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Khaleque HN, Nazem-Bokaee H, Gumulya Y, Carlson RP, Kaksonen AH. Simulating compatible solute biosynthesis using a metabolic flux model of the biomining acidophile, Acidithiobacillus ferrooxidans ATCC 23270. Res Microbiol 2024; 175:104115. [PMID: 37572823 DOI: 10.1016/j.resmic.2023.104115] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 08/01/2023] [Accepted: 08/07/2023] [Indexed: 08/14/2023]
Abstract
Halotolerant, acidophilic, bioleaching microorganisms are crucial to biomining operations that utilize saline water. Compatible solutes play an important role in the adaptation of these microorganisms to saline environments. Acidithiobacillus ferrooxidans ATCC 23270, an iron- and sulfur-oxidizing acidophilic bacterium, synthesizes trehalose as its native compatible solute but is still sensitive to salinity. Recently, halotolerant bioleaching bacteria were found to use ectoine as their key compatible solute. Previously, bioleaching bacteria were recalcitrant to genetic manipulation; however, recent advancements in genetic tools and techniques allow successful genetic modification of A. ferrooxidans ATCC 23270. Therefore, this study aimed to test, in silico, the effect of native and synthetic compatible solute biosynthesis by A. ferrooxidans ATCC 23270 on its growth and metabolism. Metabolic network flux modelling was used to provide a computational framework for the prediction of metabolic fluxes during production of native and synthetic compatible solutes by A. ferrooxidans ATCC 23270, in silico. Complete pathways for trehalose biosynthesis by the bacterium are proposed and captured in the updated metabolic model including a newly discovered UDP-dependent trehalose synthesis pathway. Finally, the effect of nitrogen sources on compatible solute production was simulated and showed that using nitrogen gas as the sole nitrogen source enables the ectoine-producing 'engineered' microbe to oxidize up to 20% more ferrous iron in comparison to the native microbe that only produces trehalose. Therefore, the predictive outcomes of the model have the potential to guide the design and optimization of a halotolerant strain of A. ferrooxidans ATCC 23270 for saline bioleaching operations.
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Affiliation(s)
- Himel Nahreen Khaleque
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Environment, 147 Underwood Avenue, Floreat, WA, Australia; Synthetic Biology Future Science Platform, CSIRO, Canberra 2601, ACT, Australia; School of Science, Edith Cowan University, Joondalup, WA, Australia.
| | - Hadi Nazem-Bokaee
- Synthetic Biology Future Science Platform, CSIRO, Canberra 2601, ACT, Australia; Australian National Herbarium, National Research Collections Australia, NCMI, CSIRO, Canberra 2601, ACT, Australia.
| | - Yosephine Gumulya
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Environment, 147 Underwood Avenue, Floreat, WA, Australia; Synthetic Biology Future Science Platform, CSIRO, Canberra 2601, ACT, Australia; Centre for Microbiome Research, School of Biomedical Sciences, Queensland University of Technology, Translational Research Institute, Woolloongabba, Queensland, Australia.
| | - Ross P Carlson
- Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA.
| | - Anna H Kaksonen
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Environment, 147 Underwood Avenue, Floreat, WA, Australia; Synthetic Biology Future Science Platform, CSIRO, Canberra 2601, ACT, Australia.
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2
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Ballesteros-Gutiérrez M, Albareda M, Barbas C, López-Gonzálvez Á, Dunn MF, Palacios JM. A host-specific diaminobutyrate aminotransferase contributes to symbiotic performance, homoserine metabolism, and competitiveness in the Rhizobium leguminosarum/ Pisum sativum system. Front Microbiol 2023; 14:1182563. [PMID: 37260681 PMCID: PMC10228743 DOI: 10.3389/fmicb.2023.1182563] [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: 03/08/2023] [Accepted: 04/25/2023] [Indexed: 06/02/2023] Open
Abstract
Rhizobium leguminosarum bv. viciae (Rlv) UPM791 effectively nodulates pea and lentil, but bacteroids contain a number of proteins differentially expressed depending on the host. One of these host-dependent proteins (C189) is similar to a diaminobutyrate-2-oxoglutarate aminotransferase (DABA-AT). DABA-AT activity was demonstrated with cell extracts and with purified protein, so C189 was renamed as Dat. The dat gene was strongly induced in the central, active area of pea nodules, but not in lentil. Mutants defective in dat were impaired in symbiotic performance with pea plants, exhibiting reduced shoot dry weight, smaller nodules, and a lower competitiveness for nodulation. In contrast, there were no significant differences between mutant and wild-type in symbiosis with lentil plants. A comparative metabolomic approach using cell-free extracts from bacteroids induced in pea and lentil showed significant differences among the strains in pea bacteroids whereas no significant differences were found in lentil. Targeted metabolomic analysis revealed that the dat mutation abolished the presence of 2,4-diaminobutyrate (DABA) in pea nodules, indicating that DABA-AT reaction is oriented toward the production of DABA from L-aspartate semialdehyde. This analysis also showed the presence of L-homoserine, a likely source of aspartate semialdehyde, in pea bacteroids but not in those induced in lentil. The dat mutant showed impaired growth when cells were grown with L-homoserine as nitrogen source. Inclusion of DABA or L-homoserine as N source suppressed pantothenate auxotropy in Rlv UPM791, suggesting DABA as source of the pantothenate precursor β-alanine. These data indicate that Rlv UPM791 Dat enzyme is part of an adaptation mechanism of this bacterium to a homoserine-rich environment such as pea nodule and rhizosphere.
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Affiliation(s)
- Marta Ballesteros-Gutiérrez
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA/CSIC), Consejo Superior de Investigaciones Científicas, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Spain
| | - Marta Albareda
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA/CSIC), Consejo Superior de Investigaciones Científicas, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
| | - Coral Barbas
- Facultad de Farmacia, Center for Metabolomics and Bioanalysis (CEMBIO), Universidad San Pablo-CEU, Boadilla del Monte, Spain
| | - Ángeles López-Gonzálvez
- Facultad de Farmacia, Center for Metabolomics and Bioanalysis (CEMBIO), Universidad San Pablo-CEU, Boadilla del Monte, Spain
| | - Michael F. Dunn
- Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas-Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - José M. Palacios
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA/CSIC), Consejo Superior de Investigaciones Científicas, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Madrid, Spain
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3
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Czech L, Gertzen C, Smits SHJ, Bremer E. Guilty by association: importers, exporters and
MscS
‐type mechanosensitive channels encoded in biosynthetic gene clusters for the stress‐protectant ectoine. Environ Microbiol 2022; 24:5306-5331. [DOI: 10.1111/1462-2920.16203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 09/07/2022] [Indexed: 11/28/2022]
Affiliation(s)
- Laura Czech
- Department of Biology, Laboratory for Microbiology and Center for Synthetic Microbiology (SYNMIKRO) Philipps‐University Marburg Marburg Germany
- Department of Chemistry and Center for Synthetic Microbiology (SYNMIKRO) Philipps‐University Marburg Marburg Germany
| | - Christoph Gertzen
- Center for Structural Studies (CSS) Heinrich‐Heine‐University Düsseldorf Düsseldorf Germany
- Institute of Pharmaceutical and Medicinal Chemistry Heinrich‐Heine‐University Düsseldorf Düsseldorf Germany
| | - Sander H. J. Smits
- Center for Structural Studies (CSS) Heinrich‐Heine‐University Düsseldorf Düsseldorf Germany
- Institute of Biochemistry Heinrich Heine University Düsseldorf Düsseldorf Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology and Center for Synthetic Microbiology (SYNMIKRO) Philipps‐University Marburg Marburg Germany
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4
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Naufal M, Wu JH, Shao YH. Glutamate Enhances Osmoadaptation of Anammox Bacteria under High Salinity: Genomic Analysis and Experimental Evidence. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:11310-11322. [PMID: 35913201 DOI: 10.1021/acs.est.2c01104] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
An osmoprotectant that alleviates the bacterial osmotic stress can improve the bioreactor treatment of saline wastewater. However, proposed candidates are expensive, and osmoprotectants of anammox bacteria and their ecophysiological roles are not fully understood. In this study, a comparative analysis of 34 high-quality public metagenome-assembled genomes from anammox bacteria revealed two distinct groups of osmoadaptation. Candidatus Scalindua and Kuenenia share a close phylogenomic relation and osmoadaptation gene profile and have pathways for glutamate transport and metabolisms for enhanced osmoadaptation. The batch assay results demonstrated that the reduced Ca. Kuenenia activity in saline conditions was substantially alleviated with the addition and subsequent synergistic effects of potassium and glutamate. The operational test of two reactors demonstrated that the reduced anammox performance under brine conditions rapidly recovered by 35.7-43.1% as a result of glutamate treatment. The Ca. Kuenenia 16S rRNA and hydrazine gene expressions were upregulated significantly (p < 0.05), and the abundance increased by approximately 19.9%, with a decrease in dominant heterotrophs. These data demonstrated the effectiveness of glutamate in alleviating the osmotic stress of Ca. Kuenenia. This study provides genomic insight into group-specific osmoadaptation of anammox bacteria and can facilitate the precision management of anammox reactors under high salinity.
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Affiliation(s)
- Muhammad Naufal
- Department of Environmental Engineering, National Cheng Kung University, No. 1, University Road, East District, Tainan City 70101, Taiwan
| | - Jer-Horng Wu
- Department of Environmental Engineering, National Cheng Kung University, No. 1, University Road, East District, Tainan City 70101, Taiwan
| | - Yung-Hsien Shao
- Department of Environmental Engineering, National Cheng Kung University, No. 1, University Road, East District, Tainan City 70101, Taiwan
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5
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Oliver Huidobro M, Tica J, Wachter GKA, Isalan M. Synthetic spatial patterning in bacteria: advances based on novel diffusible signals. Microb Biotechnol 2022; 15:1685-1694. [PMID: 34843638 PMCID: PMC9151330 DOI: 10.1111/1751-7915.13979] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 11/14/2021] [Accepted: 11/14/2021] [Indexed: 12/22/2022] Open
Abstract
Engineering multicellular patterning may help in the understanding of some fundamental laws of pattern formation and thus may contribute to the field of developmental biology. Furthermore, advanced spatial control over gene expression may revolutionize fields such as medicine, through organoid or tissue engineering. To date, foundational advances in spatial synthetic biology have often been made in prokaryotes, using artificial gene circuits. In this review, engineered patterns are classified into four levels of increasing complexity, ranging from spatial systems with no diffusible signals to systems with complex multi-diffusor interactions. This classification highlights how the field was held back by a lack of diffusible components. Consequently, we provide a summary of both previously characterized and some new potential candidate small-molecule signals that can regulate gene expression in Escherichia coli. These diffusive signals will help synthetic biologists to successfully engineer increasingly intricate, robust and tuneable spatial structures.
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Affiliation(s)
| | - Jure Tica
- Department of Life SciencesImperial College LondonLondonSW7 2AZUK
| | | | - Mark Isalan
- Department of Life SciencesImperial College LondonLondonSW7 2AZUK
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6
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Hermann L, Dempwolff F, Steinchen W, Freibert SA, Smits SHJ, Seubert A, Bremer E. The MocR/GabR Ectoine and Hydroxyectoine Catabolism Regulator EnuR: Inducer and DNA Binding. Front Microbiol 2022; 12:764731. [PMID: 35003002 PMCID: PMC8739950 DOI: 10.3389/fmicb.2021.764731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 12/01/2021] [Indexed: 11/26/2022] Open
Abstract
The compatible solutes ectoine and 5-hydroxyectoine are widely synthesized by bacteria as osmostress protectants. These nitrogen-rich tetrahydropyrimidines can also be exploited as nutrients by microorganisms. Many ectoine/5-hydroxyectoine catabolic gene clusters are associated with a regulatory gene (enuR: ectoine nutrient utilization regulator) encoding a repressor protein belonging to the MocR/GabR sub-family of GntR-type transcription factors. Focusing on EnuR from the marine bacterium Ruegeria pomeroyi, we show that the dimerization of EnuR is mediated by its aminotransferase domain. This domain can fold independently from its amino-terminal DNA reading head and can incorporate pyridoxal-5′-phosphate (PLP) as cofactor. The covalent attachment of PLP to residue Lys302 of EnuR was proven by mass-spectrometry. PLP interacts with system-specific, ectoine and 5-hydroxyectoine-derived inducers: alpha-acetyldiaminobutyric acid (alpha-ADABA), and hydroxy-alpha-acetyldiaminobutyric acid (hydroxy-alpha-ADABA), respectively. These inducers are generated in cells actively growing with ectoines as sole carbon and nitrogen sources, by the EutD hydrolase and targeted metabolic analysis allowed their detection. EnuR binds these effector molecules with affinities in the low micro-molar range. Studies addressing the evolutionary conservation of EnuR, modelling of the EnuR structure, and docking experiments with the inducers provide an initial view into the cofactor and effector binding cavity. In this cavity, the two high-affinity inducers for EnuR, alpha-ADABA and hydroxy-alpha-ADABA, are positioned such that their respective primary nitrogen group can chemically interact with PLP. Purified EnuR bound with micro-molar affinity to a 48 base pair DNA fragment containing the sigma-70 type substrate-inducible promoter for the ectoine/5-hydroxyectoine importer and catabolic gene cluster. Consistent with the function of EnuR as a repressor, the core elements of the promoter overlap with two predicted EnuR operators. Our data lend themselves to a straightforward regulatory model for the initial encounter of EnuR-possessing ectoine/5-hydroxyectoine consumers with environmental ectoines and for the situation when the external supply of these compounds has been exhausted by catabolism.
