1
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Hiis EG, Vick SHW, Molstad L, Røsdal K, Jonassen KR, Winiwarter W, Bakken LR. Unlocking bacterial potential to reduce farmland N 2O emissions. Nature 2024; 630:421-428. [PMID: 38811724 PMCID: PMC11168931 DOI: 10.1038/s41586-024-07464-3] [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: 11/27/2023] [Accepted: 04/25/2024] [Indexed: 05/31/2024]
Abstract
Farmed soils contribute substantially to global warming by emitting N2O (ref. 1), and mitigation has proved difficult2. Several microbial nitrogen transformations produce N2O, but the only biological sink for N2O is the enzyme NosZ, catalysing the reduction of N2O to N2 (ref. 3). Although strengthening the NosZ activity in soils would reduce N2O emissions, such bioengineering of the soil microbiota is considered challenging4,5. However, we have developed a technology to achieve this, using organic waste as a substrate and vector for N2O-respiring bacteria selected for their capacity to thrive in soil6-8. Here we have analysed the biokinetics of N2O reduction by our most promising N2O-respiring bacterium, Cloacibacterium sp. CB-01, its survival in soil and its effect on N2O emissions in field experiments. Fertilization with waste from biogas production, in which CB-01 had grown aerobically to about 6 × 109 cells per millilitre, reduced N2O emissions by 50-95%, depending on soil type. The strong and long-lasting effect of CB-01 is ascribed to its tenacity in soil, rather than its biokinetic parameters, which were inferior to those of other strains of N2O-respiring bacteria. Scaling our data up to the European level, we find that national anthropogenic N2O emissions could be reduced by 5-20%, and more if including other organic wastes. This opens an avenue for cost-effective reduction of N2O emissions for which other mitigation options are lacking at present.
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Affiliation(s)
- Elisabeth G Hiis
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Silas H W Vick
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Lars Molstad
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Kristine Røsdal
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | | | - Wilfried Winiwarter
- International Institute for Applied Systems Analysis, Laxenburg, Austria
- Institute of Environmental Engineering, University of Zielona Góra, Zielona Góra, Poland
| | - Lars R Bakken
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway.
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2
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Takahashi K, Oshiki M, Ruan C, Morinaga K, Toyofuku M, Nomura N, Johnson DR. Denitrification in low oxic environments increases the accumulation of nitrogen oxide intermediates and modulates the evolutionary potential of microbial populations. ENVIRONMENTAL MICROBIOLOGY REPORTS 2024; 16:e13221. [PMID: 38037543 PMCID: PMC10866065 DOI: 10.1111/1758-2229.13221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 11/15/2023] [Indexed: 12/02/2023]
Abstract
Denitrification in oxic environments occurs when a microorganism uses nitrogen oxides as terminal electron acceptors even though oxygen is available. While this phenomenon is well-established, its consequences on ecological and evolutionary processes remain poorly understood. We hypothesize here that denitrification in oxic environments can modify the accumulation profiles of nitrogen oxide intermediates with cascading effects on the evolutionary potentials of denitrifying microorganisms. To test this, we performed laboratory experiments with Paracoccus denitrificans and complemented them with individual-based computational modelling. We found that denitrification in low oxic environments significantly increases the accumulation of nitrite and nitric oxide. We further found that the increased accumulation of these intermediates has a negative effect on growth at low pH. Finally, we found that the increased negative effect at low pH increases the number of individuals that contribute to surface-associated growth. This increases the amount of genetic diversity that is preserved from the initial population, thus increasing the number of genetic targets for natural selection to act upon and resulting in higher evolutionary potentials. Together, our data highlight that denitrification in low oxic environments can affect the ecological processes and evolutionary potentials of denitrifying microorganisms by modifying the accumulation of nitrogen oxide intermediates.
