterococcus faecium GR7. ANN MICROBIOL 2014. [DOI: 10.1007/s13213-014-0981-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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21
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Repizo GD, Espariz M, Blancato VS, Suárez CA, Esteban L, Magni C. Genomic comparative analysis of the environmental Enterococcus mundtii against enterococcal representative species. BMC Genomics 2014; 15:489. [PMID: 24942651 PMCID: PMC4076982 DOI: 10.1186/1471-2164-15-489] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 06/02/2014] [Indexed: 11/30/2022] Open
Abstract
Background Enterococcus mundtii is a yellow-pigmented microorganism rarely found in human infections. The draft genome sequence of E. mundtii was recently announced. Its genome encodes at least 2,589 genes and 57 RNAs, and 4 putative genomic islands have been detected. The objective of this study was to compare the genetic content of E. mundtii with respect to other enterococcal species and, more specifically, to identify genes coding for putative virulence traits present in enterococcal opportunistic pathogens. Results An in-depth mining of the annotated genome was performed in order to uncover the unique properties of this microorganism, which allowed us to detect a gene encoding the antimicrobial peptide mundticin among other relevant features. Moreover, in this study a comparative genomic analysis against commensal and pathogenic enterococcal species, for which genomic sequences have been released, was conducted for the first time. Furthermore, our study reveals significant similarities in gene content between this environmental isolate and the selected enterococci strains (sharing an “enterococcal gene core” of 805 CDS), which contributes to understand the persistence of this genus in different niches and also improves our knowledge about the genetics of this diverse group of microorganisms that includes environmental, commensal and opportunistic pathogens. Conclusion Although E. mundtii CRL1656 is phylogenetically closer to E. faecium, frequently responsible of nosocomial infections, this strain does not encode the most relevant relevant virulence factors found in the enterococcal clinical isolates and bioinformatic predictions indicate that it possesses the lowest number of putative pathogenic genes among the most representative enterococcal species. Accordingly, infection assays using the Galleria mellonella model confirmed its low virulence. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-489) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | - Christian Magni
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET) and Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, Rosario S2002LRK, Argentina.
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22
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Lam MMC, Seemann T, Tobias NJ, Chen H, Haring V, Moore RJ, Ballard S, Grayson LM, Johnson PDR, Howden BP, Stinear TP. Comparative analysis of the complete genome of an epidemic hospital sequence type 203 clone of vancomycin-resistant Enterococcus faecium. BMC Genomics 2013; 14:595. [PMID: 24004955 PMCID: PMC3846456 DOI: 10.1186/1471-2164-14-595] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 08/28/2013] [Indexed: 11/10/2022] Open
Abstract
Background In this report we have explored the genomic and microbiological basis for a sustained increase in bloodstream infections at a major Australian hospital caused by Enterococcus faecium multi-locus sequence type (ST) 203, an outbreak strain that has largely replaced a predecessor ST17 sequence type. Results To establish a ST203 reference sequence we fully assembled and annotated the genome of Aus0085, a 2009 vancomycin-resistant Enterococcus faecium (VREfm) bloodstream isolate, and the first example of a completed ST203 genome. Aus0085 has a 3.2 Mb genome, comprising a 2.9 Mb circular chromosome and six circular plasmids (2 kb–130 kb). Twelve percent of the 3222 coding sequences (CDS) in Aus0085 are not present in ST17 E. faecium Aus0004 and ST18 E. faecium TX16. Extending this comparison to an additional 12 ST17 and 14 ST203 E. faecium hospital isolate genomes revealed only six genomic regions spanning 41 kb that were present in all ST203 and absent from all ST17 genomes. The 40 CDS have predicted functions that include ion transport, riboflavin metabolism and two phosphotransferase systems. Comparison of the vancomycin resistance-conferring Tn1549 transposon between Aus0004 and Aus0085 revealed differences in transposon length and insertion site, and van locus sequence variation that correlated with a higher vancomycin MIC in Aus0085. Additional phenotype comparisons between ST17 and ST203 isolates showed that while there were no differences in biofilm-formation and killing of Galleria mellonella, ST203 isolates grew significantly faster and out-competed ST17 isolates in growth assays. Conclusions Here we have fully assembled and annotated the first ST203 genome, and then characterized the genomic differences between ST17 and ST203 E. faecium. We also show that ST203 E. faecium are faster growing and can out-compete ST17 E. faecium. While a causal genetic basis for these phenotype differences is not provided here, this study revealed conserved genetic differences between the two clones, differences that can now be tested to explain the molecular basis for the success and emergence of ST203 E. faecium.
