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Kumar H, Leimkühler S. Changing the Electron Acceptor Specificity of Rhodobacter capsulatus Formate Dehydrogenase from NAD + to NADP . Int J Mol Sci 2023; 24:16067. [PMID: 38003259 PMCID: PMC10671435 DOI: 10.3390/ijms242216067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Revised: 11/03/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
Formate dehydrogenases catalyze the reversible oxidation of formate to carbon dioxide. These enzymes play an important role in CO2 reduction and serve as nicotinamide cofactor recycling enzymes. More recently, the CO2-reducing activity of formate dehydrogenases, especially metal-containing formate dehydrogenases, has been further explored for efficient atmospheric CO2 capture. Here, we investigate the nicotinamide binding site of formate dehydrogenase from Rhodobacter capsulatus for its specificity toward NAD+ vs. NADP+ reduction. Starting from the NAD+-specific wild-type RcFDH, key residues were exchanged to enable NADP+ binding on the basis of the NAD+-bound cryo-EM structure (PDB-ID: 6TG9). It has been observed that the lysine at position 157 (Lys157) in the β-subunit of the enzyme is essential for the binding of NAD+. RcFDH variants that had Glu259 exchanged for either a positively charged or uncharged amino acid had additional activity with NADP+. The FdsBL279R and FdsBK276A variants also showed activity with NADP+. Kinetic parameters for all the variants were determined and tested for activity in CO2 reduction. The variants were able to reduce CO2 using NADPH as an electron donor in a coupled assay with phosphite dehydrogenase (PTDH), which regenerates NADPH. This makes the enzyme suitable for applications where it can be coupled with other enzymes that use NADPH.
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Affiliation(s)
| | - Silke Leimkühler
- Department of Molecular Enzymology, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany;
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2
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Shimizu T, Hayashi Y, Arai M, McGlynn SE, Masuda T, Masuda S. Repressor Activity of SqrR, a Master Regulator of Persulfide-Responsive Genes, Is Regulated by Heme Coordination. Plant Cell Physiol 2021; 62:100-110. [PMID: 33169162 DOI: 10.1093/pcp/pcaa144] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Accepted: 11/03/2020] [Indexed: 06/11/2023]
Abstract
Reactive sulfur species (RSS) are involved in bioactive regulation via persulfidation of proteins. However, how cells regulate RSS-based signaling and RSS metabolism is poorly understood, despite the importance of universal regulation systems in biology. We previously showed that the persulfide-responsive transcriptional factor SqrR acts as a master regulator of sulfide-dependent photosynthesis in proteobacteria. Here, we demonstrated that SqrR also binds heme at a near one-to-one ratio with a binding constant similar to other heme-binding proteins. Heme does not change the DNA-binding pattern of SqrR to the target gene promoter region; however, DNA-binding affinity of SqrR is reduced by the binding of heme, altering its regulatory activity. Circular dichroism spectroscopy clearly showed secondary structural changes in SqrR by the heme binding. Incremental change in the intracellular heme concentration is associated with small, but significant reduction in the transcriptional repression by SqrR. Overall, these results indicate that SqrR has an ability to bind heme to modulate its DNA-binding activity, which may be important for the precise regulation of RSS metabolism in vivo.
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Affiliation(s)
- Takayuki Shimizu
- Department of Life Science and Technology, Tokyo Institute of Technology, Kanagawa, Japan
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
- Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Yuuki Hayashi
- Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Munehito Arai
- Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
- Department of Physics, The University of Tokyo, Tokyo, Japan
| | - Shawn E McGlynn
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
| | - Tatsuru Masuda
- Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Shinji Masuda
- Department of Life Science and Technology, Tokyo Institute of Technology, Kanagawa, Japan
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan
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3
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Selamoglu N, Önder Ö, Öztürk Y, Khalfaoui-Hassani B, Blaby-Haas CE, Garcia BA, Koch HG, Daldal F. Comparative differential cuproproteomes of Rhodobacter capsulatus reveal novel copper homeostasis related proteins. Metallomics 2020; 12:572-591. [PMID: 32149296 PMCID: PMC7192791 DOI: 10.1039/c9mt00314b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 02/28/2020] [Indexed: 12/20/2022]
Abstract
Copper (Cu) is an essential, but toxic, micronutrient for living organisms and cells have developed sophisticated response mechanisms towards both the lack and the excess of Cu in their environments. In this study, we achieved a global view of Cu-responsive changes in the prokaryotic model organism Rhodobacter capsulatus using label-free quantitative differential proteomics. Semi-aerobically grown cells under heterotrophic conditions in minimal medium (∼0.3 μM Cu) were compared with cells supplemented with either 5 μM Cu or with 5 mM of the Cu-chelator bathocuproine sulfonate. Mass spectrometry based bottom-up proteomics of unfractionated cell lysates identified 2430 of the 3632 putative proteins encoded by the genome, producing a robust proteome dataset for R. capsulatus. Use of biological and technical replicates for each growth condition yielded high reproducibility and reliable quantification for 1926 of the identified proteins. Comparison of cells grown under Cu-excess or Cu-depleted conditions to those grown under minimal Cu-sufficient conditions revealed that 75 proteins exhibited statistically significant (p < 0.05) abundance changes, ranging from 2- to 300-fold. A subset of the highly Cu-responsive proteins was orthogonally probed using molecular genetics, validating that several of them were indeed involved in cellular Cu homeostasis.
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Affiliation(s)
- Nur Selamoglu
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Pallegar P, Peña-Castillo L, Langille E, Gomelsky M, Lang AS. Cyclic di-GMP-Mediated Regulation of Gene Transfer and Motility in Rhodobacter capsulatus. J Bacteriol 2020; 202:e00554-19. [PMID: 31659012 PMCID: PMC6941535 DOI: 10.1128/jb.00554-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 10/19/2019] [Indexed: 02/08/2023] Open
Abstract
Gene transfer agents (GTAs) are bacteriophage-like particles produced by several bacterial and archaeal lineages that contain small pieces of the producing cells' genomes that can be transferred to other cells in a process similar to transduction. One well-studied GTA is RcGTA, produced by the alphaproteobacterium Rhodobacter capsulatus RcGTA gene expression is regulated by several cellular regulatory systems, including the CckA-ChpT-CtrA phosphorelay. The transcription of multiple other regulator-encoding genes is affected by the response regulator CtrA, including genes encoding putative enzymes involved in the synthesis and hydrolysis of the second messenger bis-(3'-5')-cyclic dimeric GMP (c-di-GMP). To investigate whether c-di-GMP signaling plays a role in RcGTA production, we disrupted the CtrA-affected genes potentially involved in this process. We found that disruption of four of these genes affected RcGTA gene expression and production. We performed site-directed mutagenesis of key catalytic residues in the GGDEF and EAL domains responsible for diguanylate cyclase (DGC) and c-di-GMP phosphodiesterase (PDE) activities and analyzed the functions of the wild-type and mutant proteins. We also measured RcGTA production in R. capsulatus strains where intracellular levels of c-di-GMP were altered by the expression of either a heterologous DGC or a heterologous PDE. This adds c-di-GMP signaling to the collection of cellular regulatory systems controlling gene transfer in this bacterium. Furthermore, the heterologous gene expression and the four gene disruptions had similar effects on R. capsulatus flagellar motility as found for gene transfer, and we conclude that c-di-GMP inhibits both RcGTA production and flagellar motility in R. capsulatusIMPORTANCE Gene transfer agents (GTAs) are virus-like particles that move cellular DNA between cells. In the alphaproteobacterium Rhodobacter capsulatus, GTA production is affected by the activities of multiple cellular regulatory systems, to which we have now added signaling via the second messenger dinucleotide molecule bis-(3'-5')-cyclic dimeric GMP (c-di-GMP). Similar to the CtrA phosphorelay, c-di-GMP also affects R. capsulatus flagellar motility in addition to GTA production, with lower levels of intracellular c-di-GMP favoring increased flagellar motility and gene transfer. These findings further illustrate the interconnection of GTA production with global systems of regulation in R. capsulatus, providing additional support for the notion that the production of GTAs has been maintained in this and related bacteria because it provides a benefit to the producing organisms.
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Affiliation(s)
- Purvikalyan Pallegar
- Department of Biology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Lourdes Peña-Castillo
- Department of Biology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
- Department of Computer Science, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Evan Langille
- Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Mark Gomelsky
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USA
| | - Andrew S Lang
- Department of Biology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
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Ding H, Grüll MP, Mulligan ME, Lang AS, Beatty JT. Induction of Rhodobacter capsulatus Gene Transfer Agent Gene Expression Is a Bistable Stochastic Process Repressed by an Extracellular Calcium-Binding RTX Protein Homologue. J Bacteriol 2019; 201:e00430-19. [PMID: 31501287 PMCID: PMC6832060 DOI: 10.1128/jb.00430-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Accepted: 09/06/2019] [Indexed: 01/28/2023] Open
Abstract
Bacteriophage-like gene transfer agents (GTAs) have been discovered in both of the prokaryotic branches of the three-domain phylogenetic tree of life. The production of a GTA (RcGTA) by the phototrophic alphaproteobacterium Rhodobacter capsulatus is regulated by quorum sensing and a phosphorelay homologous to systems in other species that control essential functions such as the initiation of chromosome replication and cell division. In wild-type strains, RcGTA is produced in <3% of cells in laboratory cultures. Mutants of R. capsulatus that exhibit greatly elevated production of RcGTA were created decades ago by chemical mutagenesis, but the nature and molecular consequences of the mutation were unknown. We show that the number of cells in a population that go on to express RcGTA genes is controlled by a stochastic process, in contrast to a genetic process. We used transposon mutagenesis along with a fluorescent protein reporter system and genome sequence data to identify a gene, rcc00280, that encodes an RTX family calcium-binding protein homologue. The Rc280 protein acts as an extracellular repressor of RcGTA gene expression by decreasing the percentage of cells that induce the production of RcGTA.IMPORTANCE GTAs catalyze horizontal gene transfer (HGT), which is important for genomic evolution because the majority of genes found in bacterial genomes have undergone HGT at some point in their evolution. Therefore, it is important to determine how the production of GTAs is regulated to understand the factors that modulate the frequency of gene transfer and thereby specify the tempo of evolution. This work describes a new type of genetic regulation in which an extracellular calcium-binding protein homologue represses the induction of the Rhodobacter capsulatus GTA, RcGTA.
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Affiliation(s)
- Hao Ding
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Marc P Grüll
- Department of Biology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Martin E Mulligan
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Andrew S Lang
- Department of Biology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - J Thomas Beatty
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
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Erkal NA, Eser MG, Özgür E, Gündüz U, Eroglu I, Yücel M. Transcriptome analysis of Rhodobacter capsulatus grown on different nitrogen sources. Arch Microbiol 2019; 201:661-671. [PMID: 30796473 DOI: 10.1007/s00203-019-01635-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 10/10/2018] [Accepted: 02/18/2019] [Indexed: 01/21/2023]
Abstract
This study investigated the effect of different nitrogen sources, namely, ammonium chloride and glutamate, on photoheterotrophic metabolism of Rhodobacter capsulatus grown on acetate as the carbon source. Genes that were significantly differentially expressed according to Affymetrix microarray data were categorized into Clusters of Orthologous Groups functional categories and those in acetate assimilation, hydrogen production, and photosynthetic electron transport pathways were analyzed in detail. Genes related to hydrogen production metabolism were significantly downregulated in cultures grown on ammonium chloride when compared to those grown on glutamate. In contrast, photosynthetic electron transport and acetate assimilation pathway genes were upregulated. In detail, aceA encoding isocitrate lyase, a unique enzyme of the glyoxylate cycle and ccrA encoding the rate limiting crotonyl-CoA carboxylase/reductase enzyme of ethylmalonyl-coA pathway were significantly upregulated. Our findings indicate for the first time that R. capsulatus can operate both glyoxylate and ethylmalonyl-coA cycles for acetate assimilation.