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Affiliation(s)
- Kohei Takahashi
- Graduate School of Sciences and TechnologiesUniversity of TsukubaTsukubaIbarakiJapan
- Department of Environmental MicrobiologySwiss Federal Institute of Aquatic Science and Technology (Eawag)DübendorfSwitzerland
| | - Mamoru Oshiki
- Division of Environmental Engineering, Faculty of EngineeringHokkaido UniversitySapporoHokkaidoJapan
| | - Chujin Ruan
- Department of Environmental MicrobiologySwiss Federal Institute of Aquatic Science and Technology (Eawag)DübendorfSwitzerland
| | - Kana Morinaga
- Graduate School of Sciences and TechnologiesUniversity of TsukubaTsukubaIbarakiJapan
| | - Masanori Toyofuku
- Faculty of Life and Environmental SciencesUniversity of TsukubaTsukubaIbarakiJapan
- Microbiology Research Center for SustainabilityUniversity of TsukubaTsukubaIbarakiJapan
| | - Nobuhiko Nomura
- Faculty of Life and Environmental SciencesUniversity of TsukubaTsukubaIbarakiJapan
- Microbiology Research Center for SustainabilityUniversity of TsukubaTsukubaIbarakiJapan
| | - David R. Johnson
- Department of Environmental MicrobiologySwiss Federal Institute of Aquatic Science and Technology (Eawag)DübendorfSwitzerland
- Institute of Ecology and EvolutionUniversity of BernBernSwitzerland
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3
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Yoon S, Heo H, Han H, Song DU, Bakken LR, Frostegård Å, Yoon S. Suggested role of NosZ in preventing N 2O inhibition of dissimilatory nitrite reduction to ammonium. mBio 2023; 14:e0154023. [PMID: 37737639 PMCID: PMC10653820 DOI: 10.1128/mbio.01540-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 07/31/2023] [Indexed: 09/23/2023] Open
Abstract
IMPORTANCE Dissimilatory nitrate/nitrite reduction to ammonium (DNRA) is a microbial energy-conserving process that reduces NO3 - and/or NO2 - to NH4 +. Interestingly, DNRA-catalyzing microorganisms possessing nrfA genes are occasionally found harboring nosZ genes encoding nitrous oxide reductases, i.e., the only group of enzymes capable of removing the potent greenhouse gas N2O. Here, through a series of physiological experiments examining DNRA metabolism in one of such microorganisms, Bacillus sp. DNRA2, we have discovered that N2O may delay the transition to DNRA upon an oxic-to-anoxic transition, unless timely removed by the nitrous oxide reductases. These observations suggest a novel explanation as to why some nrfA-possessing microorganisms have retained nosZ genes: to remove N2O that may otherwise interfere with the transition from O2 respiration to DNRA.
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Affiliation(s)
- Sojung Yoon
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Hokwan Heo
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Heejoo Han
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Dong-Uk Song
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Lars R. Bakken
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Åsa Frostegård
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Sukhwan Yoon
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
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4
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Garrido-Amador P, Stortenbeker N, Wessels HJCT, Speth DR, Garcia-Heredia I, Kartal B. Enrichment and characterization of a nitric oxide-reducing microbial community in a continuous bioreactor. Nat Microbiol 2023; 8:1574-1586. [PMID: 37429908 PMCID: PMC10390337 DOI: 10.1038/s41564-023-01425-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 06/14/2023] [Indexed: 07/12/2023]
Abstract
Nitric oxide (NO) is a highly reactive and climate-active molecule and a key intermediate in the microbial nitrogen cycle. Despite its role in the evolution of denitrification and aerobic respiration, high redox potential and capacity to sustain microbial growth, our understanding of NO-reducing microorganisms remains limited due to the absence of NO-reducing microbial cultures obtained directly from the environment using NO as a substrate. Here, using a continuous bioreactor and a constant supply of NO as the sole electron acceptor, we enriched and characterized a microbial community dominated by two previously unknown microorganisms that grow at nanomolar NO concentrations and survive high amounts (>6 µM) of this toxic gas, reducing it to N2 with little to non-detectable production of the greenhouse gas nitrous oxide. These results provide insight into the physiology of NO-reducing microorganisms, which have pivotal roles in the control of climate-active gases, waste removal, and evolution of nitrate and oxygen respiration.
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Affiliation(s)
| | | | - Hans J C T Wessels
- Translational Metabolic Laboratory, Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Daan R Speth
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | | | - Boran Kartal
- Max Planck Institute for Marine Microbiology, Bremen, Germany.
- School of Science, Constructor University, Bremen, Germany.
