1
|
Rathnayaka SC, Mankad NP. Coordination chemistry of the Cu Z site in nitrous oxide reductase and its synthetic mimics. Coord Chem Rev 2021; 429:213718. [PMID: 33692589 PMCID: PMC7939133 DOI: 10.1016/j.ccr.2020.213718] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Atmospheric nitrous oxide (N2O) has garnered significant attention recently due to its dual roles as an ozone depletion agent and a potent greenhouse gas. Anthropogenic N2O emissions occur primarily through agricultural disruption of nitrogen homeostasis causing N2O to build up in the atmosphere. The enzyme responsible for N2O fixation within the geochemical nitrogen cycle is nitrous oxide reductase (N2OR), which catalyzes 2H+/2e- reduction of N2O to N2 and H2O at a tetranuclear active site, CuZ. In this review, the coordination chemistry of CuZ is reviewed. Recent advances in the understanding of biological CuZ coordination chemistry is discussed, as are significant breakthroughs in synthetic modeling of CuZ that have emerged in recent years. The latter topic includes both structurally faithful, synthetic [Cu4(µ4-S)] clusters that are able to reduce N2O, as well as dicopper motifs that shed light on reaction pathways available to the critical CuI-CuIV cluster edge of CuZ. Collectively, these advances in metalloenzyme studies and synthetic model systems provide meaningful knowledge about the physiologically relevant coordination chemistry of CuZ but also open new questions that will pose challenges in the near future.
Collapse
Affiliation(s)
- Suresh C. Rathnayaka
- Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor St., Chicago, IL 60607, United States
| | - Neal P. Mankad
- Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor St., Chicago, IL 60607, United States
| |
Collapse
|
2
|
Roy S, Nirakar P, Yong NGH, Stefan W. Denitrification kinetics indicates nitrous oxide uptake is unaffected by electron competition in Accumulibacter. WATER RESEARCH 2021; 189:116557. [PMID: 33220610 DOI: 10.1016/j.watres.2020.116557] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 10/04/2020] [Accepted: 10/22/2020] [Indexed: 06/11/2023]
Abstract
Denitrifying phosphorus removal is a cost and energy efficient treatment technology that relies on polyphosphate accumulating organisms (DPAOs) utilizing nitrate or nitrite as terminal electron acceptor. Denitrification is a multistep process, but many organisms do not possess the complete pathway, leading to the accumulation of intermediates such as nitrous oxide (N2O), a potent greenhouse gas and ozone depleting substance. Candidatus Accumulibacter organisms are prevalent in denitrifying phosphorus removal processes and, according to genomic analyses, appear to vary in their denitrification abilities based on their lineage. Denitrification kinetics and nitrous oxide accumulation in the absence of inhibition from free nitrous acid is a strong indicator of denitrification capabilities of Accumulibacter exposed long-term to nitrate or nitrite as electron acceptor. Thus, we investigated the preferential use of the nitrogen oxides involved in denitrification and nitrous oxide accumulation in two enrichments of Accumulibacter and a competitor - the glycogen accumulating organism Candidatus Competibacter. We modified a metabolic model to predict phosphorus removal and denitrification rates when nitrate, nitrite or N2O were added as electron acceptors in different combinations. Unlike previous studies, no N2O accumulation was observed for Accumulibacter in the presence of multiple electron acceptors. Electron competition did not limit denitrification kinetics or lead to N2O accumulation in Accumulibacter or Competibacter. Despite the presence of sufficient internal storage polymers (polyhydroxyalkanoates, or PHA) as energy source for each denitrification step, the extent of denitrification observed was dependent on the dominant organism in the enrichment. Accumulibacter showed complete denitrification, whereas Competibacter denitrification was limited to reduction of nitrate to nitrite. These findings indicate that DPAOs can contribute to lowering N2O emissions in the presence of multiple electron acceptors under partial nitritation conditions.
Collapse
Affiliation(s)
- Samarpita Roy
- Singapore Centre for Environmental Life Sciences Engineering, National University of Singapore, Singapore 119077, Singapore.
| | - Pradhan Nirakar
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore.
| | - N G How Yong
- NUS Environmental Research Institute, National University of Singapore, 5A Engineering Drive 1, Singapore 117411, Singapore.
| | - Wuertz Stefan
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639798, Singapore.
| |
Collapse
|
3
|
Dutta N, Haldar S, Majumder A, Vijaykumar G, Carrella L, Bera M. Synthesis, structure and properties of a novel self-assembled tetranuclear copper(II) complex derived from carboxylate-based multidentate ligand. INORG CHEM COMMUN 2020. [DOI: 10.1016/j.inoche.2020.108208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
4
|
Ferousi C, Majer SH, DiMucci IM, Lancaster KM. Biological and Bioinspired Inorganic N-N Bond-Forming Reactions. Chem Rev 2020; 120:5252-5307. [PMID: 32108471 PMCID: PMC7339862 DOI: 10.1021/acs.chemrev.9b00629] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The metallobiochemistry underlying the formation of the inorganic N-N-bond-containing molecules nitrous oxide (N2O), dinitrogen (N2), and hydrazine (N2H4) is essential to the lifestyles of diverse organisms. Similar reactions hold promise as means to use N-based fuels as alternative carbon-free energy sources. This review discusses research efforts to understand the mechanisms underlying biological N-N bond formation in primary metabolism and how the associated reactions are tied to energy transduction and organismal survival. These efforts comprise studies of both natural and engineered metalloenzymes as well as synthetic model complexes.