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Affiliation(s)
- Lucas Hermann
- Faculty of Biology, Philipps-University Marburg, Marburg, Germany.,Department of Biochemistry and Synthetic Metabolism, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Felix Dempwolff
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
| | - Wieland Steinchen
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
| | - Sven-Andreas Freibert
- Department of Medicine, Institute for Cytobiology and Cytopathology, and SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
| | - Sander H J Smits
- Institute of Biochemistry, Heinrich-Heine-University, Düsseldorf, Germany.,Center for Structural Studies (CSS), Faculty of Biochemistry, Heinrich-Heine-University, Düsseldorf, Germany
| | - Andreas Seubert
- Faculty of Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Erhard Bremer
- Faculty of Biology, Philipps-University Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
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7
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M VNUM, Faidh MA, Chadha A. The ornithine cyclodeaminase/µ-crystallin superfamily of proteins: A novel family of oxidoreductases for the biocatalytic synthesis of chiral amines. CURRENT RESEARCH IN BIOTECHNOLOGY 2022. [DOI: 10.1016/j.crbiot.2022.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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8
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Frikha-Dammak D, Ayadi H, Hakim-Rekik I, Belbahri L, Maalej S. Genome analysis of the salt-resistant Paludifilum halophilum DSM 102817 T reveals genes involved in flux-tuning of ectoines and unexplored bioactive secondary metabolites. World J Microbiol Biotechnol 2021; 37:178. [PMID: 34549358 DOI: 10.1007/s11274-021-03147-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/14/2021] [Indexed: 10/20/2022]
Abstract
Paludifilum halophilum DSM 102817T is the first member of the genus Paludifilum in the Thermoactinomycetaceae family. The thermohalophilic bacterium was isolated from the solar saltern of Sfax, Tunisia and was shown to be able to produce ectoines with a relatively high-yield and to cope with salt stress conditions. In this study, the whole genome of P. halophilum was sequenced and analysed. Analysis revealed 3,789,765 base pairs with an average GC% content of 51.5%. A total of 3775 genes were predicted of which 3616 were protein-coding genes and 73 were RNA genes. The genes encoding key enzymes for ectoines (ectoine and hydroxyectoine) synthesis (ectABCD) were identified from the bacterial genome next to a gene cluster (ehuABCD) encoding a binding-protein-dependent ABC transport system responsible for ectoines mobility through the cell membrane. With the aid of KEGG analysis, we found that the central catabolic network of P. halophilum comprises the pathways of glycolysis, tricarboxylic acid cycle, and pentose phosphate. In addition, anaplerotic pathways replenishing oxaloacetate and glutamate synthesis from central metabolism needed for high ectoines biosynthetic fluxes were identified through several key enzymes. Furthermore, a total of 18 antiSMASH-predicted putative biosynthetic gene clusters for secondary metabolites with high novelty and diversity were identified in P. halophilum genome, including biosynthesis of colabomycine-A, fusaricidin-E, zwittermycin A, streptomycin, mycosubtilin and meilingmycin. Based on these data, P. halophilum emerged as a promising source for ectoines and antimicrobials with the potential to be scaled up for industrial production, which could benefit the pharmaceutical and cosmetic industries.
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Affiliation(s)
- Donyez Frikha-Dammak
- Laboratoire de Biodiversité Marine et Environnement (LR18ES30), Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000, Sfax, Tunisia
| | - Houda Ayadi
- Laboratoire de Biodiversité Marine et Environnement (LR18ES30), Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000, Sfax, Tunisia
| | - Imen Hakim-Rekik
- Unité de Génomique Fonctionnelle et Physiologie des Plantes, Université de Sfax, Institut Supérieur de Biotechnologie de Sfax, BP 1175, 3000, Sfax, Tunisia
| | - Lassaad Belbahri
- Laboratory of Soil Biology, University of Neuchatel, 11 Rue Emile Argand, 2000, Neuchâtel, Switzerland
| | - Sami Maalej
- Laboratoire de Biodiversité Marine et Environnement (LR18ES30), Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000, Sfax, Tunisia.
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9
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Hermann L, Mais CN, Czech L, Smits SHJ, Bange G, Bremer E. The ups and downs of ectoine: structural enzymology of a major microbial stress protectant and versatile nutrient. Biol Chem 2021; 401:1443-1468. [PMID: 32755967 DOI: 10.1515/hsz-2020-0223] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 07/22/2020] [Indexed: 12/13/2022]
Abstract
Ectoine and its derivative 5-hydroxyectoine are compatible solutes and chemical chaperones widely synthesized by Bacteria and some Archaea as cytoprotectants during osmotic stress and high- or low-growth temperature extremes. The function-preserving attributes of ectoines led to numerous biotechnological and biomedical applications and fostered the development of an industrial scale production process. Synthesis of ectoines requires the expenditure of considerable energetic and biosynthetic resources. Hence, microorganisms have developed ways to exploit ectoines as nutrients when they are no longer needed as stress protectants. Here, we summarize our current knowledge on the phylogenomic distribution of ectoine producing and consuming microorganisms. We emphasize the structural enzymology of the pathways underlying ectoine biosynthesis and consumption, an understanding that has been achieved only recently. The synthesis and degradation pathways critically differ in the isomeric form of the key metabolite N-acetyldiaminobutyric acid (ADABA). γ-ADABA serves as preferred substrate for the ectoine synthase, while the α-ADABA isomer is produced by the ectoine hydrolase as an intermediate in catabolism. It can serve as internal inducer for the genetic control of ectoine catabolic genes via the GabR/MocR-type regulator EnuR. Our review highlights the importance of structural enzymology to inspire the mechanistic understanding of metabolic networks at the biological scale.
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Affiliation(s)
- Lucas Hermann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Biochemistry and Synthetic Biology of Microbial Metabolism Group, Max Planck Institute for Terrestrial Microbiology, Karl-von Frisch Str. 10, D-35043 Marburg, Germany
| | - Christopher-Nils Mais
- Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Laura Czech
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Sander H J Smits
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany.,Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
| | - Gert Bange
- Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
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10
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Gregory GJ, Boyd EF. Stressed out: Bacterial response to high salinity using compatible solute biosynthesis and uptake systems, lessons from Vibrionaceae. Comput Struct Biotechnol J 2021; 19:1014-1027. [PMID: 33613867 PMCID: PMC7876524 DOI: 10.1016/j.csbj.2021.01.030] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 12/19/2022] Open
Abstract
Bacteria have evolved mechanisms that allow them to adapt to changes in osmolarity and some species have adapted to live optimally in high salinity environments such as in the marine ecosystem. Most bacteria that live in high salinity do so by the biosynthesis and/or uptake of compatible solutes, small organic molecules that maintain the turgor pressure of the cell. Osmotic stress response mechanisms and their regulation among marine heterotrophic bacteria are poorly understood. In this review, we discuss what is known about compatible solute metabolism and transport and new insights gained from studying marine bacteria belonging to the family Vibrionaceae.
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Affiliation(s)
| | - E. Fidelma Boyd
- Corresponding author at: Department of Biological Sciences, 341 Wolf Hall, University of Delaware, Newark, DE 19716, United States.
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11
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Mais CN, Hermann L, Altegoer F, Seubert A, Richter AA, Wernersbach I, Czech L, Bremer E, Bange G. Degradation of the microbial stress protectants and chemical chaperones ectoine and hydroxyectoine by a bacterial hydrolase-deacetylase complex. J Biol Chem 2020; 295:9087-9104. [PMID: 32404365 PMCID: PMC7335791 DOI: 10.1074/jbc.ra120.012722] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 05/06/2020] [Indexed: 12/12/2022] Open
Abstract
When faced with increased osmolarity in the environment, many bacterial cells accumulate the compatible solute ectoine and its derivative 5-hydroxyectoine. Both compounds are not only potent osmostress protectants, but also serve as effective chemical chaperones stabilizing protein functionality. Ectoines are energy-rich nitrogen and carbon sources that have an ecological impact that shapes microbial communities. Although the biochemistry of ectoine and 5-hydroxyectoine biosynthesis is well understood, our understanding of their catabolism is only rudimentary. Here, we combined biochemical and structural approaches to unravel the core of ectoine and 5-hydroxy-ectoine catabolisms. We show that a conserved enzyme bimodule consisting of the EutD ectoine/5-hydroxyectoine hydrolase and the EutE deacetylase degrades both ectoines. We determined the high-resolution crystal structures of both enzymes, derived from the salt-tolerant bacteria Ruegeria pomeroyi and Halomonas elongata These structures, either in their apo-forms or in forms capturing substrates or intermediates, provided detailed insights into the catalytic cores of the EutD and EutE enzymes. The combined biochemical and structural results indicate that the EutD homodimer opens the pyrimidine ring of ectoine through an unusual covalent intermediate, N-α-2 acetyl-l-2,4-diaminobutyrate (α-ADABA). We found that α-ADABA is then deacetylated by the zinc-dependent EutE monomer into diaminobutyric acid (DABA), which is further catabolized to l-aspartate. We observed that the EutD-EutE bimodule synthesizes exclusively the α-, but not the γ-isomers of ADABA or hydroxy-ADABA. Of note, α-ADABA is known to induce the MocR/GabR-type repressor EnuR, which controls the expression of many ectoine catabolic genes clusters. We conclude that hydroxy-α-ADABA might serve a similar function.
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Affiliation(s)
- Christopher-Nils Mais
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Marburg, Germany
| | - Lucas Hermann
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Biology, Marburg, Germany
| | - Florian Altegoer
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Marburg, Germany
| | - Andreas Seubert
- Philipps-University Marburg, Faculty of Chemistry, Marburg, Germany
| | - Alexandra A Richter
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Biology, Marburg, Germany
| | - Isa Wernersbach
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Marburg, Germany
| | - Laura Czech
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Biology, Marburg, Germany
| | - Erhard Bremer
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Biology, Marburg, Germany.
| | - Gert Bange
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Marburg, Germany.
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12
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Reshetnikov AS, Rozova ON, Trotsenko YA, But SY, Khmelenina VN, Mustakhimov II. Ectoine degradation pathway in halotolerant methylotrophs. PLoS One 2020; 15:e0232244. [PMID: 32353000 PMCID: PMC7192451 DOI: 10.1371/journal.pone.0232244] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 04/10/2020] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Microorganisms living in saline environments are forced to regulate turgor via the synthesis of organic osmoprotective compounds. Microbial adaptation to fluctuations in external salinity includes degradation of compatible solutes. Here we have examined the biochemical pathway of degradation of the cyclic imino acid ectoine, the major osmoprotector in halotolerant methane-utilizing bacteria. METHODS The BLAST search of the genes involved in ectoine degradation in the halotolerant methanotroph Methylotuvimicrobium alcaliphilum 20Z was performed with the reference sequences of Halomonas elongata. The genes for the key enzymes of the pathway were disrupted by insertion mutagenesis and the cellular metabolites in the methanol extracts of mutant cells were analyzed by HPLC. The doeA gene from Mm. alcaliphilum 20Z was heterologously expressed in Escherichia coli to identify the product of ectoine hydrolysis catalyzed by ectoine hydrolase DoeA. RESULTS We have shown that the halotolerant methanotroph Mm. alcaliphilum 20Z possesses the doeBDAC gene cluster coding for putative ectoine hydrolase (DoeA), Nα-acetyl-L-2,4-diaminobutyrate deacetylase (DoeB), diaminobutyrate transaminase (DoeD) and aspartate-semialdehyde dehydrogenase (DoeC). The deletion of the doeA gene resulted in accumulation of the higher level of ectoine compared to the wild type strain. Nγ-acetyl-L-2,4-diaminobutyrate (Nγ-acetyl-DAB), a substrate for ectoine synthase, was found in the cytoplasm of the wild type strain. Nα-acetyl-L-2,4-diaminobutyrate (Nα-acetyl-DAB), a substrate for the DoeB enzyme, appeared in the cells as a result of exposure of the doeB mutant to low osmotic pressure. The genes for the enzymes involved in ectoine degradation were found in all aerobic methylotrophs capable of ectoine biosynthesis. These results provide the first evidence for the in vivo operation of the ectoine degradation pathway in methanotrophs and thus expand our understanding of the regulation mechanisms of bacterial osmoadaptation. CONCLUSIONS During adaptation to the changes in external osmolarity, halophilic and halotolerant methylotrophs cleave ectoine, thereby entering the carbon and nitrogen of the compatible solute to the central metabolic pathways. The biochemical route of ectoine degradation in the halotolerant methanotroph Mm. alcaliphilum 20Z is similar to that in heterotrophic halophiles. We have shown that ectoine hydrolase DoeA in this methanotroph hydrolyzes ectoine with the formation of the only isomer: Nα-acetyl-DAB. All aerobic methylotrophs capable of ectoine biosynthesis harbor the genetic determinants for ectoine degradation.