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Affiliation(s)
- Nilüfer Afsar Erkal
- Department of Biological Sciences, Middle East Technical University, 06800, Ankara, Turkey
- Mikro Biyositemler Inc, 06530, Ankara, Turkey
| | | | - Ebru Özgür
- Mikro Biyositemler Inc, 06530, Ankara, Turkey
- Department of Chemical Engineering, Middle East Technical University, 06800, Ankara, Turkey
| | - Ufuk Gündüz
- Department of Biological Sciences, Middle East Technical University, 06800, Ankara, Turkey
| | - Inci Eroglu
- Department of Chemical Engineering, Middle East Technical University, 06800, Ankara, Turkey
| | - Meral Yücel
- Department of Biological Sciences, Middle East Technical University, 06800, Ankara, Turkey.
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7
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Abstract
Gene transfer agents (GTAs) are thought to be ancient bacteriophages that have been co-opted into serving their host and can now transfer any gene between bacteria. Production of GTAs is controlled by several global regulators through unclear mechanisms. In Rhodobacter capsulatus, gene rcc01865 encodes a putative regulatory protein that is essential for GTA production. Here, I show that rcc01865 (hereafter gafA) encodes a transcriptional regulator that binds to the GTA promoter to initiate production of structural and DNA packaging components. Expression of gafA is in turn controlled by the pleiotropic regulator protein CtrA and the quorum-sensing regulator GtaR. GafA and CtrA work together to promote GTA maturation and eventual release through cell lysis. Identification of GafA as a direct GTA regulator allows the first integrated regulatory model to be proposed and paves the way for discovery of GTAs in other species that possess gafA homologues.
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Affiliation(s)
- Paul C M Fogg
- Biology Department, University of York, Wentworth Way, York, YO10 5DD, UK.
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8
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Kessi J, Hörtensteiner S. Inhibition of bacteriochlorophyll biosynthesis in the purple phototrophic bacteria Rhodospirillumrubrum and Rhodobacter capsulatus grown in the presence of a toxic concentration of selenite. BMC Microbiol 2018; 18:81. [PMID: 30064359 PMCID: PMC6069883 DOI: 10.1186/s12866-018-1209-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Accepted: 06/27/2018] [Indexed: 11/21/2022] Open
Abstract
Background In many works, the chemical composition of bacterially-produced elemental selenium nanoparticles (Se0-nanoparticles) was investigated using electron dispersive X-ray analysis. The results suggest that these particles should be associated with organic compounds. However, a complete analysis of their chemical composition is still missing. Aiming at identifying organic compounds associated with the Se0-nanoparticles produced by the purple phototrophic bacteria Rhodospirillum rubrum and Rhodobacter capsulatus (α group of the proteobacteria), we used MALDI-TOF spectrometry.Results This technic revealed that numerous signals obtained from particles produced by both species of bacteria were from metabolites of the photosynthetic system. Furthermore, not only bacteriochlorophyll a, bacteriopheophytin a, and bacteriopheophorbide a, which are known to accumulate in stationary phase cultures of these bacteria grown phototrophically in the absence of selenite, were identified. The particles were also associated with intermediary metabolites of the bacteriochlorophyll a biosynthesis pathway such as protoporphyrin IX, protoporphyrin IX monomethyl ester, bacteriochlorophyllide a and, most likely, Mg-protoporphyrin IX-monomethyl ester, as well as with oxidation products of the substrates of protochlorophyllide reductase and chlorin reductase.Conclusion Accumulation of intermediary metabolites of the bacteriochlorophyll biosynthesis pathway in these purple phototrophic bacteria was attributed to inhibition of oxygen-sensitive enzymes involved in this pathway. Consistent with this interpretation it has been reported that these bacteria reduce selenite intracellularly, that they contain high levels of glutathione and that the reduction of selenite with glutathione is a very fast reaction accompanied by the production of reactive oxygen species. As many enzymes involved in the biosynthesis of bacteriochlorophyll contain [Fe-S] clusters in their active site, which are known to be degraded in the presence of reactive oxygen species as well as in the presence of molecular oxygen, we concluded that the substrates of these enzymes accumulate in cells during selenite reduction.Association of metabolites of bacteriochlorophyll biosynthesis and degradation with the Se0-nanoparticles produced by Rhodospirillum rubrum and Rhodobacter capsulatus is proposed to result from coating of the nanoparticles with the intracytoplasmic membrane of these bacteria, where the photochemical apparatus is concentrated.
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Affiliation(s)
- Janine Kessi
- Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, Zurich, 8008 Switzerland
- Kirschenweg 10, Würenlingen, 5303 Switzerland
| | - Stefan Hörtensteiner
- Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, Zurich, 8008 Switzerland
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Abstract
When faced with amino acid starvation, prokaryotic cells induce a stringent response that modulates their physiology. The stringent response is manifested by production of signaling molecules guanosine 5'-diphosphate,3'-diphosphate (ppGpp) and guanosine 5'-triphosphate,3'-diphosphate (pppGpp) that are also called alarmones. In many species, alarmone levels are regulated by a multidomain bifunctional alarmone synthetase/hydrolase called Rel. In this enzyme, there is an ACT domain at the carboxyl region that has an unknown function; however, similar ACT domains are present in other enzymes that have roles in controlling amino acid metabolism. In many cases, these other ACT domains have been shown to allosterically regulate enzyme activity through the binding of amino acids. Here, we show that the ACT domain present in the Rhodobacter capsulatus Rel alarmone synthetase/hydrolase binds branched-chain amino acids valine and isoleucine. We further show that the binding of these amino acids stimulates alarmone hydrolase activity both in vitro and in vivo. Furthermore, we found that the ACT domain present in Rel proteins from many diverse species also binds branched-chain amino acids. These results indicate that the cellular concentration of amino acids can directly affect Rel alarmone synthetase/hydrolase activity, thus adding another layer of control to current models of cellular control of the stringent response.
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Affiliation(s)
- Mingxu Fang
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405
| | - Carl E Bauer
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405
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Loeschcke A, Dienst D, Wewer V, Hage-Hülsmann J, Dietsch M, Kranz-Finger S, Hüren V, Metzger S, Urlacher VB, Gigolashvili T, Kopriva S, Axmann IM, Drepper T, Jaeger KE. The photosynthetic bacteria Rhodobacter capsulatus and Synechocystis sp. PCC 6803 as new hosts for cyclic plant triterpene biosynthesis. PLoS One 2017; 12:e0189816. [PMID: 29281679 PMCID: PMC5744966 DOI: 10.1371/journal.pone.0189816] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 12/01/2017] [Indexed: 11/18/2022] Open
Abstract
Cyclic triterpenes constitute one of the most diverse groups of plant natural products. Besides the intriguing biochemistry of their biosynthetic pathways, plant triterpenes exhibit versatile bioactivities, including antimicrobial effects against plant and human pathogens. While prokaryotes have been extensively used for the heterologous production of other classes of terpenes, the synthesis of cyclic triterpenes, which inherently includes the two-step catalytic formation of the universal linear precursor 2,3-oxidosqualene, is still a major challenge. We thus explored the suitability of the metabolically versatile photosynthetic α-proteobacterium Rhodobacter capsulatus SB1003 and cyanobacterium Synechocystis sp. PCC 6803 as alternative hosts for biosynthesis of cyclic plant triterpenes. Therefore, 2,3-oxidosqualene production was implemented and subsequently combined with different cyclization reactions catalyzed by the representative oxidosqualene cyclases CAS1 (cycloartenol synthase), LUP1 (lupeol synthase), THAS1 (thalianol synthase) and MRN1 (marneral synthase) derived from model plant Arabidopsis thaliana. While successful accumulation of 2,3-oxidosqualene could be detected by LC-MS analysis in both hosts, cyclase expression resulted in differential production profiles. CAS1 catalyzed conversion to only cycloartenol, but expression of LUP1 yielded lupeol and a triterpenoid matching an oxidation product of lupeol, in both hosts. In contrast, THAS1 expression did not lead to cyclic product formation in either host, whereas MRN1-dependent production of marnerol and hydroxymarnerol was observed in Synechocystis but not in R. capsulatus. Our findings thus indicate that 2,3-oxidosqualene cyclization in heterologous phototrophic bacteria is basically feasible but efficient conversion depends on both the respective cyclase enzyme and individual host properties. Therefore, photosynthetic α-proteo- and cyanobacteria are promising alternative candidates for providing new bacterial access to the broad class of triterpenes for biotechnological applications.
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Affiliation(s)
- Anita Loeschcke
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS)
| | - Dennis Dienst
- Cluster of Excellence on Plant Sciences (CEPLAS)
- Institute for Synthetic Microbiology, Department of Biology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Vera Wewer
- Cluster of Excellence on Plant Sciences (CEPLAS)
- MS Platform, Department of Biology, University of Cologne, Cologne, Germany
| | - Jennifer Hage-Hülsmann
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS)
| | - Maximilian Dietsch
- Cluster of Excellence on Plant Sciences (CEPLAS)
- Institute for Synthetic Microbiology, Department of Biology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sarah Kranz-Finger
- Cluster of Excellence on Plant Sciences (CEPLAS)
- Institute of Biochemistry II, Department of Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Vanessa Hüren
- Cluster of Excellence on Plant Sciences (CEPLAS)
- Institute for Synthetic Microbiology, Department of Biology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sabine Metzger
- Cluster of Excellence on Plant Sciences (CEPLAS)
- MS Platform, Department of Biology, University of Cologne, Cologne, Germany
| | - Vlada B. Urlacher
- Cluster of Excellence on Plant Sciences (CEPLAS)
- Institute of Biochemistry II, Department of Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Tamara Gigolashvili
- Cluster of Excellence on Plant Sciences (CEPLAS)
- Botanical Institute, University of Cologne, Cologne, Germany
| | - Stanislav Kopriva
- Cluster of Excellence on Plant Sciences (CEPLAS)
- Botanical Institute, University of Cologne, Cologne, Germany
| | - Ilka M. Axmann
- Cluster of Excellence on Plant Sciences (CEPLAS)
- Institute for Synthetic Microbiology, Department of Biology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- * E-mail: (IMA); (TD)
| | - Thomas Drepper
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS)
- * E-mail: (IMA); (TD)
| | - Karl-Erich Jaeger
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS)
- Institute of Bio- and Geosciences (IBG-1), Forschungszentrum Jülich, Jülich, Germany
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11
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Shimizu T, Shen J, Fang M, Zhang Y, Hori K, Trinidad JC, Bauer CE, Giedroc DP, Masuda S. Sulfide-responsive transcriptional repressor SqrR functions as a master regulator of sulfide-dependent photosynthesis. Proc Natl Acad Sci U S A 2017; 114:2355-2360. [PMID: 28196888 PMCID: PMC5338557 DOI: 10.1073/pnas.1614133114] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Sulfide was used as an electron donor early in the evolution of photosynthesis, with many extant photosynthetic bacteria still capable of using sulfur compounds such as hydrogen sulfide (H2S) as a photosynthetic electron donor. Although enzymes involved in H2S oxidation have been characterized, mechanisms of regulation of sulfide-dependent photosynthesis have not been elucidated. In this study, we have identified a sulfide-responsive transcriptional repressor, SqrR, that functions as a master regulator of sulfide-dependent gene expression in the purple photosynthetic bacterium Rhodobacter capsulatus SqrR has three cysteine residues, two of which, C41 and C107, are conserved in SqrR homologs from other bacteria. Analysis with liquid chromatography coupled with an electrospray-interface tandem-mass spectrometer reveals that SqrR forms an intramolecular tetrasulfide bond between C41 and C107 when incubated with the sulfur donor glutathione persulfide. SqrR is oxidized in sulfide-stressed cells, and tetrasulfide-cross-linked SqrR binds more weakly to a target promoter relative to unmodified SqrR. C41S and C107S R. capsulatus SqrRs lack the ability to respond to sulfide, and constitutively repress target gene expression in cells. These results establish that SqrR is a sensor of H2S-derived reactive sulfur species that maintain sulfide homeostasis in this photosynthetic bacterium and reveal the mechanism of sulfide-dependent transcriptional derepression of genes involved in sulfide metabolism.
