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Saghaï A, Hallin S. Diversity and ecology of NrfA-dependent ammonifying microorganisms. Trends Microbiol 2024; 32:602-613. [PMID: 38462391 DOI: 10.1016/j.tim.2024.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 02/11/2024] [Accepted: 02/13/2024] [Indexed: 03/12/2024]
Abstract
Nitrate ammonifiers are a taxonomically diverse group of microorganisms that reduce nitrate to ammonium, which is released, and thereby contribute to the retention of nitrogen in ecosystems. Despite their importance for understanding the fate of nitrate, they remain a largely overlooked group in the nitrogen cycle. Here, we present the latest advances on free-living microorganisms using NrfA to reduce nitrite during ammonification. We describe their diversity and ecology in terrestrial and aquatic environments, as well as the environmental factors influencing the competition for nitrate with denitrifiers that reduce nitrate to gaseous nitrogen species, including the greenhouse gas nitrous oxide (N2O). We further review the capacity of ammonifiers for other redox reactions, showing that they likely play multiple roles in the cycling of elements.
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Affiliation(s)
- Aurélien Saghaï
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Sara Hallin
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
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2
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Egas RA, Kurth JM, Boeren S, Sousa DZ, Welte CU, Sánchez-Andrea I. A novel mechanism for dissimilatory nitrate reduction to ammonium in Acididesulfobacillus acetoxydans. mSystems 2024; 9:e0096723. [PMID: 38323850 PMCID: PMC10949509 DOI: 10.1128/msystems.00967-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Accepted: 12/25/2023] [Indexed: 02/08/2024] Open
Abstract
The biological route of nitrate reduction has important implications for the bioavailability of nitrogen within ecosystems. Nitrate reduction via nitrite, either to ammonium (ammonification) or to nitrous oxide or dinitrogen (denitrification), determines whether nitrogen is retained within the system or lost as a gas. The acidophilic sulfate-reducing bacterium (aSRB) Acididesulfobacillus acetoxydans can perform dissimilatory nitrate reduction to ammonium (DNRA). While encoding a Nar-type nitrate reductase, A. acetoxydans lacks recognized nitrite reductase genes. In this study, A. acetoxydans was cultivated under conditions conducive to DNRA. During cultivations, we monitored the production of potential nitrogen intermediates (nitrate, nitrite, nitric oxide, hydroxylamine, and ammonium). Resting cell experiments were performed with nitrate, nitrite, and hydroxylamine to confirm their reduction to ammonium, and formed intermediates were tracked. To identify the enzymes involved in DNRA, comparative transcriptomics and proteomics were performed with A. acetoxydans growing under nitrate- and sulfate-reducing conditions. Nitrite is likely reduced to ammonia by the previously undescribed nitrite reductase activity of the NADH-linked sulfite reductase AsrABC, or by a putatively ferredoxin-dependent homolog of the nitrite reductase NirA (DEACI_1836), or both. We identified enzymes and intermediates not previously associated with DNRA and nitrosative stress in aSRB. This increases our knowledge about the metabolism of this type of bacteria and helps the interpretation of (meta)genome data from various ecosystems on their DNRA potential and the nitrogen cycle.IMPORTANCENitrogen is crucial to any ecosystem, and its bioavailability depends on microbial nitrogen-transforming reactions. Over the recent years, various new nitrogen-transforming reactions and pathways have been identified, expanding our view on the nitrogen cycle and metabolic versatility. In this study, we elucidate a novel mechanism employed by Acididesulfobacillus acetoxydans, an acidophilic sulfate-reducing bacterium, to reduce nitrate to ammonium. This finding underscores the diverse physiological nature of dissimilatory reduction to ammonium (DNRA). A. acetoxydans was isolated from acid mine drainage, an extremely acidic environment where nitrogen metabolism is poorly studied. Our findings will contribute to understanding DNRA potential and variations in extremely acidic environments.
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Affiliation(s)
- Reinier A. Egas
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Julia M. Kurth
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
- Microcosm Earth Centre, Philipps-Universität Marburg & Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Sjef Boeren
- Laboratory of Biochemistry, Wageningen University & Research, Wageningen, The Netherlands
| | - Diana Z. Sousa
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
- Centre for Living Technologies, Alliance TU/e, WUR, UU, UMC Utrecht, Utrecht, The Netherlands
| | - Cornelia U. Welte
- Department of Microbiology, Radboud Institute for Biological and Environmental Sciences, Radboud University, Nijmegen, The Netherlands
| | - Irene Sánchez-Andrea
- Laboratory of Microbiology, Wageningen University & Research, Wageningen, The Netherlands
- Department of Environmental Sciences for Sustainability, IE University, Segovia, Spain
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3
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Wang C, He T, Zhang M, Zheng C, Yang L, Yang L. Review of the mechanisms involved in dissimilatory nitrate reduction to ammonium and the efficacies of these mechanisms in the environment. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 345:123480. [PMID: 38325507 DOI: 10.1016/j.envpol.2024.123480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/30/2024] [Accepted: 01/31/2024] [Indexed: 02/09/2024]
Abstract
Dissimilatory nitrate reduction to ammonium (DNRA) is currently of great interest because it is an important method for recovering nitrogen from wastewater and offers many advantages, over other methods. A full understanding of DNRA requires the mechanisms, pathways, and functional microorganisms involved to be identified. The roles these pathways play and the effectiveness of DNRA in the environment are not well understood. The objectives of this review are to describe our current understanding of the molecular mechanisms and pathways involved in DNRA from the substrate transfer perspective and to summarize the effects of DNRA in the environment. First, the mechanisms and pathways involved in DNRA are described in detail. Second, our understanding of DNRA by actinomycetes is reviewed and gaps in our understanding are identified. Finally, the effects of DNRA in the environment are assessed. This review will help in the development of future research into DNRA to promote the use of DNRA to treat wastewater and recover nitrogen.
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Affiliation(s)
- Cerong Wang
- Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Life Science, Guizhou University, Guiyang, 550025, Guizhou Province, China.
| | - Tengxia He
- Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Life Science, Guizhou University, Guiyang, 550025, Guizhou Province, China.
| | - Manman Zhang
- Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Life Science, Guizhou University, Guiyang, 550025, Guizhou Province, China.
| | - Chunxia Zheng
- Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Life Science, Guizhou University, Guiyang, 550025, Guizhou Province, China.
| | - Li Yang
- Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Life Science, Guizhou University, Guiyang, 550025, Guizhou Province, China.
| | - Lu Yang
- Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Life Science, Guizhou University, Guiyang, 550025, Guizhou Province, China.
