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Demtröder L, Pfänder Y, Masepohl B. Rhodobacter capsulatus AnfA is essential for production of Fe-nitrogenase proteins but dispensable for cofactor biosynthesis and electron supply. Microbiologyopen 2020; 9:1234-1246. [PMID: 32207246 PMCID: PMC7294313 DOI: 10.1002/mbo3.1033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/04/2020] [Accepted: 03/06/2020] [Indexed: 01/07/2023] Open
Abstract
The photosynthetic α‐proteobacterium Rhodobacter capsulatus reduces and thereby fixes atmospheric dinitrogen (N2) by a molybdenum (Mo)‐nitrogenase and an iron‐only (Fe)‐nitrogenase. Differential expression of the structural genes of Mo‐nitrogenase (nifHDK) and Fe‐nitrogenase (anfHDGK) is strictly controlled and activated by NifA and AnfA, respectively. In contrast to NifA‐binding sites, AnfA‐binding sites are poorly defined. Here, we identified two highly similar AnfA‐binding sites in the R. capsulatus anfH promoter by studying the effects of promoter mutations on in vivo anfH expression and in vitro promoter binding by AnfA. Comparison of the experimentally determined R. capsulatus AnfA‐binding sites and presumed AnfA‐binding sites from other α‐proteobacteria revealed a consensus sequence of dyad symmetry, TAC–N6–GTA, suggesting that AnfA proteins bind their target promoters as dimers. Chromosomal replacement of the anfH promoter by the nifH promoter restored anfHDGK expression and Fe‐nitrogenase activity in an R. capsulatus strain lacking AnfA suggesting that AnfA is required for AnfHDGK production, but dispensable for biosynthesis of the iron‐only cofactor and electron delivery to Fe‐nitrogenase, pathways activated by NifA. These observations strengthen our model, in which the Fe‐nitrogenase system in R. capsulatus is largely integrated into the Mo‐nitrogenase system.
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Affiliation(s)
- Lisa Demtröder
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Yvonne Pfänder
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
| | - Bernd Masepohl
- Microbial Biology, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany
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Demtröder L, Narberhaus F, Masepohl B. Coordinated regulation of nitrogen fixation and molybdate transport by molybdenum. Mol Microbiol 2018; 111:17-30. [PMID: 30325563 DOI: 10.1111/mmi.14152] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2018] [Indexed: 12/01/2022]
Abstract
Biological nitrogen fixation, the reduction of chemically inert dinitrogen to bioavailable ammonia, is a central process in the global nitrogen cycle highly relevant for life on earth. N2 reduction to NH3 is catalyzed by nitrogenases exclusively synthesized by diazotrophic prokaryotes. All diazotrophs have a molybdenum nitrogenase containing the unique iron-molybdenum cofactor FeMoco. In addition, some diazotrophs encode one or two alternative Mo-free nitrogenases that are less efficient at reducing N2 than Mo-nitrogenase. To permit biogenesis of Mo-nitrogenase and other molybdoenzymes when Mo is scarce, bacteria synthesize the high-affinity molybdate transporter ModABC. Generally, Mo supports expression of Mo-nitrogenase genes, while it represses production of Mo-free nitrogenases and ModABC. Since all three nitrogenases and ModABC can reach very high levels at suitable Mo concentrations, tight Mo-mediated control saves considerable resources and energy. This review outlines the similarities and differences in Mo-responsive regulation of nitrogen fixation and molybdate transport in diverse diazotrophs.
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Affiliation(s)
- Lisa Demtröder
- Microbial Biology, Ruhr University Bochum, Bochum, Germany
| | | | - Bernd Masepohl
- Microbial Biology, Ruhr University Bochum, Bochum, Germany
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Hoffmann MC, Ali K, Sonnenschein M, Robrahn L, Strauss D, Narberhaus F, Masepohl B. Molybdate uptake byAgrobacterium tumefacienscorrelates with the cellular molybdenum cofactor status. Mol Microbiol 2016; 101:809-22. [DOI: 10.1111/mmi.13421] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
| | - Koral Ali
- Microbial Biology, Ruhr University Bochum; Bochum Germany
| | | | | | - Daria Strauss
- Microbial Biology, Ruhr University Bochum; Bochum Germany
| | | | - Bernd Masepohl
- Microbial Biology, Ruhr University Bochum; Bochum Germany
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Müller A, Schlicker C, Fehringer M, Masepohl B, Hofmann E. Expression, purification, crystallization and preliminary X-ray analysis of the DNA-binding domain of Rhodobacter capsulatus MopB. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:377-9. [PMID: 21393847 DOI: 10.1107/s1744309110054710] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 12/30/2010] [Indexed: 11/10/2022]
Abstract
The LysR-type regulator MopB represses transcription of several target genes (including the nitrogen-fixation gene anfA) in Rhodobacter capsulatus at high molybdenum concentrations. In this study, the isolated DNA-binding domain of MopB (MopBHTH) was overexpressed in Escherichia coli. Purified MopBHTH bound the anfA promoter as shown by DNA mobility-shift assays, demonstrating the function of the isolated regulator domain. MopBHTH was crystallized using the sitting-drop vapour-diffusion method in the presence of 0.2 M lithium sulfate, 0.1 M phosphate/citrate pH 4.2, 20%(w/v) PEG 1000 at 291 K. The crystal belonged to space group P3(1)21 or P3(2)21, with unit-cell parameters a=b=61.84, c=139.64 Å, α=β=90, γ=120°, and diffracted to 3.3 Å resolution at a synchrotron source.