Collapse
Affiliation(s)
- Christina Ferousi
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Sean H Majer
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Ida M DiMucci
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
| |
Collapse
|
5
|
Al-Mamun A, Jafary T, Baawain MS, Rahman S, Choudhury MR, Tabatabaei M, Lam SS. Energy recovery and carbon/nitrogen removal from sewage and contaminated groundwater in a coupled hydrolytic-acidogenic sequencing batch reactor and denitrifying biocathode microbial fuel cell. ENVIRONMENTAL RESEARCH 2020; 183:109273. [PMID: 32105886 DOI: 10.1016/j.envres.2020.109273] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 02/09/2020] [Accepted: 02/18/2020] [Indexed: 06/10/2023]
Abstract
Developing cost-effective technology for treatment of sewage and nitrogen-containing groundwater is one of the crucial challenges of global water industries. Microbial fuel cells (MFCs) oxidize organics from sewage by exoelectrogens on anode to produce electricity while denitrifiers on cathode utilize the generated electricity to reduce nitrogen from contaminated groundwater. As the exoelectrogens are incapable of oxidizing insoluble, polymeric, and complex organics, a novel integration of an anaerobic sequencing batch reactor (ASBR) prior to the MFC simultaneously achieve hydrolytic-acidogenic conversion of complex organics, boost power recovery, and remove Carbon/Nitrogen (C/N) from the sewage and groundwater. The results obtained revealed increases in the fractions of soluble organics and volatile fatty acids in pretreated sewage by 52 ± 19% and 120 ± 40%, respectively. The optimum power and current generation with the pretreated sewage were 7.1 W m-3 and 45.88 A m-3, respectively, corresponding to 8% and 10% improvements compared to untreated sewage. Moreover, the integration of the ASBR with the biocathode MFC led to 217% higher carbon and 136% higher nitrogen removal efficiencies compared to the similar system without ASBR. The outcomes of the present study represent the promising prospects of using ASBR pretreatment and successive utilization of solubilized organics in denitrifying biocathode MFCs for simultaneous energy recovery and C/N removal from both sewage and nitrate nitrogen-contaminated groundwater.
Collapse
Affiliation(s)
- Abdullah Al-Mamun
- Department of Civil and Architectural Engineering, Sultan Qaboos University, P.O. Box 33, Al-Khoud 123, Muscat, Oman.
| | - Tahereh Jafary
- Department of Civil and Architectural Engineering, Sultan Qaboos University, P.O. Box 33, Al-Khoud 123, Muscat, Oman; Process Engineering Department, International Maritime College, Sohar, Oman
| | - Mahad Said Baawain
- Department of Civil and Architectural Engineering, Sultan Qaboos University, P.O. Box 33, Al-Khoud 123, Muscat, Oman
| | - Sadik Rahman
- Department of Civil and Architectural Engineering, Sultan Qaboos University, P.O. Box 33, Al-Khoud 123, Muscat, Oman
| | - Mahbuboor Rahman Choudhury
- Department of Civil and Environmental Engineering, Manhattan College, 4513 Manhattan College Parkway, Riverdale, NY, 10471, USA
| | - Meisam Tabatabaei
- Faculty of Plantation and Agrotechnology, Universiti Teknologi MARA, 40450, Shah Alam, Selangor, Malaysia; Biofuel Research Team (BRTeam), Karaj, Iran; Microbial Biotechnology Department, Agricultural Biotechnology Research Institute of Iran (ABRII), Agricultural Research, Extension, and Education Organization (AREEO), Karaj, Iran; Faculty of Mechanical Engineering, Ho Chi Minh City University of Transport, Ho Chi Minh City, Viet Nam
| | - Su Shiung Lam
- Pyrolysis Technology Research Group, Institute of Tropical Aquaculture and Fisheries Research (Akuatrop) & Institute of Tropical Biodiversity and Sustainable Development (Bio-D Tropika), Universiti Malaysia Terengganu, 21030, Kuala Terengganu, Terengganu, Malaysia
| |
Collapse
|
6
|
Carreira C, Dos Santos MMC, Pauleta SR, Moura I. Proton-coupled electron transfer mechanisms of the copper centres of nitrous oxide reductase from Marinobacter hydrocarbonoclasticus - An electrochemical study. Bioelectrochemistry 2020; 133:107483. [PMID: 32120320 DOI: 10.1016/j.bioelechem.2020.107483] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 02/13/2020] [Accepted: 02/13/2020] [Indexed: 11/16/2022]
Abstract
Reduction of N2O to N2 is catalysed by nitrous oxide reductase in the last step of the denitrification pathway. This multicopper enzyme has an electron transferring centre, CuA, and a tetranuclear copper-sulfide catalytic centre, "CuZ", which exists as CuZ*(4Cu1S) or CuZ(4Cu2S). The redox behaviour of these metal centres in Marinobacter hydrocarbonoclasticus nitrous oxide reductase was investigated by potentiometry and for the first time by direct electrochemistry. The reduction potential of CuA and CuZ(4Cu2S) was estimated by potentiometry to be +275 ± 5 mV and +65 ± 5 mV vs SHE, respectively, at pH 7.6. A proton-coupled electron transfer mechanism governs CuZ(4Cu2S) reduction potential, due to the protonation/deprotonation of Lys397 with a pKox of 6.0 ± 0.1 and a pKred of 9.2 ± 0.1. The reduction potential of CuA, in enzyme samples with CuZ*(4Cu1S), is controlled by protonation of the coordinating histidine residues in a two-proton coupled electron transfer process. In the cyclic voltammograms, two redox pairs were identified corresponding to CuA and CuZ(4Cu2S), with no additional signals being detected that could be attributed to CuZ*(4Cu1S). However, an enhanced cathodic signal for the activated enzyme was observed under turnover conditions, which is explained by the binding of nitrous oxide to CuZ0(4Cu1S), an intermediate species in the catalytic cycle.