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Affiliation(s)
- Takayuki Shimizu
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Kanagawa 226-8501, Japan
| | - Jiangchuan Shen
- Department of Chemistry, Indiana University, Bloomington, IN 47405-7102
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405
| | - Mingxu Fang
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405
| | - Yixiang Zhang
- Department of Chemistry, Indiana University, Bloomington, IN 47405-7102
- Laboratory for Biological Mass Spectrometry, Indiana University, Bloomington, IN 47405-7102
| | - Koichi Hori
- School of Life Science and Technology, Tokyo Institute of Technology, Kanagawa 226-8501, Japan
| | - Jonathan C Trinidad
- Department of Chemistry, Indiana University, Bloomington, IN 47405-7102
- Laboratory for Biological Mass Spectrometry, Indiana University, Bloomington, IN 47405-7102
| | - Carl E Bauer
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405
| | - David P Giedroc
- Department of Chemistry, Indiana University, Bloomington, IN 47405-7102
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405
| | - Shinji Masuda
- Center for Biological Resources and Informatics, Tokyo Institute of Technology, Kanagawa 226-8501, Japan;
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8551, Japan
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12
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Montiel Corona V, Le Borgne S, Revah S, Morales M. Effect of light-dark cycles on hydrogen and poly-β-hydroxybutyrate production by a photoheterotrophic culture and Rhodobacter capsulatus using a dark fermentation effluent as substrate. Bioresour Technol 2017; 226:238-246. [PMID: 28011238 DOI: 10.1016/j.biortech.2016.12.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 12/04/2016] [Accepted: 12/05/2016] [Indexed: 06/06/2023]
Abstract
A Rhodobacter capsulatus strain and a photoheterotrophic culture (IZT) were cultivated to produce hydrogen under different light-dark cycles. A dark fermentation effluent (DFE) was used as substrate. It was found that IZT culture had an average cumulative hydrogen production (Paccum H2) of 1300±43mLH2L-1 under continuous illumination and light-dark cycles of 30 or 60min. In contrast, R. capsulatus reduced its Paccum H2 by 20% under 30:30min light-dark cycles, but tripled its poly-β-hydroxybutyrate (PHB) content (308±2mgPHB gdw-1) compared to continuous illumination. The highest PHB content by IZT culture was 178±10mgPHB gdw-1 under 15:15min light-dark cycles. PCR-DGGE analysis revealed that the IZT culture was mainly composed of Rhodopseudomonas palustris identified with high nucleotide similarity (99%). The evaluated cultures might be used for hydrogen and PHB production. They might provide energy savings by using light-dark cycles and DFE valorization.
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Affiliation(s)
- Virginia Montiel Corona
- Doctorado en Biotecnología, División de Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana UAM-Iztapalapa, San Rafael Atlixco 186, C.P. 09340 México, D.F., Mexico
| | - Sylvie Le Borgne
- Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Avenida Vasco de Quiroga 4871, colonia Santa Fe, Delegación Cuajimalpa de Morelos, C.P. 05348 México, D.F., Mexico
| | - Sergio Revah
- Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Avenida Vasco de Quiroga 4871, colonia Santa Fe, Delegación Cuajimalpa de Morelos, C.P. 05348 México, D.F., Mexico
| | - Marcia Morales
- Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Avenida Vasco de Quiroga 4871, colonia Santa Fe, Delegación Cuajimalpa de Morelos, C.P. 05348 México, D.F., Mexico.
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13
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Modeling hydrogen photoproduction systems in cells. Biotechnol Bioeng 2017; 114:244. [PMID: 28005285 DOI: 10.1002/bit.26102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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14
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Wen S, Liu H, He H, Luo L, Li X, Zeng G, Zhou Z, Lou W, Yang C. Treatment of anaerobically digested swine wastewater by Rhodobacter blasticus and Rhodobacter capsulatus. Bioresour Technol 2016; 222:33-38. [PMID: 27697735 DOI: 10.1016/j.biortech.2016.09.102] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 09/21/2016] [Accepted: 09/25/2016] [Indexed: 05/28/2023]
Abstract
Two strains of photosynthetic bacteria, Rhodobacter blasticus and Rhodobacter capsulatus, were used in this work to investigate the feasibility of using photosynthetic bacteria for the treatment of anaerobically digested swine wastewater. The effects of crucial factors which influence the pollutants removal efficiency were also examined. Results showed that anaerobically digested swine wastewater could be treated effectively by photosynthetic bacteria. The treatment efficiency was significantly higher by the mixed photosynthetic bacteria than that by any unitary bacterium. The optimal treatment condition by mixed bacteria was inoculation of 10.0%(v/v) of the two bacteria by 1:1, initial pH of 7.0 and initial chemical oxygen demand of 4800mgL-1. Under these conditions, the removal rate of chemical oxygen demand was 83.3%, which was 19.3% higher than when using Rhodobacter blasticus or 10.6% higher than when using Rhodobacter capsulatus separately. This mixed photosynthetic bacteria achieved high chemical oxygen demand removal and cell yields.
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Affiliation(s)
- Shan Wen
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Hongyu Liu
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Huijun He
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Le Luo
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Xiang Li
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Guangming Zeng
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China
| | - Zili Zhou
- Hunan Hikee Environmental Technology Co., Ltd., Changsha 410001, PR China
| | - Wei Lou
- Hunan Hikee Environmental Technology Co., Ltd., Changsha 410001, PR China
| | - Chunping Yang
- College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China; Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, College of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, Zhejiang 310018, PR China.
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15
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Kuleta P, Sarewicz M, Postila P, Róg T, Osyczka A. Identifying involvement of Lys251/Asp252 pair in electron transfer and associated proton transfer at the quinone reduction site of Rhodobacter capsulatus cytochrome bc1. Biochim Biophys Acta 2016; 1857:1661-8. [PMID: 27421232 PMCID: PMC5001787 DOI: 10.1016/j.bbabio.2016.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 06/22/2016] [Accepted: 07/10/2016] [Indexed: 11/23/2022]
Abstract
Describing dynamics of proton transfers in proteins is challenging, but crucial for understanding processes which use them for biological functions. In cytochrome bc1, one of the key enzymes of respiration or photosynthesis, proton transfers engage in oxidation of quinol (QH2) and reduction of quinone (Q) taking place at two distinct catalytic sites. Here we evaluated by site-directed mutagenesis the contribution of Lys251/Asp252 pair (bacterial numbering) in electron transfers and associated with it proton uptake to the quinone reduction site (Qi site). We showed that the absence of protonable group at position 251 or 252 significantly changes the equilibrium levels of electronic reactions including the Qi-site mediated oxidation of heme bH, reverse reduction of heme bH by quinol and heme bH/Qi semiquinone equilibrium. This implicates the role of H-bonding network in binding of quinone/semiquinone and defining thermodynamic properties of Q/SQ/QH2 triad. The Lys251/Asp252 proton path is disabled only when both protonable groups are removed. With just one protonable residue from this pair, the entrance of protons to the catalytic site is sustained, albeit at lower rates, indicating that protons can travel through parallel routes, possibly involving water molecules. This shows that proton paths display engineering tolerance for change as long as all the elements available for functional cooperation secure efficient proton delivery to the catalytic site.
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Affiliation(s)
- Patryk Kuleta
- Department of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7, 30-387 Kraków, Poland
| | - Marcin Sarewicz
- Department of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7, 30-387 Kraków, Poland
| | - Pekka Postila
- Structural Bioinformatics Laboratory, Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Tomasz Róg
- Department of Physics, Tampere University of Technology, P.O. Box 692, FI-33101 Tampere, Finland; Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Artur Osyczka
- Department of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7, 30-387 Kraków, Poland.
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16
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Francia F, Malferrari M, Lanciano P, Steimle S, Daldal F, Venturoli G. The cytochrome b Zn binding amino acid residue histidine 291 is essential for ubihydroquinone oxidation at the Q o site of bacterial cytochrome bc 1. Biochim Biophys Acta 2016; 1857:1796-1806. [PMID: 27550309 DOI: 10.1016/j.bbabio.2016.08.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 06/27/2016] [Accepted: 08/17/2016] [Indexed: 11/18/2022]
Abstract
The ubiquinol:cytochrome (cyt) c oxidoreductase (or cyt bc1) is an important membrane protein complex in photosynthetic and respiratory energy transduction. In bacteria such as Rhodobacter capsulatus it is constituted of three subunits: the iron-sulfur protein, cyt b and cyt c1, which form two catalytic domains, the Qo (hydroquinone (QH2) oxidation) and Qi (quinone (Q) reduction) sites. At the Qo site, the pathways of bifurcated electron transfers emanating from QH2 oxidation are known, but the associated proton release routes are not well defined. In energy transducing complexes, Zn2+ binding amino acid residues often correlate with proton uptake or release pathways. Earlier, using combined EXAFS and structural studies, we identified Zn coordinating residues of mitochondrial and bacterial cyt bc1. In this work, using the genetically tractable bacterial cyt bc1, we substituted each of the proposed Zn binding residues with non-protonatable side chains. Among these mutants, only the His291Leu substitution destroyed almost completely the Qo site catalysis without perturbing significantly the redox properties of the cofactors or the assembly of the complex. In this mutant, which is unable to support photosynthetic growth, the bifurcated electron transfer reactions that result from QH2 oxidation at the Qo site, as well as the associated proton(s) release, were dramatically impaired. Based on these findings, on the putative role of His291 in liganding Zn, and on its solvent exposed and highly conserved position, we propose that His291 of cyt b is critical for proton release associated to QH2 oxidation at the Qo site of cyt bc1.