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Affiliation(s)
- Aleksander S. Reshetnikov
- Federal Research Center «Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences», G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, Russian Federation
| | - Olga N. Rozova
- Federal Research Center «Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences», G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, Russian Federation
| | - Yuri A. Trotsenko
- Federal Research Center «Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences», G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, Russian Federation
| | - Sergey Yu. But
- Federal Research Center «Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences», G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, Russian Federation
| | - Valentina N. Khmelenina
- Federal Research Center «Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences», G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, Russian Federation
| | - Ildar I. Mustakhimov
- Federal Research Center «Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences», G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, Russian Federation
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13
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Richter AA, Mais CN, Czech L, Geyer K, Hoeppner A, Smits SHJ, Erb TJ, Bange G, Bremer E. Biosynthesis of the Stress-Protectant and Chemical Chaperon Ectoine: Biochemistry of the Transaminase EctB. Front Microbiol 2019; 10:2811. [PMID: 31921013 PMCID: PMC6915088 DOI: 10.3389/fmicb.2019.02811] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 11/20/2019] [Indexed: 12/20/2022] Open
Abstract
Bacteria frequently adapt to high osmolarity surroundings through the accumulation of compatible solutes. Ectoine is a prominent member of these types of stress protectants and is produced via an evolutionarily conserved biosynthetic pathway beginning with the L-2,4-diaminobutyrate (DAB) transaminase (TA) EctB. Here, we studied EctB from the thermo-tolerant Gram-positive bacterium Paenibacillus lautus (Pl) and show that this tetrameric enzyme is highly tolerant to salt, pH, and temperature. During ectoine biosynthesis, EctB converts L-glutamate and L-aspartate-beta-semialdehyde into 2-oxoglutarate and DAB, but it also catalyzes the reverse reaction. Our analysis unravels that EctB enzymes are mechanistically identical to the PLP-dependent gamma-aminobutyrate TAs (GABA-TAs) and only differ with respect to substrate binding. Inspection of the genomic context of the ectB gene in P. lautus identifies an unusual arrangement of juxtapositioned genes for ectoine biosynthesis and import via an Ehu-type binding-protein-dependent ABC transporter. This operon-like structure suggests the operation of a highly coordinated system for ectoine synthesis and import to maintain physiologically adequate cellular ectoine pools under osmotic stress conditions in a resource-efficient manner. Taken together, our study provides an in-depth mechanistic and physiological description of EctB, the first enzyme of the ectoine biosynthetic pathway.
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Affiliation(s)
- Alexandra A Richter
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
| | - Christopher-Nils Mais
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany.,Department of Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Laura Czech
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
| | - Kyra Geyer
- Department of Biochemistry and Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Astrid Hoeppner
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sander H J Smits
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.,Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Tobias J Erb
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany.,Department of Biochemistry and Synthetic Metabolism, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Gert Bange
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany.,Department of Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
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14
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High ectoine production by an engineered Halomonas hydrothermalis Y2 in a reduced salinity medium. Microb Cell Fact 2019; 18:184. [PMID: 31655591 PMCID: PMC6815383 DOI: 10.1186/s12934-019-1230-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 10/11/2019] [Indexed: 12/02/2022] Open
Abstract
Background As an attracted compatible solute, 1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid (ectoine) showed great potentials in various field. However, lower productivity and high saline medium seriously hinder its wide applications. Results The entire ectoine metabolism, including pathways for ectoine synthesis and catabolism, was identified in the genome of an ectoine-excreting strain Halomonas hydrothermalis Y2. By in-frame deletion of genes encoding ectoine hydroxylase (EctD) and (or) ectoine hydrolase (DoeA) that responsible for ectoine catabolism, the pathways for ectoine utilization were disrupted and resulted in an obviously enhanced productivity. Using an optimized medium containing 100 g L−1 NaCl in a 500-mL flask, the double mutant of Y2/ΔectD/ΔdoeA synthesized 3.13 g L−1 ectoine after 30 h cultivation. This is much higher than that of the wild type strain (1.91 g L−1), and also exceeds the production of Y2/ΔectD (2.21 g L−1). The remarkably enhanced accumulation of ectoine by Y2/ΔectD/ΔdoeA implied a critical function of Doe pathway in the ectoine catabolism. Furthermore, to reduce the salinity of fermentation medium and overcome the wastewater treatment difficulty, mutants that lacking key Na+/H+ antiporter, Mrp and (or) NhaD2, were constructed based on strain Y2/ΔectD/ΔdoeA. As a result, the Mrp-deficient strain could synthesize equal amount of ectoine (around 7 g L−1 or 500 mg (g DCW) −1) in the medium containing lower concentration of NaCl. During a fed-batch fermentation process with 60 g L−1 NaCl stress, a maximum 10.5 g L−1 ectoine was accumulated by the Mrp-deficient strain, with a specific production of 765 mg (g DCW)−1 and a yield of 0.21 g g−1 monosodium glutamate. Conclusion The remarkably enhanced production of ectoine by Y2/ΔectD/ΔdoeA implied the critical function of Doe pathway in the ectoine catabolism. Moreover, the reduced salinity requirement of Mrp-deficient strain implied a feasible protocol for many compatible solute biosynthesis, i.e., by silencing some Na+/H+ antiporters in their halophilic producers and thus lowering the medium salinity.![]()
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15
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Khaleque HN, González C, Shafique R, Kaksonen AH, Holmes DS, Watkin ELJ. Uncovering the Mechanisms of Halotolerance in the Extremely Acidophilic Members of the Acidihalobacter Genus Through Comparative Genome Analysis. Front Microbiol 2019; 10:155. [PMID: 30853944 PMCID: PMC6396713 DOI: 10.3389/fmicb.2019.00155] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 01/22/2019] [Indexed: 12/21/2022] Open
Abstract
There are few naturally occurring environments where both acid and salinity stress exist together, consequently, there has been little evolutionary pressure for microorganisms to develop systems that enable them to deal with both stresses simultaneously. Members of the genus Acidihalobacter are iron- and sulfur-oxidizing, halotolerant acidophiles that have developed the ability to tolerate acid and saline stress and, therefore, have the potential to bioleach ores with brackish or saline process waters under acidic conditions. The genus consists of four members, A. prosperus DSM 5130T, A. prosperus DSM 14174, A. prosperus F5 and "A. ferrooxidans" DSM 14175. An in depth genome comparison was undertaken in order to provide a more comprehensive description of the mechanisms of halotolerance used by the different members of this genus. Pangenome analysis identified 29, 3 and 9 protein families related to halotolerance in the core, dispensable and unique genomes, respectively. The genes for halotolerance showed Ka/Ks ratios between 0 and 0.2, confirming that they are conserved and stabilized. All the Acidihalobacter genomes contained similar genes for the synthesis and transport of ectoine, which was recently found to be the dominant osmoprotectant in A. prosperus DSM 14174 and A. prosperus DSM 5130T. Similarities also existed in genes encoding low affinity potassium pumps, however, A. prosperus DSM 14174 was also found to contain genes encoding high affinity potassium pumps. Furthermore, only A. prosperus DSM 5130T and "A. ferrooxidans" DSM 14175 contained genes allowing the uptake of taurine as an osmoprotectant. Variations were also seen in genes encoding proteins involved in the synthesis and/or transport of periplasmic glucans, sucrose, proline, and glycine betaine. This suggests that versatility exists in the Acidihalobacter genus in terms of the mechanisms they can use for halotolerance. This information is useful for developing hypotheses for the search for life on exoplanets and moons.
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Affiliation(s)
- Himel N. Khaleque
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
- CSIRO Land and Water, Floreat, WA, Australia
| | - Carolina González
- Center for Bioinformatics and Genome Biology, Science for Life Foundation, Santiago, Chile
| | | | | | - David S. Holmes
- Center for Bioinformatics and Genome Biology, Science for Life Foundation, Santiago, Chile
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Elizabeth L. J. Watkin
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia
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16
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diCenzo GC, Zamani M, Checcucci A, Fondi M, Griffitts JS, Finan TM, Mengoni A. Multidisciplinary approaches for studying rhizobium–legume symbioses. Can J Microbiol 2019; 65:1-33. [DOI: 10.1139/cjm-2018-0377] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The rhizobium–legume symbiosis is a major source of fixed nitrogen (ammonia) in the biosphere. The potential for this process to increase agricultural yield while reducing the reliance on nitrogen-based fertilizers has generated interest in understanding and manipulating this process. For decades, rhizobium research has benefited from the use of leading techniques from a very broad set of fields, including population genetics, molecular genetics, genomics, and systems biology. In this review, we summarize many of the research strategies that have been employed in the study of rhizobia and the unique knowledge gained from these diverse tools, with a focus on genome- and systems-level approaches. We then describe ongoing synthetic biology approaches aimed at improving existing symbioses or engineering completely new symbiotic interactions. The review concludes with our perspective of the future directions and challenges of the field, with an emphasis on how the application of a multidisciplinary approach and the development of new methods will be necessary to ensure successful biotechnological manipulation of the symbiosis.
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Affiliation(s)
- George C. diCenzo
- Department of Biology, University of Florence, Sesto Fiorentino, FI 50019, Italy
| | - Maryam Zamani
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Alice Checcucci
- Department of Biology, University of Florence, Sesto Fiorentino, FI 50019, Italy
| | - Marco Fondi
- Department of Biology, University of Florence, Sesto Fiorentino, FI 50019, Italy
| | - Joel S. Griffitts
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT 84602, USA
| | - Turlough M. Finan
- Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Alessio Mengoni
- Department of Biology, University of Florence, Sesto Fiorentino, FI 50019, Italy
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17
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Tramonti A, Nardella C, di Salvo ML, Pascarella S, Contestabile R. The MocR-like transcription factors: pyridoxal 5'-phosphate-dependent regulators of bacterial metabolism. FEBS J 2018; 285:3925-3944. [PMID: 29974999 DOI: 10.1111/febs.14599] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/14/2018] [Accepted: 06/25/2018] [Indexed: 12/22/2022]
Abstract
Many biological functions played by current proteins were not created by evolution from scratch, rather they were obtained combining already available protein scaffolds. This is the case of MocR-like bacterial transcription factors (MocR-TFs), a subclass of GntR transcription regulators, whose structure is the outcome of the fusion between DNA-binding proteins and pyridoxal 5'-phosphate (PLP)-dependent enzymes. The resultant chimeras can count on the properties of both protein classes, i.e. the capability to recognize specific DNA sequences and to bind PLP and amino-compounds; it is the modulation of such binding properties to confer to MocR-TFs chimeras the ability to interact with effector molecules and DNA so as to regulate transcription. MocR-TFs control different metabolic processes involving vitamin B6 and amino acids, which are canonical ligands of PLP-dependent enzymes. However, MocR-TFs are also implicated in the metabolism of compounds that are not substrates of PLP-dependent enzymes, such as rhizopine and ectoine. Genomic analyses show that MocR-TFs are widespread among eubacteria, implying an essential role in their metabolism and highlighting the scarcity of our knowledge on these important players in microbial metabolism. Although MocR-TFs have been discovered 15 years ago, the research activity on these transcriptional regulators has only recently intensified, producing a wealth of information that needs to be brought back to general principles. This is the main task of this review, which reports and analyses the available information concerning MocR-TFs functional role, structural features, interaction with effector molecules and the characteristics of DNA transcriptional factor-binding sites of MocR-based regulatory systems.