Collapse
Affiliation(s)
- Cíntia Carreira
- Microbial Stress Lab, UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal; Biological Chemistry Lab, LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal
| | - Margarida M C Dos Santos
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Sofia R Pauleta
- Microbial Stress Lab, UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal. http://docentes.fct.unl.pt/srp/
| | - Isabel Moura
- Biological Chemistry Lab, LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal.
| |
Collapse
|
7
|
Bacterial nitrous oxide respiration: electron transport chains and copper transfer reactions. Adv Microb Physiol 2019; 75:137-175. [PMID: 31655736 DOI: 10.1016/bs.ampbs.2019.07.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Biologically catalyzed nitrous oxide (N2O, laughing gas) reduction to dinitrogen gas (N2) is a desirable process in the light of ever-increasing atmospheric concentrations of this important greenhouse gas and ozone depleting substance. A diverse range of bacterial species produce the copper cluster-containing enzyme N2O reductase (NosZ), which is the only known enzyme that converts N2O to N2. Based on phylogenetic analyses, NosZ enzymes have been classified into clade I or clade II and it has turned out that this differentiation is also applicable to nos gene clusters (NGCs) and some physiological traits of the corresponding microbial cells. The NosZ enzyme is the terminal reductase of anaerobic N2O respiration, in which electrons derived from a donor substrate are transferred to NosZ by means of an electron transport chain (ETC) that conserves energy through proton motive force generation. This chapter presents models of the ETCs involved in clade I and clade II N2O respiration as well as of the respective NosZ maturation and maintenance processes. Despite differences in NGCs and growth yields of N2O-respiring microorganisms, the deduced bioenergetic framework in clade I and clade II N2O respiration is assumed to be equivalent. In both cases proton motive quinol oxidation by N2O is thought to be catalyzed by the Q cycle mechanism of a membrane-bound Rieske/cytochrome bc complex. However, clade I and clade II organisms are expected to differ significantly in terms of auxiliary electron transport processes as well as NosZ active site maintenance and repair.
Collapse
|
8
|
|
9
|
Cheng HY, Tian XD, Li CH, Wang SS, Su SG, Wang HC, Zhang B, Sharif HMA, Wang AJ. Microbial Photoelectrotrophic Denitrification as a Sustainable and Efficient Way for Reducing Nitrate to Nitrogen. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:12948-12955. [PMID: 29025260 DOI: 10.1021/acs.est.7b02557] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Biological removal of nitrate, a highly concerning contaminant, is limited when the aqueous environment lacks bioavailable electron donors. In this study, we demonstrated, for the first time, that bacteria can directly use the electrons originated from the photoelectrochemical process to carry out the denitrification. In such photoelectrotrophic denitrification (PEDeN) systems (denitrification biocathode coupling with TiO2 photoanode), nitrogen removal was verified solely relying on the illumination dosing without consuming additional chemical reductant or electric power. Under the UV illumination (30 mW·cm-2, wavelength at 380 ± 20 nm), nitrate reduction in PEDeN apparently followed the first-order kinetics with a constant of 0.13 ± 0.023 h-1. Nitrate was found to be almost completely converted to nitrogen gas at the end of batch test. Compared to the electrotrophic denitrification systems driven by organics (OEDeN, biocathode/acetate consuming bioanode) or electricity (EEDeN, biocathode/abiotic anode), the denitrification rate in PEDeN equaled that in OEDeN with a COD/N ratio of 9.0 or that in EEDeN with an applied voltage at 2.0 V. This study provides a sustainable technical approach for eliminating nitrate from water. PEDeN as a novel microbial metabolism may shed further light onto the role of sunlight played in the nitrogen cycling in certain semiconductive and conductive minerals-enriched aqueous environment.