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Affiliation(s)
- Francesco Francia
- Laboratorio di Biochimica e Biofisica Molecolare, Dipartimento di Farmacia e Biotecnologie, FaBiT, Università di Bologna, 40126 Bologna, Italy
| | - Marco Malferrari
- Laboratorio di Biochimica e Biofisica Molecolare, Dipartimento di Farmacia e Biotecnologie, FaBiT, Università di Bologna, 40126 Bologna, Italy
| | - Pascal Lanciano
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Stefan Steimle
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Fevzi Daldal
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Giovanni Venturoli
- Laboratorio di Biochimica e Biofisica Molecolare, Dipartimento di Farmacia e Biotecnologie, FaBiT, Università di Bologna, 40126 Bologna, Italy; Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia (CNISM), Dipartimento di Fisica, Università di Bologna, 40127 Bologna, Italy
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17
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Borghese R, Canducci L, Musiani F, Cappelletti M, Ciurli S, Turner RJ, Zannoni D. On the role of a specific insert in acetate permeases (ActP) for tellurite uptake in bacteria: Functional and structural studies. J Inorg Biochem 2016; 163:103-109. [PMID: 27421695 DOI: 10.1016/j.jinorgbio.2016.06.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 06/14/2016] [Accepted: 06/23/2016] [Indexed: 11/17/2022]
Abstract
The oxyanion tellurite (TeO32-) is extremely toxic to bacterial cells. In Rhodobacter capsulatus, tellurite enters the cytosol by means of the high uptake-rate acetate permease RcActP2, encoded by one of the three actP genes present in this species (actP1, actP2 and actP3). Conversely, in Escherichia coli a low rate influx of the oxyanion is measured, which depends mainly on the phosphate transporter EcPitA, even though E. coli contains its own EcActP acetate permease. Here we report that when the actP2 gene from R. capsulatus is expressed in wild-type E. coli HB101 and in E. coli JW3460 ΔpitA mutant, the cellular intake of tellurite increases up to four times, suggesting intrinsic structural differences between EcActP and RcActP2. Indeed, a sequence analysis indicated the presence in RcActP2 of an insert of 15-16 residues, located between trans-membrane (TM) helices 6 and 7, which is absent in both EcActP and RcActP1. Based on this observation, the molecular models of homodimeric RcActP1 and RcActP2 were calculated and analyzed. In the RcActP2 model, the insert induces a perturbation in the conformation of the loop between TM helices 6 and 7, located at the RcActP2 dimerization interface. This perturbation opens a cavity on the periplasmic side that is closed, instead, in the RcActP1 model. This cavity also features an increase of the positive electric potential on the protein surface, an effect ascribed to specific residues Lys261, Lys281 and Arg560. We propose that this positively charged patch in RcActP2 is involved in recognition and translocation of the TeO32- anion, attributing to RcActP2 a greater ability as compared to RcActP1 to transport this inorganic poison inside the cells.
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Affiliation(s)
- Roberto Borghese
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy.
| | - Laura Canducci
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Francesco Musiani
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Martina Cappelletti
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Stefano Ciurli
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Raymond J Turner
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Davide Zannoni
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
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18
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Borghese R, Brucale M, Fortunato G, Lanzi M, Mezzi A, Valle F, Cavallini M, Zannoni D. Extracellular production of tellurium nanoparticles by the photosynthetic bacterium Rhodobacter capsulatus. J Hazard Mater 2016; 309:202-209. [PMID: 26894294 DOI: 10.1016/j.jhazmat.2016.02.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 02/03/2016] [Accepted: 02/04/2016] [Indexed: 06/05/2023]
Abstract
The toxic oxyanion tellurite (TeO3(2-)) is acquired by cells of Rhodobacter capsulatus grown anaerobically in the light, via acetate permease ActP2 and then reduced to Te(0) in the cytoplasm as needle-like black precipitates. Interestingly, photosynthetic cultures of R. capsulatus can also generate Te(0) nanoprecipitates (TeNPs) outside the cells upon addition of the redox mediator lawsone (2-hydroxy-1,4-naphtoquinone). TeNPs generation kinetics were monitored to define the optimal conditions to produce TeNPs as a function of various carbon sources and lawsone concentration. We report that growing cultures over a 10 days period with daily additions of 1mM tellurite led to the accumulation in the growth medium of TeNPs with dimensions from 200 up to 600-700 nm in length as determined by atomic force microscopy (AFM). This result suggests that nucleation of TeNPs takes place over the entire cell growth period although the addition of new tellurium Te(0) to pre-formed TeNPs is the main strategy used by R. capsulatus to generate TeNPs outside the cells. Finally, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) analysis of TeNPs indicate they are coated with an organic material which keeps the particles in solution in aqueous solvents.
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Affiliation(s)
- Roberto Borghese
- Dept. of Pharmacy and Biotechnology, University of Bologna, Italy.
| | - Marco Brucale
- Institute for the Study of Nanostructured Materials (CNR-ISMN), Rome, Italy
| | | | - Massimiliano Lanzi
- Dept. of Industrial Chemistry "Toso Montanari", University of Bologna, Italy
| | - Alessio Mezzi
- Institute for the Study of Nanostructured Materials (CNR-ISMN), Rome, Italy
| | - Francesco Valle
- Institute for the Study of Nanostructured Materials (CNR-ISMN), Bologna, Italy
| | | | - Davide Zannoni
- Dept. of Pharmacy and Biotechnology, University of Bologna, Italy
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19
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Silva FTM, Moreira LR, de Souza Ferreira J, Batista FRX, Cardoso VL. Replacement of sugars to hydrogen production by Rhodobacter capsulatus using dark fermentation effluent as substrate. Bioresour Technol 2016; 200:72-80. [PMID: 26476167 DOI: 10.1016/j.biortech.2015.10.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 10/01/2015] [Accepted: 10/03/2015] [Indexed: 06/05/2023]
Abstract
Hydrogen is a promising alternative for the increased global energy demand since it has high energy density and is a clean fuel. The aim of this work was to evaluate the photo-fermentation by Rhodobacter capsulatus, using the dark fermentation effluent as substrate. Different systems were tested by changing the type of sugar in the dark fermentation, investigating the influence of supplementing DFE with sugar and adding alternate and periodically lactose and glucose throughout the process. The supplementation of the DFE with sugar resulted in higher H2 productivity and the replacement of the sugars repeatedly during the photo-fermentation process was important to maintain the cell culture active. By controlling the residual amount of sugar, bacteria inhibition was avoided; lactic acid, that was toxic to the biomass, was consumed and the metabolic route of butyric acid production was predominant. Under optimum conditions, the H2 productivity reached 208.40mmolH2/Ld in 52h.
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Affiliation(s)
- Felipe Thales Moreira Silva
- School of Chemical Engineering, Federal University of Uberlandia, Av. Joao Naves de Avila 2121, Santa Monica 38408-144, Uberlandia/MG, Brazil
| | - Luiza Rojas Moreira
- School of Chemical Engineering, Federal University of Uberlandia, Av. Joao Naves de Avila 2121, Santa Monica 38408-144, Uberlandia/MG, Brazil
| | - Juliana de Souza Ferreira
- School of Chemical Engineering, Federal University of Uberlandia, Av. Joao Naves de Avila 2121, Santa Monica 38408-144, Uberlandia/MG, Brazil
| | - Fabiana Regina Xavier Batista
- School of Chemical Engineering, Federal University of Uberlandia, Av. Joao Naves de Avila 2121, Santa Monica 38408-144, Uberlandia/MG, Brazil.
| | - Vicelma Luiz Cardoso
- School of Chemical Engineering, Federal University of Uberlandia, Av. Joao Naves de Avila 2121, Santa Monica 38408-144, Uberlandia/MG, Brazil
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20
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Gürgan M, Erkal NA, Özgür E, Gündüz U, Eroglu I, Yücel M. Transcriptional Profiling of Hydrogen Production Metabolism of Rhodobacter capsulatus under Temperature Stress by Microarray Analysis. Int J Mol Sci 2015; 16:13781-97. [PMID: 26086826 PMCID: PMC4490523 DOI: 10.3390/ijms160613781] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 06/09/2015] [Indexed: 12/28/2022] Open
Abstract
Biohydrogen is a clean and renewable form of hydrogen, which can be produced by photosynthetic bacteria in outdoor large-scale photobioreactors using sunlight. In this study, the transcriptional response of Rhodobacter capsulatus to cold (4 °C) and heat (42 °C) stress was studied using microarrays. Bacteria were grown in 30/2 acetate/glutamate medium at 30 °C for 48 h under continuous illumination. Then, cold and heat stresses were applied for two and six hours. Growth and hydrogen production were impaired under both stress conditions. Microarray chips for R. capsulatus were custom designed by Affymetrix (GeneChip®. TR_RCH2a520699F). The numbers of significantly changed genes were 328 and 293 out of 3685 genes under cold and heat stress, respectively. Our results indicate that temperature stress greatly affects the hydrogen production metabolisms of R. capsulatus. Specifically, the expression of genes that participate in nitrogen metabolism, photosynthesis and the electron transport system were induced by cold stress, while decreased by heat stress. Heat stress also resulted in down regulation of genes related to cell envelope, transporter and binding proteins. Transcriptome analysis and physiological results were consistent with each other. The results presented here may aid clarification of the genetic mechanisms for hydrogen production in purple non-sulfur (PNS) bacteria under temperature stress.
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Affiliation(s)
- Muazzez Gürgan
- Department of Biological Sciences, Middle East Technical University, Ankara 06800, Turkey.
| | - Nilüfer Afşar Erkal
- Department of Biological Sciences, Middle East Technical University, Ankara 06800, Turkey.
| | - Ebru Özgür
- Micro-Electro-Mechanical Systems, Middle East Technical University, Ankara 06800, Turkey.
| | - Ufuk Gündüz
- Department of Biological Sciences, Middle East Technical University, Ankara 06800, Turkey.
| | - Inci Eroglu
- Department of Chemical Engineering, Middle East Technical University, Ankara 06800, Turkey.
| | - Meral Yücel
- Department of Biological Sciences, Middle East Technical University, Ankara 06800, Turkey.
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21
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Khan NE, Myers JA, Tuerk AL, Curtis WR. A process economic assessment of hydrocarbon biofuels production using chemoautotrophic organisms. Bioresour Technol 2014; 172:201-211. [PMID: 25262429 DOI: 10.1016/j.biortech.2014.08.118] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 08/25/2014] [Accepted: 08/26/2014] [Indexed: 06/03/2023]
Abstract
Economic analysis of an ARPA-e Electrofuels (http://arpa-e.energy.gov/?q=arpa-e-programs/electrofuels) process is presented, utilizing metabolically engineered Rhodobacter capsulatus or Ralstonia eutropha to produce the C30+ hydrocarbon fuel, botryococcene, from hydrogen, carbon dioxide, and oxygen. The analysis is based on an Aspen plus® bioreactor model taking into account experimentally determined Rba. capsulatus and Rls. eutropha growth and maintenance requirements, reactor residence time, correlations for gas-liquid mass-transfer coefficient, gas composition, and specific cellular fuel productivity. Based on reactor simulation results encompassing technically relevant parameter ranges, the capital and operating costs of the process were estimated for 5000 bbl-fuel/day plant and used to predict fuel cost. Under the assumptions used in this analysis and crude oil prices, the Levelized Cost of Electricity (LCOE) required for economic feasibility must be less than 2¢/kWh. While not feasible under current market prices and costs, this work identifies key variables impacting process cost and discusses potential alternative paths toward economic feasibility.
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Affiliation(s)
- Nymul E Khan
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - John A Myers
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Amalie L Tuerk
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Wayne R Curtis
- Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802, USA.