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4
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Li Y, Xiong L, Yu H, Zeng K, Wei Y, Li H, Zeng W, Ji X. Function and distribution of nitrogen-cycling microbial communities in the Napahai plateau wetland. Arch Microbiol 2023; 205:357. [PMID: 37872393 DOI: 10.1007/s00203-023-03695-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 09/27/2023] [Accepted: 09/29/2023] [Indexed: 10/25/2023]
Abstract
Nitrogen is an essential component of living organisms and a major nutrient that limits life on Earth. Until now, freely available nitrogen mainly comes from atmospheric nitrogen, but most organisms rely on bioavailable forms of nitrogen, which depends on the complex network of microorganisms with a wide variety of metabolic functions. Microbial-mediated nitrogen cycling contributes to the biogeochemical cycling of wetlands, but its specific microbial abundance, composition, and distribution need to be studied. Based on the metagenomic data, we described the composition and functional characteristics of microbial nitrogen cycle-related genes in the Napahai plateau wetland. Six nitrogen cycling pathways existed, such as dissimilatory nitrate reduction, denitrification, nitrogen fixation, nitrification, anammox, and nitrate assimilation. Most genes related to the nitrogen cycling in this region come from bacteria, mainly from Proteobacteria and Acidobacteria. Habitat types and nitrogen cycle-related genes largely explained the relative abundance of total nitrogen pathways. Phylogenetic trees were constructed based on nitrogen cycle-related genes from different habitats and sources, combined with PCoA analysis, most of them clustered separately, indicating richness and uniqueness. Some microbial groups seemed to be special or general in the nitrogen cycling. In conclusion, it suggested that microorganisms regulated the N cycling process, and may lead to N loss throughout the wetland, thus providing a basis for further elucidation of the microbial regulation of N cycling processes and the Earth's elemental cycles.
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Affiliation(s)
- Yanmei Li
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, China
| | - Lingling Xiong
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, China
| | - Hang Yu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, China
| | - Kun Zeng
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, China
| | - Yunlin Wei
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, 650500, China
| | - Haiyan Li
- Medical School, Kunming University of Science and Technology, Kunming, 650500, China
| | - Weikun Zeng
- School of Medicine, Kunming University, Kunming, 650214, China
| | - Xiuling Ji
- Medical School, Kunming University of Science and Technology, Kunming, 650500, China.
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5
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Sorokin DY, Tikhonova TV, Koch H, van den Berg EM, Hinderks RS, Pabst M, Dergousova NI, Soloveva AY, Kuenen GJ, Popov VO, van Loosdrecht MCM, Lücker S. Trichlorobacter ammonificans, a dedicated acetate-dependent ammonifier with a novel module for dissimilatory nitrate reduction to ammonia. THE ISME JOURNAL 2023; 17:1639-1648. [PMID: 37443340 PMCID: PMC10504241 DOI: 10.1038/s41396-023-01473-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 06/22/2023] [Accepted: 06/28/2023] [Indexed: 07/15/2023]
Abstract
Dissimilatory nitrate reduction to ammonia (DNRA) is a common biochemical process in the nitrogen cycle in natural and man-made habitats, but its significance in wastewater treatment plants is not well understood. Several ammonifying Trichlorobacter strains (former Geobacter) were previously enriched from activated sludge in nitrate-limited chemostats with acetate as electron (e) donor, demonstrating their presence in these systems. Here, we isolated and characterized the new species Trichlorobacter ammonificans strain G1 using a combination of low redox potential and copper-depleted conditions. This allowed purification of this DNRA organism from competing denitrifiers. T. ammonificans is an extremely specialized ammonifier, actively growing only with acetate as e-donor and carbon source and nitrate as e-acceptor, but H2 can be used as an additional e-donor. The genome of G1 does not encode the classical ammonifying modules NrfAH/NrfABCD. Instead, we identified a locus encoding a periplasmic nitrate reductase immediately followed by an octaheme cytochrome c that is conserved in many Geobacteraceae species. We purified this octaheme cytochrome c protein (TaNiR), which is a highly active dissimilatory ammonifying nitrite reductase loosely associated with the cytoplasmic membrane. It presumably interacts with two ferredoxin subunits (NapGH) that donate electrons from the menaquinol pool to the periplasmic nitrate reductase (NapAB) and TaNiR. Thus, the Nap-TaNiR complex represents a novel type of highly functional DNRA module. Our results indicate that DNRA catalyzed by octaheme nitrite reductases is a metabolic feature of many Geobacteraceae, representing important community members in various anaerobic systems, such as rice paddy soil and wastewater treatment facilities.
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Affiliation(s)
- Dimitry Y Sorokin
- Department of Biotechnology, Delft University of Technology, Delft, The Netherlands.
- Winogradsky Institute of Microbiology, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia.
| | - Tamara V Tikhonova
- Bach Institute of Biochemistry, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Hanna Koch
- Department of Microbiology, Radboud Institute for Biological and Environmental Sciences, Radboud University, Nijmegen, The Netherlands
| | | | - Renske S Hinderks
- Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | - Martin Pabst
- Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | - Natalia I Dergousova
- Bach Institute of Biochemistry, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Anastasia Y Soloveva
- Bach Institute of Biochemistry, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | - Gijs J Kuenen
- Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | - Vladimir O Popov
- Bach Institute of Biochemistry, Research Centre of Biotechnology, Russian Academy of Sciences, Moscow, Russia
| | | | - Sebastian Lücker
- Department of Microbiology, Radboud Institute for Biological and Environmental Sciences, Radboud University, Nijmegen, The Netherlands.
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Bollmeyer MM, Coleman RE, Majer SH, Ferrao SD, Lancaster KM. Cytochrome P460 Cofactor Maturation Proceeds via Peroxide-Dependent Post-translational Modification. J Am Chem Soc 2023; 145:14404-14416. [PMID: 37338957 PMCID: PMC10431212 DOI: 10.1021/jacs.3c03608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2023]
Abstract
Cytochrome P460s are heme enzymes that oxidize hydroxylamine to nitrous oxide. They bear specialized "heme P460" cofactors that are cross-linked to their host polypeptides by a post-translationally modified lysine residue. Wild-type N. europaea cytochrome P460 may be isolated as a cross-link-deficient proenzyme following anaerobic overexpression in E. coli. When treated with peroxide, this proenzyme undergoes maturation to active enzyme with spectroscopic and catalytic properties that match wild-type cyt P460. This maturation reactivity requires no chaperones─it is intrinsic to the protein. This behavior extends to the broader cytochrome c'β superfamily. Accumulated data reveal key contributions from the secondary coordination sphere that enable selective, complete maturation. Spectroscopic data support the intermediacy of a ferryl species along the maturation pathway.