Collapse
Affiliation(s)
- Hao-Yi Cheng
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , No. 18 Shuangqing Road, Haidian District, Beijing 100085, China
| | - Xia-Di Tian
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , No. 18 Shuangqing Road, Haidian District, Beijing 100085, China
- University of Chinese Academy of Sciences , No. 19 Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Chuan-Hao Li
- School of Environmental Science and Engineering, Sun Yat-Sen University , East Campus, No. 135 Waihuan Road, Daxuecheng District, Guangzhou 510006, China
| | - Shu-Sen Wang
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , No. 18 Shuangqing Road, Haidian District, Beijing 100085, China
- University of Chinese Academy of Sciences , No. 19 Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Shi-Gang Su
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , No. 18 Shuangqing Road, Haidian District, Beijing 100085, China
- University of Chinese Academy of Sciences , No. 19 Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Hong-Cheng Wang
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , No. 18 Shuangqing Road, Haidian District, Beijing 100085, China
- University of Chinese Academy of Sciences , No. 19 Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Bo Zhang
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , No. 18 Shuangqing Road, Haidian District, Beijing 100085, China
| | - Hafiz Muhammad Adeel Sharif
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , No. 18 Shuangqing Road, Haidian District, Beijing 100085, China
- University of Chinese Academy of Sciences , No. 19 Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Ai-Jie Wang
- Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , No. 18 Shuangqing Road, Haidian District, Beijing 100085, China
- University of Chinese Academy of Sciences , No. 19 Yuquan Road, Shijingshan District, Beijing 100049, China
| |
Collapse
|
10
|
The catalytic cycle of nitrous oxide reductase - The enzyme that catalyzes the last step of denitrification. J Inorg Biochem 2017; 177:423-434. [PMID: 28927704 DOI: 10.1016/j.jinorgbio.2017.09.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 09/02/2017] [Accepted: 09/08/2017] [Indexed: 01/27/2023]
Abstract
The reduction of the potent greenhouse gas nitrous oxide requires a catalyst to overcome the large activation energy barrier of this reaction. Its biological decomposition to the inert dinitrogen can be accomplished by denitrifiers through nitrous oxide reductase, the enzyme that catalyzes the last step of the denitrification, a pathway of the biogeochemical nitrogen cycle. Nitrous oxide reductase is a multicopper enzyme containing a mixed valence CuA center that can accept electrons from small electron shuttle proteins, triggering electron flow to the catalytic sulfide-bridged tetranuclear copper "CuZ center". This enzyme has been isolated with its catalytic center in two forms, CuZ*(4Cu1S) and CuZ(4Cu2S), proven to be spectroscopic and structurally different. In the last decades, it has been a challenge to characterize the properties of this complex enzyme, due to the different oxidation states observed for each of its centers and the heterogeneity of its preparations. The substrate binding site in those two "CuZ center" forms and which is the active form of the enzyme is still a matter of debate. However, in the last years the application of different spectroscopies, together with theoretical calculations have been useful in answering these questions and in identifying intermediate species of the catalytic cycle. An overview of the spectroscopic, kinetics and structural properties of the two forms of the catalytic "CuZ center" is given here, together with the current knowledge on nitrous oxide reduction mechanism by nitrous oxide reductase and its intermediate species.
Collapse
|
11
|
Solomon EI, Heppner DE, Johnston EM, Ginsbach JW, Cirera J, Qayyum M, Kieber-Emmons MT, Kjaergaard CH, Hadt RG, Tian L. Copper active sites in biology. Chem Rev 2014; 114:3659-853. [PMID: 24588098 PMCID: PMC4040215 DOI: 10.1021/cr400327t] [Citation(s) in RCA: 1133] [Impact Index Per Article: 113.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
| | - David E. Heppner
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | - Jake W. Ginsbach
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Jordi Cirera
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Munzarin Qayyum
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | | | - Ryan G. Hadt
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Li Tian
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| |
Collapse
|
12
|
Miao Z, Zeng W, Wang S, Peng Y, Cao G, Weng D, Xue G, Yang Q. Effect of temperature on anoxic metabolism of nitrites to nitrous oxide by polyphosphate accumulating organisms. J Environ Sci (China) 2014; 26:264-273. [PMID: 25076517 DOI: 10.1016/s1001-0742(13)60406-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Temperature is an important physical factor, which strongly influences biomass and metabolic activity. In this study, the effects of temperature on the anoxic metabolism of nitrite (NO2(-)) to nitrous oxide (N2O) by polyphosphate accumulating organisms, and the process of the accumulation of N2O (during nitrite reduction), which acts as an electron acceptor, were investigated using 91% +/- 4% Candidatus Accumulibacter phosphatis sludge. The results showed that N2O is accumulated when Accumulibacter first utilize nitrite instead of oxygen as the sole electron acceptor during the denitrifying phosphorus removal process. Properties such as nitrite reduction rate, phosphorus uptake rate, N2O reduction rate, and polyhydroxyalkanoate degradation rate were all influenced by temperature variation (over the range from 10 to 30 degrees C reaching maximum values at 25 degrees C). The reduction rate of N2O by N2O reductase was more sensitive to temperature when N2O was utilized as the sole electron acceptor instead of N2O, and the N2O reduction rates, ranging from 0.48 to 3.53 N20-N/(hr x g VSS), increased to 1.45 to 8.60 mg N2O-N/(hr x g VSS). The kinetics processes for temperature variation of 10 to 30 degrees C were (theta1 = 1.140-1.216 and theta2 = 1.139-1.167). In the range of 10 degrees C to 30 degrees C, almost all of the anoxic stoichiometry was sensitive to temperature changes. In addition, a rise in N2O reduction activity leading to a decrease in N2O accumulation in long term operations at the optimal temperature (27 degrees C calculated by the Arrhenius model).