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22
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Borghese R, Baccolini C, Francia F, Sabatino P, Turner RJ, Zannoni D. Reduction of chalcogen oxyanions and generation of nanoprecipitates by the photosynthetic bacterium Rhodobacter capsulatus. J Hazard Mater 2014; 269:24-30. [PMID: 24462199 DOI: 10.1016/j.jhazmat.2013.12.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 11/26/2013] [Accepted: 12/04/2013] [Indexed: 06/03/2023]
Abstract
The facultative photosynthetic bacterium Rhodobacter capsulatus is characterized in its interaction with the toxic oxyanions tellurite (Te(IV)) and selenite (Se(IV)) by a highly variable level of resistance that is dependent on the growth mode making this bacterium an ideal organism for the study of the microbial interaction with chalcogens. As we have reported in the past, while the oxyanion tellurite is taken up by R. capsulatus cells via acetate permease and it is reduced to Te(0) in the cytoplasm in the form of splinter-like black intracellular deposits no clear mechanism was described for Se(0) precipitation. Here, we present the first report on the biotransformation of tellurium and selenium oxyanions into extracellular Te(0) and Se(0)nanoprecipitates (NPs) by anaerobic photosynthetically growing cultures of R. capsulatus as a function of exogenously added redox-mediator lawsone, i.e. 2-hydroxy-1,4-naphthoquinone. The NPs formation was dependent on the carbon source used for the bacterial growth and the rate of chalcogen reduction was constant at different lawsone concentrations, in line with a catalytic role for the redox mediator. X-ray diffraction (XRD) analysis demonstrated the Te(0) and Se(0) nature of the nanoparticles.
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Affiliation(s)
- Roberto Borghese
- Department of Pharmacy and Biotechnology, University of Bologna, Italy.
| | - Chiara Baccolini
- Department of Pharmacy and Biotechnology, University of Bologna, Italy
| | - Francesco Francia
- Department of Pharmacy and Biotechnology, University of Bologna, Italy
| | - Piera Sabatino
- Department of Chemistry G. Ciamician, University of Bologna, Italy
| | - Raymond J Turner
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Davide Zannoni
- Department of Pharmacy and Biotechnology, University of Bologna, Italy.
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Sznee K, Crouch LI, Jones MR, Dekker JP, Frese RN. Variation in supramolecular organisation of the photosynthetic membrane of Rhodobacter sphaeroides induced by alteration of PufX. Photosynth Res 2014; 119:243-256. [PMID: 24197265 DOI: 10.1007/s11120-013-9949-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 10/24/2013] [Indexed: 06/02/2023]
Abstract
In purple bacteria of the genus Rhodobacter (Rba.), an LH1 antenna complex surrounds the photochemical reaction centre (RC) with a PufX protein preventing the LH1 complex from completely encircling the RC. In membranes of Rba. sphaeroides, RC-LH1 complexes associate as dimers which in turn assemble into longer range ordered arrays. The present work uses linear dichroism (LD) and dark-minus-light difference LD (ΔLD) to probe the organisation of genetically altered RC-LH1 complexes in intact membranes. The data support previous proposals that Rba. capsulatus, and Rba. sphaeroides heterologously expressing the PufX protein from Rba. capsulatus, produce monomeric core complexes in membranes that lack long-range order. Similarly, Rba. sphaeroides with a point mutation in the Gly 51 residue of PufX, which is located on the membrane-periplasm interface, assembles mainly non-ordered RC-LH1 complexes that are most likely monomeric. All the Rba. sphaeroides membranes in their ΔLD spectra exhibited a spectral fingerprint of small degree of organisation implying the possibility of ordering influence of LH1, and leading to an important conclusion that PufX itself has no influence on ordering RC-LH1 complexes, as long-range order appears to be induced only through its role of configuring RC-LH1 complexes into dimers.
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Affiliation(s)
- Kinga Sznee
- Division of Physics and Astronomy, Faculty of Sciences, VU University Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands,
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Lin HZ, Yue YH, Lü JC, Zhao GC, Yang PS. Variation in composition and relative content of accumulated photopigments in a newly isolated Rhodobacter capsulatus strain XJ-1 in response to arsenic. J Environ Sci Health A Tox Hazard Subst Environ Eng 2014; 49:1493-1500. [PMID: 25137537 DOI: 10.1080/10934529.2014.937168] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This study aimed to isolate and characterize a new arsenic (As)-tolerant bacterial strain (XJ-1) from the Halosol soil, to evaluate its As tolerance, and to examine the variation in composition and relative content of accumulated photosynthetic pigments in response to As. The experiments were performed with high-performance liquid chromatography (HPLC), inductively-coupled plasma mass spectrometry (ICP-MS), liquid chromatography/mass spectrometry (LC/MS), thin-layer chromatography (TLC) and grayscale intensity image analysis using Gel-Pro analyzer software. Strain XJ-1 was identified as Rhodobacter (R.) capsulatus based on 16S rRNA gene sequencing and physiological characteristics. Strain XJ-1 was able to grow when exposed to arsenite [As(III)] and arsenate [As(V)] under anaerobic-light conditions. The median effective concentrations (EC50) of As(III) and As(V) were 0.61 mM and 2.03 mM, respectively. Strain XJ-1 could reduce As(V) to As(III), but As(III) could not be transformed back to As(V) or other organic As compounds. Accumulation of bacteriochlorophylls and carotenoids in strain XJ-1 varied in the presence of 0.2-1.2 mM As(III) and 0-2.5 mM As(V). As exposure resulted in pronounced variation in compositions and contents of photosynthetic pigments, especially hydroxyspheroidene, bacteriophaeophytin, the ratio of tetrahydrogeranylgeranyl to phytylated BChl a, and the ratio of spheroidene to spheroidenone. This research highlights the adaptative response of R. capsulatus strain XJ-1 photosystems to environmental As, and demonstrates the potential of utilizing the sensitivity of its photosynthetic pigments to As(III) and As(V) for the biodetection of As in the environment.
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Affiliation(s)
- Hua Z Lin
- a College of Life Science , Shanxi University , Taiyuan , China
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25
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Collins HF, Biedendieck R, Leech HK, Gray M, Escalante-Semerena JC, McLean KJ, Munro AW, Rigby SEJ, Warren MJ, Lawrence AD. Bacillus megaterium has both a functional BluB protein required for DMB synthesis and a related flavoprotein that forms a stable radical species. PLoS One 2013; 8:e55708. [PMID: 23457476 PMCID: PMC3573010 DOI: 10.1371/journal.pone.0055708] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Accepted: 12/29/2012] [Indexed: 01/05/2023] Open
Abstract
Despite the extensive study of the biosynthesis of the complex molecule B12 (cobalamin), the mechanism by which the lower ligand 5,6-dimethylbenzimidazole (DMB) is formed has remained something of a mystery. However, recent work has identified and characterized a DMB-synthase (BluB) responsible for the oxygen-dependent, single enzyme conversion of FMN to DMB. In this work, we have identified BluB homologs from the aerobic purple, nonsulfur, photosynthetic bacterium Rhodobacter capsulatus and the aerobic soil bacterium Bacillus megaterium and have demonstrated DMB synthesis by the use of a novel complementation assay in which a B12 deficient strain, substituted with the precursor cobinamide is recovered either by the addition of DMB or by the recombinant expression of a bluB gene. The DMB-synthetic activity of the purified recombinant BluB enzymes was further confirmed in vitro by providing the enzyme with FMNH2 and oxygen and observing the formation of DMB by HPLC. The formation of a 4a-peroxyflavin intermediate, the first step in the oxygen dependent mechanism of DMB biosynthesis, is reported here and is the first intermediate in the enzyme catalysed reaction to be demonstrated experimentally to date. The identification and characterization of an FMN-binding protein found on the cobI operon of B. megaterium, CbiY, is also detailed, revealing an FMN-containing enzyme which is able to stabilize a blue flavin semiquinone upon reduction with a 1-electron donor.
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Affiliation(s)
- Hannah F. Collins
- School of Biosciences, University of Kent, Canterbury, Kent, United Kingdom
| | - Rebekka Biedendieck
- Institute of Microbiology, Technical University Braunschweig, Braunschweig, Germany
| | - Helen K. Leech
- School of Biosciences, University of Kent, Canterbury, Kent, United Kingdom
| | - Michael Gray
- Department of Bacteriology, University of Wisconsin, Madison, Wisconsin, United States of America
| | | | - Kirsty J. McLean
- Manchester Interdisciplinary Biocentre, University of Manchester, Manchester, United Kingdom
| | - Andrew W. Munro
- Manchester Interdisciplinary Biocentre, University of Manchester, Manchester, United Kingdom
| | - Stephen E. J. Rigby
- Manchester Interdisciplinary Biocentre, University of Manchester, Manchester, United Kingdom
| | - Martin J. Warren
- School of Biosciences, University of Kent, Canterbury, Kent, United Kingdom
| | - Andrew D. Lawrence
- School of Biosciences, University of Kent, Canterbury, Kent, United Kingdom
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26
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Ghosh D, Sobro IF, Hallenbeck PC. Optimization of the hydrogen yield from single-stage photofermentation of glucose by Rhodobacter capsulatus JP91 using response surface methodology. Bioresour Technol 2012; 123:199-206. [PMID: 22940320 DOI: 10.1016/j.biortech.2012.07.061] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 07/15/2012] [Accepted: 07/17/2012] [Indexed: 05/08/2023]
Abstract
Hydrogen production from glucose via single-stage photofermentation was examined with the photosynthetic bacterium Rhodobacter capsulatus JP91 (hup-). Response surface methodology with Box-Behnken design was used to optimize the independent experimental variables of glucose concentration, glutamate concentration and light intensity, as well as examining their interactive effects for maximization of molar hydrogen yield. Under optimal condition with a light intensity of 175W/m(2), 35mM glucose, and 4.5mM glutamate, a maximum hydrogen yield of 5.5 (±0.15)molH(2)/molglucose, and a maximum nitrogenase activity of 246 (±3.5)nmolC(2)H(4)/ml/min were obtained. Densitometric analysis of nitrogenase Fe-protein expression under different conditions showed significant variation in Fe-protein expression with a maximum at the optimized central point. Even under optimum conditions for hydrogen production, a significant fraction of the Fe-protein was found in the ADP-ribosylated state, suggesting that further improvement in yields might be possible.
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Affiliation(s)
- Dipankar Ghosh
- Département de Microbiologie et Immunologie, Université de Montréal, CP 6128 Succursale Centre-ville, Montréal, Québec, Canada H3C 3J7
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Fogg PCM, Westbye AB, Beatty JT. One for all or all for one: heterogeneous expression and host cell lysis are key to gene transfer agent activity in Rhodobacter capsulatus. PLoS One 2012; 7:e43772. [PMID: 22916305 PMCID: PMC3423380 DOI: 10.1371/journal.pone.0043772] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 07/25/2012] [Indexed: 11/19/2022] Open
Abstract
The gene transfer agent (RcGTA) of Rhodobacter capsulatus is the model for a family of novel bacteriophage-related genetic elements that carry out lateral transfer of essentially random host DNA. Genuine and putative gene transfer agents have been discovered in diverse genera and are becoming recognized as potentially an important source of genetic exchange and microbial evolution in the oceans. Despite being discovered over 30 years ago, little is known about many essential aspects of RcGTA biology. Here, we validate the use of direct fluorescence reporter constructs, which express the red fluorescent protein mCherry in R. capsulatus. A construct containing the RcGTA promoter fused to mCherry was used to examine the single-cell expression profiles of wild type and RcGTA overproducer R. capsulatus populations, under different growth conditions and growth phases. The majority of RcGTA production clearly arises from a small, distinct sub-set of the population in the wild type strain and a larger sub-set in the overproducer. The most likely RcGTA release mechanism concomitant with this expression pattern is host cell lysis and we present direct evidence for the release of an intracellular enzyme accompanying RcGTA release. RcGTA ORF s is annotated as a ‘cell wall peptidase’ but we rule out a role in host lysis and propose an alternative function as a key contributor to RcGTA invasion of a target cell during infection.
