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Hird K, Campeciño JO, Lehnert N, Hegg EL. Recent mechanistic developments for cytochrome c nitrite reductase, the key enzyme in the dissimilatory nitrate reduction to ammonium pathway. J Inorg Biochem 2024; 256:112542. [PMID: 38631103 DOI: 10.1016/j.jinorgbio.2024.112542] [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: 02/15/2024] [Revised: 03/19/2024] [Accepted: 03/23/2024] [Indexed: 04/19/2024]
Abstract
Cytochrome c nitrite reductase, NrfA, is a soluble, periplasmic pentaheme cytochrome responsible for the reduction of nitrite to ammonium in the Dissimilatory Nitrate Reduction to Ammonium (DNRA) pathway, a vital reaction in the global nitrogen cycle. NrfA catalyzes this six-electron and eight-proton reduction of nitrite at a single active site with the help of its quinol oxidase partners. In this review, we summarize the latest progress in elucidating the reaction mechanism of ammonia production, including new findings about the active site architecture of NrfA, as well as recent results that elucidate electron transfer and storage in the pentaheme scaffold of this enzyme.
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Affiliation(s)
- Krystina Hird
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Julius O Campeciño
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Nicolai Lehnert
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Eric L Hegg
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI, USA.
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2
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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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3
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Manickas EC, LaLonde AB, Hu MY, Alp EE, Lehnert N. Stabilization of a Heme-HNO Model Complex Using a Bulky Bis-Picket Fence Porphyrin and Reactivity Studies with NO. J Am Chem Soc 2023; 145:23014-23026. [PMID: 37824502 DOI: 10.1021/jacs.3c05333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
Nitroxyl, HNO/NO-, the one-electron reduced form of NO, is suggested to take part in distinct signaling pathways in mammals and is also a key intermediate in various heme-catalyzed NOx interconversions in the nitrogen cycle. Cytochrome P450nor (Cyt P450nor) is a heme-containing enzyme that performs NO reduction to N2O in fungal denitrification. The reactive intermediate in this enzyme, termed "Intermediate I", is proposed to be an Fe-NHO/Fe-NHOH type species, but it is difficult to study its electronic structure and exact protonation state due to its instability. Here, we utilize a bulky bis-picket fence porphyrin to obtain the first stable heme-HNO model complex, [Fe(3,5-Me-BAFP)(MI)(NHO)], as a model for Intermediate I, and more generally HNO adducts of heme proteins. Due to the steric hindrance of the bis-picket fence porphyrin, [Fe(3,5-Me-BAFP)(MI)(NHO)] is stable (τ1/2 = 56 min at -30 °C), can be isolated as a solid, and is available for thorough spectroscopic characterization. In particular, we were able to solve a conundrum in the literature and provide the first full vibrational characterization of a heme-HNO complex using IR and nuclear resonance vibrational spectroscopy (NRVS). Reactivity studies of [Fe(3,5-Me-BAFP)(MI)(NHO)] with NO gas show a 91 ± 10% yield for N2O formation, demonstrating that heme-HNO complexes are catalytically competent intermediates for NO reduction to N2O in Cyt P450nor. The implications of these results for the mechanism of Cyt P450nor are further discussed.
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Affiliation(s)
- Elizabeth C Manickas
- Department of Chemistry and Department of Biophysics, The University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Ashley B LaLonde
- Department of Chemistry and Department of Biophysics, The University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Michael Y Hu
- Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, Illinois 60439, United States
| | - E Ercan Alp
- Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, Illinois 60439, United States
| | - Nicolai Lehnert
- Department of Chemistry and Department of Biophysics, The University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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4
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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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5
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Yin Y, Liu C, Zhao G, Chen Y. Versatile mechanisms and enhanced strategies of pollutants removal mediated by Shewanella oneidensis: A review. JOURNAL OF HAZARDOUS MATERIALS 2022; 440:129703. [PMID: 35963088 DOI: 10.1016/j.jhazmat.2022.129703] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 07/17/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
The removal of environmental pollutants is important for a sustainable ecosystem and human health. Shewanella oneidensis (S. oneidensis) has diverse electron transfer pathways and can use a variety of contaminants as electron acceptors or electron donors. This paper reviews S. oneidensis's function in removing environmental pollutants, including heavy metals, inorganic non-metallic ions (INMIs), and toxic organic pollutants. S. oneidensis can mineralize o-xylene (OX), phenanthrene (PHE), and pyridine (Py) as electron donors, and also reduce azo dyes, nitro aromatic compounds (NACs), heavy metals, and iodate by extracellular electron transfer (EET). For azo dyes, NACs, Cr(VI), nitrite, nitrate, thiosulfate, and sulfite that can cross the membrane, S. oneidensis transfers electrons to intracellular reductases to catalyze their reduction. However, most organic pollutants cannot be directly degraded by S. oneidensis, but S. oneidensis can remove these pollutants by self-synthesizing catalysts or photocatalysts, constructing bio-photocatalytic systems, driving Fenton reactions, forming microbial consortia, and genetic engineering. However, the industrial-scale application of S. oneidensis is insufficient. Future research on the metabolism of S. oneidensis and interfacial reactions with other materials needs to be deepened, and large-scale reactors should be developed that can be used for practical engineering applications.