Collapse
|
13
|
Simone D, Bay DC, Leach T, Turner RJ. Diversity and evolution of bacterial twin arginine translocase protein, TatC, reveals a protein secretion system that is evolving to fit its environmental niche. PLoS One 2013; 8:e78742. [PMID: 24236045 PMCID: PMC3827258 DOI: 10.1371/journal.pone.0078742] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 09/20/2013] [Indexed: 11/18/2022] Open
Abstract
Background The twin-arginine translocation (Tat) protein export system enables the transport of fully folded proteins across a membrane. This system is composed of two integral membrane proteins belonging to TatA and TatC protein families and in some systems a third component, TatB, a homolog of TatA. TatC participates in substrate protein recognition through its interaction with a twin arginine leader peptide sequence. Methodology/Principal Findings The aim of this study was to explore TatC diversity, evolution and sequence conservation in bacteria to identify how TatC is evolving and diversifying in various bacterial phyla. Surveying bacterial genomes revealed that 77% of all species possess one or more tatC loci and half of these classes possessed only tatC and tatA genes. Phylogenetic analysis of diverse TatC homologues showed that they were primarily inherited but identified a small subset of taxonomically unrelated bacteria that exhibited evidence supporting lateral gene transfer within an ecological niche. Examination of bacilli tatCd/tatCy isoform operons identified a number of known and potentially new Tat substrate genes based on their frequent association to tatC loci. Evolutionary analysis of these Bacilli isoforms determined that TatCy was the progenitor of TatCd. A bacterial TatC consensus sequence was determined and highlighted conserved and variable regions within a three dimensional model of the Escherichia coli TatC protein. Comparative analysis between the TatC consensus sequence and Bacilli TatCd/y isoform consensus sequences revealed unique sites that may contribute to isoform substrate specificity or make TatA specific contacts. Synonymous to non-synonymous nucleotide substitution analyses of bacterial tatC homologues determined that tatC sequence variation differs dramatically between various classes and suggests TatC specialization in these species. Conclusions/Significance TatC proteins appear to be diversifying within particular bacterial classes and its specialization may be driven by the substrates it transports and the environment of its host.
Collapse
Affiliation(s)
- Domenico Simone
- Institute of Biomembranes and Bioenergetics, National Research Council, Bari, Bari, Italy
| | - Denice C. Bay
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Thorin Leach
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Raymond J. Turner
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
- * E-mail:
| |
Collapse
|
14
|
|
15
|
Direct electron transfer from pseudoazurin to nitrous oxide reductase in catalytic N2O reduction. J Inorg Biochem 2012; 115:163-73. [DOI: 10.1016/j.jinorgbio.2012.07.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 07/09/2012] [Accepted: 07/10/2012] [Indexed: 11/22/2022]
|
16
|
Sundararajan M, Neese F. Detailed QM/MM study of the Electron Paramagnetic Resonance Parameters of Nitrosyl Myoglobin. J Chem Theory Comput 2012; 8:563-74. [DOI: 10.1021/ct200401q] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Mahesh Sundararajan
- Max-Planck Institutfür Bioanorganische Chemie, Stiftstrasse 32-34, D-45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck Institutfür Bioanorganische Chemie, Stiftstrasse 32-34, D-45470 Mülheim an der Ruhr, Germany
| |
Collapse
|
17
|
Zhou Y, Oehmen A, Lim M, Vadivelu V, Ng WJ. The role of nitrite and free nitrous acid (FNA) in wastewater treatment plants. WATER RESEARCH 2011; 45:4672-82. [PMID: 21762944 DOI: 10.1016/j.watres.2011.06.025] [Citation(s) in RCA: 237] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 06/17/2011] [Accepted: 06/21/2011] [Indexed: 05/06/2023]
Abstract
Nitrite is known to accumulate in wastewater treatment plants (WWTPs) under certain environmental conditions. The protonated form of nitrite, free nitrous acid (FNA), has been found to cause severe inhibition to numerous bioprocesses at WWTPs. However, this inhibitory effect of FNA may possibly be gainfully exploited, such as repressing nitrite oxidizing bacteria (NOB) growth to achieve N removal via the nitrite shortcut. However, the inhibition threshold of FNA to repress NOB (∼0.02 mg HNO2-N/L) may also inhibit other bioprocesses. This paper reviews the inhibitory effects of FNA on nitrifiers, denitrifiers, anammox bacteria, phosphorus accumulating organisms (PAO), methanogens, and other microorganisms in populations used in WWTPs. The possible inhibition mechanisms of FNA on microorganisms are discussed and compared. It is concluded that a single inhibition mechanism is not sufficient to explain the negative impacts of FNA on microbial metabolisms and that multiple inhibitory effects can be generated from FNA. The review would suggest further research is necessary before the FNA inhibition mechanisms can be more effectively used to optimize WWTP bioprocesses. Perspectives on research directions, how the outcomes may be used to manipulate bioprocesses and the overall implications of FNA on WWTPs are also discussed.