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Affiliation(s)
- Paul C. M. Fogg
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Alexander B. Westbye
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - J. Thomas Beatty
- Department of Microbiology & Immunology, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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Ma C, Wang X, Guo L, Wu X, Yang H. Enhanced photo-fermentative hydrogen production by Rhodobacter capsulatus with pigment content manipulation. Bioresour Technol 2012; 118:490-5. [PMID: 22717568 DOI: 10.1016/j.biortech.2012.04.105] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 04/13/2012] [Accepted: 04/19/2012] [Indexed: 05/08/2023]
Abstract
High content of pigment in purple nonsulfur photosynthetic bacteria hinders its photo-hydrogen production rate under intense light irradiation. In order to alleviate the light shielding effect and improve its photo-fermentative hydrogen production performance, pufQ, which is the regulatory gene of bacteriochlorophyll biosynthesis in Rhodobacter capsulatus, was cloned and relocated in the genome under cbb3 promoter by homologous recombination. The UV-vis spectra indicated that the light absorption of the mutant between 300 and 900 nm was reduced. Photo-hydrogen production experiments by the recombinant and wild type strain were carried out in 350 mL photo bioreactors using acetic and butyric acid as substrate. The results showed that the hydrogen production of recombinant with reduced pigment was 27% higher than that of its parental strain, indicating that it is effective on enhancing photo-fermentative hydrogen production by manipulating pigment biosynthesis in purple nonsulfur photosynthetic bacteria.
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Affiliation(s)
- Chao Ma
- International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, PR China
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29
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Rademacher C, Hoffmann MC, Lackmann JW, Moser R, Pfänder Y, Leimkühler S, Narberhaus F, Masepohl B. Tellurite resistance gene trgB confers copper tolerance to Rhodobacter capsulatus. Biometals 2012; 25:995-1008. [PMID: 22767205 DOI: 10.1007/s10534-012-9566-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 06/15/2012] [Indexed: 11/25/2022]
Abstract
To identify copper homeostasis genes in Rhodobacter capsulatus, we performed random transposon Tn5 mutagenesis. Screening of more than 10,000 Tn5 mutants identified tellurite resistance gene trgB as a so far unrecognized major copper tolerance determinant. The trgB gene is flanked by tellurite resistance gene trgA and cysteine synthase gene cysK2. While growth of trgA mutants was only moderately restricted by tellurite, trgB and cysK2 mutants were severely affected by tellurite, which implies that viability under tellurite stress requires increased cysteine levels. Mutational analyses revealed that trgB was the only gene in this chromosomal region conferring cross-tolerance towards copper. Expression of the monocistronic trgB gene required promoter elements overlapping the trgA coding region as shown by nested deletions. Neither copper nor tellurite affected trgB transcription as demonstrated by reverse transcriptase PCR and trgB-lacZ fusions. Addition of tellurite or copper gave rise to increased cellular tellurium and copper concentrations, respectively, as determined by inductively coupled plasma-optical emission spectroscopy. By contrast, cellular iron concentrations remained fairly constant irrespective of tellurite or copper addition. This is the first study demonstrating a direct link between copper and tellurite response in bacteria.
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Affiliation(s)
- Corinna Rademacher
- Biologie der Mikroorganismen, Fakultät für Biologie und Biotechnologie, Ruhr-Universität Bochum, 44780, Bochum, Germany
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Abstract
This study investigates the role iron oxidation plays in the purple non-sulfur bacterium Rhodobacter capsulatus SB1003. This organism is unable to grow photoautotrophically on unchelated ferrous iron [Fe(II)] despite its ability to oxidize chelated Fe(II). This apparent paradox was partly resolved by the discovery that SB1003 can grow photoheterotrophically on the photochemical breakdown products of certain ferric iron-ligand complexes, yet whether it could concomitantly benefit from the oxidation of Fe(II) to fix CO(2) was unknown. Here, we examine carbon fixation by stable isotope labeling of the inorganic carbon pool in cultures growing phototrophically on acetate with and without Fe(II). We show that R. capsulatus SB1003, an organism formally thought incapable of phototrophic growth on Fe(II), can actually harness the reducing power of this substrate and grow photomixotrophically, deriving carbon both from organic sources and from fixation of inorganic carbon. This suggests the possibility of a wider occurrence of photoferrotrophy than previously assumed.
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Affiliation(s)
| | - Dianne K. Newman
- Division of Geological and Planetary Sciences, Pasadena, CA 91125
- Division of Biological Sciences, California Institute of Technology, Pasadena, CA 91125
- Howard Hughes Medical Institute, Pasadena, CA 91125
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Leung MM, Brimacombe CA, Spiegelman GB, Beatty JT. The GtaR protein negatively regulates transcription of the gtaRI operon and modulates gene transfer agent (RcGTA) expression in Rhodobacter capsulatus. Mol Microbiol 2012; 83:759-74. [PMID: 22211723 PMCID: PMC3641048 DOI: 10.1111/j.1365-2958.2011.07963.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The gtaI gene of Rhodobacter capsulatus encodes an N-acyl-homoserine lactone (acyl-HSL) synthase. Immediately 5' of the gtaI gene is ORF rcc00328 that encodes a potential acyl-HSL receptor protein. A combination of genetic and biochemical approaches showed that rcc00328 (renamed gtaR) modulates the production of a genetic exchange element called the gene transfer agent (RcGTA), and regulates the transcription of gtaI. Although gtaI mutants exhibited decreased levels of RcGTA production, mutagenesis of gtaR did not, whereas a gtaR/gtaI double mutant produced wild-type levels of RcGTA. Because mutagenesis of gtaR suppressed the effect of the gtaI mutation, we suggest that the GtaR protein is a negative transcriptional regulator of RcGTA gene expression. We discovered that the gtaR and gtaI genes are co-transcribed, and also negatively regulated by the GtaR protein in the absence of acyl-HSL. A His-tagged GtaR protein was purified, and DNA-binding experiments revealed a binding site in the promoter region of the gtaRI operon. This GtaR protein did not bind to the RcGTA promoter region, and therefore modulation of RcGTA production appears to require at least one additional factor. We found that RcGTA production was stimulated by spent media from other species, and identified exogenous acyl-HSLs that induce RcGTA.
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Affiliation(s)
| | | | - G. B. Spiegelman
- Department of Microbiology and Immunology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - J. Thomas Beatty
- Department of Microbiology and Immunology, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
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Müller AH, Gough SP, Bollivar DW, Meldal M, Willows RD, Hansson M. Methods for the preparation of chlorophyllide a: an intermediate of the chlorophyll biosynthetic pathway. Anal Biochem 2011; 419:271-6. [PMID: 21925479 DOI: 10.1016/j.ab.2011.08.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 07/29/2011] [Accepted: 08/15/2011] [Indexed: 11/18/2022]
Abstract
Chlorophyllide a is a metabolite late in the biosynthesis of chlorophylls and bacteriochlorophylls. Isolation procedures for chlorophyllide a from Rhodobacter capsulatus CB1200 and barley (Hordeum vulgare L.) are described and compared. R. capsulatus CB1200 is a double mutant in the bacteriochlorophyllide a biosynthetic pathway, and chlorophyllide a is excreted by the cells when grown in Tween 80-containing liquid medium. It was purified by liquid or solid phase extraction, yielding 7 mg of chlorophyllide a from 1 L of culture. In a second approach, intrinsic chlorophyllase activity was used to dephytylate chlorophyll in an acetonic preparation of leaves of wild-type or chlorophyll b-deficient barley. Purification was achieved by liquid phase extraction, yielding 14 μg of chlorophyllide a per gram of barley leaves. Chlorophyllide a was identified by thin layer chromatography, absorption spectroscopy, and mass spectrometry.
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Golomysova AN, Ivanov PS. [Investigation of the anaerobic metabolism of Rhodobacter capsulatus with a flux model]. Biofizika 2011; 56:85-98. [PMID: 21442889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A flux model of the anaerobic metabolism of Rhodobacter capsulatus related to hydrogen production has been constructed. The performance of this model has been assessed by comparing the computed metabolic fluxes with experimental values obtained by several research groups who worked on various strains of R. capsulatus and utilized different growth setups. We have investigated the photoheterotrophic metabolism of R. capsulatus on acetate and have shown that in this mode the bacterium can produce hydrogen or biopolymers. Analysis of the flux model reveled several mutants that can evolve hydrogen with a higher rate than the wild type.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Yang H, Guo L, Liu F. Enhanced bio-hydrogen production from corncob by a two-step process: dark- and photo-fermentation. Bioresour Technol 2010; 101:2049-2052. [PMID: 19963373 DOI: 10.1016/j.biortech.2009.10.078] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 10/25/2009] [Accepted: 10/27/2009] [Indexed: 05/28/2023]
Abstract
Enhanced bio-hydrogen production from pretreated corncob by integrating dark-fermentation with photo-fermentation process was investigated in this study. In the first step, the maximum bio-hydrogen yield and rate from corncob by dark-fermentation was 120.3+/-5.2 mL H(2)/g-corncob and 150 mL H(2)/(Lh), respectively. In the second step, a hydrogen yield of 713.6+/-44.1 mL H(2)/g-COD was obtained from digesting the effluent of dark-fermentation by photosynthetic bacteria. Meanwhile, COD removal efficiency achieved 90%. Bio-hydrogen production in the first step was mainly attributed to the bioconversion of the reducing sugars and oligosaccharides in the hydrolyzate of corncob. Bio-hydrogen production in the second step was due to the biodegradation of acetic acid, butyric acid, butyl alcohol and ethanol in the effluent of dark-fermentation.
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Affiliation(s)
- Honghui Yang
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, PR China
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36
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Abstract
The purple anoxygenic photosynthetic bacterium Rhodobacter capsulatus is capable of growing in aerobic or anaerobic conditions, in the dark or using light, etc. Achieving versatile metabolic adaptations from respiration to photosynthesis requires the use of tetrapyrroles such as heme and bacteriochlorophyll, in order to carry oxygen, to transfer electrons, and to harvest light energy. A third tetrapyrrole, cobalamin (vitamin B(12)), is synthesized and used as a cofactor for many enzymes. Heme, bacteriochlorophyll, and vitamin B(12) constitute three major end products of the tetrapyrrole biosynthetic pathway in purple bacteria. Their respective synthesis involves a plethora of enzymes, several that have been characterized and several that are uncharacterized, as described in this review. To respond to changes in metabolic requirements, the pathway undergoes complex regulation to direct the flow of tetrapyrrole intermediates into a specific branch(s) at the expense of other branches of the pathway. Transcriptional regulation of the tetrapyrrole synthesizing enzymes by redox conditions and pathway intermediates is reviewed. In addition, we discuss the involvement of several transcription factors (RegA, CrtJ, FnrL, AerR, HbrL, Irr) as well as the role of riboswitches. Finally, the interdependence of the tetrapyrrole branches on each other synthesis is discussed.
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Affiliation(s)
- Sébastien Zappa
- Biology Department, Indiana University, Bloomington, IN 47405, USA.