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5
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Ray A, Spiro S. DksA, ppGpp, and RegAB Regulate Nitrate Respiration in Paracoccus denitrificans. J Bacteriol 2023; 205:e0002723. [PMID: 36920204 PMCID: PMC10127633 DOI: 10.1128/jb.00027-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 02/17/2023] [Indexed: 03/16/2023] Open
Abstract
The periplasmic (NAP) and membrane-associated (Nar) nitrate reductases of Paracoccus denitrificans are responsible for nitrate reduction under aerobic and anaerobic conditions, respectively. Expression of NAP is elevated in cells grown on a relatively reduced carbon and energy source (such as butyrate); it is believed that NAP contributes to redox homeostasis by coupling nitrate reduction to the disposal of excess reducing equivalents. Here, we show that deletion of either dksA1 (one of two dksA homologs in the P. denitrificans genome) or relA/spoT (encoding a bifunctional ppGpp synthetase and hydrolase) eliminates the butyrate-dependent increase in nap promoter and NAP enzyme activity. We conclude that ppGpp likely signals growth on a reduced substrate and, together with DksA1, mediates increased expression of the genes encoding NAP. Support for this model comes from the observation that nap promoter activity is increased in cultures exposed to a protein synthesis inhibitor that is known to trigger ppGpp synthesis in other organisms. We also show that, under anaerobic growth conditions, the redox-sensing RegAB two-component pair acts as a negative regulator of NAP expression and as a positive regulator of expression of the membrane-associated nitrate reductase Nar. The dksA1 and relA/spoT genes are conditionally synthetically lethal; the double mutant has a null phenotype for growth on butyrate and other reduced substrates while growing normally on succinate and citrate. We also show that the second dksA homolog (dksA2) and relA/spoT have roles in regulation of expression of the flavohemoglobin Hmp and in biofilm formation. IMPORTANCE Paracoccus denitrificans is a metabolically versatile Gram-negative bacterium that is used as a model for studies of respiratory metabolism. The organism can utilize nitrate as an electron acceptor for anaerobic respiration, reducing it to dinitrogen via nitrite, nitric oxide, and nitrous oxide. This pathway (known as denitrification) is important as a route for loss of fixed nitrogen from soil and as a source of the greenhouse gas nitrous oxide. Thus, it is important to understand those environmental and genetic factors that govern flux through the denitrification pathway. Here, we identify four proteins and a small molecule (ppGpp) which function as previously unknown regulators of expression of enzymes that reduce nitrate and oxidize nitric oxide.
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Affiliation(s)
- Ashvini Ray
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Stephen Spiro
- Department of Biological Sciences, University of Texas at Dallas, Richardson, Texas, USA
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6
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Preparation for Denitrification and Phenotypic Diversification at the Cusp of Anoxia: a Purpose for N 2O Reductase Vis-à-Vis Multiple Roles of O 2. Appl Environ Microbiol 2022; 88:e0105322. [PMID: 36250705 PMCID: PMC9642011 DOI: 10.1128/aem.01053-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Adaptation to anoxia by synthesizing a denitrification proteome costs metabolic energy, and the anaerobic respiration conserves less energy per electron than aerobic respiration. This implies a selective advantage of the stringent O2 repression of denitrification gene transcription, which is found in most denitrifying bacteria. In some bacteria, the metabolic burden of adaptation can be minimized further by phenotypic diversification, colloquially termed "bet-hedging," where all cells synthesize the N2O reductase (NosZ) but only a minority synthesize nitrite reductase (NirS), as demonstrated for the model strain Paracoccus denitrificans. We hypothesized that the cells lacking NirS would be entrapped in anoxia but with the possibility of escape if supplied with O2 or N2O. To test this, cells were exposed to gradual O2 depletion or sudden anoxia and subsequent spikes of O2 and N2O. The synthesis of NirS in single cells was monitored by using an mCherry-nirS fusion replacing the native nirS, and their growth was detected as dilution of green, fluorescent fluorescein isothiocyanate (FITC) stain. We demonstrate anoxic entrapment due to e--acceptor deprivation and show that O2 spiking leads to bet-hedging, while N2O spiking promotes NirS synthesis and growth in all cells carrying NosZ. The cells rescued by the N2O spike had much lower respiration rates than those rescued by the O2 spike, however, which could indicate that the well-known autocatalytic synthesis of NirS via NO production requires O2. Our results bring into relief a fitness advantage of pairing restrictive nirS expression with universal NosZ synthesis in energy-limited systems. IMPORTANCE Denitrifying bacteria have evolved elaborate regulatory networks securing their respiratory metabolism in environments with fluctuating oxygen concentrations. Here, we provide new insight regarding their bet-hedging in response to hypoxia, which minimizes their N2O emissions because all cells express NosZ, reducing N2O to N2, while a minority express NirS + Nor, reducing NO2- to N2O. We hypothesized that the cells without Nir were entrapped in anoxia, without energy to synthesize Nir, and that they could be rescued by short spikes of O2 or N2O. We confirm such entrapment and the rescue of all cells by an N2O spike but only a fraction by an O2 spike. The results shed light on the role of O2 repression in bet-hedging and generated a novel hypothesis regarding the autocatalytic nirS expression via NO production. Insight into the regulation of denitrification, including bet-hedging, holds a clue to understanding, and ultimately curbing, the escalating emissions of N2O, which contribute to anthropogenic climate forcing.