Collapse
Affiliation(s)
- Yan Zhou
- Advanced Environmental Biotechnology Centre (AEBC), Nanyang Environment and Water Research Institute (NEWRI), Nanyang Technological University, School of Biological Science, Level N-B2-01, 60 Nanyang Avenue, Singapore 639798, Singapore.
| | | | | | | | | |
Collapse
|
18
|
Pomowski A, Zumft WG, Kroneck PMH, Einsle O. N2O binding at a [4Cu:2S] copper–sulphur cluster in nitrous oxide reductase. Nature 2011; 477:234-7. [DOI: 10.1038/nature10332] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Accepted: 06/23/2011] [Indexed: 12/21/2022]
|
19
|
Dell'acqua S, Moura I, Moura JJG, Pauleta SR. The electron transfer complex between nitrous oxide reductase and its electron donors. J Biol Inorg Chem 2011; 16:1241-54. [PMID: 21739254 DOI: 10.1007/s00775-011-0812-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 06/20/2011] [Indexed: 11/25/2022]
Abstract
Identifying redox partners and the interaction surfaces is crucial for fully understanding electron flow in a respiratory chain. In this study, we focused on the interaction of nitrous oxide reductase (N(2)OR), which catalyzes the final step in bacterial denitrification, with its physiological electron donor, either a c-type cytochrome or a type 1 copper protein. The comparison between the interaction of N(2)OR from three different microorganisms, Pseudomonas nautica, Paracoccus denitrificans, and Achromobacter cycloclastes, with their physiological electron donors was performed through the analysis of the primary sequence alignment, electrostatic surface, and molecular docking simulations, using the bimolecular complex generation with global evaluation and ranking algorithm. The docking results were analyzed taking into account the experimental data, since the interaction is suggested to have either a hydrophobic nature, in the case of P. nautica N(2)OR, or an electrostatic nature, in the case of P. denitrificans N(2)OR and A. cycloclastes N(2)OR. A set of well-conserved residues on the N(2)OR surface were identified as being part of the electron transfer pathway from the redox partner to N(2)OR (Ala495, Asp519, Val524, His566 and Leu568 numbered according to the P. nautica N(2)OR sequence). Moreover, we built a model for Wolinella succinogenes N(2)OR, an enzyme that has an additional c-type-heme-containing domain. The structures of the N(2)OR domain and the c-type-heme-containing domain were modeled and the full-length structure was obtained by molecular docking simulation of these two domains. The orientation of the c-type-heme-containing domain relative to the N(2)OR domain is similar to that found in the other electron transfer complexes.
Collapse
Affiliation(s)
- Simone Dell'acqua
- REQUIMTE/CQFB, Departamento de Química, Universidade Nova de Lisboa, Caparica, Portugal
| | | | | | | |
Collapse
|
20
|
Dell'Acqua S, Pauleta SR, Moura I, Moura JJG. The tetranuclear copper active site of nitrous oxide reductase: the CuZ center. J Biol Inorg Chem 2011; 16:183-94. [PMID: 21240533 DOI: 10.1007/s00775-011-0753-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 01/03/2011] [Indexed: 01/24/2023]
Abstract
This review focuses on the novel CuZ center of nitrous oxide reductase, an important enzyme owing to the environmental significance of the reaction it catalyzes, reduction of nitrous oxide, and the unusual nature of its catalytic center, named CuZ. The structure of the CuZ center, the unique tetranuclear copper center found in this enzyme, opened a novel area of research in metallobiochemistry. In the last decade, there has been progress in defining the structure of the CuZ center, characterizing the mechanism of nitrous oxide reduction, and identifying intermediates of this reaction. In addition, the determination of the structure of the CuZ center allowed a structural interpretation of the spectroscopic data, which was supported by theoretical calculations. The current knowledge of the structure, function, and spectroscopic characterization of the CuZ center is described here. We would like to stress that although many questions have been answered, the CuZ center remains a scientific challenge, with many hypotheses still being formed.
Collapse
Affiliation(s)
- Simone Dell'Acqua
- REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Caparica, Portugal
| | | | | | | |
Collapse
|
21
|
Mitigating release of the potent greenhouse gas N(2)O from the nitrogen cycle - could enzymic regulation hold the key? Trends Biotechnol 2009; 27:388-97. [PMID: 19497629 DOI: 10.1016/j.tibtech.2009.03.009] [Citation(s) in RCA: 241] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 03/30/2009] [Accepted: 03/30/2009] [Indexed: 11/21/2022]
Abstract
When faced with a shortage of oxygen, many bacterial species use nitrate to support respiration via the process of denitrification. This takes place extensively in nitrogen-rich soils and generates the gaseous products nitric oxide (NO), nitrous oxide (N(2)O) and dinitrogen (N(2)). The denitrifying bacteria protect themselves from the endogenous cytotoxic NO produced by converting it to N(2)O, which can be released into the atmosphere. However, N(2)O is a potent greenhouse gas and hence the activity of the enzyme that breaks down N(2)O has a crucial role in restricting its atmospheric levels. Here, we review the current understanding of the process by which N(2)O is produced and destroyed and discuss the potential for feeding this into new approaches for combating N(2)O release.