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Affiliation(s)
- Yue Yin
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
| | - Chao Liu
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
| | - Guohua Zhao
- School of Chemical Science and Engineering, Tongji University, Shanghai 200092, China
| | - Yinguang Chen
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
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6
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Homology modeling and virtual characterization of cytochrome c nitrite reductase (NrfA) in three model bacteria responsible for short-circuit pathway, DNRA in the terrestrial nitrogen cycle. World J Microbiol Biotechnol 2022; 38:168. [DOI: 10.1007/s11274-022-03352-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 07/04/2022] [Indexed: 11/26/2022]
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8
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Lehnert N, Kim E, Dong HT, Harland JB, Hunt AP, Manickas EC, Oakley KM, Pham J, Reed GC, Alfaro VS. The Biologically Relevant Coordination Chemistry of Iron and Nitric Oxide: Electronic Structure and Reactivity. Chem Rev 2021; 121:14682-14905. [PMID: 34902255 DOI: 10.1021/acs.chemrev.1c00253] [Citation(s) in RCA: 96] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Nitric oxide (NO) is an important signaling molecule that is involved in a wide range of physiological and pathological events in biology. Metal coordination chemistry, especially with iron, is at the heart of many biological transformations involving NO. A series of heme proteins, nitric oxide synthases (NOS), soluble guanylate cyclase (sGC), and nitrophorins, are responsible for the biosynthesis, sensing, and transport of NO. Alternatively, NO can be generated from nitrite by heme- and copper-containing nitrite reductases (NIRs). The NO-bearing small molecules such as nitrosothiols and dinitrosyl iron complexes (DNICs) can serve as an alternative vehicle for NO storage and transport. Once NO is formed, the rich reaction chemistry of NO leads to a wide variety of biological activities including reduction of NO by heme or non-heme iron-containing NO reductases and protein post-translational modifications by DNICs. Much of our understanding of the reactivity of metal sites in biology with NO and the mechanisms of these transformations has come from the elucidation of the geometric and electronic structures and chemical reactivity of synthetic model systems, in synergy with biochemical and biophysical studies on the relevant proteins themselves. This review focuses on recent advancements from studies on proteins and model complexes that not only have improved our understanding of the biological roles of NO but also have provided foundations for biomedical research and for bio-inspired catalyst design in energy science.
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Affiliation(s)
- Nicolai Lehnert
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Eunsuk Kim
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Hai T Dong
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Jill B Harland
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Andrew P Hunt
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Elizabeth C Manickas
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Kady M Oakley
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - John Pham
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Garrett C Reed
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Victor Sosa Alfaro
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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9
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Kroneck PMH. Nature's nitrite-to-ammonia expressway, with no stop at dinitrogen. J Biol Inorg Chem 2021; 27:1-21. [PMID: 34865208 PMCID: PMC8840924 DOI: 10.1007/s00775-021-01921-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 11/22/2021] [Indexed: 12/26/2022]
Abstract
Since the characterization of cytochrome c552 as a multiheme nitrite reductase, research on this enzyme has gained major interest. Today, it is known as pentaheme cytochrome c nitrite reductase (NrfA). Part of the NH4+ produced from NO2- is released as NH3 leading to nitrogen loss, similar to denitrification which generates NO, N2O, and N2. NH4+ can also be used for assimilatory purposes, thus NrfA contributes to nitrogen retention. It catalyses the six-electron reduction of NO2- to NH4+, hosting four His/His ligated c-type hemes for electron transfer and one structurally differentiated active site heme. Catalysis occurs at the distal side of a Fe(III) heme c proximally coordinated by lysine of a unique CXXCK motif (Sulfurospirillum deleyianum, Wolinella succinogenes) or, presumably, by the canonical histidine in Campylobacter jejeuni. Replacement of Lys by His in NrfA of W. succinogenes led to a significant loss of enzyme activity. NrfA forms homodimers as shown by high resolution X-ray crystallography, and there exist at least two distinct electron transfer systems to the enzyme. In γ-proteobacteria (Escherichia coli) NrfA is linked to the menaquinol pool in the cytoplasmic membrane through a pentaheme electron carrier (NrfB), in δ- and ε-proteobacteria (S. deleyianum, W. succinogenes), the NrfA dimer interacts with a tetraheme cytochrome c (NrfH). Both form a membrane-associated respiratory complex on the extracellular side of the cytoplasmic membrane to optimize electron transfer efficiency. This minireview traces important steps in understanding the nature of pentaheme cytochrome c nitrite reductases, and discusses their structural and functional features.
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Affiliation(s)
- Peter M H Kroneck
- Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany.
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Shahid S, Ali M, Legaspi-Humiston D, Wilcoxen J, Pacheco AA. A Kinetic Investigation of the Early Steps in Cytochrome c Nitrite Reductase (ccNiR)-Catalyzed Reduction of Nitrite. Biochemistry 2021; 60:2098-2115. [PMID: 34143605 DOI: 10.1021/acs.biochem.1c00172] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The decaheme enzyme cytochrome c nitrite reductase (ccNiR) catalyzes reduction of nitrite to ammonium in a six-electron, eight-proton process. With a strong reductant as the electron source, ammonium is the sole product. However, intermediates accumulate when weaker reductants are employed, facilitating study of the ccNiR mechanism. Herein, the early stages of Shewanella oneidensis ccNiR-catalyzed nitrite reduction were investigated by using the weak reductants N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) and ferrocyanide. In stopped-flow experiments, reduction of nitrite-loaded ccNiR by TMPD generated a transient intermediate, identified as FeH1II(NO2-), where FeH1 represents the ccNiR active site. FeH1II(NO2-) accumulated rapidly and was then more slowly converted to the two-electron-reduced moiety {FeH1NO}7; ccNiR was not reduced beyond the {FeH1NO}7 state. The midpoint potentials for sequential reduction of FeH1III(NO2-) to FeH1II(NO2-) and then to {FeH1NO}7 were estimated to be 130 and 370 mV versus the standard hydrogen electrode, respectively. FeH1II(NO2-) does not accumulate at equilibrium because its reduction to {FeH1NO}7 is so much easier than the reduction of FeH1III(NO2-) to FeH1II(NO2-). With weak reductants, free NO• was released from nitrite-loaded ccNiR. The release of NO• from {FeH1NO}7 is exceedingly slow (k ∼ 0.001 s-1), but it is somewhat faster (k ∼ 0.050 s-1) while FeH1III(NO2-) is being reduced to {FeH1NO}7; then, the release of NO• from the undetectable transient {FeH1NO}6 can compete with reduction of {FeH1NO}6 to {FeH1NO}7. CcNiR appears to be optimized to capture nitrite and minimize the release of free NO•. Nitrite capture is achieved by reducing bound nitrite with even weak electron donors, while NO• release is minimized by stabilizing the substitutionally inert {FeH1NO}7 over the more labile {FeH1NO}6.