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Affiliation(s)
- Angela Tramonti
- Istituto di Biologia e Patologia Molecolari, Consiglio Nazionale delle Ricerche, Roma, Italy.,Dipartimento di Scienze Biochimiche "A. Rossi Fanelli", Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza Università di Roma, Italy
| | - Caterina Nardella
- Dipartimento di Scienze Biochimiche "A. Rossi Fanelli", Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza Università di Roma, Italy
| | - Martino L di Salvo
- Dipartimento di Scienze Biochimiche "A. Rossi Fanelli", Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza Università di Roma, Italy
| | - Stefano Pascarella
- Dipartimento di Scienze Biochimiche "A. Rossi Fanelli", Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza Università di Roma, Italy
| | - Roberto Contestabile
- Dipartimento di Scienze Biochimiche "A. Rossi Fanelli", Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza Università di Roma, Italy
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18
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Han J, Gao QX, Zhang YG, Li L, Mohamad OAA, Rao MPN, Xiao M, Hozzein WN, Alkhalifah DHM, Tao Y, Li WJ. Transcriptomic and Ectoine Analysis of Halotolerant Nocardiopsis gilva YIM 90087 T Under Salt Stress. Front Microbiol 2018; 9:618. [PMID: 29651284 PMCID: PMC5884947 DOI: 10.3389/fmicb.2018.00618] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/16/2018] [Indexed: 11/25/2022] Open
Abstract
The genus Nocardiopsis is an unique actinobacterial group that widely distributed in hypersaline environments. In this study, we investigated the growth conditions, transcriptome analysis, production and accumulation of ectoine by Nocardiopsis gilva YIM 90087T under salt stress. The colony color of N. gilva YIM 90087T changed from yellow to white under salt stress conditions. Accumulation of ectoine and hydroxyectoine in cells was an efficient way to regulate osmotic pressure. The ectoine synthesis was studied by transferring the related genes (ectA, ectB, and ectC) to Escherichia coli. Transcriptomic analysis showed that the pathways of ABC transporters (ko02010) and glycine, serine, and threonine metabolism (ko00260) played a vital role under salt stress environment. The ectABC from N. gilva YIM 90087T was activated under the salt stress. Addition of exogenous ectoine and hydroxyectoine were helpful to protect N. gilva YIM 90087T from salt stress.
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Affiliation(s)
- Jian Han
- Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Ürümqi, China.,Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Quan-Xiu Gao
- Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yong-Guang Zhang
- Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Ürümqi, China
| | - Li Li
- Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Ürümqi, China
| | - Osama A A Mohamad
- Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Ürümqi, China.,Institute for Post Graduate Environmental Studies, Environmental Science Department, Arish University, North Sinai, Egypt
| | - Manik Prabhu Narsing Rao
- State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Min Xiao
- State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Wael N Hozzein
- Botany and Microbiology Department, Faculty of Science, Beni-Suef University, Beni Suef, Egypt.,Bioproducts Research Chair, Zoology Department, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Dalal H M Alkhalifah
- Biology Department, Faculty of Science, Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia
| | - Yong Tao
- Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Wen-Jun Li
- Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Ürümqi, China.,State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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19
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Czech L, Hermann L, Stöveken N, Richter AA, Höppner A, Smits SHJ, Heider J, Bremer E. Role of the Extremolytes Ectoine and Hydroxyectoine as Stress Protectants and Nutrients: Genetics, Phylogenomics, Biochemistry, and Structural Analysis. Genes (Basel) 2018; 9:genes9040177. [PMID: 29565833 PMCID: PMC5924519 DOI: 10.3390/genes9040177] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 03/13/2018] [Accepted: 03/15/2018] [Indexed: 01/26/2023] Open
Abstract
Fluctuations in environmental osmolarity are ubiquitous stress factors in many natural habitats of microorganisms, as they inevitably trigger osmotically instigated fluxes of water across the semi-permeable cytoplasmic membrane. Under hyperosmotic conditions, many microorganisms fend off the detrimental effects of water efflux and the ensuing dehydration of the cytoplasm and drop in turgor through the accumulation of a restricted class of organic osmolytes, the compatible solutes. Ectoine and its derivative 5-hydroxyectoine are prominent members of these compounds and are synthesized widely by members of the Bacteria and a few Archaea and Eukarya in response to high salinity/osmolarity and/or growth temperature extremes. Ectoines have excellent function-preserving properties, attributes that have led to their description as chemical chaperones and fostered the development of an industrial-scale biotechnological production process for their exploitation in biotechnology, skin care, and medicine. We review, here, the current knowledge on the biochemistry of the ectoine/hydroxyectoine biosynthetic enzymes and the available crystal structures of some of them, explore the genetics of the underlying biosynthetic genes and their transcriptional regulation, and present an extensive phylogenomic analysis of the ectoine/hydroxyectoine biosynthetic genes. In addition, we address the biochemistry, phylogenomics, and genetic regulation for the alternative use of ectoines as nutrients.
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Affiliation(s)
- Laura Czech
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Lucas Hermann
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Nadine Stöveken
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
| | - Alexandra A Richter
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Astrid Höppner
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
| | - Sander H J Smits
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
- Institute of Biochemistry, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
| | - Johann Heider
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
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20
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León MJ, Hoffmann T, Sánchez-Porro C, Heider J, Ventosa A, Bremer E. Compatible Solute Synthesis and Import by the Moderate Halophile Spiribacter salinus: Physiology and Genomics. Front Microbiol 2018; 9:108. [PMID: 29497403 PMCID: PMC5818414 DOI: 10.3389/fmicb.2018.00108] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 01/17/2018] [Indexed: 11/13/2022] Open
Abstract
Members of the genus Spiribacter are found worldwide and are abundant in ecosystems possessing intermediate salinities between seawater and saturated salt concentrations. Spiribacter salinus M19-40 is the type species of this genus and its first cultivated representative. In the habitats of S. salinus M19-40, high salinity is a key determinant for growth and we therefore focused on the cellular adjustment strategy to this persistent environmental challenge. We coupled these experimental studies to the in silico mining of the genome sequence of this moderate halophile with respect to systems allowing this bacterium to control its potassium and sodium pools, and its ability to import and synthesize compatible solutes. S. salinus M19-40 produces enhanced levels of the compatible solute ectoine, both under optimal and growth-challenging salt concentrations, but the genes encoding the corresponding biosynthetic enzymes are not organized in a canonical ectABC operon. Instead, they are scrambled (ectAC; ectB) and are physically separated from each other on the S. salinus M19-40 genome. Genomes of many phylogenetically related bacteria also exhibit a non-canonical organization of the ect genes. S. salinus M19-40 also synthesizes trehalose, but this compatible solute seems to make only a minor contribution to the cytoplasmic solute pool under osmotic stress conditions. However, its cellular levels increase substantially in stationary phase cells grown under optimal salt concentrations. In silico genome mining revealed that S. salinus M19-40 possesses different types of uptake systems for compatible solutes. Among the set of compatible solutes tested in an osmostress protection growth assay, glycine betaine and arsenobetaine were the most effective. Transport studies with radiolabeled glycine betaine showed that S. salinus M19-40 increases the pool size of this osmolyte in a fashion that is sensitively tied to the prevalent salinity of the growth medium. It was amassed in salt-stressed cells in unmodified form and suppressed the synthesis of ectoine. In conclusion, the data presented here allow us to derive a genome-scale picture of the cellular adjustment strategy of a species that represents an environmentally abundant group of ecophysiologically important halophilic microorganisms.
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Affiliation(s)
- María J León
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Seville, Spain
| | - Tamara Hoffmann
- Laboratory for Microbiology, Department of Biology, Philipps University of Marburg, Marburg, Germany
| | - Cristina Sánchez-Porro
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Seville, Spain
| | - Johann Heider
- Laboratory for Microbiology, Department of Biology, Philipps University of Marburg, Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps University of Marburg, Marburg, Germany
| | - Antonio Ventosa
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Seville, Spain
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps University of Marburg, Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps University of Marburg, Marburg, Germany
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21
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Schulz A, Hermann L, Freibert SA, Bönig T, Hoffmann T, Riclea R, Dickschat JS, Heider J, Bremer E. Transcriptional regulation of ectoine catabolism in response to multiple metabolic and environmental cues. Environ Microbiol 2017; 19:4599-4619. [PMID: 28892254 DOI: 10.1111/1462-2920.13924] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 08/29/2017] [Accepted: 08/31/2017] [Indexed: 01/04/2023]
Abstract
Ectoine and hydroxyectoine are effective microbial osmostress protectants, but can also serve as versatile nutrients for bacteria. We have studied the genetic regulation of ectoine and hydroxyectoine import and catabolism in the marine Roseobacter species Ruegeria pomeroyi and identified three transcriptional regulators involved in these processes: the GabR/MocR-type repressor EnuR, the feast and famine-type regulator AsnC and the two-component system NtrYX. The corresponding genes are widely associated with ectoine and hydroxyectoine uptake and catabolic gene clusters (enuR, asnC), and with microorganisms predicted to consume ectoines (ntrYX). EnuR contains a covalently bound pyridoxal-5'-phosphate as a co-factor and the chemistry underlying the functioning of MocR/GabR-type regulators typically requires a system-specific low molecular mass effector molecule. Through ligand binding studies with purified EnuR, we identified N-(alpha)-L-acetyl-2,4-diaminobutyric acid and L-2,4-diaminobutyric acid as inducers for EnuR that are generated through ectoine catabolism. AsnC/Lrp-type proteins can wrap DNA into nucleosome-like structures, and we found that the asnC gene was essential for use of ectoines as nutrients. Furthermore, we discovered through transposon mutagenesis that the NtrYX two-component system is required for their catabolism. Database searches suggest that our findings have important ramifications for an understanding of the molecular biology of most microbial consumers of ectoines.
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Affiliation(s)
- Annina Schulz
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Lucas Hermann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Sven-Andreas Freibert
- Department of Medicine, Institute for Cytobiology and Cytopathology, Philipps-University Marburg, Robert-Koch Str. 6, D-35032 Marburg, Germany
| | - Tobias Bönig
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Tamara Hoffmann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Ramona Riclea
- Institute of Organic Chemistry, Technical University Braunschweig, D-38106 Braunschweig, Germany.,Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-Universität Bonn, D-53121 Bonn, Germany
| | - Jeroen S Dickschat
- Institute of Organic Chemistry, Technical University Braunschweig, D-38106 Braunschweig, Germany.,Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-Universität Bonn, D-53121 Bonn, Germany
| | - Johann Heider
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
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22
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Olsson BE, Korsakova ES, Anan'ina LN, Pyankova AA, Mavrodi OV, Plotnikova EG, Mavrodi DV. Draft genome sequences of strains Salinicola socius SMB35 T, Salinicola sp. MH3R3-1 and Chromohalobacter sp. SMB17 from the Verkhnekamsk potash mining region of Russia. Stand Genomic Sci 2017; 12:39. [PMID: 28729898 PMCID: PMC5518125 DOI: 10.1186/s40793-017-0251-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 07/12/2017] [Indexed: 09/03/2023] Open
Abstract
Halomonads are moderately halophilic bacteria that are studied as models of prokaryotic osmoadaptation and sources of enzymes and chemicals for biotechnological applications. Despite the progress in understanding the diversity of these organisms, our ability to explain ecological, metabolic, and biochemical traits of halomonads at the genomic sequence level remains limited. This study addresses this gap by presenting draft genomes of Salinicola socius SMB35T, Salinicola sp. MH3R3–1 and Chromohalobacter sp. SMB17, which were isolated from potash mine tailings in the Verkhnekamsk salt deposit area of Russia. The analysis of these genomes confirmed the importance of ectoines and quaternary amines to the capacity of halomonads to tolerate osmotic stress and adapt to hypersaline environments. The study also revealed that Chromohalobacter and Salinicola share 75–90% of the predicted proteome, but also harbor a set of genus-specific genes, which in Salinicola amounted to approximately 0.5 Mbp. These genus-specific genome segments may contribute to the phenotypic diversity of the Halomonadaceae and the ability of these organisms to adapt to changing environmental conditions and colonize new ecological niches.