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Affiliation(s)
- Melissa M. Bollmeyer
- Department of Chemistry and Chemical Biology Cornell University, Baker Laboratory, 162 Sciences Drive, Ithaca, NY 14853, USA
| | - Rachael E. Coleman
- Department of Chemistry and Chemical Biology Cornell University, Baker Laboratory, 162 Sciences Drive, Ithaca, NY 14853, USA
| | - Sean H. Majer
- Department of Chemistry and Chemical Biology Cornell University, Baker Laboratory, 162 Sciences Drive, Ithaca, NY 14853, USA
| | - Silas D. Ferrao
- Department of Chemistry and Chemical Biology Cornell University, Baker Laboratory, 162 Sciences Drive, Ithaca, NY 14853, USA
| | - Kyle M. Lancaster
- Department of Chemistry and Chemical Biology Cornell University, Baker Laboratory, 162 Sciences Drive, Ithaca, NY 14853, USA
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7
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Bizic M, Brad T, Ionescu D, Barbu-Tudoran L, Zoccarato L, Aerts JW, Contarini PE, Gros O, Volland JM, Popa R, Ody J, Vellone D, Flot JF, Tighe S, Sarbu SM. Cave Thiovulum (Candidatus Thiovulum stygium) differs metabolically and genomically from marine species. THE ISME JOURNAL 2023; 17:340-353. [PMID: 36528730 PMCID: PMC9938260 DOI: 10.1038/s41396-022-01350-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 11/29/2022] [Accepted: 12/02/2022] [Indexed: 12/23/2022]
Abstract
Thiovulum spp. (Campylobacterota) are large sulfur bacteria that form veil-like structures in aquatic environments. The sulfidic Movile Cave (Romania), sealed from the atmosphere for ~5 million years, has several aqueous chambers, some with low atmospheric O2 (~7%). The cave's surface-water microbial community is dominated by bacteria we identified as Thiovulum. We show that this strain, and others from subsurface environments, are phylogenetically distinct from marine Thiovulum. We assembled a closed genome of the Movile strain and confirmed its metabolism using RNAseq. We compared the genome of this strain and one we assembled from public data from the sulfidic Frasassi caves to four marine genomes, including Candidatus Thiovulum karukerense and Ca. T. imperiosus, whose genomes we sequenced. Despite great spatial and temporal separation, the genomes of the Movile and Frasassi Thiovulum were highly similar, differing greatly from the very diverse marine strains. We concluded that cave Thiovulum represent a new species, named here Candidatus Thiovulum stygium. Based on their genomes, cave Thiovulum can switch between aerobic and anaerobic sulfide oxidation using O2 and NO3- as electron acceptors, the latter likely via dissimilatory nitrate reduction to ammonia. Thus, Thiovulum is likely important to both S and N cycles in sulfidic caves. Electron microscopy analysis suggests that at least some of the short peritrichous structures typical of Thiovulum are type IV pili, for which genes were found in all strains. These pili may play a role in veil formation, by connecting adjacent cells, and in the motility of these exceptionally fast swimmers.
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Affiliation(s)
- Mina Bizic
- Leibniz Institute for Freshwater Ecology and Inland Fisheries, IGB, Dep 3, Plankton and Microbial Ecology, Zur Alte Fischerhütte 2, OT Neuglobsow, 16775, Stechlin, Germany. .,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany.
| | - Traian Brad
- "Emil Racoviţă" Institute of Speleology, Clinicilor 5-7, 400006, Cluj-Napoca Romania, Romania.
| | - Danny Ionescu
- Leibniz Institute for Freshwater Ecology and Inland Fisheries, IGB, Dep 3, Plankton and Microbial Ecology, Zur Alte Fischerhütte 2, OT Neuglobsow, 16775, Stechlin, Germany. .,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany.
| | - Lucian Barbu-Tudoran
- grid.7399.40000 0004 1937 1397Center for Electron Microscopy, “Babeș-Bolyai” University, Clinicilor 5, 400006 Cluj-Napoca, Romania
| | - Luca Zoccarato
- Leibniz Institute for Freshwater Ecology and Inland Fisheries, IGB, Dep 3, Plankton and Microbial Ecology, Zur Alte Fischerhütte 2, OT Neuglobsow, 16775 Stechlin, Germany ,grid.5173.00000 0001 2298 5320Institute of Computational Biology, University of Natural Resources and Life Sciences, Gregor-Mendel-Straße 3, 31180 Vienna, Austria
| | - Joost W. Aerts
- grid.12380.380000 0004 1754 9227Department of Molecular Cell Physiology, Faculty of Earth and Life sciences, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Paul-Emile Contarini
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum National d’Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, 97110 Pointe-à-Pitre, France ,Laboratory for Research in Complex Systems, Menlo Park, CA USA
| | - Olivier Gros
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Muséum National d’Histoire Naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, 97110 Pointe-à-Pitre, France
| | - Jean-Marie Volland
- Laboratory for Research in Complex Systems, Menlo Park, CA USA ,grid.184769.50000 0001 2231 4551Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, 94720 Berkeley, CA USA
| | - Radu Popa
- River Road Research, 62 Leslie St, Buffalo, NY 1421 USA
| | - Jessica Ody
- grid.4989.c0000 0001 2348 0746Evolutionary Biology and Ecology, Université libre de Bruxelles (ULB), C.P. 160/12, Avenue F.D. Roosevelt 50, 1050 Brussels, Belgium
| | - Daniel Vellone
- grid.59062.380000 0004 1936 7689Vermont Integrative Genomics Lab, University of Vermont Cancer Center, Health Science Research Facility, Burlington, Vermont, VT 05405 USA
| | - Jean-François Flot
- grid.4989.c0000 0001 2348 0746Evolutionary Biology and Ecology, Université libre de Bruxelles (ULB), C.P. 160/12, Avenue F.D. Roosevelt 50, 1050 Brussels, Belgium ,Interuniversity Institute of Bioinformatics in Brussels—(IB)², Brussels, Belgium
| | - Scott Tighe
- grid.59062.380000 0004 1936 7689Vermont Integrative Genomics Lab, University of Vermont Cancer Center, Health Science Research Facility, Burlington, Vermont, VT 05405 USA
| | - Serban M. Sarbu
- grid.501624.40000 0001 2260 1489“Emil Racoviţă” Institute of Speleology, Frumoasă 31-B, 010986 Bucureşti, Romania ,grid.253555.10000 0001 2297 1981Department of Biological Sciences, California State University, Chico, CA 95929 USA
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Denkhaus L, Siffert F, Einsle O. An unusual active site architecture in cytochrome c nitrite reductase NrfA-1 from Geobacter metallireducens. FEMS Microbiol Lett 2023; 370:fnad068. [PMID: 37460131 DOI: 10.1093/femsle/fnad068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 06/21/2023] [Accepted: 07/14/2023] [Indexed: 08/13/2023] Open
Abstract
Dissimilatory nitrate reduction to ammonia (DNRA) is a central pathway in the biogeochemical nitrogen cycle, allowing for the utilization of nitrate or nitrite as terminal electron acceptors. In contrast to the competing denitrification to N2, a major part of the essential nutrient nitrogen in DNRA is retained within the ecosystem and made available as ammonium to serve as a nitrogen source for other organisms. The second step of DNRA is mediated by the pentahaem cytochrome c nitrite reductase NrfA that catalyzes the six-electron reduction of nitrite to ammonium and is widely distributed among bacteria. A recent crystal structure of an NrfA ortholog from Geobacter lovleyi was the first characterized representative of a novel subclass of NrfA enzymes that lacked the canonical Ca2+ ion close to the active site haem 1. Here, we report the structural and functional characterization of NrfA from the closely related G. metallireducens. We established the recombinant production of catalytically active NrfA with its unique, lysine-coordinated active site haem heterologously in Escherichia coli and determined its three-dimensional structure by X-ray crystallography to 1.9 Å resolution. The structure confirmed GmNrfA as a further calcium-independent NrfA protein, and it also shows an altered active site that contained an unprecedented aspartate residue, D80, close to the substrate-binding site. This residue formed part of a loop that also caused a changed arrangement of the conserved substrate/product channel relative to other NrfA proteins and rendered the protein insensitive to the inhibitor sulphate. To elucidate the relevance of D80, we produced and studied the variants D80A and D80N that showed significantly reduced catalytic activity.