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Affiliation(s)
- Margaret M C Lam
- Department of Microbiology and Immunology, University of Melbourne, Parkville 3010, Victoria, Australia.
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Ca2+-citrate uptake and metabolism in Lactobacillus casei ATCC 334. Appl Environ Microbiol 2013; 79:4603-12. [PMID: 23709502 DOI: 10.1128/aem.00925-13] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The putative citrate metabolic pathway in Lactobacillus casei ATCC 334 consists of the transporter CitH, a proton symporter of the citrate-divalent metal ion family of transporters CitMHS, citrate lyase, and the membrane-bound oxaloacetate decarboxylase complex OAD-ABDH. Resting cells of Lactobacillus casei ATCC 334 metabolized citrate in complex with Ca(2+) and not as free citrate or the Mg(2+)-citrate complex, thereby identifying Ca(2+)-citrate as the substrate of the transporter CitH. The pathway was induced in the presence of Ca(2+) and citrate during growth and repressed by the presence of glucose and of galactose, most likely by a carbon catabolite repression mechanism. The end products of Ca(2+)-citrate metabolism by resting cells of Lb. casei were pyruvate, acetate, and acetoin, demonstrating the activity of the membrane-bound oxaloacetate decarboxylase complex OAD-ABDH. Following pyruvate, the pathway splits into two branches. One branch is the classical citrate fermentation pathway producing acetoin by α-acetolactate synthase and α-acetolactate decarboxylase. The other branch yields acetate, for which the route is still obscure. Ca(2+)-citrate metabolism in a modified MRS medium lacking a carbohydrate did not significantly affect the growth characteristics, and generation of metabolic energy in the form of proton motive force (PMF) was not observed in resting cells. In contrast, carbohydrate/Ca(2+)-citrate cometabolism resulted in a higher biomass yield in batch culture. However, also with these cells, no generation of PMF was associated with Ca(2+)-citrate metabolism. It is concluded that citrate metabolism in Lb. casei is beneficial when it counteracts acidification by carbohydrate metabolism in later growth stages.
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Biochemical and genetic characterization of the Enterococcus faecalis oxaloacetate decarboxylase complex. Appl Environ Microbiol 2013; 79:2882-90. [PMID: 23435880 DOI: 10.1128/aem.03980-12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enterococcus faecalis encodes a biotin-dependent oxaloacetate decarboxylase (OAD), which is constituted by four subunits: E. faecalis carboxyltransferase subunit OadA (termed Ef-A), membrane pump Ef-B, biotin acceptor protein Ef-D, and the novel subunit Ef-H. Our results show that in E. faecalis, subunits Ef-A, Ef-D, and Ef-H form a cytoplasmic soluble complex (termed Ef-AHD) which is also associated with the membrane. In order to characterize the role of the novel Ef-H subunit, coexpression of oad genes was performed in Escherichia coli, showing that this subunit is vital for Ef-A and Ef-D interaction. Diminished growth of the oadA and oadD single deletion mutants in citrate-supplemented medium indicated that the activity of the complex is essential for citrate utilization. Remarkably, the oadB-deficient strain was still capable of growing to wild-type levels but with a delay during the citrate-consuming phase, suggesting that the soluble Ef-AHD complex is functional in E. faecalis. These results suggest that the Ef-AHD complex is active in its soluble form, and that it is capable of interacting in a dynamic way with the membrane-bound Ef-B subunit to achieve its maximal alkalinization capacity during citrate fermentation.