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Affiliation(s)
- Shahid Shahid
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Mahbbat Ali
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Desiree Legaspi-Humiston
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Jarett Wilcoxen
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - A Andrew Pacheco
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
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11
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Sosa Alfaro V, Campeciño J, Tracy M, Elliott SJ, Hegg EL, Lehnert N. Elucidating Electron Storage and Distribution within the Pentaheme Scaffold of Cytochrome c Nitrite Reductase (NrfA). Biochemistry 2021; 60:1853-1867. [PMID: 34061493 DOI: 10.1021/acs.biochem.0c00977] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytochrome c nitrite reductases (CcNIR or NrfA) play important roles in the global nitrogen cycle by conserving the usable nitrogen in the soil. Here, the electron storage and distribution properties within the pentaheme scaffold of Geobacter lovleyi NrfA were investigated via electron paramagnetic resonance (EPR) spectroscopy coupled with chemical titration experiments. Initially, a chemical reduction method was established to sequentially add electrons to the fully oxidized protein, 1 equiv at a time. The step-by-step reduction of the hemes was then followed using ultraviolet-visible absorption and EPR spectroscopy. EPR spectral simulations were used to elucidate the sequence of heme reduction within the pentaheme scaffold of NrfA and identify the signals of all five hemes in the EPR spectra. Electrochemical experiments ascertain the reduction potentials for each heme, observed in a narrow range from +10 mV (heme 5) to -226 mV (heme 3) (vs the standard hydrogen electrode). On the basis of quantitative analysis and simulation of the EPR data, we demonstrate that hemes 4 and 5 are reduced first (before the active site heme 1) and serve the purpose of an electron storage unit within the protein. To probe the role of the central heme 3, an H108M NrfA variant was generated where the reduction potential of heme 3 is shifted positively (from -226 to +48 mV). The H108M mutation significantly impacts the distribution of electrons within the pentaheme scaffold and the reduction potentials of the hemes, reducing the catalytic activity of the enzyme to 1% compared to that of the wild type. We propose that this is due to heme 3's important role as an electron gateway in the wild-type enzyme.
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Affiliation(s)
- Victor Sosa Alfaro
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Julius Campeciño
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan 48824, United States
| | - Matthew Tracy
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Sean J Elliott
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Eric L Hegg
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan 48824, United States
| | - Nicolai Lehnert
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Amanullah S, Saha P, Nayek A, Ahmed ME, Dey A. Biochemical and artificial pathways for the reduction of carbon dioxide, nitrite and the competing proton reduction: effect of 2nd sphere interactions in catalysis. Chem Soc Rev 2021; 50:3755-3823. [DOI: 10.1039/d0cs01405b] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Reduction of oxides and oxoanions of carbon and nitrogen are of great contemporary importance as they are crucial for a sustainable environment.
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Affiliation(s)
- Sk Amanullah
- School of Chemical Sciences
- Indian Association for the Cultivation of Science
- Kolkata
- India
| | - Paramita Saha
- School of Chemical Sciences
- Indian Association for the Cultivation of Science
- Kolkata
- India
| | - Abhijit Nayek
- School of Chemical Sciences
- Indian Association for the Cultivation of Science
- Kolkata
- India
| | - Md Estak Ahmed
- School of Chemical Sciences
- Indian Association for the Cultivation of Science
- Kolkata
- India
| | - Abhishek Dey
- School of Chemical Sciences
- Indian Association for the Cultivation of Science
- Kolkata
- India
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13
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Campeciño J, Lagishetty S, Wawrzak Z, Sosa Alfaro V, Lehnert N, Reguera G, Hu J, Hegg EL. Cytochrome c nitrite reductase from the bacterium Geobacter lovleyi represents a new NrfA subclass. J Biol Chem 2020; 295:11455-11465. [PMID: 32518164 PMCID: PMC7450111 DOI: 10.1074/jbc.ra120.013981] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/07/2020] [Indexed: 01/07/2023] Open
Abstract
Cytochrome c nitrite reductase (NrfA) catalyzes the reduction of nitrite to ammonium in the dissimilatory nitrate reduction to ammonium (DNRA) pathway, a process that competes with denitrification, conserves nitrogen, and minimizes nutrient loss in soils. The environmental bacterium Geobacter lovleyi has recently been recognized as a key driver of DNRA in nature, but its enzymatic pathway is still uncharacterized. To address this limitation, here we overexpressed, purified, and characterized G. lovleyi NrfA. We observed that the enzyme crystallizes as a dimer but remains monomeric in solution. Importantly, its crystal structure at 2.55-Å resolution revealed the presence of an arginine residue in the region otherwise occupied by calcium in canonical NrfA enzymes. The presence of EDTA did not affect the activity of G. lovleyi NrfA, and site-directed mutagenesis of this arginine reduced enzymatic activity to <3% of the WT levels. Phylogenetic analysis revealed four separate emergences of Arg-containing NrfA enzymes. Thus, the Ca2+-independent, Arg-containing NrfA from G. lovleyi represents a new subclass of cytochrome c nitrite reductase. Most genera from the exclusive clades of Arg-containing NrfA proteins are also represented in clades containing Ca2+-dependent enzymes, suggesting convergent evolution.