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7
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Guo K, Gao H. Physiological Roles of Nitrite and Nitric Oxide in Bacteria: Similar Consequences from Distinct Cell Targets, Protection, and Sensing Systems. Adv Biol (Weinh) 2021; 5:e2100773. [PMID: 34310085 DOI: 10.1002/adbi.202100773] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 06/19/2021] [Indexed: 12/22/2022]
Abstract
Nitrite and nitric oxide (NO) are two active nitrogen oxides that display similar biochemical properties, especially when interacting with redox-sensitive proteins (i.e., hemoproteins), an observation serving as the foundation of the notion that the antibacterial effect of nitrite is largely attributed to NO formation. However, a growing body of evidence suggests that they are largely treated as distinct molecules by bacterial cells. Although both nitrite and NO are formed and decomposed by enzymes participating in the transformation of these nitrogen species, NO can also be generated via amino acid metabolism by bacterial NO synthetase and scavenged by flavohemoglobin. NO seemingly interacts with all hemoproteins indiscriminately, whereas nitrite shows high specificity to heme-copper oxidases. Consequently, the homeostasis of redox-sensitive proteins may be responsible for the substantial difference in NO-targets identified to date among different bacteria. In addition, most protective systems against NO damage have no significant role in alleviating inhibitory effects of nitrite. Furthermore, when functioning as signal molecules, nitrite and NO are perceived by completely different sensing systems, through which they are linked to different biological processes.
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Affiliation(s)
- Kailun Guo
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Haichun Gao
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
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8
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Sen A, Imlay JA. How Microbes Defend Themselves From Incoming Hydrogen Peroxide. Front Immunol 2021; 12:667343. [PMID: 33995399 PMCID: PMC8115020 DOI: 10.3389/fimmu.2021.667343] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 03/19/2021] [Indexed: 12/02/2022] Open
Abstract
Microbes rely upon iron as a cofactor for many enzymes in their central metabolic processes. The reactive oxygen species (ROS) superoxide and hydrogen peroxide react rapidly with iron, and inside cells they can generate both enzyme and DNA damage. ROS are formed in some bacterial habitats by abiotic processes. The vulnerability of bacteria to ROS is also apparently exploited by ROS-generating host defense systems and bacterial competitors. Phagocyte-derived O 2 - can toxify captured bacteria by damaging unidentified biomolecules on the cell surface; it is unclear whether phagocytic H2O2, which can penetrate into the cell interior, also plays a role in suppressing bacterial invasion. Both pathogenic and free-living microbes activate defensive strategies to defend themselves against incoming H2O2. Most bacteria sense the H2O2via OxyR or PerR transcription factors, whereas yeast uses the Grx3/Yap1 system. In general these regulators induce enzymes that reduce cytoplasmic H2O2 concentrations, decrease the intracellular iron pools, and repair the H2O2-mediated damage. However, individual organisms have tailored these transcription factors and their regulons to suit their particular environmental niches. Some bacteria even contain both OxyR and PerR, raising the question as to why they need both systems. In lab experiments these regulators can also respond to nitric oxide and disulfide stress, although it is unclear whether the responses are physiologically relevant. The next step is to extend these studies to natural environments, so that we can better understand the circumstances in which these systems act. In particular, it is important to probe the role they may play in enabling host infection by microbial pathogens.