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Auger C, Lemire J, Cecchini D, Bignucolo A, Appanna VD. The metabolic reprogramming evoked by nitrosative stress triggers the anaerobic utilization of citrate in Pseudomonas fluorescens. PLoS One 2011; 6:e28469. [PMID: 22145048 PMCID: PMC3228765 DOI: 10.1371/journal.pone.0028469] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 11/08/2011] [Indexed: 02/01/2023] Open
Abstract
Nitrosative stress is an ongoing challenge that most organisms have to contend with. When nitric oxide (NO) that may be generated either exogenously or endogenously encounters reactive oxygen species (ROS), it produces a set of toxic moieties referred to as reactive nitrogen species (RNS). As these RNS can severely damage essential biomolecules, numerous organisms have evolved elaborate detoxification strategies to nullify RNS. However, the contribution of cellular metabolism in fending off nitrosative stress is poorly understood. Using a variety of functional proteomic and metabolomic analyses, we have identified how the soil microbe Pseudomonas fluorescens reprogrammed its metabolic networks to survive in an environment enriched by sodium nitroprusside (SNP), a generator of nitrosative stress. To combat the RNS-induced ineffective aconitase (ACN) and tricarboxylic acid (TCA) cycle, the microbe invoked the participation of citrate lyase (CL), phosphoenolpyruvate carboxylase (PEPC) and pyruvate phosphate dikinase (PPDK) to convert citrate, the sole source of carbon into pyruvate and ATP. These enzymes were not evident in the control conditions. This metabolic shift was coupled to the concomitant increase in the activities of such classical RNS detoxifiers as nitrate reductase (NR), nitrite reductase (NIR) and S-nitrosoglutathione reductase (GSNOR). Hence, metabolism may hold the clues to the survival of organisms subjected to nitrosative stress and may provide therapeutic cues against RNS-resistant microbes.
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Affiliation(s)
- Christopher Auger
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, Canada
| | - Joseph Lemire
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, Canada
| | - Dominic Cecchini
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, Canada
| | - Adam Bignucolo
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, Canada
| | - Vasu D. Appanna
- Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, Canada
- * E-mail:
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Suárez CA, Blancato VS, Poncet S, Deutscher J, Magni C. CcpA represses the expression of the divergent cit operons of Enterococcus faecalis through multiple cre sites. BMC Microbiol 2011; 11:227. [PMID: 21989394 PMCID: PMC3198936 DOI: 10.1186/1471-2180-11-227] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 10/11/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In Enterococcus faecalis the genes encoding the enzymes involved in citrate metabolism are organized in two divergent operons, citHO and oadHDB-citCDEFX-oadA-citMG (citCL locus). Expression of both operons is specifically activated by adding citrate to the medium. This activation is mediated by binding of the GntR-like transcriptional regulator (CitO) to the cis-acting sequences located in the cit intergenic region. Early studies indicated that citrate and glucose could not be co-metabolized suggesting some form of catabolite repression, however the molecular mechanism remained unknown. RESULTS In this study, we observed that the citHO promoter is repressed in the presence of sugars transported by the Phosphoenolpyruvate:carbohydrate Phosphotranserase System (PTS sugars). This result strongly suggested that Carbon Catabolic Repression (CCR) impedes the expression of the activator CitO and the subsequent induction of the cit pathway. In fact, we demonstrate that CCR is acting on both promoters. It is partially relieved in a ccpA-deficient E. faecalis strain indicating that a CcpA-independent mechanism is also involved in regulation of the two operons. Furthermore, sequence analysis of the citH/oadH intergenic region revealed the presence of three putative catabolite responsive elements (cre). We found that they are all active and able to bind the CcpA/P-Ser-HPr complex, which downregulates the expression of the cit operons. Systematic mutation of the CcpA/P-Ser-HPr binding sites revealed that cre1 and cre2 contribute to citHO repression, while cre3 is involved in CCR of citCL. CONCLUSION In conclusion, our study establishes that expression of the cit operons in E. faecalis is controlled by CCR via CcpA-dependent and -independent mechanisms.
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Affiliation(s)
- Cristian A Suárez
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, (S2002LRK) Rosario, Argentina
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Espariz M, Repizo G, Blancato V, Mortera P, Alarcón S, Magni C. Identification of malic and soluble oxaloacetate decarboxylase enzymes in Enterococcus faecalis. FEBS J 2011; 278:2140-51. [PMID: 21518252 DOI: 10.1111/j.1742-4658.2011.08131.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two paralogous genes, maeE and citM, that encode putative malic enzyme family members were identified in the Enterococcus faecalis genome. MaeE (41 kDa) and CitM (42 kDa) share a high degree of homology between them (47% identities and 68% conservative substitutions). However, the genetic context of each gene suggested that maeE is associated with malate utilization whereas citM is linked to the citrate fermentation pathway. In the present work, we focus on the biochemical characterization and physiological contribution of these enzymes in E. faecalis. With this aim, the recombinant versions of the two proteins were expressed in Escherichia coli, affinity purified and finally their kinetic parameters were determined. This approach allowed us to establish that MaeE is a malate oxidative decarboxylating enzyme and CitM is a soluble oxaloacetate decarboxylase. Moreover, our genetic studies in E. faecalis showed that the citrate fermentation phenotype is not affected by citM deletion. On the other hand, maeE gene disruption resulted in a malate fermentation deficient strain indicating that MaeE is responsible for malate metabolism in E. faecalis. Lastly, it was demonstrated that malate fermentation in E. faecalis is associated with cytoplasmic and extracellular alkalinization which clearly contributes to pH homeostasis in neutral or mild acidic conditions.