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Poulain AJ, Newman DK. Rhodobacter capsulatus catalyzes light-dependent Fe(II) oxidation under anaerobic conditions as a potential detoxification mechanism. Appl Environ Microbiol 2009; 75:6639-46. [PMID: 19717624 PMCID: PMC2772431 DOI: 10.1128/aem.00054-09] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Accepted: 08/22/2009] [Indexed: 11/20/2022] Open
Abstract
Diverse bacteria are known to oxidize millimolar concentrations of ferrous iron [Fe(II)] under anaerobic conditions, both phototrophically and chemotrophically. Yet whether they can do this under conditions that are relevant to natural systems is understood less well. In this study, we tested how light, Fe(II) speciation, pH, and salinity affected the rate of Fe(II) oxidation by Rhodobacter capsulatus SB1003. Although R. capsulatus cannot grow photoautotrophically on Fe(II), it oxidizes Fe(II) at rates comparable to those of bacteria that do grow photoautotrophically on Fe(II) as soon as it is exposed to light, provided it has a functional photosystem. Chelation of Fe(II) by diverse organic ligands promotes Fe(II) oxidation, and as the pH increases, so does the oxidation rate, except in the presence of nitrilotriacetate; nonchelated forms of Fe(II) are also more rapidly oxidized at higher pH. Salt concentrations typical of marine environments inhibit Fe(II) oxidation. When growing photoheterotrophically on humic substances, R. capsulatus is highly sensitive to low concentrations of Fe(II); it is inhibited in the presence of concentrations as low as 5 microM. The product of Fe(II) oxidation, ferric iron, does not hamper growth under these conditions. When other parameters, such as pH or the presence of chelators, are adjusted to promote Fe(II) oxidation, the growth inhibition effect of Fe(II) is alleviated. Together, these results suggest that Fe(II) is toxic to R. capsulatus growing under strictly anaerobic conditions and that Fe(II) oxidation alleviates this toxicity.
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Affiliation(s)
- Alexandre J. Poulain
- Biaology Department, Massachusetts Institute of Technology, 68-380, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, Earth, Atmospheric and Planetary Sciences Department, Massachusetts Institute of Technology, 68-380, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, Howard Hughes Medical Institute, 68-380, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139
| | - Dianne K. Newman
- Biaology Department, Massachusetts Institute of Technology, 68-380, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, Earth, Atmospheric and Planetary Sciences Department, Massachusetts Institute of Technology, 68-380, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, Howard Hughes Medical Institute, 68-380, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139
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38
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Sanders C, Turkarslan S, Lee DW, Onder O, Kranz RG, Daldal F. The cytochrome c maturation components CcmF, CcmH, and CcmI form a membrane-integral multisubunit heme ligation complex. J Biol Chem 2008; 283:29715-22. [PMID: 18753134 PMCID: PMC2573057 DOI: 10.1074/jbc.m805413200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Revised: 08/27/2008] [Indexed: 11/06/2022] Open
Abstract
Cytochrome c maturation (Ccm) is a post-translational and post-export protein modification process that involves ten (CcmABCDEFGHI and CcdA or DsbD) components in most Gram-negative bacteria. The absence of any of these components abolishes the ability of cells to form cytochrome c, leading in the case of Rhodobacter capsulatus to the loss of photosynthetic proficiency and respiratory cytochrome oxidase activity. Based on earlier molecular genetic studies, we inferred that R. capsulatus CcmF, CcmH, and CcmI interact with each other to perform heme-apocytochrome c ligation. Here, using functional epitope-tagged derivatives of these components coproduced in appropriate mutant strains, we determined protein-protein interactions between them in detergent-dispersed membranes. Reciprocal affinity purification as well as tandem size exclusion and affinity chromatography analyses provided the first biochemical evidence that CcmF, CcmH, and CcmI associate stably with each other, indicating that these Ccm components form a membrane-integral complex. Under the conditions used, the CcmFHI complex does not contain CcmG, suggesting that the latter thio-reduction component is not always associated with the heme ligation components. The findings are discussed with respect to defining the obligatory components of a minimalistic heme-apocytochrome c ligation complex in R. capsulatus.
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Affiliation(s)
- Carsten Sanders
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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39
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Oztürk Y, Lee DW, Mandaci S, Osyczka A, Prince RC, Daldal F. Soluble variants of Rhodobacter capsulatus membrane-anchored cytochrome cy are efficient photosynthetic electron carriers. J Biol Chem 2008; 283:13964-72. [PMID: 18343817 PMCID: PMC2376234 DOI: 10.1074/jbc.m800090200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 03/11/2008] [Indexed: 11/06/2022] Open
Abstract
Photosynthetic (Ps) electron transport pathways often contain multiple electron carriers with overlapping functions. Here we focus on two c-type cytochromes (cyt) in facultative phototrophic bacteria of the Rhodobacter genus: the diffusible cyt c2 and the membrane-anchored cyt c(y). In species like R. capsulatus, cyt c(y) functions in both Ps and respiratory electron transport chains, whereas in other species like R. sphaeroides, it does so only in respiration. The molecular bases of this difference was investigated by producing a soluble variant of cyt c(y) (S-c(y)), by fusing genetically the cyt c2 signal sequence to the cyt c domain of cyt c(y). This novel electron carrier was unable to support the Ps growth of R. capsulatus. However, strains harboring cyt S-c(y) regained Ps growth ability by acquiring mutations in its cyt c domain. They produced cyt S-c(y) variants at amounts comparable with that of cyt c2, and conferred Ps growth. Chemical titration indicated that the redox midpoint potential of cyt S-c(y) was about 340 mV, similar to that of cyts c2 or c(y). Remarkably, electron transfer kinetics from the cyt bc1 complex to the photochemical reaction center (RC) mediated by cyt S-c(y) was distinct from those seen with the cyt c2 or cyt c(y). The kinetics exhibited a pronounced slow phase, suggesting that cyt S-c(y) interacted with the RC less tightly than cyt c2. Comparison of structural models of cyts c2 and S-c(y) revealed that several of the amino acid residues implicated in long-range electrostatic interactions promoting binding of cyt c2 to the RC are not conserved in cyt c(y), whereas those supporting short-range hydrophobic interactions are conserved. These findings indicated that attaching electron carrier cytochromes to the membrane allowed them to weaken their interactions with their partners so that they could accommodate more rapid multiple turnovers.
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40
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Sirijovski N, Lundqvist J, Rosenbäck M, Elmlund H, Al-Karadaghi S, Willows RD, Hansson M. Substrate-binding Model of the Chlorophyll Biosynthetic Magnesium Chelatase BchH Subunit. J Biol Chem 2008; 283:11652-60. [PMID: 18263581 DOI: 10.1074/jbc.m709172200] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Nickolche Sirijovski
- Department of Biochemistry, Center for Molecular Protein Science, Lund University, SE-22100 Lund, Sweden
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41
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Gough SP, Rzeznicka K, Peterson Wulff R, Francisco JDC, Hansson A, Jensen PE, Hansson M. A new method for isolating physiologically active Mg-protoporphyrin monomethyl ester, the substrate of the cyclase enzyme of the chlorophyll biosynthetic pathway. Plant Physiol Biochem 2007; 45:932-936. [PMID: 17949988 DOI: 10.1016/j.plaphy.2007.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Indexed: 05/25/2023]
Abstract
Mg-protoporphyrin monomethyl ester (MPE) is a biosynthetic intermediate of chlorophyll and converted by MPE cyclase to protochlorophyllide. Limited availability of MPE has so far hampered cyclase research. In a new, simplified, method MPE was prepared from freeze dried bchE mutant Rhodobacter capsulatus DB575 cells by extraction with acetone/H(2)O/25% NH(3). Isolated MPE was identified by absorption and fluorescence spectroscopy, and its purity was analyzed by HPLC. The extracted MPE was dried and redissolved in buffered DMSO and its substrate activity is shown by enzymatic cyclase assays. A linear time course was observed for MPE conversion to protochlorophyllide by enzymes from barley etioplasts. Our innovation of freeze drying the R. capsulatus cells before extraction provides a high yield method for MPE, which is significantly faster and more reproducible than previous extraction methods.
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Affiliation(s)
- Simon P Gough
- Department of Biochemistry, Lund University, Lund, Sweden
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42
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Willett J, Smart JL, Bauer CE. RegA control of bacteriochlorophyll and carotenoid synthesis in Rhodobacter capsulatus. J Bacteriol 2007; 189:7765-73. [PMID: 17616588 PMCID: PMC2168725 DOI: 10.1128/jb.00853-07] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Accepted: 06/29/2007] [Indexed: 11/20/2022] Open
Abstract
We provide in vivo genetic and in vitro biochemical evidence that RegA directly regulates bacteriochlorophyll and carotenoid biosynthesis in Rhodobacter capsulatus. beta-Galactosidase expression assays with a RegA-disrupted strain containing reporter plasmids for Mg-protoporphyrin IX monomethyl ester oxidative cyclase (bchE), Mg-protoporphyrin IX chelatase (bchD), and phytoene dehydrogenase (crtI) demonstrate RegA is responsible for fourfold anaerobic induction of bchE, threefold induction of bchD, and twofold induction of crtI. Promoter mapping studies, coupled with DNase I protection assays, map the region of RegA binding to three sites in the bchE promoter region. Similar studies at the crtA and crtI promoters indicate that RegA binds to a single region equidistant from these divergent promoters. These results demonstrate that RegA is directly responsible for anaerobic induction of bacteriochlorophyll biosynthesis genes bchE, bchD, bchJ, bchI, bchG, and bchP and carotenoid biosynthesis genes crtI, crtB, and crtA.
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Abstract
Many Gram-negative bacteria have two cytoplasmic thioredoxins, thioredoxin-1 and -2, encoded by the trxA and trxC genes, respectively. Both thioredoxins have the highly conserved WCGPC motif and function as disulfide-bond reductases. However, thioredoxin-2 has unique features: it has an N-terminal motif that binds a zinc ion, and its transcription is under the control of OxyR, which allows it to be up-regulated under oxidative stress. Here, we report the crystal structure of thioredoxin-2 from Rhodobacter capsulatus. The C-terminal region of thioredoxin-2 forms a canonical thioredoxin fold with a central beta-sheet consisting of five strands and four flanking alpha-helices on either side. The N-terminal zinc finger is composed of four short beta-strands (S1-S4) connected by three short loops (L1-L3). The four cysteines are at loops L1 and L3 and form a tetragonal binding site for a zinc ion. The zinc finger is close to the first beta-strand and first alpha-helix of the thioredoxin fold. Nevertheless, the zinc finger may not directly affect the oxidoreductase activity of thioredoxin-2 because the zinc finger is not near the active site of a protomer and because thioredoxin-2 is a monomer in solution. On the basis of structural similarity to the zinc fingers in Npl4 and Vps36, we propose that the N-terminal zinc finger of thioredoxin-2 mediates protein-protein interactions, possibly with its substrates or chaperones.