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Affiliation(s)
- Julius Campeciño
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan, USA
| | - Satyanarayana Lagishetty
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan, USA
| | - Zdzislaw Wawrzak
- Synchrotron Research Center, Life Science Collaborative Access Team, Northwestern University, Argonne, Illinois, USA
| | - Victor Sosa Alfaro
- Department of Chemistry and Biophysics, The University of Michigan, Ann Arbor, Michigan, USA
| | - Nicolai Lehnert
- Department of Chemistry and Biophysics, The University of Michigan, Ann Arbor, Michigan, USA
| | - Gemma Reguera
- Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Jian Hu
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan, USA,Department of Chemistry, Michigan State University, East Lansing, Michigan, USA
| | - Eric L. Hegg
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan, USA,For correspondence: Eric L. Hegg,
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14
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Regulation and Maturation of the Shewanella oneidensis Sulfite Reductase SirA. Sci Rep 2020; 10:953. [PMID: 31969587 PMCID: PMC6976685 DOI: 10.1038/s41598-020-57587-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 12/27/2019] [Indexed: 01/12/2023] Open
Abstract
Shewanella oneidensis, a metal reducer and facultative anaerobe, expresses a large number of c-type cytochromes, many of which function as anaerobic reductases. All of these proteins contain the typical heme-binding motif CXXCH and require the Ccm proteins for maturation. Two c-type cytochrome reductases also possess atypical heme-binding sites, the NrfA nitrite reductase (CXXCK) and the SirA sulfite reductase (CX12NKGCH). S. oneidensis MR-1 encodes two cytochrome c synthetases (CcmF and SirE) and two apocytochrome c chaperones (CcmI and SirG). SirE located in the sir gene cluster is required for the maturation of SirA, but not NrfA. Here we show that maturation of SirA requires the combined function of the two apocytochrome c chaperones CcmI and SirG. Loss of either protein resulted in decreased sulfite reductase. Furthermore, SirA was not detected in a mutant that lacked both chaperones, perhaps due to misfolding or instability. These results suggest that CcmI interacts with SirEFG during SirA maturation, and with CcmF during maturation of NrfA. Additionally, we show that CRP regulates expression of sirA via the newly identified transcriptional regulatory protein, SirR.
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15
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Lemaire ON, Méjean V, Iobbi-Nivol C. The Shewanella genus: ubiquitous organisms sustaining and preserving aquatic ecosystems. FEMS Microbiol Rev 2020; 44:155-170. [DOI: 10.1093/femsre/fuz031] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 01/09/2020] [Indexed: 12/16/2022] Open
Abstract
ABSTRACT
The Gram-negative Shewanella bacterial genus currently includes about 70 species of mostly aquatic γ-proteobacteria, which were isolated around the globe in a multitude of environments such as surface freshwater and the deepest marine trenches. Their survival in such a wide range of ecological niches is due to their impressive physiological and respiratory versatility. Some strains are among the organisms with the highest number of respiratory systems, depending on a complex and rich metabolic network. Implicated in the recycling of organic and inorganic matter, they are important components of organism-rich oxic/anoxic interfaces, but they also belong to the microflora of a broad group of eukaryotes from metazoans to green algae. Examples of long-term biological interactions like mutualism or pathogeny have been described, although molecular determinants of such symbioses are still poorly understood. Some of these bacteria are key organisms for various biotechnological applications, especially the bioremediation of hydrocarbons and metallic pollutants. The natural ability of these prokaryotes to thrive and detoxify deleterious compounds explains their use in wastewater treatment, their use in energy generation by microbial fuel cells and their importance for resilience of aquatic ecosystems.
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Affiliation(s)
- Olivier N Lemaire
- Aix-Marseille Université, Laboratoire de Bioénergétique et Ingénierie des Protéines, UMR 7281, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, 13402 Marseille, France
| | - Vincent Méjean
- Aix-Marseille Université, Laboratoire de Bioénergétique et Ingénierie des Protéines, UMR 7281, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, 13402 Marseille, France
| | - Chantal Iobbi-Nivol
- Aix-Marseille Université, Laboratoire de Bioénergétique et Ingénierie des Protéines, UMR 7281, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, 13402 Marseille, France
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16
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Ali M, Stein N, Mao Y, Shahid S, Schmidt M, Bennett B, Pacheco AA. Trapping of a Putative Intermediate in the Cytochrome c Nitrite Reductase (ccNiR)-Catalyzed Reduction of Nitrite: Implications for the ccNiR Reaction Mechanism. J Am Chem Soc 2019; 141:13358-13371. [DOI: 10.1021/jacs.9b03036] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mahbbat Ali
- Department of Chemistry and Biochemistry, University of Wisconsin−Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Natalia Stein
- Department of Chemistry and Biochemistry, University of Wisconsin−Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Yingxi Mao
- Department of Chemistry and Biochemistry, University of Wisconsin−Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Shahid Shahid
- Department of Chemistry and Biochemistry, University of Wisconsin−Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Marius Schmidt
- Department of Physics, University of Wisconsin−Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Brian Bennett
- Department of Physics, Marquette University, Milwaukee, Wisconsin 53233, United States
| | - A. Andrew Pacheco
- Department of Chemistry and Biochemistry, University of Wisconsin−Milwaukee, Milwaukee, Wisconsin 53211, United States
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17
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Schmidt M. Time-Resolved Macromolecular Crystallography at Pulsed X-ray Sources. Int J Mol Sci 2019; 20:ijms20061401. [PMID: 30897736 PMCID: PMC6470897 DOI: 10.3390/ijms20061401] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 03/14/2019] [Accepted: 03/18/2019] [Indexed: 11/30/2022] Open
Abstract
The focus of structural biology is shifting from the determination of static structures to the investigation of dynamical aspects of macromolecular function. With time-resolved macromolecular crystallography (TRX), intermediates that form and decay during the macromolecular reaction can be investigated, as well as their reaction dynamics. Time-resolved crystallographic methods were initially developed at synchrotrons. However, about a decade ago, extremely brilliant, femtosecond-pulsed X-ray sources, the free electron lasers for hard X-rays, became available to a wider community. TRX is now possible with femtosecond temporal resolution. This review provides an overview of methodological aspects of TRX, and at the same time, aims to outline the frontiers of this method at modern pulsed X-ray sources.