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Affiliation(s)
- Martín Espariz
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Universidad Nacional de Rosario, Argentina
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Lensbouer JJ, Doyle RP. Secondary transport of metal-citrate complexes: the CitMHS family. Crit Rev Biochem Mol Biol 2011; 45:453-62. [PMID: 20735204 DOI: 10.3109/10409238.2010.504701] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Primary and secondary transport of citrate has been extensively studied in pathogenic and non-pathogenic bacteria. Primary transporters of citrate complexed with metal ions, particularly Fe, have also garnered attention, with the fec system of E. coli being a classic example. In contrast, little is known about secondary transporters of metal-citrate complexes. Recently, a family of proteins responsible for secondary metal-citrate transport in bacteria was discovered and designated as the CitMHS transporter family. Several members have been functionally characterized to date and serve as the foundation for understanding this family. Three subfamilies have been categorized, depending on the main metal ion transported. These subfamilies are the Mg(2+)-citrate transporter, the Ca(2+)-citrate transporter, and the Fe(3+)-citrate transporter. Each subfamily is believed to be substrate-selective due to the metal-citrate complexes being abundantly present in their environment and/or the ability of the complex to be metabolized by the organism. The implication of this family in the pathogenic access to Fe, information about transcriptional control, putative structure, predicted family members, members characterized to date and potential use in bioremediation are discussed.
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Affiliation(s)
- Joshua J Lensbouer
- Department of Chemistry, Center for Science and Technology, Syracuse University, Syracuse, NY 13244-4100, USA
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Scheu PD, Kim OB, Griesinger C, Unden G. Sensing by the membrane-bound sensor kinase DcuS: exogenous versus endogenous sensing of C4-dicarboxylates in bacteria. Future Microbiol 2010; 5:1383-402. [DOI: 10.2217/fmb.10.103] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Bacteria are able to grow at the expense of both common (succinate, L-malate, fumarate and aspartate) and uncommon (L-tartrate and D-malate) C4-dicarboxylates, which are components of central metabolism. Two types of sensors/regulators responding to the C4-dicarboxylates function in Escherichia coli, Bacillus, Lactobacillus and related bacteria. The first type represents membrane-integral two-component systems, while the second includes cytoplasmic LysR-type transcriptional regulators. The difference in location and substrate specificity allows the exogenous induction of metabolic genes by common C4-dicarboxylates, and endogenous induction by uncommon C4-dicarboxylates. The two-component sensors, DcuS and CitA, are composed of an extracellular Per-Arnt-Sim (PAS) domain, two transmembrane helices, a cytoplasmic PAS and the kinase domain. The structures of the extracellular PAS domains of DcuS and CitA have been determined in the ligand-bound and the apo form. Binding of the ligand results in closing and compaction of the binding site, and the structural change gives rise to piston-type movement of the adjacent membrane-spanning helix-2, and signal transmission to the cytoplasmic side. For DcuS, a membrane-embedded construct has been developed that suggests (by experimentation and modeling) that plasticity of the cytoplasmic PAS domain is central to signal transduction from the membrane to the kinase. Sensor kinase DcuS of E. coli requires the C4-dicarboxylate transporters DctA or DcuB as co-sensors for function under aerobic and anaerobic conditions, respectively. DcuB contains a regulatory site that controls the function of DcuS and is independent from the transport region. Therefore, DcuS senses C4-dicarboxylates in two independent modes, responding to the effector concentration and the metabolic flux of extracellular C4-dicarboxylates.