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Affiliation(s)
- Lukas Denkhaus
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Fanny Siffert
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Oliver Einsle
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, 79104 Freiburg im Breisgau, Germany
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9
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Microbial communities of Auka hydrothermal sediments shed light on vent biogeography and the evolutionary history of thermophily. THE ISME JOURNAL 2022; 16:1750-1764. [PMID: 35352015 PMCID: PMC9213671 DOI: 10.1038/s41396-022-01222-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 01/18/2022] [Accepted: 02/09/2022] [Indexed: 01/04/2023]
Abstract
Hydrothermal vents have been key to our understanding of the limits of life, and the metabolic and phylogenetic diversity of thermophilic organisms. Here we used environmental metagenomics combined with analysis of physicochemical data and 16S rRNA gene amplicons to characterize the sediment-hosted microorganisms at the recently discovered Auka vents in the Gulf of California. We recovered 325 metagenome assembled genomes (MAGs) representing 54 phyla, over 30% of those currently known, showing the microbial community in Auka hydrothermal sediments is highly diverse. 16S rRNA gene amplicon screening of 224 sediment samples across the vent field indicates that the MAGs retrieved from a single site are representative of the microbial community in the vent field sediments. Metabolic reconstruction of a vent-specific, deeply branching clade within the Desulfobacterota suggests these organisms metabolize sulfur using novel octaheme cytochrome-c proteins related to hydroxylamine oxidoreductase. Community-wide comparison between Auka MAGs and MAGs from Guaymas Basin revealed a remarkable 20% species-level overlap, suggestive of long-distance species transfer over 400 km and subsequent sediment colonization. Optimal growth temperature prediction on the Auka MAGs, and thousands of reference genomes, shows that thermophily is a trait that has evolved frequently. Taken together, our Auka vent field results offer new perspectives on our understanding of hydrothermal vent microbiology.
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10
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Spring S, Rohde M, Bunk B, Spröer C, Will SE, Neumann-Schaal M. New insights into the energy metabolism and taxonomy of Deferribacteres revealed by the characterization of a new isolate from a hypersaline microbial mat. Environ Microbiol 2022; 24:2543-2575. [PMID: 35415868 DOI: 10.1111/1462-2920.15999] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 04/04/2022] [Indexed: 12/13/2022]
Abstract
Strain L21-Ace-BEST , isolated from a lithifying cyanobacterial mat, could be assigned to a novel species and genus within the Deferribacteres. It is an important model organism for the study of anaerobic acetate degradation under hypersaline conditions. The metabolism of strain L21-Ace-BEST was characterized by biochemical studies, comparative genome analyses, and the evaluation of gene expression patterns. The central metabolic pathway is the citric acid cycle, which is mainly controlled by the enzyme succinyl-CoA:acetate-CoA transferase. The potential use of a reversed oxidative citric acid cycle to fix CO2 has been revealed through genome analysis. However, no autotrophic growth was detected in this strain, whereas sulfide and H2 can be used mixotrophically. Preferred electron acceptors for the anaerobic oxidation of acetate are nitrate, fumarate and DMSO, while oxygen can be utilized only under microoxic conditions. Aerotolerant growth by fermentation was observed at higher oxygen concentrations. The redox cycling of sulfur/sulfide enables the generation of reducing power for the assimilation of acetate during growth and could prevent the over-reduction of cells in stationary phase. Extracellular electron transfer appears to be an essential component of the respiratory metabolism in this clade of Deferribacteres and may be involved in the reduction of nitrite to ammonium. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Stefan Spring
- Department Microorganisms, Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Manfred Rohde
- Central Facility for Microscopy, Helmholtz Centre for Infection Research, HZI, Braunschweig, Germany
| | - Boyke Bunk
- Department Bioinformatics, Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Cathrin Spröer
- Department Bioinformatics, Leibniz Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Sabine Eva Will
- Research Group Metabolomics, Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Meina Neumann-Schaal
- Research Group Metabolomics, Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
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Millimeter-scale vertical partitioning of nitrogen cycling in hypersaline mats reveals prominence of genes encoding multi-heme and prismane proteins. THE ISME JOURNAL 2022; 16:1119-1129. [PMID: 34862473 PMCID: PMC8940962 DOI: 10.1038/s41396-021-01161-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 11/09/2021] [Accepted: 11/18/2021] [Indexed: 12/01/2022]
Abstract
Microbial mats are modern analogues of the first ecosystems on the Earth. As extant representatives of microbial communities where free oxygen may have first been available on a changing planet, they offer an ecosystem within which to study the evolution of biogeochemical cycles requiring and inhibited by oxygen. Here, we report the distribution of genes involved in nitrogen metabolism across a vertical oxygen gradient at 1 mm resolution in a microbial mat using quantitative PCR (qPCR), retro-transcribed qPCR (RT-qPCR) and metagenome sequencing. Vertical patterns in the presence and expression of nitrogen cycling genes, corresponding to oxygen requiring and non-oxygen requiring nitrogen metabolism, could be seen across gradients of dissolved oxygen and ammonium. Metagenome analysis revealed that genes annotated as hydroxylamine dehydrogenase (proper enzyme designation EC 1.7.2.6, hao) and hydroxylamine reductase (hcp) were the most abundant nitrogen metabolism genes in the mat. The recovered hao genes encode hydroxylamine dehydrogenase EC 1.7.2.6 (HAO) proteins lacking the tyrosine residue present in aerobic ammonia oxidizing bacteria (AOB). Phylogenetic analysis confirmed that those proteins were more closely related to ɛHao protein present in Campylobacterota lineages (previously known as Epsilonproteobacteria) rather than oxidative HAO of AOB. The presence of hao sequences related with ɛHao protein, as well as numerous hcp genes encoding a prismane protein, suggest the presence of a nitrogen cycling pathway previously described in Nautilia profundicola as ancestral to the most commonly studied present day nitrogen cycling pathways.