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Affiliation(s)
| | - James A. Imlay
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
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9
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Cole JA. Anaerobic bacterial response to nitric oxide stress: Widespread misconceptions and physiologically relevant responses. Mol Microbiol 2021; 116:29-40. [PMID: 33706420 DOI: 10.1111/mmi.14713] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 03/04/2021] [Accepted: 03/09/2021] [Indexed: 11/27/2022]
Abstract
How anaerobic bacteria protect themselves against nitric oxide-induced stress is controversial, not least because far higher levels of stress were used in the experiments on which most of the literature is based than bacteria experience in their natural environments. This results in chemical damage to enzymes that inactivates their physiological function. This review illustrates how transcription control mechanisms reveal physiological roles of the encoded gene products. Evidence that the hybrid cluster protein, Hcp, is a major high affinity NO reductase in anaerobic bacteria is reviewed: if so, its trans-nitrosation activity is a nonspecific secondary consequence of chemical inactivation. Whether the flavorubredoxin, NorV, is equally effective at such low [NO] is unknown. YtfE is proposed to be an enzyme rather than a source of iron for the repair of iron-sulfur proteins damaged by nitrosative stress. Any reaction catalyzed by YtfE needs to be revealed. The concentration of NO that accumulates in the cytoplasm of anaerobic bacteria is unknown, but indirect evidence indicates that it is in the pM to low nM range. Also unknown are the functions of the NO-inducible cytoplasmic proteins YgbA, YeaR, or YoaG. Experiments to resolve some of these questions are proposed.
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Affiliation(s)
- J A Cole
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
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10
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Functional interactions between nitrite reductase and nitric oxide reductase from Paracoccus denitrificans. Sci Rep 2019; 9:17234. [PMID: 31754148 PMCID: PMC6872814 DOI: 10.1038/s41598-019-53553-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 10/29/2019] [Indexed: 12/25/2022] Open
Abstract
Denitrification is a microbial pathway that constitutes an important part of the nitrogen cycle on earth. Denitrifying organisms use nitrate as a terminal electron acceptor and reduce it stepwise to nitrogen gas, a process that produces the toxic nitric oxide (NO) molecule as an intermediate. In this work, we have investigated the possible functional interaction between the enzyme that produces NO; the cd1 nitrite reductase (cd1NiR) and the enzyme that reduces NO; the c-type nitric oxide reductase (cNOR), from the model soil bacterium P. denitrificans. Such an interaction was observed previously between purified components from P. aeruginosa and could help channeling the NO (directly from the site of formation to the side of reduction), in order to protect the cell from this toxic intermediate. We find that electron donation to cNOR is inhibited in the presence of cd1NiR, presumably because cd1NiR binds cNOR at the same location as the electron donor. We further find that the presence of cNOR influences the dimerization of cd1NiR. Overall, although we find no evidence for a high-affinity, constant interaction between the two enzymes, our data supports transient interactions between cd1NiR and cNOR that influence enzymatic properties of cNOR and oligomerization properties of cd1NiR. We speculate that this could be of particular importance in vivo during metabolic switches between aerobic and denitrifying conditions.