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Affiliation(s)
- Marius Schmidt
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
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18
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Paquete CM, Rusconi G, Silva AV, Soares R, Louro RO. A brief survey of the "cytochromome". Adv Microb Physiol 2019; 75:69-135. [PMID: 31655743 DOI: 10.1016/bs.ampbs.2019.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Multihaem cytochromes c are widespread in nature where they perform numerous roles in diverse anaerobic metabolic pathways. This is achieved in two ways: multihaem cytochromes c display a remarkable diversity of ways to organize multiple hemes within the protein frame; and the hemes possess an intrinsic reactive versatility derived from diverse spin, redox and coordination states. Here we provide a brief survey of multihaem cytochromes c that have been characterized in the context of their metabolic role. The contribution of multihaem cytochromes c to dissimilatory pathways handling metallic minerals, nitrogen compounds, sulfur compounds, organic compounds and phototrophism are described. This aims to set the stage for the further exploration of the vast unknown "cytochromome" that can be anticipated from genomic databases.
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19
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Electron transfer and transport through multi-heme proteins: recent progress and future directions. Curr Opin Chem Biol 2018; 47:24-31. [DOI: 10.1016/j.cbpa.2018.06.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 06/24/2018] [Indexed: 12/20/2022]
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20
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Gnandt D, Na S, Koslowski T. Simulating biological charge transfer: Continuum dielectric theory or molecular dynamics? Biophys Chem 2018; 241:1-7. [PMID: 30036762 DOI: 10.1016/j.bpc.2018.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 07/01/2018] [Indexed: 10/28/2022]
Abstract
We study the thermodynamic parameters of Marcus's theory of charge transfer, the driving forces and the reorganization energies, using two widely applied approaches to bioenergetic problems that seem to be radically different: continuum dielectric theory via a numerical solution of Poisson's equation, and the thermodynamic integration approach based upon classical Newtonian molecular dynamics, as perfomed by Na et al., PCCP 19, 18,938 (2017). With application to a nitrite reductase NrfHA protein heterodimer, we obtain an excellent agreement between the respective driving forces with an r.m.s. deviation of 1.7 kcal/mol, and a lower limit to the reorganization energies. The computational methods turn out to be mutually supportive: molecular dynamics can be used to determine the parameters of a dielectric theory computation, which on the other hand can be used to properly rescale the reorganization energies and partition them into aqueous and protein contributions. In addition, we use the electrostatic approach to study the influence of Ca2+ ions on the free energy landscape of charge transfer.
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Affiliation(s)
- David Gnandt
- Institut für Physikalische Chemie, Universität Freiburg, Albertstraße 23a, 79104 Freiburg im Breisgau, Germany
| | - Sehee Na
- Institut für Physikalische Chemie, Universität Freiburg, Albertstraße 23a, 79104 Freiburg im Breisgau, Germany
| | - Thorsten Koslowski
- Institut für Physikalische Chemie, Universität Freiburg, Albertstraße 23a, 79104 Freiburg im Breisgau, Germany.
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21
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McGarry JM, Pacheco AA. Upon further analysis, neither cytochrome c 554 from Nitrosomonas europaea nor its F156A variant display NO reductase activity, though both proteins bind nitric oxide reversibly. J Biol Inorg Chem 2018; 23:861-878. [PMID: 29946979 DOI: 10.1007/s00775-018-1582-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 06/15/2018] [Indexed: 01/02/2023]
Abstract
A re-investigation of the interaction with NO of the small tetraheme protein cytochrome c554 (C554) from Nitrosomonas europaea has shown that the 5-coordinate heme II of the two- or four-electron-reduced protein will nitrosylate reversibly. The process is first order in C554, first order in NO, and second-order overall. The rate constant for NO binding to the heme is 3000 ± 140 M-1s-1, while that for dissociation is 0.034 ± 0.009 s-1; the degree of protein reduction does not appear to significantly influence the nitrosylation rate. In contrast to a previous report (Upadhyay AK, et al. J Am Chem Soc 128:4330, 2006), this study found no evidence of C554-catalyzed NO reduction, either with [Formula: see text] or with [Formula: see text] Some sub-stoichiometric oxidation of the lowest potential heme IV was detected when [Formula: see text] was exposed to an excess of NO, but this is believed to arise from partial intramolecular electron transfer that generates {Fe(NO)}8 at heme II. The vacant heme II coordination site of C554 is crowded by three non-bonding hydrophobic amino acids. After replacing one of these (Phe156) with the smaller alanine, the nitrosylation rate for F156A2- and F156A4- was about 400× faster than for the wild type, though the rate of the reverse denitrosylation process was almost unchanged. Unlike in the wild-type C554, the 6-coordinate low-spin hemes of F156A4- oxidized over the course of several minutes after exposure to NO. Concomitant formation of N2O could explain this heme oxidation, though alternative explanations are equally plausible given the available data.
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Affiliation(s)
- Jennifer M McGarry
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, 3210 N. Cramer Street, Milwaukee, WI, 53211, USA
| | - A Andrew Pacheco
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, 3210 N. Cramer Street, Milwaukee, WI, 53211, USA.
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22
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Tikhonova TV, Slutskaya ES, Popov VO. Peroxidase activity of octaheme nitrite reductases from bacteria of the Thioalkalivibrio genus. APPL BIOCHEM MICRO+ 2017. [DOI: 10.1134/s0003683817020168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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23
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Abstract
Time-resolved macromolecular crystallography unifies protein structure determination with chemical kinetics. With the advent of fourth generation X-ray sources the time-resolution can be on the order of 10-40 fs, which opens the ultrafast time scale to structure determination. Fundamental motions and transitions associated with chemical reactions in proteins can now be observed. Moreover, new experimental approaches at synchrotrons allow for the straightforward investigation of all kind of reactions in biological macromolecules. Here, recent developments in the field are reviewed.