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12
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Marzocchi U, Thorup C, Dam AS, Schramm A, Risgaard-Petersen N. Dissimilatory nitrate reduction by a freshwater cable bacterium. THE ISME JOURNAL 2022; 16:50-57. [PMID: 34215856 PMCID: PMC8692496 DOI: 10.1038/s41396-021-01048-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 06/10/2021] [Accepted: 06/23/2021] [Indexed: 02/06/2023]
Abstract
Cable bacteria (CB) are filamentous Desulfobulbaceae that split the energy-conserving reaction of sulfide oxidation into two half reactions occurring in distinct cells. CB can use nitrate, but the reduction pathway is unknown, making it difficult to assess their direct impact on the N-cycle. Here we show that the freshwater cable bacterium Ca. Electronema sp. GS performs dissimilatory nitrate reduction to ammonium (DNRA). 15NO3--amended sediment with Ca. Electronema sp. GS showed higher rates of DNRA and nitrite production than sediment without Ca. Electronema sp. GS. Electron flux from sulfide oxidation, inferred from electric potential (EP) measurements, matched the electron flux needed to drive CB-mediated nitrate reduction to nitrite and ammonium. Ca. Electronema sp. GS expressed a complete nap operon for periplasmic nitrate reduction to nitrite, and a putative octaheme cytochrome c (pOCC), whose involvement in nitrite reduction to ammonium remains to be verified. Phylogenetic analysis suggests that the capacity for DNRA was acquired in multiple events through horizontal gene transfer from different organisms, before CB split into different salinity niches. The architecture of the nitrate reduction system suggests absence of energy conservation through oxidative phosphorylation, indicating that CB primarily conserve energy through the half reaction of sulfide oxidation.
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Affiliation(s)
- Ugo Marzocchi
- grid.8767.e0000 0001 2290 8069Department of Chemistry, Vrije Universiteit Brussel, Brussel, Belgium ,grid.7048.b0000 0001 1956 2722Center for Electromicrobiology, Section for Microbiology, Department of Biology, Aarhus University, Aarhus, Denmark ,grid.7048.b0000 0001 1956 2722Center for Water Technology (WATEC), Department of Biology, Aarhus University, Aarhus, Denmark
| | - Casper Thorup
- grid.7048.b0000 0001 1956 2722Center for Electromicrobiology, Section for Microbiology, Department of Biology, Aarhus University, Aarhus, Denmark ,grid.7048.b0000 0001 1956 2722Center for Geomicrobiology, Section for Microbiology, Department of Biology, Aarhus University, Aarhus, Denmark
| | - Ann-Sofie Dam
- grid.7048.b0000 0001 1956 2722Center for Electromicrobiology, Section for Microbiology, Department of Biology, Aarhus University, Aarhus, Denmark ,grid.7048.b0000 0001 1956 2722Center for Geomicrobiology, Section for Microbiology, Department of Biology, Aarhus University, Aarhus, Denmark
| | - Andreas Schramm
- grid.7048.b0000 0001 1956 2722Center for Electromicrobiology, Section for Microbiology, Department of Biology, Aarhus University, Aarhus, Denmark ,grid.7048.b0000 0001 1956 2722Center for Geomicrobiology, Section for Microbiology, Department of Biology, Aarhus University, Aarhus, Denmark
| | - Nils Risgaard-Petersen
- grid.7048.b0000 0001 1956 2722Center for Electromicrobiology, Section for Microbiology, Department of Biology, Aarhus University, Aarhus, Denmark ,grid.7048.b0000 0001 1956 2722Center for Geomicrobiology, Section for Microbiology, Department of Biology, Aarhus University, Aarhus, Denmark ,grid.7048.b0000 0001 1956 2722Section of Aquatic Biology, Department of Biology, Aarhus University, Aarhus, Denmark
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Liu Q, Tang S, Meng X, Zhu H, Zhu Y, Liu D, Shen Q. Proteomic Analysis Demonstrates a Molecular Dialog Between Trichoderma guizhouense NJAU 4742 and Cucumber ( Cucumis sativus L.) Roots: Role in Promoting Plant Growth. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:631-644. [PMID: 33496609 DOI: 10.1094/mpmi-08-20-0240-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Trichoderma is a genus of filamentous fungi that play notable roles in stimulating plant growth after colonizing the root surface. However, the key proteins and molecular mechanisms governing this stimulation have not been completely elucidated. In this study, Trichoderma guizhouense NJAU 4742 was investigated in a hydroponic culture system after interacting with cucumber roots. The total proteins of the fungus were characterized, and the key metabolic pathways along with related genes were analyzed through proteomic and transcriptomic analyses. The roles played by the regulated proteins during the interaction between plants and NJAU 4742 were further examined. The intracellular or extracellular proteins from NJAU 4742 and extracellular proteins from cucumber were quantified, and the high-abundance proteins were determined which were primarily involved in the shikimate pathway (tryptophan, tyrosine, and phenylalanine metabolism, auxin biosynthesis, and secondary metabolite synthesis). Moreover, 15N-KNO3 labeling analysis indicated that NJAU 4742 had a strong ability to convert nitrogenous amino acids, nitrate, nitrile, and amines into ammonia. The auxin synthesis and ammonification metabolism pathways of NJAU 4742 significantly contributed to plant growth. The results of this study demonstrated the crucial metabolic pathways involved in the interactions between Trichoderma spp. and plants.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Qiumei Liu
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-saving fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples Republic of China
| | - Siyu Tang
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-saving fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples Republic of China
| | - Xiaohui Meng
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-saving fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples Republic of China
| | - Han Zhu