Collapse
|
22
|
Mandal D, Chauhan M, Arjmand F, Aromí G, Ray D. Interaction with DNA of a heteronuclear [Na2Cu4] coordination cluster obtained from the assembly of two hydroxo-bridged [CuII2] units by a dimeric sodium nitrate template. Dalton Trans 2009:9183-91. [DOI: 10.1039/b909249h] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
|
23
|
Zhou Y, Pijuan M, Zeng RJ, Yuan Z. Free nitrous acid inhibition on nitrous oxide reduction by a denitrifying-enhanced biological phosphorus removal sludge. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:8260-8265. [PMID: 19068803 DOI: 10.1021/es800650j] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Nitrite has generally been recognized as an inhibitor of N2O reduction during denitrification. This inhibitory effect is investigated under various pH conditions using a denitrifying-enhanced biological phosphorus removal (EBPR) sludge. The degree of inhibition was observed to correlate much more strongly with the free nitrous acid (FNA) concentration than with the nitrite concentration, suggesting that FNA, rather than nitrite, is likely the true inhibitor on N2O reduction. Fifty percent inhibition was observed at an FNA concentration of 0.0007-0.001 mg HNO2-N/L (equivalent to approximately 3-4 mg NO2(-) -N/L at pH 7), while complete inhibition occurred when the FNA concentration was greater than 0.004 mg HNO2-N/L. The results also suggest that the inhibition on N2O reduction was not due to the electron competition between N2O and NO2- reductases. The inhibition was found to be reversible, with the rate of recovery independent of the duration of the inhibition, but dependent on the concentration of FNAthe biomass was exposed to during the inhibition period. A higher FNA concentration caused slower recovery.
Collapse
Affiliation(s)
- Yan Zhou
- Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia
| | | | | | | |
Collapse
|
24
|
Dell’Acqua S, Pauleta SR, Monzani E, Pereira AS, Casella L, Moura JJG, Moura I. Electron Transfer Complex between Nitrous Oxide Reductase and Cytochrome c552 from Pseudomonas nautica: Kinetic, Nuclear Magnetic Resonance, and Docking Studies. Biochemistry 2008; 47:10852-62. [DOI: 10.1021/bi801375q] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Simone Dell’Acqua
- REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal, and Dipartimento di Chimica Generale, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| | - Sofia R. Pauleta
- REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal, and Dipartimento di Chimica Generale, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| | - Enrico Monzani
- REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal, and Dipartimento di Chimica Generale, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| | - Alice S. Pereira
- REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal, and Dipartimento di Chimica Generale, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| | - Luigi Casella
- REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal, and Dipartimento di Chimica Generale, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| | - José J. G. Moura
- REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal, and Dipartimento di Chimica Generale, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| | - Isabel Moura
- REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal, and Dipartimento di Chimica Generale, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| |
Collapse
|
25
|
Fujita K, Chan JM, Bollinger JA, Alvarez ML, Dooley DM. Anaerobic purification, characterization and preliminary mechanistic study of recombinant nitrous oxide reductase from Achromobacter cycloclastes. J Inorg Biochem 2007; 101:1836-44. [PMID: 17681606 DOI: 10.1016/j.jinorgbio.2007.06.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Revised: 06/04/2007] [Accepted: 06/06/2007] [Indexed: 11/20/2022]
Abstract
An overexpression system for nitrous oxide reductase (N(2)OR), an enzyme that catalyzes the conversion of N(2)O to N(2) and H(2)O, has been developed in Achromobacter cycloclastes. Anaerobically purified A. cycloclastes recombinant N(2)OR (AcN(2)OR) has on average 4.5 Cu and 1.2 S per monomer. Upon reduction by methyl viologen, AcN(2)OR displays a high specific activity: 124 U/mg at 25 degrees C. Anaerobically purified AcN(2)OR displays a unique absorption spectrum. UV-visible and EPR spectra, combined with kinetics studies, indicate that the as-purified form of the enzyme is predominately a mixture of the fully-reduced Cu(Z)=[4Cu(I)] state and the Cu(Z)=[3Cu(I).Cu(II)] state, with the latter readily reducible by reduced forms of viologens. CD spectra of the as-purified AcN(2)OR over a range of pH values reveal perturbations of the protein conformation induced by pH variations, although the principal secondary structure elements are largely unaltered. Further, the activity of AcN(2)OR in D(2)O is significantly decreased compared with that in H(2)O, indicative of a significant solvent isotope effect on N(2)O reduction. These data are in good agreement with conclusions reached in recent studies on the effect of pH on catalysis by N(2)OR [K. Fujita, D.M. Dooley, Inorg. Chem. 46 (2007) 613-615].