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Affiliation(s)
- Björn E Olsson
- University of Skövde, School of Bioscience, Skövde, Sweden
| | - Ekaterina S Korsakova
- Institute of Ecology and Genetics of Microorganisms, Ural Branch of the Russian Academy of Sciences, Perm, Russia
| | - Lyudmila N Anan'ina
- Institute of Ecology and Genetics of Microorganisms, Ural Branch of the Russian Academy of Sciences, Perm, Russia
| | - Anna A Pyankova
- Institute of Ecology and Genetics of Microorganisms, Ural Branch of the Russian Academy of Sciences, Perm, Russia
| | - Olga V Mavrodi
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406 USA
| | - Elena G Plotnikova
- Institute of Ecology and Genetics of Microorganisms, Ural Branch of the Russian Academy of Sciences, Perm, Russia
| | - Dmitri V Mavrodi
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406 USA
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23
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Robledo M, Peregrina A, Millán V, García-Tomsig NI, Torres-Quesada O, Mateos PF, Becker A, Jiménez-Zurdo JI. A conserved α-proteobacterial small RNA contributes to osmoadaptation and symbiotic efficiency of rhizobia on legume roots. Environ Microbiol 2017; 19:2661-2680. [PMID: 28401641 DOI: 10.1111/1462-2920.13757] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 04/05/2017] [Accepted: 04/05/2017] [Indexed: 02/02/2023]
Abstract
Small non-coding RNAs (sRNAs) are expected to have pivotal roles in the adaptive responses underlying symbiosis of nitrogen-fixing rhizobia with legumes. Here, we provide primary insights into the function and activity mechanism of the Sinorhizobium meliloti trans-sRNA NfeR1 (Nodule Formation Efficiency RNA). Northern blot probing and transcription tracking with fluorescent promoter-reporter fusions unveiled high nfeR1 expression in response to salt stress and throughout the symbiotic interaction. The strength and differential regulation of nfeR1 transcription are conferred by a motif, which is conserved in nfeR1 promoter regions in α-proteobacteria. NfeR1 loss-of-function compromised osmoadaptation of free-living bacteria, whilst causing misregulation of salt-responsive genes related to stress adaptation, osmolytes catabolism and membrane trafficking. Nodulation tests revealed that lack of NfeR1 affected competitiveness, infectivity, nodule development and symbiotic efficiency of S. meliloti on alfalfa roots. Comparative computer predictions and a genetic reporter assay evidenced a redundant role of three identical NfeR1 unpaired anti Shine-Dalgarno motifs for targeting and downregulation of translation of multiple mRNAs from transporter genes. Our data provide genetic evidence of the hyperosmotic conditions of the endosymbiotic compartments. NfeR1-mediated gene regulation in response to this cue could contribute to coordinate nutrient uptake with the metabolic reprogramming concomitant to symbiotic transitions.
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Affiliation(s)
- Marta Robledo
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - Alexandra Peregrina
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - Vicenta Millán
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - Natalia I García-Tomsig
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - Omar Torres-Quesada
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - Pedro F Mateos
- Departamento de Microbiología y Genética and CIALE, Edificio Departamental, Campus Miguel de Unamuno, Universidad de Salamanca, 37007 Salamanca, Spain
| | - Anke Becker
- LOEWE Center for Synthetic Microbiology and Faculty of Biology, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - José I Jiménez-Zurdo
- Grupo de Ecología Genética de la Rizosfera, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
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24
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Cleary JL, Condren AR, Zink KE, Sanchez LM. Calling all hosts: Bacterial communication in situ. Chem 2017; 2:334-358. [PMID: 28948238 DOI: 10.1016/j.chempr.2017.02.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Bacteria are cosmopolitan organisms that in recent years have demonstrated many roles in maintaining host equilibrium. In this review, we discuss three roles bacteria can occupy in a host: pathogenic, symbiotic, and transient, with a specific focus on how bacterial small molecules contribute to homeostasis or dysbiosis. First, we will dissect how small molecules produced by pathogenic bacteria can be used as a source for communication during colonization and as protection against host immune responses. The ability to achieve a higher level of organization through small molecule communication gives pathogenic bacteria an opportunity for increased virulence and fitness. Conversely, in symbiotic relationships with hosts, small molecules are used in the initial acquisition, colonization, and maintenance of this beneficial population. Chemical signals can come from both the host and symbiont, and it is often observed that these interKingdom symbioses result in coevolution of both species involved. Furthermore, the transition from transient to commensal or opportunistic likely relies on molecular mechanisms. The small molecules utilized and produced by transient bacteria are desirable for both the immune and nutritional benefits they provide to the host. Finally, the advantages and disadvantages of modern analytical techniques that are available to researchers in order to study small molecules in situ is an important aspect of this review. It is our opinion that small molecules produced by bacteria are central to many biological processes and a larger focus on uncovering the function and identity of these small molecules is required to gain a deeper understanding of host-microbe associations.
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Affiliation(s)
- Jessica L Cleary
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago IL 60612, USA
| | - Alanna R Condren
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago IL 60612, USA
| | - Katherine E Zink
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago IL 60612, USA
| | - Laura M Sanchez
- Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago IL 60612, USA
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25
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Salar-García MJ, Bernal V, Pastor JM, Salvador M, Argandoña M, Nieto JJ, Vargas C, Cánovas M. Understanding the interplay of carbon and nitrogen supply for ectoines production and metabolic overflow in high density cultures of Chromohalobacter salexigens. Microb Cell Fact 2017; 16:23. [PMID: 28179004 PMCID: PMC5299690 DOI: 10.1186/s12934-017-0643-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Accepted: 02/01/2017] [Indexed: 01/27/2023] Open
Abstract
Background The halophilic bacterium Chromohalobacter salexigens has been proposed as promising cell factory for the production of the compatible solutes ectoine and hydroxyectoine. This bacterium has evolved metabolic adaptations to efficiently grow under high salt concentrations by accumulating ectoines as compatible solutes. However, metabolic overflow, which is a major drawback for the efficient conversion of biological feedstocks, occurs as a result of metabolic unbalances during growth and ectoines production. Optimal production of ectoines is conditioned by the interplay of carbon and nitrogen metabolisms. In this work, we set out to determine how nitrogen supply affects the production of ectoines. Results Chromohalobacter salexigens was challenged to grow in media with unbalanced carbon/nitrogen ratio. In C. salexigens, overflow metabolism and ectoines production are a function of medium composition. At low ammonium conditions, the growth rate decreased importantly, up to 80%. Shifts in overflow metabolism were observed when changing the C/N ratio in the culture medium. 13C-NMR analysis of ectoines labelling revealed a high metabolic rigidity, with almost constant flux ratios in all conditions assayed. Unbalanced C/N ratio led to pyruvate accumulation, especially upon N-limitation. Analysis of an ect− mutant demonstrated the link between metabolic overflow and ectoine biosynthesis. Under non ectoine synthesizing conditions, glucose uptake and metabolic overflow decreased importantly. Finally, in fed-batch cultures, biomass yield was affected by the feeding scheme chosen. High growth (up to 42.4 g L−1) and volumetric ectoine yields (up to 4.21 g L−1) were obtained by minimizing metabolite overflow and nutrient accumulation in high density cultures in a low nitrogen fed-batch culture. Moreover, the yield coefficient calculated for the transformation of glucose into biomass was 30% higher in fed-batch than in the batch culture, demonstrating that the metabolic efficiency of C. salexigens can be improved by careful design of culture feeding schemes. Conclusions Metabolic shifts observed at low ammonium concentrations were explained by a shift in the energy required for nitrogen assimilation. Carbon-limited fed-batch cultures with reduced ammonium supply were the best conditions for cultivation of C. salexigens, supporting high density growth and maintaining high ectoines production. Electronic supplementary material The online version of this article (doi:10.1186/s12934-017-0643-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- María J Salar-García
- Departamento de Bioquímica y Biología Molecular B e Inmunología, Facultad de Química, Universidad de Murcia, Campus Regional de Excelencia Internacional "Campus Mare Nostrum", 30100, Murcia, Spain.,Departamento de Ingeniería Química y Ambiental, Universidad Politécnica de Cartagena, Campus Regional de Excelencia Internacional "Campus Mare Nostrum", Campus Muralla del MarCalle Doctor Fleming S/N, 30202, Cartagena, Spain
| | - Vicente Bernal
- Departamento de Bioquímica y Biología Molecular B e Inmunología, Facultad de Química, Universidad de Murcia, Campus Regional de Excelencia Internacional "Campus Mare Nostrum", 30100, Murcia, Spain. .,Área de Biología, Dirección de Tecnología Química y Nuevas Energías, Centro de Tecnología de Repsol S.A., Ctra. de Extremadura A-5, Km. 18, 28375, Móstoles, Spain.
| | - José M Pastor
- Departamento de Bioquímica y Biología Molecular B e Inmunología, Facultad de Química, Universidad de Murcia, Campus Regional de Excelencia Internacional "Campus Mare Nostrum", 30100, Murcia, Spain
| | - Manuel Salvador
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, 41012, Seville, Spain
| | - Montserrat Argandoña
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, 41012, Seville, Spain
| | - Joaquín J Nieto
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, 41012, Seville, Spain
| | - Carmen Vargas
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, 41012, Seville, Spain
| | - Manuel Cánovas
- Departamento de Bioquímica y Biología Molecular B e Inmunología, Facultad de Química, Universidad de Murcia, Campus Regional de Excelencia Internacional "Campus Mare Nostrum", 30100, Murcia, Spain.
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26
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Negative Regulation of Ectoine Uptake and Catabolism in Sinorhizobium meliloti: Characterization of the EhuR Gene. J Bacteriol 2016; 199:JB.00119-16. [PMID: 27795315 DOI: 10.1128/jb.00119-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 09/20/2016] [Indexed: 12/21/2022] Open
Abstract
Ectoine has osmoprotective effects on Sinorhizobium meliloti that differ from its effects in other bacteria. Ectoine does not accumulate in S. meliloti cells; instead, it is degraded. The products of the ehuABCD-eutABCDE operon were previously discovered to be responsible for the uptake and catabolism of ectoine in S. meliloti However, the mechanism by which ectoine is involved in the regulation of the ehuABCD-eutABCDE operon remains unclear. The ehuR gene, which is upstream of and oriented in the same direction as the ehuABCD-eutABCDE operon, encodes a member of the MocR/GntR family of transcriptional regulators. Quantitative reverse transcription-PCR and promoter-lacZ reporter fusion experiments revealed that EhuR represses transcription of the ehuABCD-eutABCDE operon, but this repression is inhibited in the presence of ectoine. Electrophoretic mobility shift assays and DNase I footprinting assays revealed that EhuR bound specifically to the DNA regions overlapping the -35 region of the ehuA promoter and the +1 region of the ehuR promoter. Surface plasmon resonance assays further demonstrated direct interactions between EhuR and the two promoters, although EhuR was found to have higher affinity for the ehuA promoter than for the ehuR promoter. In vitro, DNA binding by EhuR could be directly inhibited by a degradation product of ectoine. Our work demonstrates that EhuR is an important negative transcriptional regulator involved in the regulation of ectoine uptake and catabolism and is likely regulated by one or more end products of ectoine catabolism. IMPORTANCE Sinorhizobium meliloti is an important soil bacterium that displays symbiotic interactions with legume hosts. Ectoine serves as a key osmoprotectant for S. meliloti However, ectoine does not accumulate in the cells; rather, it is degraded. In this study, we characterized the transcriptional regulation of the operon responsible for ectoine uptake and catabolism in S. meliloti We identified and characterized the transcription repressor EhuR, which is the first MocR/GntR family member found to be involved in the regulation of compatible solute uptake and catabolism. More importantly, we demonstrated for the first time that an ectoine catabolic end product could modulate EhuR DNA-binding activity. Therefore, this work provides new insights into the unique mechanism of ectoine-induced osmoprotection in S. meliloti.
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27
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Schulz A, Stöveken N, Binzen IM, Hoffmann T, Heider J, Bremer E. Feeding on compatible solutes: A substrate-induced pathway for uptake and catabolism of ectoines and its genetic control by EnuR. Environ Microbiol 2016; 19:926-946. [PMID: 27318028 DOI: 10.1111/1462-2920.13414] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 06/19/2016] [Indexed: 01/19/2023]
Abstract
Ectoine and 5-hydroxyectoine are widely synthesized microbial osmostress protectants. They are also versatile nutrients but their catabolism and the genetic regulation of the corresponding genes are incompletely understood. Using the marine bacterium Ruegeria pomeroyi DSS-3, we investigated the utilization of ectoines and propose a seven steps comprising catabolic route that entails an initial conversion of 5-hydroxyectoine to ectoine, the opening of the ectoine ring, and the subsequent degradation of this intermediate to l-aspartate. The catabolic genes are co-transcribed with three genes encoding a 5-hydroxyectoine/ectoine-specific TRAP transporter. A chromosomal deletion of this entire gene cluster abolishes the utilization of ectoines as carbon and nitrogen sources. The presence of ectoines in the growth medium triggers enhanced expression of the importer and catabolic operon, a process dependent on a substrate-inducible promoter that precedes this gene cluster. EnuR, a member of the MocR/GabR-type transcriptional regulators, controls the activity of this promoter and functions as a repressor. EnuR contains a covalently bound pyridoxal-5'-phosphate, and we suggest that this co-factor is critical for the substrate-mediated induction of the 5-hydroxyectoine/ectoine import and catabolic genes. Bioinformatics showed that ectoine consumers are restricted to the Proteobacteria and that EnuR is likely a central regulator for most ectoine/5-hydroxyectoine catabolic genes.