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-saving fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples Republic of China
| | - Yiyong Zhu
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-saving fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples Republic of China
| | - Dongyang Liu
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-saving fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples Republic of China
| | - Qirong Shen
- Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-saving fertilizers, Nanjing Agricultural University, Nanjing 210095, Jiangsu, Peoples Republic of China
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Duarte AG, Barbosa ACC, Ferreira D, Manteigas G, Domingos RM, Pereira IAC. Redox loops in anaerobic respiration - The role of the widespread NrfD protein family and associated dimeric redox module. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148416. [PMID: 33753023 DOI: 10.1016/j.bbabio.2021.148416] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 02/25/2021] [Accepted: 03/11/2021] [Indexed: 02/06/2023]
Abstract
In prokaryotes, the proton or sodium motive force required for ATP synthesis is produced by respiratory complexes that present an ion-pumping mechanism or are involved in redox loops performed by membrane proteins that usually have substrate and quinone-binding sites on opposite sides of the membrane. Some respiratory complexes include a dimeric redox module composed of a quinone-interacting membrane protein of the NrfD family and an iron‑sulfur protein of the NrfC family. The QrcABCD complex of sulfate reducers, which includes the QrcCD module homologous to NrfCD, was recently shown to perform electrogenic quinone reduction providing the first conclusive evidence for energy conservation among this family. Similar redox modules are present in multiple respiratory complexes, which can be associated with electroneutral, energy-driven or electrogenic reactions. This work discusses the presence of the NrfCD/PsrBC dimeric redox module in different bioenergetics contexts and its role in prokaryotic energy conservation mechanisms.
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Affiliation(s)
- Américo G Duarte
- Instituto de Tecnologia Química e Biológica António Xavier/Universidade Nova de Lisboa, Av. da República, Estação Agronómica Nacional, 2780-157 Oeiras, Portugal.
| | - Ana C C Barbosa
- Instituto de Tecnologia Química e Biológica António Xavier/Universidade Nova de Lisboa, Av. da República, Estação Agronómica Nacional, 2780-157 Oeiras, Portugal
| | - Delfim Ferreira
- Instituto de Tecnologia Química e Biológica António Xavier/Universidade Nova de Lisboa, Av. da República, Estação Agronómica Nacional, 2780-157 Oeiras, Portugal
| | - Gonçalo Manteigas
- Instituto de Tecnologia Química e Biológica António Xavier/Universidade Nova de Lisboa, Av. da República, Estação Agronómica Nacional, 2780-157 Oeiras, Portugal
| | - Renato M Domingos
- Instituto de Tecnologia Química e Biológica António Xavier/Universidade Nova de Lisboa, Av. da República, Estação Agronómica Nacional, 2780-157 Oeiras, Portugal
| | - Inês A C Pereira
- Instituto de Tecnologia Química e Biológica António Xavier/Universidade Nova de Lisboa, Av. da República, Estação Agronómica Nacional, 2780-157 Oeiras, Portugal.
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15
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Ferousi C, Schmitz RA, Maalcke WJ, Lindhoud S, Versantvoort W, Jetten MSM, Reimann J, Kartal B. Characterization of a nitrite-reducing octaheme hydroxylamine oxidoreductase that lacks the tyrosine cross-link. J Biol Chem 2021; 296:100476. [PMID: 33652023 PMCID: PMC8042395 DOI: 10.1016/j.jbc.2021.100476] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/18/2021] [Accepted: 02/24/2021] [Indexed: 02/06/2023] Open
Abstract
The hydroxylamine oxidoreductase (HAO) family consists of octaheme proteins that harbor seven bis-His ligated electron-transferring hemes and one 5-coordinate catalytic heme with His axial ligation. Oxidative HAOs have a homotrimeric configuration with the monomers covalently attached to each other via a unique double cross-link between a Tyr residue and the catalytic heme moiety of an adjacent subunit. This cross-linked active site heme, termed the P460 cofactor, has been hypothesized to modulate enzyme reactivity toward oxidative catalysis. Conversely, the absence of this cross-link is predicted to favor reductive catalysis. However, this prediction has not been directly tested. In this study, an HAO homolog that lacks the heme-Tyr cross-link (HAOr) was purified to homogeneity from the nitrite-dependent anaerobic ammonium-oxidizing (anammox) bacterium Kuenenia stuttgartiensis, and its catalytic and spectroscopic properties were assessed. We show that HAOr reduced nitrite to nitric oxide and also reduced nitric oxide and hydroxylamine as nonphysiological substrates. In contrast, HAOr was not able to oxidize hydroxylamine or hydrazine supporting the notion that cross-link-deficient HAO enzymes are reductases. Compared with oxidative HAOs, we found that HAOr harbors an active site heme with a higher (at least 80 mV) midpoint potential and a much lower degree of porphyrin ruffling. Based on the physiology of anammox bacteria and our results, we propose that HAOr reduces nitrite to nitric oxide in vivo, providing anammox bacteria with NO, which they use to activate ammonium in the absence of oxygen.
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Affiliation(s)
- Christina Ferousi
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Rob A Schmitz
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Wouter J Maalcke
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Simon Lindhoud
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Wouter Versantvoort
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Mike S M Jetten
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Joachim Reimann
- Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Boran Kartal
- Microbial Physiology Group, Max Planck Institute for Marine Microbiology, Bremen, Germany.