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Affiliation(s)
- Jiqing Ye
- Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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Caiazza NC, Lies DP, Newman DK. Phototrophic Fe(II) oxidation promotes organic carbon acquisition by Rhodobacter capsulatus SB1003. Appl Environ Microbiol 2007; 73:6150-8. [PMID: 17693559 PMCID: PMC2074999 DOI: 10.1128/aem.02830-06] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Accepted: 08/01/2007] [Indexed: 11/20/2022] Open
Abstract
Anoxygenic phototrophic Fe(II) oxidation is usually considered to be a lithoautotrophic metabolism that contributes to primary production in Fe-based ecosystems. In this study, we employed Rhodobacter capsulatus SB1003 as a model organism to test the hypothesis that phototrophic Fe(II) oxidation can be coupled to organic carbon acquisition. R. capsulatus SB1003 oxidized Fe(II) under anoxic conditions in a light-dependent manner, but it failed to grow lithoautotrophically on soluble Fe(II). When the strain was provided with Fe(II)-citrate, however, growth was observed that was dependent upon microbially catalyzed Fe(II) oxidation, resulting in the formation of Fe(III)-citrate. Subsequent photochemical breakdown of Fe(III)-citrate yielded acetoacetic acid that supported growth in the light but not the dark. The deletion of genes (RRC00247 and RRC00248) that encode homologs of atoA and atoD, required for acetoacetic acid utilization, severely impaired the ability of R. capsulatus SB1003 to grow on Fe(II)-citrate. The growth yield achieved by R. capsulatus SB1003 in the presence of citrate cannot be explained by lithoautotrophic growth on Fe(II) enabled by indirect effects of the ligand [such as altering the thermodynamics of Fe(II) oxidation or preventing cell encrustation]. Together, these results demonstrate that R. capsulatus SB1003 grows photoheterotrophically on Fe(II)-citrate. Nitrilotriacetic acid also supported light-dependent growth on Fe(II), suggesting that Fe(II) oxidation may be a general mechanism whereby some Fe(II)-oxidizing bacteria mine otherwise inaccessible organic carbon sources.
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Affiliation(s)
- Nicky C Caiazza
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA
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45
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Leduc D, Escartin F, Nijhout HF, Reed MC, Liebl U, Skouloubris S, Myllykallio H. Flavin-dependent thymidylate synthase ThyX activity: implications for the folate cycle in bacteria. J Bacteriol 2007; 189:8537-45. [PMID: 17890305 PMCID: PMC2168944 DOI: 10.1128/jb.01380-07] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although flavin-dependent ThyX proteins show thymidylate synthase activity in vitro and functionally complement thyA defects in heterologous systems, direct proof of their cellular functions is missing. Using insertional mutagenesis of Rhodobacter capsulatus thyX, we constructed the first defined thyX inactivation mutant. Phenotypic analyses of the obtained mutant strain confirmed that R. capsulatus ThyX is required for de novo thymidylate synthesis. Full complementation of the R. capsulatus thyX::spec strain to thymidine prototrophy required not only the canonical thymidylate synthase ThyA but also the dihydrofolate reductase FolA. Strikingly, we also found that addition of exogenous methylenetetrahydrofolate transiently inhibited the growth of the different Rhodobacter strains used in this work. To rationalize these experimental results, we used a mathematical model of bacterial folate metabolism. This model suggests that a very low dihydrofolate reductase activity is enough to rescue significant thymidylate synthesis in the presence of ThyX proteins and is in agreement with the notion that intracellular accumulation of folates results in growth inhibition. In addition, our observations suggest that the presence of flavin-dependent thymidylate synthase X provides growth benefits under conditions in which the level of reduced folate derivatives is compromised.
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Affiliation(s)
- Damien Leduc
- INSERM Avenir group, Institut de Génétique et de Microbiologie, CNRS UMR8621, F-91405 Orsay, France
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Borghese R, Marchetti D, Zannoni D. The highly toxic oxyanion tellurite (TeO (3) (2-) ) enters the phototrophic bacterium Rhodobacter capsulatus via an as yet uncharacterized monocarboxylate transport system. Arch Microbiol 2007; 189:93-100. [PMID: 17713758 DOI: 10.1007/s00203-007-0297-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Revised: 06/21/2007] [Accepted: 07/26/2007] [Indexed: 11/25/2022]
Abstract
The facultative phototroph Rhodobacter capsulatus takes up the highly toxic oxyanion tellurite when grown under both photosynthetic and respiratory growth conditions. Previous works on Escherichia coli and R. capsulatus suggested that tellurite uptake occurred through a phosphate transporter. Here we present evidences indicating that tellurite enters R. capsulatus cells via a monocarboxylate transport system. Indeed, intracellular accumulation of tellurite was inhibited by the addition of monocarboxylates such as pyruvate, lactate and acetate, but not by dicarboxylates like malate or succinate. Acetate was the strongest tellurite uptake antagonist and this effect was concentration dependent, being already evident at 1 microM acetate. Conversely, tellurite at 100 microM was able to restrict the acetate entry into the cells. Both tellurite and acetate uptakes were energy dependent processes, since they were abolished by the protonophore FCCP and by the respiratory electron transport inhibitor KCN. Interestingly, cells grown on acetate, lactate or pyruvate showed a high level resistance to tellurite, whereas cells grown on malate or succinate proved to be very sensitive to the oxyanion. Taking these data together, we propose that: (a) tellurite enters R. capsulatus cells via an as yet uncharacterized monocarboxylate(s) transporter, (b) competition between acetate and tellurite results in a much higher level of tolerance against the oxyanion and (c) the toxic action of tellurite at the cytosolic level is significantly restricted by preventing tellurite uptake.
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Affiliation(s)
- Roberto Borghese
- Department of Biology, University of Bologna, Via Irnerio 42, 40126, Bologna, Italy.
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47
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Feng Y, Yu Y, Wang Y, Lin X. Biosorption and Bioreduction of Trivalent Aurum by Photosynthetic Bacteria Rhodobacter capsulatus. Curr Microbiol 2007; 55:402-8. [PMID: 17713815 DOI: 10.1007/s00284-007-9007-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Accepted: 05/20/2007] [Indexed: 11/25/2022]
Abstract
Biosorption has been shown to be an eco-friendly approach to remove heavy metal ions. In this study, the photosynthetic bacteria Rhodobacter capsulatus was screened and found to have strong ability to adsorb Au(III). The maximum specific uptake of living cells was over 92.43 mg HAuCl(4)/g dry weight of cell in the logarithmic phase. Biosorpion ability would be enhanced by an acidic environment. As the main cations, during biosorption the quantity of Mg(2+) exchanged was more than Na(+). Biosorbed Au(III) could be reduced by carotenoid and enzymes embedded and/or excreted by R. capsulatus, which might be the mechanism of photosynthtic bacteria metal tolerance.
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Affiliation(s)
- Youzhi Feng
- Laboratory of Biochemistry, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu, 210008, China
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Gregor J, Zeller T, Balzer A, Haberzettl K, Klug G. Bacterial Regulatory Networks Include Direct Contact of Response Regulator Proteins: Interaction of RegA and NtrX in Rhodobacter capsulatus. J Mol Microbiol Biotechnol 2007; 13:126-39. [PMID: 17693720 DOI: 10.1159/000103604] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The formation of photosynthetic complexes in facultatively photosynthetic bacteria is controlled by the oxygen tension in the environment. In Rhodobacter capsulatus the two-component system RegB/RegA plays a major role in the redox control of photosynthesis genes but also controls other redox-dependent systems. The response regulator RegA is phosphorylated under low oxygen tension and activates the puf and puc operons, which encode pigment binding proteins, by binding to their promoter regions. Data from a yeast two-hybrid analysis as well as an in vitroanalysis indicate that RegA interacts with the NtrX protein, the response regulator of the NtrY/NtrX two-component system which is believed to be involved in regulation of nitrogen fixation genes. Our further analysis revealed that NtrX is indeed involved in the regulation of the puf and puc operons. Furthermore, we showed that an altered NtrX protein, which is predicted to adopt the conformation of phosphorylated NtrX protein, binds within the puf promoter region close to the RegA binding sites. We conclude that a direct interaction of two response regulators connects the regulatory systems for redox control and nitrogen control.
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Affiliation(s)
- Jutta Gregor
- Institut für Mikrobiologie und Molekularbiologie, University of Giessen, Giessen, Germany
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Tremblay PL, Drepper T, Masepohl B, Hallenbeck PC. Membrane sequestration of PII proteins and nitrogenase regulation in the photosynthetic bacterium Rhodobacter capsulatus. J Bacteriol 2007; 189:5850-9. [PMID: 17586647 PMCID: PMC1952044 DOI: 10.1128/jb.00680-07] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Both Rhodobacter capsulatus PII homologs GlnB and GlnK were found to be necessary for the proper regulation of nitrogenase activity and modification in response to an ammonium shock. As previously reported for several other bacteria, ammonium addition triggered the AmtB-dependent association of GlnK with the R. capsulatus membrane. Native polyacrylamide gel electrophoresis analysis indicates that the modification/demodification of one PII homolog is aberrant in the absence of the other. In a glnK mutant, more GlnB was found to be membrane associated under these conditions. In a glnB mutant, GlnK fails to be significantly sequestered by AmtB, even though it appears to be fully deuridylylated. Additionally, the ammonium-induced enhanced sequestration by AmtB of the unmodifiable GlnK variant GlnK-Y51F follows the wild-type GlnK pattern with a high level in the cytoplasm without the addition of ammonium and an increased level in the membrane fraction after ammonium treatment. These results suggest that factors other than PII modification are driving its association with AmtB in the membrane in R. capsulatus.
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Affiliation(s)
- Pier-Luc Tremblay
- Département de Microbiologie et Immunologie, Université de Montréal, CP 6128, Succursale Centre-ville, Montréal, Québec, Canada
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Devanathan S, Salamon Z, Tollin G, Fitch JC, Meyer TE, Berry EA, Cusanovich MA. Plasmon waveguide resonance spectroscopic evidence for differential binding of oxidized and reduced Rhodobacter capsulatus cytochrome c2 to the cytochrome bc1 complex mediated by the conformation of the Rieske iron-sulfur protein. Biochemistry 2007; 46:7138-45. [PMID: 17516628 PMCID: PMC2565683 DOI: 10.1021/bi602649u] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The dissociation constants for the binding of Rhodobacter capsulatus cytochrome c2 and its K93P mutant to the cytochrome bc1 complex embedded in a phospholipid bilayer were measured by plasmon waveguide resonance spectroscopy in the presence and absence of the inhibitor stigmatellin. The reduced form of cytochrome c2 strongly binds to reduced cytochrome bc1 (Kd = 0.02 microM) but binds much more weakly to the oxidized form (Kd = 3.1 microM). In contrast, oxidized cytochrome c2 binds to oxidized cytochrome bc1 in a biphasic fashion with Kd values of 0.11 and 0.58 microM. Such a biphasic interaction is consistent with binding to two separate sites or conformations of oxidized cytochrome c2 and/or cytochrome bc1. However, in the presence of stigmatellin, we find that oxidized cytochrome c2 binds to oxidized cytochrome bc1 in a monophasic fashion with high affinity (Kd = 0.06 microM) and reduced cytochrome c2 binds less strongly (Kd = 0.11 microM) but approximately 30-fold more tightly than in the absence of stigmatellin. Structural studies with cytochrome bc1, with and without the inhibitor stigmatellin, have led to the proposal that the Rieske protein is mobile, moving between the cytochrome b and cytochrome c1 components during turnover. In one conformation, the Rieske protein binds near the heme of cytochrome c1, while the cytochrome c2 binding site is also near the cytochrome c1 heme but on the opposite side from the Rieske site, where cytochrome c2 cannot directly interact with Rieske. However, the inhibitor, stigmatellin, freezes the Rieske protein iron-sulfur cluster in a conformation proximal to cytochrome b and distal to cytochrome c1. We conclude from this that the dual conformation of the Rieske protein is primarily responsible for biphasic binding of oxidized cytochrome c2 to cytochrome c1. This optimizes turnover by maximizing binding of the substrate, oxidized cytochrome c2, when the iron-sulfur cluster is proximal to cytochrome b and minimizing binding of the product, reduced cytochrome c2, when it is proximal to cytochrome c1.
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Affiliation(s)
- S Devanathan
- Department of Biochemistry and Molecular Biophysics, University of Arizona, Tucson, Arizona 85721, USA
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