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Abstract
SIGNIFICANCE The molecule nitric oxide (NO) has been shown to regulate behaviors in bacteria, including biofilm formation. NO detection and signaling in bacteria is typically mediated by hemoproteins such as the bis-(3',5')-cyclic dimeric adenosine monophosphate-specific phosphodiesterase YybT, the transcriptional regulator dissimilative nitrate respiration regulator, or heme-NO/oxygen binding (H-NOX) domains. H-NOX domains are well-characterized primary NO sensors that are capable of detecting nanomolar NO and influencing downstream signal transduction in many bacterial species. However, many bacteria, including the human pathogen Pseudomonas aeruginosa, respond to nanomolar concentrations of NO but do not contain an annotated H-NOX domain, indicating the existence of an additional nanomolar NO-sensing protein (NosP). Recent Advances: A newly discovered bacterial hemoprotein called NosP may also act as a primary NO sensor in bacteria, in addition to, or in place of, H-NOX. NosP was first described as a regulator of a histidine kinase signal transduction pathway that is involved in biofilm formation in P. aeruginosa. CRITICAL ISSUES The molecular details of NO signaling in bacteria are still poorly understood. There are still many bacteria that are NO responsive but do encode either H-NOX or NosP domains in their genomes. Even among bacteria that encode H-NOX or NosP, many questions remain. FUTURE DIRECTIONS The molecular mechanisms of NO regulation in many bacteria remain to be established. Future studies are required to gain knowledge about the mechanism of NosP signaling. Advancements on structural and molecular understanding of heme-based sensors in bacteria could lead to strategies to alleviate or control bacterial biofilm formation or persistent biofilm-related infections.
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Affiliation(s)
| | - Lisa-Marie Nisbett
- 2 Graduate Program in Biochemistry and Structural Biology, Stony Brook University , Stony Brook, New York
| | - Bezalel Bacon
- 2 Graduate Program in Biochemistry and Structural Biology, Stony Brook University , Stony Brook, New York
| | - Elizabeth Boon
- 1 Department of Chemistry, Stony Brook University , Stony Brook, New York.,2 Graduate Program in Biochemistry and Structural Biology, Stony Brook University , Stony Brook, New York.,3 Institute of Chemical Biology and Drug Design, Stony Brook University , Stony Brook, New York
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12
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Lycus P, Soriano-Laguna MJ, Kjos M, Richardson DJ, Gates AJ, Milligan DA, Frostegård Å, Bergaust L, Bakken LR. A bet-hedging strategy for denitrifying bacteria curtails their release of N 2O. Proc Natl Acad Sci U S A 2018; 115:11820-11825. [PMID: 30385636 PMCID: PMC6243289 DOI: 10.1073/pnas.1805000115] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
When oxygen becomes limiting, denitrifying bacteria must prepare for anaerobic respiration by synthesizing the reductases NAR (NO3- → NO2-), NIR (NO2- → NO), NOR (2NO → N2O), and NOS (N2O → N2), either en bloc or sequentially, to avoid entrapment in anoxia without energy. Minimizing the metabolic burden of this precaution is a plausible fitness trait, and we show that the model denitrifier Paracoccus denitrificans achieves this by synthesizing NOS in all cells, while only a minority synthesize NIR. Phenotypic diversification with regards to NIR is ascribed to stochastic initiation of gene transcription, which becomes autocatalytic via NO production. Observed gas kinetics suggest that such bet hedging is widespread among denitrifying bacteria. Moreover, in response to oxygenation, P. denitrificans preserves NIR in the poles of nongrowing persister cells, ready to switch to anaerobic respiration in response to sudden anoxia. Our findings add dimensions to the regulatory biology of denitrification and identify regulatory traits that decrease N2O emissions.