Collapse
Affiliation(s)
- Koyu Fujita
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA
| | | | | | | | | |
Collapse
|
26
|
Fujita K, Dooley DM. Insights into the Mechanism of N2O Reduction by Reductively Activated N2O Reductase from Kinetics and Spectroscopic Studies of pH Effects. Inorg Chem 2007; 46:613-5. [PMID: 17257001 DOI: 10.1021/ic061843f] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nitrous oxide reductase (N2OR) from Achromobacter cycloclastes (Ac) can be reductively activated with reduced methyl viologen over a broad range of pH. Activated Ac N2OR displays a complex activity profile as a function of the pH at which catalytic turnover is measured. Spectroscopic and steady-state kinetics data suggest that [H+] has multiple effects on both the activation and the catalytic reactions. These experimental results are in good agreement with previous theoretical studies, which suggested that the transition state is stabilized by H-bonding interactions between the active site and an N2O-derived intermediate bound to the catalytic CuZ cluster.
Collapse
Affiliation(s)
- Koyu Fujita
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA
| | | |
Collapse
|
27
|
Zumft WG, Kroneck PMH. Respiratory transformation of nitrous oxide (N2O) to dinitrogen by Bacteria and Archaea. Adv Microb Physiol 2006; 52:107-227. [PMID: 17027372 DOI: 10.1016/s0065-2911(06)52003-x] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
N2O is a potent greenhouse gas and stratospheric reactant that has been steadily on the rise since the beginning of industrialization. It is an obligatory inorganic metabolite of denitrifying bacteria, and some production of N2O is also found in nitrifying and methanotrophic bacteria. We focus this review on the respiratory aspect of N2O transformation catalysed by the multicopper enzyme nitrous oxide reductase (N2OR) that provides the bacterial cell with an electron sink for anaerobic growth. Two types of Cu centres discovered in N2OR were both novel structures among the Cu proteins: the mixed-valent dinuclear Cu(A) species at the electron entry site of the enzyme, and the tetranuclear Cu(Z) centre as the first catalytically active Cu-sulfur complex known. Several accessory proteins function as Cu chaperone and ABC transporter systems for the biogenesis of the catalytic centre. We describe here the paradigm of Z-type N2OR, whose characteristics have been studied in most detail in the genera Pseudomonas and Paracoccus. Sequenced bacterial genomes now provide an invaluable additional source of information. New strains harbouring nos genes and capability of N2O utilization are being uncovered. This reveals previously unknown relationships and allows pattern recognition and predictions. The core nos genes, nosZDFYL, share a common phylogeny. Most principal taxonomic lineages follow the same biochemical and genetic pattern and share the Z-type enzyme. A modified N2OR is found in Wolinella succinogenes, and circumstantial evidence also indicates for certain Archaea another type of N2OR. The current picture supports the view of evolution of N2O respiration prior to the separation of the domains Bacteria and Archaea. Lateral nos gene transfer from an epsilon-proteobacterium as donor is suggested for Magnetospirillum magnetotacticum and Dechloromonas aromatica. In a few cases, nos gene clusters are plasmid borne. Inorganic N2O metabolism is associated with a diversity of physiological traits and biochemically challenging metabolic modes or habitats, including halorespiration, diazotrophy, symbiosis, pathogenicity, psychrophily, thermophily, extreme halophily and the marine habitat down to the greatest depth. Components for N2O respiration cover topologically the periplasm and the inner and outer membranes. The Sec and Tat translocons share the task of exporting Nos components to their functional sites. Electron donation to N2OR follows pathways with modifications depending on the host organism. A short chronology of the field is also presented.
Collapse
Affiliation(s)
- Walter G Zumft
- Institute of Applied Biosciences, Division of Molecular Microbiology, University of Karlsruhe, D-76128 Karlsruhe, Germany
| | | |
Collapse
|
28
|
Tolman WB. Using synthetic chemistry to understand copper protein active sites: a personal perspective. J Biol Inorg Chem 2006; 11:261-71. [PMID: 16447049 DOI: 10.1007/s00775-006-0078-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 01/03/2006] [Indexed: 10/25/2022]
Abstract
The results of studies performed in the author's laboratory are surveyed, with particular emphasis on demonstrating the value of a multidisciplinary synthetic modeling approach for discovering new and unusual chemistry helpful for understanding the properties of the active sites of copper proteins or assessing the feasibility of mechanistic pathways they might follow during catalysis. The discussion focuses on the progress made to date toward comprehending the nitrite reductase catalytic site and mechanism, the electronic structures of copper thiolate electron transfer centers, the sulfido-bridged "CuZ" site in nitrous oxide reductase, and the processes of dioxygen binding and activation by mono- and dicopper centers in oxidases and oxygenases.
Collapse
Affiliation(s)
- William B Tolman
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455, USA.
| |
Collapse
|
29
|
|
30
|
Garner D, McMaster J, Raven E, Walton P. Dalton Discussion No. 8. Metals: centres of biological activity. Dalton Trans 2005:3372-4. [PMID: 16234913 DOI: 10.1039/b513314a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|