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Affiliation(s)
- Annina Schulz
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg, D-35043, Germany
| | - Nadine Stöveken
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg, D-35043, Germany.,Philipps-University Marburg, LOEWE-Center for Synthetic Microbiology, Hans-Meerwein Str. 6, Marburg, D-35043, Germany
| | - Ina M Binzen
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg, D-35043, Germany
| | - Tamara Hoffmann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg, D-35043, Germany
| | - Johann Heider
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg, D-35043, Germany.,Philipps-University Marburg, LOEWE-Center for Synthetic Microbiology, Hans-Meerwein Str. 6, Marburg, D-35043, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, Marburg, D-35043, Germany.,Philipps-University Marburg, LOEWE-Center for Synthetic Microbiology, Hans-Meerwein Str. 6, Marburg, D-35043, Germany
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28
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Suvorova IA, Rodionov DA. Comparative genomics of pyridoxal 5'-phosphate-dependent transcription factor regulons in Bacteria. Microb Genom 2016; 2:e000047. [PMID: 28348826 PMCID: PMC5320631 DOI: 10.1099/mgen.0.000047] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 12/16/2015] [Indexed: 12/13/2022] Open
Abstract
The MocR-subfamily transcription factors (MocR-TFs) characterized by the GntR-family DNA-binding domain and aminotransferase-like sensory domain are broadly distributed among certain lineages of Bacteria. Characterized MocR-TFs bind pyridoxal 5'-phosphate (PLP) and control transcription of genes involved in PLP, gamma aminobutyric acid (GABA) and taurine metabolism via binding specific DNA operator sites. To identify putative target genes and DNA binding motifs of MocR-TFs, we performed comparative genomics analysis of over 250 bacterial genomes. The reconstructed regulons for 825 MocR-TFs comprise structural genes from over 200 protein families involved in diverse biological processes. Using the genome context and metabolic subsystem analysis we tentatively assigned functional roles for 38 out of 86 orthologous groups of studied regulators. Most of these MocR-TF regulons are involved in PLP metabolism, as well as utilization of GABA, taurine and ectoine. The remaining studied MocR-TF regulators presumably control genes encoding enzymes involved in reduction/oxidation processes, various transporters and PLP-dependent enzymes, for example aminotransferases. Predicted DNA binding motifs of MocR-TFs are generally similar in each orthologous group and are characterized by two to four repeated sequences. Identified motifs were classified according to their structures. Motifs with direct and/or inverted repeat symmetry constitute the majority of inferred DNA motifs, suggesting preferable TF dimerization in head-to-tail or head-to-head configuration. The obtained genomic collection of in silico reconstructed MocR-TF motifs and regulons in Bacteria provides a basis for future experimental characterization of molecular mechanisms for various regulators in this family.
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Affiliation(s)
- Inna A. Suvorova
- A. A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Science, Moscow, Russia
| | - Dmitry A. Rodionov
- A. A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Science, Moscow, Russia
- Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
- Correspondence D. A. Rodionov ()
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29
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Yin L, Xue Y, Ma Y. Global Microarray Analysis of Alkaliphilic Halotolerant Bacterium Bacillus sp. N16-5 Salt Stress Adaptation. PLoS One 2015; 10:e0128649. [PMID: 26030352 PMCID: PMC4452262 DOI: 10.1371/journal.pone.0128649] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 04/29/2015] [Indexed: 11/29/2022] Open
Abstract
The alkaliphilic halotolerant bacterium Bacillus sp. N16-5 is often exposed to salt stress in its natural habitats. In this study, we used one-colour microarrays to investigate adaptive responses of Bacillus sp. N16-5 transcriptome to long-term growth at different salinity levels (0%, 2%, 8%, and 15% NaCl) and to a sudden salt increase from 0% to 8% NaCl. The common strategies used by bacteria to survive and grow at high salt conditions, such as K+ uptake, Na+ efflux, and the accumulation of organic compatible solutes (glycine betaine and ectoine), were observed in Bacillus sp. N16-5. The genes of SigB regulon involved in general stress responses and chaperone-encoding genes were also induced by high salt concentration. Moreover, the genes regulating swarming ability and the composition of the cytoplasmic membrane and cell wall were also differentially expressed. The genes involved in iron uptake were down-regulated, whereas the iron homeostasis regulator Fur was up-regulated, suggesting that Fur may play a role in the salt adaption of Bacillus sp. N16-5. In summary, we present a comprehensive gene expression profiling of alkaliphilic Bacillus sp. N16-5 cells exposed to high salt stress, which would help elucidate the mechanisms underlying alkaliphilic Bacillus spp. survival in and adaptation to salt stress.
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Affiliation(s)
- Liang Yin
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yanfen Xue
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yanhe Ma
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- * E-mail: (YM)
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30
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Abstract
Rhizobia are bacteria in the α-proteobacterial genera Rhizobium, Sinorhizobium, Mesorhizobium, Azorhizobium and Bradyrhizobium that reduce (fix) atmospheric nitrogen in symbiotic association with a compatible host plant. In free-living and/or symbiotically associated rhizobia, amino acids may, in addition to their incorporation into proteins, serve as carbon, nitrogen or sulfur sources, signals of cellular nitrogen status and precursors of important metabolites. Depending on the rhizobia-host plant combination, microsymbiont amino acid metabolism (biosynthesis, transport and/or degradation) is often crucial to the establishment and maintenance of an effective nitrogen-fixing symbiosis and is intimately interconnected with the metabolism of the plant. This review summarizes past findings and current research directions in rhizobial amino acid metabolism and evaluates the genetic, biochemical and genome expression studies from which these are derived. Specific sections deal with the regulation of rhizobial amino acid metabolism, amino acid transport, and finally the symbiotic roles of individual amino acids in different plant-rhizobia combinations.
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Galardini M, Pini F, Bazzicalupo M, Biondi EG, Mengoni A. Replicon-dependent bacterial genome evolution: the case of Sinorhizobium meliloti. Genome Biol Evol 2013; 5:542-58. [PMID: 23431003 PMCID: PMC3622305 DOI: 10.1093/gbe/evt027] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Many bacterial species, such as the alphaproteobacterium Sinorhizobium meliloti, are characterized by open pangenomes and contain multipartite genomes consisting of a chromosome and other large-sized replicons, such as chromids, megaplasmids, and plasmids. The evolutionary forces in both functional and structural aspects that shape the pangenome of species with multipartite genomes are still poorly understood. Therefore, we sequenced the genomes of 10 new S. meliloti strains, analyzed with four publicly available additional genomic sequences. Results indicated that the three main replicons present in these strains (a chromosome, a chromid, and a megaplasmid) partly show replicon-specific behaviors related to strain differentiation. In particular, the pSymB chromid was shown to be a hot spot for positively selected genes, and, unexpectedly, genes resident in the pSymB chromid were also found to be more widespread in distant taxa than those located in the other replicons. Moreover, through the exploitation of a DNA proximity network, a series of conserved “DNA backbones” were found to shape the evolution of the genome structure, with the rest of the genome experiencing rearrangements. The presented data allow depicting a scenario where the pSymB chromid has a distinctive role in intraspecies differentiation and in evolution through positive selection, whereas the pSymA megaplasmid mostly contributes to structural fluidity and to the emergence of new functions, indicating a specific evolutionary role for each replicon in the pangenome evolution.
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Affiliation(s)
- Marco Galardini
- Department of Biology, University of Firenze, Firenze, Italy
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Mosier AC, Justice NB, Bowen BP, Baran R, Thomas BC, Northen TR, Banfield JF. Metabolites associated with adaptation of microorganisms to an acidophilic, metal-rich environment identified by stable-isotope-enabled metabolomics. mBio 2013; 4:e00484-12. [PMID: 23481603 PMCID: PMC3604775 DOI: 10.1128/mbio.00484-12] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 02/11/2013] [Indexed: 01/10/2023] Open
Abstract
UNLABELLED Microorganisms grow under a remarkable range of extreme conditions. Environmental transcriptomic and proteomic studies have highlighted metabolic pathways active in extremophilic communities. However, metabolites directly linked to their physiology are less well defined because metabolomics methods lag behind other omics technologies due to a wide range of experimental complexities often associated with the environmental matrix. We identified key metabolites associated with acidophilic and metal-tolerant microorganisms using stable isotope labeling coupled with untargeted, high-resolution mass spectrometry. We observed >3,500 metabolic features in biofilms growing in pH ~0.9 acid mine drainage solutions containing millimolar concentrations of iron, sulfate, zinc, copper, and arsenic. Stable isotope labeling improved chemical formula prediction by >50% for larger metabolites (>250 atomic mass units), many of which were unrepresented in metabolic databases and may represent novel compounds. Taurine and hydroxyectoine were identified and likely provide protection from osmotic stress in the biofilms. Community genomic, transcriptomic, and proteomic data implicate fungi in taurine metabolism. Leptospirillum group II bacteria decrease production of ectoine and hydroxyectoine as biofilms mature, suggesting that biofilm structure provides some resistance to high metal and proton concentrations. The combination of taurine, ectoine, and hydroxyectoine may also constitute a sulfur, nitrogen, and carbon currency in the communities. IMPORTANCE Microbial communities are central to many critical global processes and yet remain enigmatic largely due to their complex and distributed metabolic interactions. Metabolomics has the possibility of providing mechanistic insights into the function and ecology of microbial communities. However, our limited knowledge of microbial metabolites, the difficulty of identifying metabolites from complex samples, and the inability to link metabolites directly to community members have proven to be major limitations in developing advances in systems interactions. Here, we show that combining stable-isotope-enabled metabolomics with genomics, transcriptomics, and proteomics can illuminate the ecology of microorganisms at the community scale.
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Affiliation(s)
- Annika C. Mosier
- Department of Earth and Planetary Science, University of California, Berkeley, California, USA
| | - Nicholas B. Justice
- Department of Earth and Planetary Science, University of California, Berkeley, California, USA
| | - Benjamin P. Bowen
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Richard Baran
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Brian C. Thomas
- Department of Earth and Planetary Science, University of California, Berkeley, California, USA
| | - Trent R. Northen
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
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Eilert E, Kranz A, Hollenberg CP, Piontek M, Suckow M. Synthesis and release of the bacterial compatible solute 5-hydroxyectoine in Hansenula polymorpha. J Biotechnol 2013; 167:85-93. [PMID: 23467000 DOI: 10.1016/j.jbiotec.2013.02.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 02/07/2013] [Accepted: 02/11/2013] [Indexed: 11/30/2022]
Abstract
Ectoine and 5-hydroxyectoine belong to the family of compatible solutes which are known to mainly contribute to the adaptation of the cell to osmotic stress by mediation of a constant turgor. In addition the cell's essential functions are maintained under stress conditions like high salinity, heat or aridity stress. Hansenula polymorpha was engineered to catalyze the transformation of monomeric substrates to 5-hydroxyectoine. For this purpose four genes encoding the enzymes of the 5-hydroxyectoine biosynthesis pathway of Halomonas elongata, EctA, EctB, EctC, and EctD, were inserted into the genome of H. polymorpha. Subsequently the syntheses of ectoine and 5-hydroxyectoine were analyzed and optimized. We showed that H. polymorpha is a suitable system for recombinant 5-hydroxyectoine synthesis in gram per liter scale (2.8 g L⁻¹ culture supernatant, 365 μmol/g dcw) in which almost 100% conversion of ectoine to 5-hydroxyectoine without necessity of high salinity were achieved.
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Affiliation(s)
- Eva Eilert
- ARTES Biotechnology GmbH, Elisabeth-Selbert-Str. 9, 40764 Langenfeld-Rheinland, Germany.