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Affiliation(s)
- Pawel Lycus
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1430 Ås, Norway
| | | | - Morten Kjos
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1430 Ås, Norway
| | - David John Richardson
- School of Biological Sciences, University of East Anglia, NR4 7TJ Norwich, United Kingdom
| | - Andrew James Gates
- School of Biological Sciences, University of East Anglia, NR4 7TJ Norwich, United Kingdom
| | - Daniel Aleksanteri Milligan
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1430 Ås, Norway
| | - Åsa Frostegård
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1430 Ås, Norway
| | - Linda Bergaust
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1430 Ås, Norway;
| | - Lars Reier Bakken
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1430 Ås, Norway;
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13
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Milker S, Fink MJ, Oberleitner N, Ressmann AK, Bornscheuer UT, Mihovilovic MD, Rudroff F. Kinetic Modeling of an Enzymatic Redox Cascade In Vivo Reveals Bottlenecks Caused by Cofactors. ChemCatChem 2017. [DOI: 10.1002/cctc.201700573] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Sofia Milker
- Institute of Applied Chemistry; TU Wien; Getreidemarkt 9/163-OC 1060 Vienna Austria
| | - Michael J. Fink
- Department of Chemistry and Chemical Biology; Harvard University; 12 Oxford St Cambridge MA 02138 USA
| | - Nikolin Oberleitner
- Institute of Applied Chemistry; TU Wien; Getreidemarkt 9/163-OC 1060 Vienna Austria
| | - Anna K. Ressmann
- Institute of Applied Chemistry; TU Wien; Getreidemarkt 9/163-OC 1060 Vienna Austria
| | - Uwe T. Bornscheuer
- Institute of Biochemistry, Dept. of Biotechnology & Enzyme Catalysis; Greifswald University; Felix-Hausdorff-Str. 4 17489 Greifswald Germany
| | - Marko D. Mihovilovic
- Institute of Applied Chemistry; TU Wien; Getreidemarkt 9/163-OC 1060 Vienna Austria
| | - Florian Rudroff
- Institute of Applied Chemistry; TU Wien; Getreidemarkt 9/163-OC 1060 Vienna Austria
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14
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Abstract
Low concentrations of nitric oxide (NO) modulate varied behaviours in bacteria including biofilm dispersal and quorum sensing-dependent light production. H-NOX (haem-nitric oxide/oxygen binding) is a haem-bound protein domain that has been shown to be involved in mediating these bacterial responses to NO in several organisms. However, many bacteria that respond to nanomolar concentrations of NO do not contain an annotated H-NOX domain. Nitric oxide sensing protein (NosP), a newly discovered bacterial NO-sensing haemoprotein, may fill this role. The focus of this review is to discuss structure, ligand binding, and activation of H-NOX proteins, as well as to discuss the early evidence for NO sensing and regulation by NosP domains. Further, these findings are connected to the regulation of bacterial biofilm phenotypes and symbiotic relationships.
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Affiliation(s)
- Bezalel Bacon
- Stony Brook University, Stony Brook, NY, United States
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15
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Abstract
Nitric oxide (NO) is a freely diffusible, radical gas that has now been established as an integral signaling molecule in eukaryotes and bacteria. It has been demonstrated that NO signaling is initiated upon ligation to the heme iron of an H-NOX domain in mammals and in some bacteria. Bacterial H-NOX proteins have been found to interact with enzymes that participate in signaling pathways and regulate bacterial processes such as quorum sensing, biofilm formation, and symbiosis. Here, we review the biochemical characterization of these signaling pathways and, where available, describe how ligation of NO to H-NOX specifically regulates the activity of these pathways and their associated bacterial phenotypes.
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Affiliation(s)
- Lisa-Marie Nisbett
- Graduate Program in Biochemistry and Structural Biology, Stony Brook University, Stony Brook, NY, 11794-3400
| | - Elizabeth M. Boon
- Department of Chemistry, Stony Brook University, Stony Brook, NY, 11794-3400
- Institute of Chemical Biology & Drug Discovery, Stony Brook University, Stony Brook, NY, 11794-3400
- Graduate Program in Biochemistry and Structural Biology, Stony Brook University, Stony Brook, NY, 11794-3400
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16
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Wang J, Vine CE, Balasiny BK, Rizk J, Bradley CL, Tinajero-Trejo M, Poole RK, Bergaust LL, Bakken LR, Cole JA. The roles of the hybrid cluster protein, Hcp and its reductase, Hcr, in high affinity nitric oxide reduction that protects anaerobic cultures ofEscherichia coliagainst nitrosative stress. Mol Microbiol 2016; 100:877-92. [DOI: 10.1111/mmi.13356] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/13/2016] [Indexed: 01/24/2023]
Affiliation(s)
- Jing Wang
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - Claire E. Vine
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - Basema K. Balasiny
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - John Rizk
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - Charlene L. Bradley
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
| | - Mariana Tinajero-Trejo
- Department of Molecular Biology & Biotechnology; University of Sheffield, Firth Court, Western Bank; Sheffield S10 2TN UK
| | - Robert K. Poole
- Department of Molecular Biology & Biotechnology; University of Sheffield, Firth Court, Western Bank; Sheffield S10 2TN UK
| | | | - Lars R. Bakken
- Norwegian University of Life Science; PO box 5003 N-1432 Ås Norway
| | - Jeffrey A. Cole
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham; Birmingham B15 2TT UK
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