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Affiliation(s)
- Marius Schmidt
- Kenwood Interdisciplinary Research Complex, Physics Department, University of Wisconsin-Milwaukee, Room 3087, 3135 North Maryland Avenue, Milwaukee, WI, 53211, USA.
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24
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Koebke KJ, Waletzko MT, Pacheco AA. Direct Monitoring of the Reaction between Photochemically Generated Nitric Oxide and Mycobacterium tuberculosis Truncated Hemoglobin N Wild Type and Variant Forms: An Assessment of Computational Mechanistic Predictions. Biochemistry 2016; 55:686-96. [DOI: 10.1021/acs.biochem.5b01145] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Karl J. Koebke
- Department of Chemistry and
Biochemistry, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Michael T. Waletzko
- Department of Chemistry and
Biochemistry, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - A. Andrew Pacheco
- Department of Chemistry and
Biochemistry, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, United States
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25
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Schmidt M. Time-Resolved Crystallography at X-ray Free Electron Lasers and Synchrotron Light Sources. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/08940886.2015.1101324] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Marius Schmidt
- University of Wisconsin-Milwaukee, Physics Department, Milwaukee, Wisconsin, USA
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26
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Bykov D, Neese F. Six-Electron Reduction of Nitrite to Ammonia by Cytochrome c Nitrite Reductase: Insights from Density Functional Theory Studies. Inorg Chem 2015; 54:9303-16. [DOI: 10.1021/acs.inorgchem.5b01506] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Dmytro Bykov
- qLEAP Center
for Theoretical Chemistry, Department of Chemistry, Aarhus University, Gustav
Wieds Vej 10A, DK-8000 Aarhus C, Denmark
| | - Frank Neese
- Max-Planck Institut für Chemische Energiekonversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
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27
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Breuer M, Rosso KM, Blumberger J, Butt JN. Multi-haem cytochromes in Shewanella oneidensis MR-1: structures, functions and opportunities. J R Soc Interface 2015; 12:20141117. [PMID: 25411412 DOI: 10.1098/rsif.2014.1117] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Multi-haem cytochromes are employed by a range of microorganisms to transport electrons over distances of up to tens of nanometres. Perhaps the most spectacular utilization of these proteins is in the reduction of extracellular solid substrates, including electrodes and insoluble mineral oxides of Fe(III) and Mn(III/IV), by species of Shewanella and Geobacter. However, multi-haem cytochromes are found in numerous and phylogenetically diverse prokaryotes where they participate in electron transfer and redox catalysis that contributes to biogeochemical cycling of N, S and Fe on the global scale. These properties of multi-haem cytochromes have attracted much interest and contributed to advances in bioenergy applications and bioremediation of contaminated soils. Looking forward, there are opportunities to engage multi-haem cytochromes for biological photovoltaic cells, microbial electrosynthesis and developing bespoke molecular devices. As a consequence, it is timely to review our present understanding of these proteins and we do this here with a focus on the multitude of functionally diverse multi-haem cytochromes in Shewanella oneidensis MR-1. We draw on findings from experimental and computational approaches which ideally complement each other in the study of these systems: computational methods can interpret experimentally determined properties in terms of molecular structure to cast light on the relation between structure and function. We show how this synergy has contributed to our understanding of multi-haem cytochromes and can be expected to continue to do so for greater insight into natural processes and their informed exploitation in biotechnologies.
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Affiliation(s)
- Marian Breuer
- Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
| | - Kevin M Rosso
- Pacific Northwest National Laboratory, Richland, WA, USA
| | - Jochen Blumberger
- Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
| | - Julea N Butt
- School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich NR4 7TJ, UK
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28
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Heterologous expression and purification of a multiheme cytochrome from a Gram-positive bacterium capable of performing extracellular respiration. Protein Expr Purif 2015; 111:48-52. [DOI: 10.1016/j.pep.2015.03.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/12/2015] [Accepted: 03/15/2015] [Indexed: 01/16/2023]
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29
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Alves MN, Neto SE, Alves AS, Fonseca BM, Carrêlo A, Pacheco I, Paquete CM, Soares CM, Louro RO. Characterization of the periplasmic redox network that sustains the versatile anaerobic metabolism of Shewanella oneidensis MR-1. Front Microbiol 2015; 6:665. [PMID: 26175726 PMCID: PMC4484225 DOI: 10.3389/fmicb.2015.00665] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 06/17/2015] [Indexed: 01/14/2023] Open
Abstract
The versatile anaerobic metabolism of the Gram-negative bacterium Shewanella oneidensis MR-1 (SOMR-1) relies on a multitude of redox proteins found in its periplasm. Most are multiheme cytochromes that carry electrons to terminal reductases of insoluble electron acceptors located at the cell surface, or bona fide terminal reductases of soluble electron acceptors. In this study, the interaction network of several multiheme cytochromes was explored by a combination of NMR spectroscopy, activity assays followed by UV-visible spectroscopy and comparison of surface electrostatic potentials. From these data the small tetraheme cytochrome (STC) emerges as the main periplasmic redox shuttle in SOMR-1. It accepts electrons from CymA and distributes them to a number of terminal oxidoreductases involved in the respiration of various compounds. STC is also involved in the electron transfer pathway to reduce nitrite by interaction with the octaheme tetrathionate reductase (OTR), but not with cytochrome c nitrite reductase (ccNiR). In the main pathway leading the metal respiration STC pairs with flavocytochrome c (FccA), the other major periplasmic cytochrome, which provides redundancy in this important pathway. The data reveals that the two proteins compete for the binding site at the surface of MtrA, the decaheme cytochrome inserted on the periplasmic side of the MtrCAB-OmcA outer-membrane complex. However, this is not observed for the MtrA homologues. Indeed, neither STC nor FccA interact with MtrD, the best replacement for MtrA, and only STC is able to interact with the decaheme cytochrome DmsE of the outer-membrane complex DmsEFABGH. Overall, these results shown that STC plays a central role in the anaerobic respiratory metabolism of SOMR-1. Nonetheless, the trans-periplasmic electron transfer chain is functionally resilient as a consequence of redundancies that arise from the presence of alternative pathways that bypass/compete with STC.