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Ormeño-Orrillo E, Menna P, Almeida LGP, Ollero FJ, Nicolás MF, Pains Rodrigues E, Shigueyoshi Nakatani A, Silva Batista JS, Oliveira Chueire LM, Souza RC, Ribeiro Vasconcelos AT, Megías M, Hungria M, Martínez-Romero E. Genomic basis of broad host range and environmental adaptability of Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 which are used in inoculants for common bean (Phaseolus vulgaris L.). BMC Genomics 2012; 13:735. [PMID: 23270491 PMCID: PMC3557214 DOI: 10.1186/1471-2164-13-735] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 12/15/2012] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 are α-Proteobacteria that establish nitrogen-fixing symbioses with a range of legume hosts. These strains are broadly used in commercial inoculants for application to common bean (Phaseolus vulgaris) in South America and Africa. Both strains display intrinsic resistance to several abiotic stressful conditions such as low soil pH and high temperatures, which are common in tropical environments, and to several antimicrobials, including pesticides. The genetic determinants of these interesting characteristics remain largely unknown. RESULTS Genome sequencing revealed that CIAT 899 and PRF 81 share a highly-conserved symbiotic plasmid (pSym) that is present also in Rhizobium leucaenae CFN 299, a rhizobium displaying a similar host range. This pSym seems to have arisen by a co-integration event between two replicons. Remarkably, three distinct nodA genes were found in the pSym, a characteristic that may contribute to the broad host range of these rhizobia. Genes for biosynthesis and modulation of plant-hormone levels were also identified in the pSym. Analysis of genes involved in stress response showed that CIAT 899 and PRF 81 are well equipped to cope with low pH, high temperatures and also with oxidative and osmotic stresses. Interestingly, the genomes of CIAT 899 and PRF 81 had large numbers of genes encoding drug-efflux systems, which may explain their high resistance to antimicrobials. Genome analysis also revealed a wide array of traits that may allow these strains to be successful rhizosphere colonizers, including surface polysaccharides, uptake transporters and catabolic enzymes for nutrients, diverse iron-acquisition systems, cell wall-degrading enzymes, type I and IV pili, and novel T1SS and T5SS secreted adhesins. CONCLUSIONS Availability of the complete genome sequences of CIAT 899 and PRF 81 may be exploited in further efforts to understand the interaction of tropical rhizobia with common bean and other legume hosts.
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Affiliation(s)
- Ernesto Ormeño-Orrillo
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - Pâmela Menna
- Embrapa Soja, C. P. 231, Londrina, Paraná, 86001-970, Brazil
| | - Luiz Gonzaga P Almeida
- Laboratório Nacional de Computação Científica (LNCC), Avenida Getúlio Vargas 333, Petrópolis, Rio de Janeiro, Brazil
| | | | - Marisa Fabiana Nicolás
- Laboratório Nacional de Computação Científica (LNCC), Avenida Getúlio Vargas 333, Petrópolis, Rio de Janeiro, Brazil
| | | | | | | | | | - Rangel Celso Souza
- Laboratório Nacional de Computação Científica (LNCC), Avenida Getúlio Vargas 333, Petrópolis, Rio de Janeiro, Brazil
| | | | - Manuel Megías
- Universidad de Sevilla, Apdo Postal 874, Sevilla, 41080, Spain
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Osmoprotection of Bacillus subtilis through import and proteolysis of proline-containing peptides. Appl Environ Microbiol 2012; 79:576-87. [PMID: 23144141 DOI: 10.1128/aem.01934-12] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Bacillus subtilis can attain cellular protection against the detrimental effects of high osmolarity through osmotically induced de novo synthesis and uptake of the compatible solute l-proline. We have now found that B. subtilis can also exploit exogenously provided proline-containing peptides of various lengths and compositions as osmoprotectants. Osmoprotection by these types of peptides is generally dependent on their import via the peptide transport systems (Dpp, Opp, App, and DtpT) operating in B. subtilis and relies on their hydrolysis to liberate proline. The effectiveness with which proline-containing peptides confer osmoprotection varies considerably, and this can be correlated with the amount of the liberated and subsequently accumulated free proline by the osmotically stressed cell. Through gene disruption experiments, growth studies, and the quantification of the intracellular proline pool, we have identified the PapA (YqhT) and PapB (YkvY) peptidases as responsible for the hydrolysis of various types of Xaa-Pro dipeptides and Xaa-Pro-Xaa tripeptides. The PapA and PapB peptidases possess overlapping substrate specificities. In contrast, osmoprotection by peptides of various lengths and compositions with a proline residue positioned at their N terminus was not affected by defects in the PapA and PapB peptidases. Taken together, our data provide new insight into the physiology of the osmotic stress response of B. subtilis. They illustrate the flexibility of this ubiquitously distributed microorganism to effectively exploit environmental resources in its acclimatization to sustained high-osmolarity surroundings through the accumulation of compatible solutes.
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Exposure to solute stress affects genome-wide expression but not the polycyclic aromatic hydrocarbon-degrading activity of Sphingomonas sp. strain LH128 in biofilms. Appl Environ Microbiol 2012; 78:8311-20. [PMID: 23001650 DOI: 10.1128/aem.02516-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Members of the genus Sphingomonas are important catalysts for removal of polycyclic aromatic hydrocarbons (PAHs) in soil, but their activity can be affected by various stress factors. This study examines the physiological and genome-wide transcription response of the phenanthrene-degrading Sphingomonas sp. strain LH128 in biofilms to solute stress (invoked by 450 mM NaCl solution), either as an acute (4-h) or a chronic (3-day) exposure. The degree of membrane fatty acid saturation was increased as a response to chronic stress. Oxygen consumption in the biofilms and phenanthrene mineralization activities of biofilm cells were, however, not significantly affected after imposing either acute or chronic stress. This finding was in agreement with the transcriptomic data, since genes involved in PAH degradation were not differentially expressed in stressed conditions compared to nonstressed conditions. The transcriptomic data suggest that LH128 adapts to NaCl stress by (i) increasing the expression of genes coping with osmolytic and ionic stress such as biosynthesis of compatible solutes and regulation of ion homeostasis, (ii) increasing the expression of genes involved in general stress response, (iii) changing the expression of general and specific regulatory functions, and (iv) decreasing the expression of protein synthesis such as proteins involved in motility. Differences in gene expression between cells under acute and chronic stress suggest that LH128 goes through changes in genome-wide expression to fully adapt to NaCl stress, without significantly changing phenanthrene degrading activity.
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Jankevics A, Merlo ME, de Vries M, Vonk RJ, Takano E, Breitling R. Metabolomic analysis of a synthetic metabolic switch in Streptomyces coelicolor A3(2). Proteomics 2011; 11:4622-31. [PMID: 21956891 DOI: 10.1002/pmic.201100254] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 08/12/2011] [Accepted: 09/13/2011] [Indexed: 01/09/2023]
Abstract
The global analysis of metabolism by liquid chromatography coupled to mass spectrometry is often hampered by a large amount of biological and technical variability. Here, we introduce an experimental and analytical strategy that can produce robust metabolome profiles in the face of this challenge. By applying a new computational approach based on concordance analysis to an extremely large number of analytical replicates, we are able to show that the overexpression of an antisense non-coding RNA targeting glutamine synthetase I results in a major reorganization of the metabolism of Streptomyces coelicolor, the model species of antibiotic-producing bacteria. We identified 97 metabolites with statistically significant reproducible dynamic behavior across the time series. The observed metabolic changes are very rapid, specific and widespread across metabolism, but focus on the nitrogen assimilation pathways. Our results demonstrate the power of highly replicated experimental designs for the robust characterization of metabolite dynamics. The identified global rearrangement of metabolism suggests the usefulness of RNA interference as an efficient strategy to manipulate the physiology of bacteria with wider biotechnological applicability in microorganisms.
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Affiliation(s)
- Andris Jankevics
- Groningen Bioinformatics Centre, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
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Abstract
The shewanellae are ubiquitous in aquatic and sedimentary systems that are chemically stratified on a permanent or seasonal basis. In addition to their ability to utilize a diverse array of terminal electron acceptors, the microorganisms have evolved both common and unique responding mechanisms to cope with various stresses. This paper focuses on the response and adaptive mechanism of the shewanellae, largely based on transcriptional data.
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Ectoine and hydroxyectoine as protectants against osmotic and cold stress: uptake through the SigB-controlled betaine-choline- carnitine transporter-type carrier EctT from Virgibacillus pantothenticus. J Bacteriol 2011; 193:4699-708. [PMID: 21764932 DOI: 10.1128/jb.05270-11] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Virgibacillus pantothenticus has been shown to synthesize the compatible solute ectoine in response to high salinity or low growth temperature. We found that exogenously provided ectoine and hydroxyectoine also serve as protectants against these challenges. Transport studies with [(14)C]ectoine revealed that both types of stress induced a high-affinity ectoine uptake activity in V. pantothenticus. By using an Escherichia coli mutant defective in osmoprotectant uptake systems, a functional complementation approach for osmostress resistance in the presence of ectoine was employed to retrieve a gene encoding an ectoine transporter from V. pantothenticus. The cloned gene (ectT) encodes a protein (EctT) that is a member of the BCCT (betaine-choline-carnitine-transporter) family of carriers. Osmoprotection assays demonstrated that the EctT carrier mediates the preferential import of ectoine and hydroxyectoine but also possesses minor uptake activities for the compatible solutes proline and glycine betaine. Northern blot analysis with RNA isolated from V. pantothenticus revealed that a rise in the external osmolality or a reduction in growth temperature strongly increased the transcription of the ectT gene. Primer extension analysis demonstrated that ectT was transcribed under these conditions from a SigB-type promoter. SigB is the master regulator of the general stress regulon of bacilli and provides protection to cells against various challenges, including high salinity and low temperature. Both the synthesis of ectoine and the EctT-mediated uptake of ectoine and hydroxyectoine are triggered by the same environmental cues, high salinity and cold stress, and thereby provide, in a concerted fashion, the protection of V. pantothenticus against these challenges.
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Employing site-specific recombination for conditional genetic analysis in Sinorhizobium meliloti. Appl Environ Microbiol 2011; 77:3916-22. [PMID: 21515717 DOI: 10.1128/aem.00544-11] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The ability to remove a genetic function from an organism with good temporal resolution is crucial for characterizing essential genes or genes that act in complex developmental programs. The rhizobium-legume symbiosis involves an elaborate two-organism interaction requiring multiple levels of signal exchange. As an important step toward probing rhizobium genetic functions with temporal resolution, we present the development of a conditional gene deletion system in Sinorhizobium meliloti that employs Cre/loxP site-specific recombination. This system enables chemically inducible and irreversible gene deletion or gene upregulation. Recombinase-mediated excision events can be positively or negatively selected or monitored by a colorimetric assay. The system may be adaptable to various bacterial species, in which recombinase activity may be placed under the control of diverse user-defined promoters. This system also shows promise for uses in promoter trapping and biosensing applications.
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Pandey SP, Minesinger BK, Kumar J, Walker GC. A highly conserved protein of unknown function in Sinorhizobium meliloti affects sRNA regulation similar to Hfq. Nucleic Acids Res 2011; 39:4691-708. [PMID: 21325267 PMCID: PMC3113577 DOI: 10.1093/nar/gkr060] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The SMc01113/YbeY protein, belonging to the UPF0054 family, is highly conserved in nearly every bacterium. However, the function of these proteins still remains elusive. Our results show that SMc01113/YbeY proteins share structural similarities with the MID domain of the Argonaute (AGO) proteins, and might similarly bind to a small-RNA (sRNA) seed, making a special interaction with the phosphate on the 5′-side of the seed, suggesting they may form a component of the bacterial sRNA pathway. Indeed, eliminating SMc01113/YbeY expression in Sinorhizobium meliloti produces symbiotic and physiological phenotypes strikingly similar to those of the hfq mutant. Hfq, an RNA chaperone, is central to bacterial sRNA-pathway. We evaluated the expression of 13 target genes in the smc01113 and hfq mutants. Further, we predicted the sRNAs that may potentially target these genes, and evaluated the accumulation of nine sRNAs in WT and smc01113 and hfq mutants. Similar to hfq, smc01113 regulates the accumulation of sRNAs as well as the target mRNAs. AGOs are central components of the eukaryotic sRNA machinery and conceptual parallels between the prokaryotic and eukaryotic sRNA pathways have long been drawn. Our study provides the first line of evidence for such conceptual parallels. Furthermore, our investigation gives insights into the sRNA-mediated regulation of stress adaptation in S. meliloti.