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Affiliation(s)
- Patrick D Scheu
- Institute for Microbiology & Wine Research, University of Mainz, 55099 Mainz, Germany
| | - Ok Bin Kim
- Department of Life Sciences, Ewha Womans University, Seoul, Republic of Korea
| | - Christian Griesinger
- Max-Planck-Institute for Biophysical Chemistry, Department of NMR-Based Structural Biology, Göttingen, Germany
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Comparative genomic analysis of pathogenic and probiotic Enterococcus faecalis isolates, and their transcriptional responses to growth in human urine. PLoS One 2010; 5:e12489. [PMID: 20824220 PMCID: PMC2930860 DOI: 10.1371/journal.pone.0012489] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 07/11/2010] [Indexed: 01/01/2023] Open
Abstract
Urinary tract infection (UTI) is the most common infection caused by enterococci, and Enterococcus faecalis accounts for the majority of enterococcal infections. Although a number of virulence related traits have been established, no comprehensive genomic or transcriptomic studies have been conducted to investigate how to distinguish pathogenic from non-pathogenic E. faecalis in their ability to cause UTI. In order to identify potential genetic traits or gene regulatory features that distinguish pathogenic from non-pathogenic E. faecalis with respect to UTI, we have performed comparative genomic analysis, and investigated growth capacity and transcriptome profiling in human urine in vitro. Six strains of different origins were cultivated and all grew readily in human urine. The three strains chosen for transcriptional analysis showed an overall similar response with respect to energy and nitrogen metabolism, stress mechanism, cell envelope modifications, and trace metal acquisition. Our results suggest that citrate and aspartate are significant for growth of E. faecalis in human urine, and manganese appear to be a limiting factor. The majority of virulence factors were either not differentially regulated or down-regulated. Notably, a significant up-regulation of genes involved in biofilm formation was observed. Strains from different origins have similar capacity to grow in human urine. The overall similar transcriptional responses between the two pathogenic and the probiotic strain suggest that the pathogenic potential of a certain E. faecalis strain may to a great extent be determined by presence of fitness and virulence factors, rather than the level of expression of such traits.
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Blancato VS, Magni C. A chimeric vector for efficient chromosomal modification in Enterococcus faecalis and other lactic acid bacteria. Lett Appl Microbiol 2010; 50:542-6. [PMID: 20158606 DOI: 10.1111/j.1472-765x.2010.02815.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM To construct a chimeric vector named pBVGh for quickly generating gene modifications in Enterococcus faecalis. METHODS AND RESULTS The constructed plasmid pBVGh carries the pG(+)host replicon (a thermosensitive (TS) derivative of pWV01), allowing a simple generation of mutants by growing colonies first at the permissive temperature and then switching the culture to the nonpermissive temperature. Additionally, this vector facilitates the screening of mutants by a rapid colorimetric blue-white discrimination of plasmid-free bacteria. CONCLUSIONS The pBVGh vector allows a straightforward inactivation or modification of target genes as well as a fast selection of enterococcal mutant strains. SIGNIFICANCE AND IMPACT OF THE STUDY The broad range of the TS replicon utilized in this plasmid permits the easy establishment and the efficient generation of food-grade mutant strains in Ent. faecalis and several other gram-positive bacteria.
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Affiliation(s)
- V S Blancato
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET) and Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, Rosario, Argentina
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Linares DM, Fernández M, Martín MC, Alvarez MA. Tyramine biosynthesis in Enterococcus durans is transcriptionally regulated by the extracellular pH and tyrosine concentration. Microb Biotechnol 2009; 2:625-33. [PMID: 21255297 PMCID: PMC3815318 DOI: 10.1111/j.1751-7915.2009.00117.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The microbial decarboxylation of some amino acids leads to the undesirable presence of biogenic amines in foods. One of the most abundant and frequent biogenic amines found in fermented foods is tyramine, which is produced by the decarboxylation of tyrosine. In the present work, transcriptional analysis of tyramine biosynthesis in Enterococcus durans IPLA655, a strain isolated from cheese, was studied. The gene coding for the tyrosine decarboxylase (tdcA) and that coding for the tyrosine-tyramine antiporter (tyrP) form an operon transcribed from the promoter P(tdcA), the expression of which is regulated by the extracellular pH and tyrosine concentration. Quantification of gene expression during the log phase of growth showed high concentrations of tyrosine and acidic pH conditions to induce tdcA-tyrP polycistronic messenger transcription.
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Affiliation(s)
- Daniel M Linares
- Instituto de Productos Lácteos de Asturias (IPLA), Consejo Superior de Investigaciones Científicas (CSIC), Carretera de Infiesto s/n, 33300 Villaviciosa, Asturias, Spain
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Hoskisson PA, Rigali S. Chapter 1 Variation in Form and Function. ADVANCES IN APPLIED MICROBIOLOGY 2009; 69:1-22. [DOI: 10.1016/s0065-2164(09)69001-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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