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Affiliation(s)
- Mónica N Alves
- Inorganic Biochemistry and NMR Laboratory, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa Oeiras, Portugal
| | - Sónia E Neto
- Inorganic Biochemistry and NMR Laboratory, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa Oeiras, Portugal
| | - Alexandra S Alves
- Inorganic Biochemistry and NMR Laboratory, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa Oeiras, Portugal
| | - Bruno M Fonseca
- Inorganic Biochemistry and NMR Laboratory, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa Oeiras, Portugal
| | - Afonso Carrêlo
- Inorganic Biochemistry and NMR Laboratory, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa Oeiras, Portugal
| | - Isabel Pacheco
- Inorganic Biochemistry and NMR Laboratory, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa Oeiras, Portugal
| | - Catarina M Paquete
- Inorganic Biochemistry and NMR Laboratory, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa Oeiras, Portugal
| | - Cláudio M Soares
- Inorganic Biochemistry and NMR Laboratory, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa Oeiras, Portugal
| | - Ricardo O Louro
- Inorganic Biochemistry and NMR Laboratory, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa Oeiras, Portugal
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30
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Stein N, Love D, Judd ET, Elliott SJ, Bennett B, Pacheco AA. Correlations between the Electronic Properties of Shewanella oneidensis Cytochrome c Nitrite Reductase (ccNiR) and Its Structure: Effects of Heme Oxidation State and Active Site Ligation. Biochemistry 2015; 54:3749-58. [PMID: 26042961 DOI: 10.1021/acs.biochem.5b00330] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electrochemical properties of Shewanella oneidensis cytochrome c nitrite reductase (ccNiR), a homodimer that contains five hemes per protomer, were investigated by UV-visible and electron paramagnetic resonance (EPR) spectropotentiometries. Global analysis of the UV-vis spectropotentiometric results yielded highly reproducible values for the heme midpoint potentials. These midpoint potential values were then assigned to specific hemes in each protomer (as defined in previous X-ray diffraction studies) by comparing the EPR and UV-vis spectropotentiometric results, taking advantage of the high sensitivity of EPR spectra to the structural microenvironment of paramagnetic centers. Addition of the strong-field ligand cyanide led to a 70 mV positive shift of the active site's midpoint potential, as the cyanide bound to the initially five-coordinate high-spin heme and triggered a high-spin to low-spin transition. With cyanide present, three of the remaining hemes gave rise to distinctive and readily assignable EPR spectral changes upon reduction, while a fourth was EPR-silent. At high applied potentials, interpretation of the EPR spectra in the absence of cyanide was complicated by a magnetic interaction that appears to involve three of five hemes in each protomer. At lower applied potentials, the spectra recorded in the presence and absence of cyanide were similar, which aided global assignment of the signals. The midpoint potential of the EPR-silent heme could be assigned by default, but the assignment was also confirmed by UV-vis spectropotentiometric analysis of the H268M mutant of ccNiR, in which one of the EPR-silent heme's histidine axial ligands was replaced with a methionine.
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Affiliation(s)
- Natalia Stein
- †Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Daniel Love
- †Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | | | | | - Brian Bennett
- §Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, United States
| | - A Andrew Pacheco
- †Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
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Abstract
Despite evidence for the prevalence of horizontal gene transfer of respiratory genes, little is known about how pathways functionally integrate within new hosts. One example of a mobile respiratory metabolism is bacterial chlorate reduction, which is frequently encoded on composite transposons. This implies that the essential components of the metabolism are encoded on these mobile elements. To test this, we heterologously expressed genes for chlorate reduction from Shewanella algae ACDC in the non-chlorate-reducing Shewanella oneidensis MR-1. The construct that ultimately endowed robust growth on chlorate included cld, a cytochrome c gene, clrABDC, and two genes of unknown function. Although strain MR-1 was unable to grow on chlorate after initial insertion of these genes into the chromosome, 11 derived strains capable of chlorate respiration were obtained through adaptive evolution. Genome resequencing indicated that all of the evolved chlorate-reducing strains replicated a large genomic region containing chlorate reduction genes. Contraction in copy number and loss of the ability to reduce chlorate were also observed, indicating that this phenomenon was extremely dynamic. Although most strains contained more than six copies of the replicated region, a single strain with less duplication also grew rapidly. This strain contained three additional mutations that we hypothesized compensated for the low copy number. We remade the mutations combinatorially in the unevolved strain and determined that a single nucleotide polymorphism (SNP) upstream of cld enabled growth on chlorate and was epistatic to a second base pair change in the NarP binding sequence between narQP and nrfA that enhanced growth. The ability of chlorate reduction composite transposons to form functional metabolisms after transfer to a new host is an important part of their propagation. To study this phenomenon, we engineered Shewanella oneidensis MR-1 into a chlorate reducer. We defined a set of genes sufficient to endow growth on chlorate from a plasmid, but found that chromosomal insertion of these genes was nonfunctional. Evolution of this inoperative strain into a chlorate reducer showed that tandem duplication was a dominant mechanism of activation. While copy number changes are a relatively rapid way of increasing gene dosage, replicating almost 1 megabase of extra DNA is costly. Mutations that alleviate the need for high copy number are expected to arise and eventually predominate, and we identified a single nucleotide polymorphism (SNP) that relieved the copy number requirement. This study uses both rational and evolutionary approaches to gain insight into the evolution of a fascinating respiratory metabolism.