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Affiliation(s)
- Alexandra Müller
- Lehrstuhl für Biologie der Mikroorganismen, Fakultät für Biologie und Biotechnologie, Ruhr-Universität Bochum, 44780 Bochum, Germany
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Gisin J, Müller A, Pfänder Y, Leimkühler S, Narberhaus F, Masepohl B. A Rhodobacter capsulatus member of a universal permease family imports molybdate and other oxyanions. J Bacteriol 2010; 192:5943-52. [PMID: 20851900 PMCID: PMC2976454 DOI: 10.1128/jb.00742-10] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Accepted: 09/03/2010] [Indexed: 02/04/2023] Open
Abstract
Molybdenum (Mo) is an important trace element that is toxic at high concentrations. To resolve the mechanisms underlying Mo toxicity, Rhodobacter capsulatus mutants tolerant to high Mo concentrations were isolated by random transposon Tn5 mutagenesis. The insertion sites of six independent isolates mapped within the same gene predicted to code for a permease of unknown function located in the cytoplasmic membrane. During growth under Mo-replete conditions, the wild-type strain accumulated considerably more Mo than the permease mutant. For mutants defective for the permease, the high-affinity molybdate importer ModABC, or both transporters, in vivo Mo-dependent nitrogenase (Mo-nitrogenase) activities at different Mo concentrations suggested that ModABC and the permease import molybdate in nanomolar and micromolar ranges, respectively. Like the permease mutants, a mutant defective for ATP sulfurylase tolerated high Mo concentrations, suggesting that ATP sulfurylase is the main target of Mo inhibition in R. capsulatus. Sulfate-dependent growth of a double mutant defective for the permease and the high-affinity sulfate importer CysTWA was reduced compared to those of the single mutants, implying that the permease plays an important role in sulfate uptake. In addition, permease mutants tolerated higher tungstate and vanadate concentrations than the wild type, suggesting that the permease acts as a general oxyanion importer. We propose to call this permease PerO (for oxyanion permease). It is the first reported bacterial molybdate transporter outside the ABC transporter family.
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Affiliation(s)
- Jonathan Gisin
- Biologie der Mikroorganismen, Fakultät für Biologie und Biotechnologie, Ruhr-Universität Bochum, 44780 Bochum, Germany, Molekulare Mikrobiologie und Enzymologie, Fachbereich Biologie, Universität Konstanz, 78457 Constance, Germany, Molekulare Enzymologie, Institut für Biochemie und Biologie, Universität Potsdam, 14469 Potsdam, Germany
| | - Alexandra Müller
- Biologie der Mikroorganismen, Fakultät für Biologie und Biotechnologie, Ruhr-Universität Bochum, 44780 Bochum, Germany, Molekulare Mikrobiologie und Enzymologie, Fachbereich Biologie, Universität Konstanz, 78457 Constance, Germany, Molekulare Enzymologie, Institut für Biochemie und Biologie, Universität Potsdam, 14469 Potsdam, Germany
| | - Yvonne Pfänder
- Biologie der Mikroorganismen, Fakultät für Biologie und Biotechnologie, Ruhr-Universität Bochum, 44780 Bochum, Germany, Molekulare Mikrobiologie und Enzymologie, Fachbereich Biologie, Universität Konstanz, 78457 Constance, Germany, Molekulare Enzymologie, Institut für Biochemie und Biologie, Universität Potsdam, 14469 Potsdam, Germany
| | - Silke Leimkühler
- Biologie der Mikroorganismen, Fakultät für Biologie und Biotechnologie, Ruhr-Universität Bochum, 44780 Bochum, Germany, Molekulare Mikrobiologie und Enzymologie, Fachbereich Biologie, Universität Konstanz, 78457 Constance, Germany, Molekulare Enzymologie, Institut für Biochemie und Biologie, Universität Potsdam, 14469 Potsdam, Germany
| | - Franz Narberhaus
- Biologie der Mikroorganismen, Fakultät für Biologie und Biotechnologie, Ruhr-Universität Bochum, 44780 Bochum, Germany, Molekulare Mikrobiologie und Enzymologie, Fachbereich Biologie, Universität Konstanz, 78457 Constance, Germany, Molekulare Enzymologie, Institut für Biochemie und Biologie, Universität Potsdam, 14469 Potsdam, Germany
| | - Bernd Masepohl
- Biologie der Mikroorganismen, Fakultät für Biologie und Biotechnologie, Ruhr-Universität Bochum, 44780 Bochum, Germany, Molekulare Mikrobiologie und Enzymologie, Fachbereich Biologie, Universität Konstanz, 78457 Constance, Germany, Molekulare Enzymologie, Institut für Biochemie und Biologie, Universität Potsdam, 14469 Potsdam, Germany
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