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16
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Soler-Jofra A, Pérez J, van Loosdrecht MCM. Hydroxylamine and the nitrogen cycle: A review. WATER RESEARCH 2021; 190:116723. [PMID: 33352529 DOI: 10.1016/j.watres.2020.116723] [Citation(s) in RCA: 81] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 11/21/2020] [Accepted: 12/01/2020] [Indexed: 06/12/2023]
Abstract
Aerobic ammonium oxidizing bacteria were first isolated more than 100 years ago and hydroxylamine is known to be an intermediate. The enzymatic steps involving hydroxylamine conversion to nitrite are still under discussion. For a long time it was assumed that hydroxylamine was directly converted to nitrite by a hydroxylamine oxidoreductase. Recent enzymatic evidences suggest that the actual product of hydroxylamine conversion is NO and a third, yet unknown, enzyme further converts NO to nitrite. More recently, ammonium oxidizing archaea and complete ammonium oxidizing bacteria were isolated and identified. Still the central nitrogen metabolism of these microorganisms presents to researchers the same puzzle: how hydroxylamine is transformed to nitrite. Nitrogen losses in the form of NO and N2O have been identified in all three types of aerobic ammonium oxidizing microorganisms and hydroxylamine is known to play a significant role in the formation. Yet, the pathways and the factors promoting the greenhouse gas emissions are to be fully characterized. Hydroxylamine also plays a yet poorly understood role on anaerobic ammonium oxidizing bacteria and is known to inhibit nitrite oxidizing bacteria. In this review, the role of this elusive intermediate in the metabolism of different key players of the nitrogen cycle is discussed, as well as the putative importance of hydroxylamine as a key nitrogen metabolite for microbial interactions within microbial communities and engineered systems. Overall, for the first time putting together the acquired knowledge about hydroxylamine and the nitrogen cycle over the years in a review, setting potential hypothesis and highlighting possible next steps for research.
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Affiliation(s)
- Aina Soler-Jofra
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - Julio Pérez
- Department of Chemical, Biological and Environmental Engineering, Universitat Autonoma de Barcelona, Cerdanyola del Valles, Spain
| | - Mark C M van Loosdrecht
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, the Netherlands.
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17
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Tracey JC, Coronado M, Giessen TW, Lau MCY, Silver PA, Ward BB. The Discovery of Twenty-Eight New Encapsulin Sequences, Including Three in Anammox Bacteria. Sci Rep 2019; 9:20122. [PMID: 31882935 PMCID: PMC6934571 DOI: 10.1038/s41598-019-56533-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 12/12/2019] [Indexed: 12/22/2022] Open
Abstract
Many prokaryotes encode protein-based encapsulin nanocompartments, including anaerobic ammonium oxidizing (anammox) bacteria. This study expands the list of known anammox encapsulin systems from freshwater species to include the marine genus Scalindua. Two novel systems, identified in "Candidatus Scalindua rubra" and "Candidatus Scalindua sp. SCAELEC01 167" possess different architectures than previously studied freshwater anammox encapsulins. Characterization of the S. rubra encapsulin confirms that it can self-assemble to form compartments when heterologously expressed in Escherichia coli. BLASTp and HMMER searches of additional genomes and metagenomes spanning a range of environments returned 26 additional novel encapsulins, including a freshwater anammox encapsulin identified in "Candidatus Brocadia caroliniensis". Phylogenetic analysis comparing these 28 new encapsulin sequences and cargo to that of their closest known relatives shows that encapsulins cluster by cargo protein type and therefore likely evolved together. Lastly, prokaryotic encapsulins may be more common and diverse than previously thought. Through searching a small sample size of all public metagenomes and genomes, many new encapsulin systems were unearthed by this study. This suggests that many additional encapsulins likely remain to be discovered.
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Affiliation(s)
- John C Tracey
- Princeton University, Department of Geosciences, Guyot Hall, Princeton, NJ, 08544, USA.
| | - Maricela Coronado
- Princeton University, Department of Geosciences, Guyot Hall, Princeton, NJ, 08544, USA
| | - Tobias W Giessen
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
- Harvard Medical School, Department of Systems Biology, Boston, MA, 02115, USA
- Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Boston, MA, 02115, USA
| | - Maggie C Y Lau
- Princeton University, Department of Geosciences, Guyot Hall, Princeton, NJ, 08544, USA
- Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences, Sanya, Hainan, China
| | - Pamela A Silver
- Harvard Medical School, Department of Systems Biology, Boston, MA, 02115, USA
- Wyss Institute for Biologically Inspired Engineering, 3 Blackfan Circle, Boston, MA, 02115, USA
| | - Bess B Ward
- Princeton University, Department of Geosciences, Guyot Hall, Princeton, NJ, 08544, USA
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18
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How Thermophilic Gram-Positive Organisms Perform Extracellular Electron Transfer: Characterization of the Cell Surface Terminal Reductase OcwA. mBio 2019; 10:mBio.01210-19. [PMID: 31431546 PMCID: PMC6703420 DOI: 10.1128/mbio.01210-19] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Thermophilic Gram-positive organisms were recently shown to be a promising class of organisms to be used in bioelectrochemical systems for the production of electrical energy. These organisms present a thick peptidoglycan layer that was thought to preclude them to perform extracellular electron transfer (i.e., exchange catabolic electrons with solid electron acceptors outside the cell). In this paper, we describe the structure and functional mechanisms of the multiheme cytochrome OcwA, the terminal reductase of the Gram-positive bacterium Thermincola potens JR found at the cell surface of this organism. The results presented here show that this protein can take the role of a respiratory “Swiss Army knife,” allowing this organism to grow in environments with soluble and insoluble substrates. Moreover, it is shown that it is unrelated to terminal reductases found at the cell surface of other electroactive organisms. Instead, OcwA is similar to terminal reductases of soluble electron acceptors. Our data reveal that terminal oxidoreductases of soluble and insoluble substrates are evolutionarily related, providing novel insights into the evolutionary pathway of multiheme cytochromes. Extracellular electron transfer is the key process underpinning the development of bioelectrochemical systems for the production of energy or added-value compounds. Thermincola potens JR is a promising Gram-positive bacterium to be used in these systems because it is thermophilic. In this paper, we describe the structural and functional properties of the nonaheme cytochrome OcwA, which is the terminal reductase of this organism. The structure of OcwA, determined at 2.2-Å resolution, shows that the overall fold and organization of the hemes are not related to other metal reductases and instead are similar to those of multiheme cytochromes involved in the biogeochemical cycles of nitrogen and sulfur. We show that, in addition to solid electron acceptors, OcwA can also reduce soluble electron shuttles and oxyanions. These data reveal that OcwA can work as a multipurpose respiratory enzyme allowing this organism to grow in environments with rapidly changing availability of terminal electron acceptors without the need for transcriptional regulation and protein synthesis.