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Affiliation(s)
- Shree P Pandey
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA
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Eitinger T, Rodionov DA, Grote M, Schneider E. Canonical and ECF-type ATP-binding cassette importers in prokaryotes: diversity in modular organization and cellular functions. FEMS Microbiol Rev 2011; 35:3-67. [PMID: 20497229 DOI: 10.1111/j.1574-6976.2010.00230.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Affiliation(s)
- Thomas Eitinger
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Berlin, Germany
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Rodríguez-Moya J, Argandoña M, Reina-Bueno M, Nieto JJ, Iglesias-Guerra F, Jebbar M, Vargas C. Involvement of EupR, a response regulator of the NarL/FixJ family, in the control of the uptake of the compatible solutes ectoines by the halophilic bacterium Chromohalobacter salexigens. BMC Microbiol 2010; 10:256. [PMID: 20942908 PMCID: PMC2964678 DOI: 10.1186/1471-2180-10-256] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Accepted: 10/13/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Osmosensing and associated signal transduction pathways have not yet been described in obligately halophilic bacteria. Chromohalobacter salexigens is a halophilic bacterium with a broad range of salt tolerance. In response to osmotic stress, it synthesizes and accumulates large amounts of the compatible solutes ectoine and hydroxyectoine. In a previous work, we showed that ectoines can be also accumulated upon transport from the external medium, and that they can be used as carbon sources at optimal, but not at low salinity. This was related to an insufficient ectoine(s) transport under these conditions. RESULTS A C. salexigens Tn1732-induced mutant (CHR95) showed a delayed growth with glucose at low and optimal salinities, could not grow at high salinity, and was able to use ectoines as carbon sources at low salinity. CHR95 was affected in the transport and/or metabolism of glucose, and showed a deregulated ectoine uptake at any salinity, but it was not affected in ectoine metabolism. Transposon insertion in CHR95 caused deletion of three genes, Csal0865-Csal0867: acs, encoding an acetyl-CoA synthase, mntR, encoding a transcriptional regulator of the DtxR/MntR family, and eupR, encoding a putative two-component response regulator with a LuxR_C-like DNA-binding helix-turn-helix domain. A single mntR mutant was sensitive to manganese, suggesting that mntR encodes a manganese-dependent transcriptional regulator. Deletion of eupR led to salt-sensitivity and enabled the mutant strain to use ectoines as carbon source at low salinity. Domain analysis included EupR as a member of the NarL/FixJ family of two component response regulators. Finally, the protein encoded by Csal869, located three genes downstream of eupR was suggested to be the cognate histidine kinase of EupR. This protein was predicted to be a hybrid histidine kinase with one transmembrane and one cytoplasmic sensor domain. CONCLUSIONS This work represents the first example of the involvement of a two-component response regulator in the osmoadaptation of a true halophilic bacterium. Our results pave the way to the elucidation of the signal transduction pathway involved in the control of ectoine transport in C. salexigens.
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Affiliation(s)
- Javier Rodríguez-Moya
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Seville, Spain
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Schwibbert K, Marin-Sanguino A, Bagyan I, Heidrich G, Lentzen G, Seitz H, Rampp M, Schuster SC, Klenk HP, Pfeiffer F, Oesterhelt D, Kunte HJ. A blueprint of ectoine metabolism from the genome of the industrial producer Halomonas elongata DSM 2581 T. Environ Microbiol 2010; 13:1973-94. [PMID: 20849449 PMCID: PMC3187862 DOI: 10.1111/j.1462-2920.2010.02336.x] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The halophilic γ-proteobacterium Halomonas elongata DSM 2581T thrives at high salinity by synthesizing and accumulating the compatible solute ectoine. Ectoine levels are highly regulated according to external salt levels but the overall picture of its metabolism and control is not well understood. Apart from its critical role in cell adaptation to halophilic environments, ectoine can be used as a stabilizer for enzymes and as a cell protectant in skin and health care applications and is thus produced annually on a scale of tons in an industrial process using H. elongata as producer strain. This paper presents the complete genome sequence of H. elongata (4 061 296 bp) and includes experiments and analysis identifying and characterizing the entire ectoine metabolism, including a newly discovered pathway for ectoine degradation and its cyclic connection to ectoine synthesis. The degradation of ectoine (doe) proceeds via hydrolysis of ectoine (DoeA) to Nα-acetyl-l-2,4-diaminobutyric acid, followed by deacetylation to diaminobutyric acid (DoeB). In H. elongata, diaminobutyric acid can either flow off to aspartate or re-enter the ectoine synthesis pathway, forming a cycle of ectoine synthesis and degradation. Genome comparison revealed that the ectoine degradation pathway exists predominantly in non-halophilic bacteria unable to synthesize ectoine. Based on the resulting genetic and biochemical data, a metabolic flux model of ectoine metabolism was derived that can be used to understand the way H. elongata survives under varying salt stresses and that provides a basis for a model-driven improvement of industrial ectoine production.
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Affiliation(s)
- Karin Schwibbert
- Materials and Environment Division, Federal Institute for Materials Research and Testing (BAM), Berlin, Germany
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Ectoines in cell stress protection: uses and biotechnological production. Biotechnol Adv 2010; 28:782-801. [PMID: 20600783 DOI: 10.1016/j.biotechadv.2010.06.005] [Citation(s) in RCA: 230] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 06/18/2010] [Accepted: 06/22/2010] [Indexed: 11/20/2022]
Abstract
Microorganisms produce and accumulate compatible solutes aiming at protecting themselves from environmental stresses. Among them, the wide spread in nature ectoines are receiving increasing attention by the scientific community because of their multiple applications. In fact, increasing commercial demand has led to a multiplication of efforts in order to improve processes for their production. In this review, the importance of current and potential applications of ectoines as protecting agents for macromolecules, cells and tissues, together with their potential as therapeutic agents for certain diseases are analyzed and current theories for the understanding of the molecular basis of their biological activity are discussed. The genetic, biochemical and environmental determinants of ectoines biosynthesis by natural and engineered producers are described. The major limitations of current bioprocesses used for ectoines production are discussed, with emphasis on the different microorganisms, environments, molecular engineering and fermentation strategies used to optimize the production and recovery of ectoines. The combined application of both bioprocess and metabolic engineering strategies, allowing a deeper understanding of the main factors controlling the production process is also stated. Finally, this review aims to summarize and update the state of the art in ectoines uses and applications and industrial scale production using bacteria, emphasizing the importance of reactor design and operation strategies, together with the metabolic engineering aspects and the need for feedback between wet and in silico work to optimize bioproduction.
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Flechard M, Fontenelle C, Blanco C, Goude R, Ermel G, Trautwetter A. RpoE2 of Sinorhizobium meliloti is necessary for trehalose synthesis and growth in hyperosmotic media. Microbiology (Reading) 2010; 156:1708-1718. [DOI: 10.1099/mic.0.034850-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Adaptation to osmotic stress can be achieved by the accumulation of compatible solutes that aid in turgor maintenance and macromolecule stabilization. The genetic regulation of solute accumulation is poorly understood, and has been described well at the molecular level only in enterobacteria. In this study, we show the importance of the alternative sigma factor RpoE2 in Sinorhizobium meliloti osmoadaptation. Construction and characterization of an S. meliloti rpoE2 mutant revealed compromised growth in hyperosmotic media. This defect was due to the lack of trehalose, a minor carbohydrate osmolyte normally produced in the initial stages of growth and in stationary phase. We demonstrate here that all three trehalose synthesis pathways are RpoE2 dependent, but only the OtsA pathway is important for osmoinducible trehalose synthesis. Furthermore, we confirm that the absence of RpoE2-dependent induction of otsA is the cause of the osmotic phenotype of the rpoE2 mutant. In conclusion, we have highlighted that, despite its low level, trehalose is a crucial compatible solute in S. meliloti, and the OtsA pathway induced by RpoE2 is needed for its accumulation under hyperosmotic conditions.
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Affiliation(s)
- Maud Flechard
- UMR CNRS 6026, DUALS, Université de Rennes I, Campus de Beaulieu, Av. du Général Leclerc, 35042 Rennes, France
| | - Catherine Fontenelle
- UMR CNRS 6026, DUALS, Université de Rennes I, Campus de Beaulieu, Av. du Général Leclerc, 35042 Rennes, France
| | - Carlos Blanco
- UMR CNRS 6026, DUALS, Université de Rennes I, Campus de Beaulieu, Av. du Général Leclerc, 35042 Rennes, France
| | - Renan Goude
- UMR CNRS 6026, DUALS, Université de Rennes I, Campus de Beaulieu, Av. du Général Leclerc, 35042 Rennes, France
| | - Gwennola Ermel
- UMR CNRS 6026, DUALS, Université de Rennes I, Campus de Beaulieu, Av. du Général Leclerc, 35042 Rennes, France
| | - Annie Trautwetter
- UMR CNRS 6026, DUALS, Université de Rennes I, Campus de Beaulieu, Av. du Général Leclerc, 35042 Rennes, France
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Doronina NV, Ezhov VA, Beschastnyi AP, Trotsenko YA. Biosynthesis of the bioprotectant ectoin by aerobic methylotrophic bacteria from methanol. APPL BIOCHEM MICRO+ 2010. [DOI: 10.1134/s0003683810020080] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Proteomic alterations explain phenotypic changes in Sinorhizobium meliloti lacking the RNA chaperone Hfq. J Bacteriol 2010; 192:1719-29. [PMID: 20081032 DOI: 10.1128/jb.01429-09] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The ubiquitous bacterial RNA-binding protein Hfq is involved in stress resistance and pathogenicity. In Sinorhizobium meliloti, Hfq is essential for the establishment of symbiosis with Medicago sativa and for nitrogen fixation. A proteomic analysis identifies 55 proteins with significantly affected expression in the hfq mutant; most of them are involved in cell metabolism or stress resistance. Important determinants of oxidative stress resistance, such as CysK, Gsh, Bfr, SodC, KatB, KatC, and a putative peroxiredoxine (SMc00072), are downregulated in the hfq mutant. The hfq mutant is affected for H(2)O(2), menadione, and heat stress resistance. Part of these defects could result from the reductions of rpoE1, rpoE2, rpoE3, and rpoE4 expression levels in the hfq mutant. Some proteins required for efficient symbiosis are reduced in the hfq mutant, contributing to the drastic defect in nodulation observed in this mutant.
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Global transcriptional, physiological, and metabolite analyses of the responses of Desulfovibrio vulgaris hildenborough to salt adaptation. Appl Environ Microbiol 2009; 76:1574-86. [PMID: 20038696 DOI: 10.1128/aem.02141-09] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The response of Desulfovibrio vulgaris Hildenborough to salt adaptation (long-term NaCl exposure) was examined by performing physiological, global transcriptional, and metabolite analyses. Salt adaptation was reflected by increased expression of genes involved in amino acid biosynthesis and transport, electron transfer, hydrogen oxidation, and general stress responses (e.g., heat shock proteins, phage shock proteins, and oxidative stress response proteins). The expression of genes involved in carbon metabolism, cell growth, and phage structures was decreased. Transcriptome profiles of D. vulgaris responses to salt adaptation were compared with transcriptome profiles of D. vulgaris responses to salt shock (short-term NaCl exposure). Metabolite assays showed that glutamate and alanine accumulated under salt adaptation conditions, suggesting that these amino acids may be used as osmoprotectants in D. vulgaris. Addition of amino acids (glutamate, alanine, and tryptophan) or yeast extract to the growth medium relieved salt-related growth inhibition. A conceptual model that links the observed results to currently available knowledge is proposed to increase our understanding of the mechanisms of D. vulgaris adaptation to elevated NaCl levels.
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Lecher J, Pittelkow M, Zobel S, Bursy J, Bönig T, Smits SHJ, Schmitt L, Bremer E. The crystal structure of UehA in complex with ectoine-A comparison with other TRAP-T binding proteins. J Mol Biol 2009; 389:58-73. [PMID: 19362561 DOI: 10.1016/j.jmb.2009.03.077] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Revised: 03/30/2009] [Accepted: 03/31/2009] [Indexed: 11/24/2022]
Abstract
Substrate-binding proteins or extracellular solute receptors (ESRs) are components of both ABC (ATP binding cassette) and TRAP-T (tripartite ATP-independent periplasmic transporter). The TRAP-T system UehABC from Silicibacter pomeroyi DSS-3 imports the compatible solutes ectoine and 5-hydroxyectoine as nutrients. UehA, the ESR of the UehABC operon, binds both ectoine and 5-hydroxyectoine with high affinity (K(d) values of 1.4+/-0.1 and 1.1+/-0.1 microM, respectively) and delivers them to the TRAP-T complex. The crystal structure of UehA in complex with ectoine was determined at 2.9-A resolution and revealed an overall fold common for all ESR proteins from TRAP systems determined so far. A comparison of the recently described structure of TeaA from Halomonas elongata and an ectoine-binding protein (EhuB) from an ABC transporter revealed a conserved ligand binding mode that involves both directed and cation-pi interactions. Furthermore, a comparison with other known TRAP-T ESRs revealed a helix that might act as a selectivity filter imposing restraints on the ESRs that fine-tune ligand recognition and binding and finally might determine the selection of the cognate substrate.
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Affiliation(s)
- Justin Lecher
- Institute of Biochemistry, Heinrich-Heine-University Duesseldorf, Germany
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