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Smith MA, Majer SH, Vilbert AC, Lancaster KM. Controlling a burn: outer-sphere gating of hydroxylamine oxidation by a distal base in cytochrome P460. Chem Sci 2019; 10:3756-3764. [PMID: 31015919 PMCID: PMC6457333 DOI: 10.1039/c9sc00195f] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Accepted: 02/14/2019] [Indexed: 01/19/2023] Open
Abstract
One amino acid makes the difference between a metalloenzyme and a metalloprotein in two otherwise effectively identical cytochrome P460s.
Ammonia oxidizing bacteria (AOB) use the cytotoxic, energetic molecule hydroxylamine (NH2OH) as a source of reducing equivalents for cellular respiration. Despite disproportionation or violent decomposition being typical outcomes of reactions of NH2OH with iron, AOB and anammox heme P460 proteins including cytochrome (cyt) P460 and hydroxylamine oxidoreductase (HAO) effect controlled, stepwise oxidation of NH2OH to nitric oxide (NO). Curiously, a recently characterized cyt P460 variant from the AOB Nitrosomonas sp. AL212 is able to form all intermediates of cyt P460 catalysis, but is nevertheless incompetent for NH2OH oxidation. We now show via site-directed mutagenesis, activity assays, spectroscopy, and structural biology that this lack of activity is attributable to the absence of a critical basic glutamate residue in the distal pocket above the heme P460 cofactor. This substitution is the only distinguishing characteristic of a protein that is otherwise effectively structurally and spectroscopically identical to an active variant. This highlights and reinforces a fundamental principal of metalloenzymology: metallocofactor inner-sphere geometric and electronic structures are in many cases insufficient for imbuing reactivity; a precisely defined outer coordination sphere contributed by the polypeptide matrix can be the key differentiator between a metalloenzyme and an unreactive metalloprotein.
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Affiliation(s)
- Meghan A Smith
- Department of Chemistry and Chemical Biology , Baker Laboratory , Cornell University , Ithaca , NY 14853 , USA .
| | - Sean H Majer
- Department of Chemistry and Chemical Biology , Baker Laboratory , Cornell University , Ithaca , NY 14853 , USA .
| | - Avery C Vilbert
- Department of Chemistry and Chemical Biology , Baker Laboratory , Cornell University , Ithaca , NY 14853 , USA .
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology , Baker Laboratory , Cornell University , Ithaca , NY 14853 , USA .
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20
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Dietl A, Maalcke WJ, Ferousi C, Jetten MSM, Kartal B, Barends TRM. A 60-heme reductase complex from an anammox bacterium shows an extended electron transfer pathway. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2019; 75:333-341. [DOI: 10.1107/s2059798318017473] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Accepted: 12/10/2018] [Indexed: 11/10/2022]
Abstract
The hydroxylamine oxidoreductase/hydrazine dehydrogenase (HAO/HDH) protein family constitutes an important group of octaheme cytochromes c (OCCs). The majority of these proteins form homotrimers, with their subunits being covalently attached to each other via a rare cross-link between the catalytic heme moiety and a conserved tyrosine residue in an adjacent subunit. This covalent cross-link has been proposed to modulate the active-site heme towards oxidative catalysis by distorting the heme plane. In this study, the crystal structure of a stable complex of an HAO homologue (KsHAOr) with its diheme cytochrome c redox partner (KsDH) from the anammox bacterium Kuenenia stuttgartiensis was determined. KsHAOr lacks the tyrosine cross-link and is therefore tuned to reductive catalysis. The molecular model of the KsHAOr–KsDH complex at 2.6 Å resolution shows a heterododecameric (α6β6) assembly, which was also shown to be the oligomeric state in solution by analytical ultracentrifugation and multi-angle static light scattering. The 60-heme-containing protein complex reveals a unique extended electron transfer pathway and provides deeper insights into catalysis and electron transfer in reductive OCCs.
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21
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Two dedicated class C radical S-adenosylmethionine methyltransferases concertedly catalyse the synthesis of 7,8-dimethylmenaquinone. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:300-308. [DOI: 10.1016/j.bbabio.2018.01.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 01/24/2018] [Accepted: 01/28/2018] [Indexed: 12/24/2022]
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23
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Hein S, Witt S, Simon J. Clade II nitrous oxide respiration of Wolinella succinogenes depends on the NosG, -C1, -C2, -H electron transport module, NosB and a Rieske/cytochrome bc complex. Environ Microbiol 2017; 19:4913-4925. [PMID: 28925551 DOI: 10.1111/1462-2920.13935] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 09/14/2017] [Accepted: 09/16/2017] [Indexed: 01/20/2023]
Abstract
Microbial reduction of nitrous oxide (N2 O) is an environmentally significant process in the biogeochemical nitrogen cycle. However, it has been recognized only recently that the gene encoding N2 O reductase (nosZ) is organized in varying genetic contexts, thereby defining clade I (or 'typical') and clade II (or 'atypical') N2 O reductases and nos gene clusters. This study addresses the enzymology of the clade II Nos system from Wolinella succinogenes, a nitrate-ammonifying and N2 O-respiring Epsilonproteobacterium that contains a cytochrome c N2 O reductase (cNosZ). The characterization of single non-polar nos gene deletion mutants demonstrated that the NosG, -C1, -C2, -H and -B proteins were essential for N2 O respiration. Moreover, cells of a W. succinogenes mutant lacking a putative menaquinol-oxidizing Rieske/cytochrome bc complex (QcrABC) were found to be incapable of N2 O (and also nitrate) respiration. Proton motive menaquinol oxidation by N2 O is suggested, supported by the finding that the molar yield for W. succinogenes cells grown by N2 O respiration using formate as electron donor exceeded that of fumarate respiration by about 30%. The results demand revision of the electron transport chain model of clade II N2 O respiration and challenge the assumption that NosGH(NapGH)-type iron-sulfur proteins are menaquinol-reactive.
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Affiliation(s)
- Sascha Hein
- Microbial Energy Conversion and Biotechnology, Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 10, 64287 Darmstadt, Germany
| | - Samantha Witt
- Microbial Energy Conversion and Biotechnology, Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 10, 64287 Darmstadt, Germany
| | - Jörg Simon
- Microbial Energy Conversion and Biotechnology, Department of Biology, Technische Universität Darmstadt, Schnittspahnstraße 10, 64287 Darmstadt, Germany
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