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32
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Mordkovich NN, Okorokova NA, Veiko VP. Investigation of protein translocation Sec-system with heterologous gene expression in Shewanella oneidensis MR-1 bacterium cells. APPL BIOCHEM MICRO+ 2015. [DOI: 10.1134/s0003683815030126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Lockwood CWJ, Burlat B, Cheesman MR, Kern M, Simon J, Clarke TA, Richardson DJ, Butt JN. Resolution of Key Roles for the Distal Pocket Histidine in Cytochrome c Nitrite Reductases. J Am Chem Soc 2015; 137:3059-68. [DOI: 10.1021/ja512941j] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
| | | | | | - Melanie Kern
- 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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Tikhonova TV, Popov VO. Structural and functional studies of multiheme cytochromes c involved in extracellular electron transport in bacterial dissimilatory metal reduction. BIOCHEMISTRY (MOSCOW) 2015; 79:1584-601. [DOI: 10.1134/s0006297914130094] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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35
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Fu H, Jin M, Wan F, Gao H. Shewanella oneidensis cytochrome c maturation component CcmI is essential for heme attachment at the non-canonical motif of nitrite reductase NrfA. Mol Microbiol 2014; 95:410-25. [PMID: 25402661 DOI: 10.1111/mmi.12865] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/12/2014] [Indexed: 11/28/2022]
Abstract
Shewanella oneidensis is renowned for its respiratory versatility, which is largely due to abundant c-type cytochromes. Maturation of these proteins depends on a Ccm system encoded by genes in an unusual chromosomal arrangement, but the detailed mechanism is not understood. In this study, we identify SO0265 as CcmI, an apocytochrome c chaperone that is important and essential for maturation of c-type cytochromes with the canonical heme binding motif(s) (HBM; CX(2)CH) and nitrite reductase NrfA carrying a non-canonical CX(2)CK motif respectively. We show that the N-terminal transmembrane segment of CcmI, CcmI-1, is sufficient for maturation of the former but the entire protein is required for maturation of the latter. Although S. oneidensis possesses a heme lyase, SirEFG, dedicated for non-canonical HBMs, it is specific for SirA, a sulfite reductase with a CX(15)CH motif. By presenting evidence that the periplasmic portion of CcmI, CcmI-2, interacts with NrfA, we suggest that CcmI also takes the role of Escherichia coli NrfG for chaperoning apo-NrfA for maturation at CX(2)CK. Moreover, intact CcmI is required for maturation of NrfA, presumably by ensuring that heme attachment at canonical HBMs occurs before apoprotein degradation.
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Affiliation(s)
- Huihui Fu
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China
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36
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Judd ET, Stein N, Pacheco AA, Elliott SJ. Hydrogen bonding networks tune proton-coupled redox steps during the enzymatic six-electron conversion of nitrite to ammonia. Biochemistry 2014; 53:5638-46. [PMID: 25137350 PMCID: PMC4159211 DOI: 10.1021/bi500854p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
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Multielectron
multiproton reactions play an important role in both
biological systems and chemical reactions involved in energy storage
and manipulation. A key strategy employed by nature in achieving such
complex chemistry is the use of proton-coupled redox steps. Cytochrome c nitrite reductase (ccNiR) catalyzes the six-electron seven-proton
reduction of nitrite to ammonia. While a catalytic mechanism for ccNiR
has been proposed on the basis of studies combining computation and
crystallography, there have been few studies directly addressing the
nature of the proton-coupled events that are predicted to occur along
the nitrite reduction pathway. Here we use protein film voltammetry
to directly interrogate the proton-coupled steps that occur during
nitrite reduction by ccNiR. We find that conversion of nitrite to
ammonia by ccNiR adsorbed to graphite electrodes is defined by two
distinct phases; one is proton-coupled, and the other is not. Mutation
of key active site residues (H257, R103, and Y206) modulates these
phases and specifically alters the properties of the detected proton-dependent
step but does not inhibit the ability of ccNiR to conduct the full
reduction of nitrite to ammonia. We conclude that the active site
residues examined are responsible for tuning the protonation steps
that occur during catalysis, likely through an extensive hydrogen
bonding network, but are not necessarily required for the reaction
to proceed. These results provide important insight into how enzymes
can specifically tune proton- and electron transfer steps to achieve
high turnover numbers in a physiological pH range.
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Affiliation(s)
- Evan T Judd
- Department of Chemistry, Boston University , 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
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Affiliation(s)
- Luisa B. Maia
- REQUIMTE/CQFB, Departamento
de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - José J. G. Moura
- REQUIMTE/CQFB, Departamento
de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
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38
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Youngblut M, Pauly DJ, Stein N, Walters D, Conrad JA, Moran GR, Bennett B, Pacheco AA. Shewanella oneidensis cytochrome c nitrite reductase (ccNiR) does not disproportionate hydroxylamine to ammonia and nitrite, despite a strongly favorable driving force. Biochemistry 2014; 53:2136-44. [PMID: 24645742 DOI: 10.1021/bi401705d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cytochrome c nitrite reductase (ccNiR) from Shewanella oneidensis, which catalyzes the six-electron reduction of nitrite to ammonia in vivo, was shown to oxidize hydroxylamine in the presence of large quantities of this substrate, yielding nitrite as the sole free nitrogenous product. UV-visible stopped-flow and rapid-freeze-quench electron paramagnetic resonance data, along with product analysis, showed that the equilibrium between hydroxylamine and nitrite is fairly rapidly established in the presence of high initial concentrations of hydroxylamine, despite said equilibrium lying far to the left. By contrast, reduction of hydroxylamine to ammonia did not occur, even though disproportionation of hydroxylamine to yield both nitrite and ammonia is strongly thermodynamically favored. This suggests a kinetic barrier to the ccNiR-catalyzed reduction of hydroxylamine to ammonia. A mechanism for hydroxylamine reduction is proposed in which the hydroxide group is first protonated and released as water, leaving what is formally an NH2(+) moiety bound at the heme active site. This species could be a metastable intermediate or a transition state but in either case would exist only if it were stabilized by the donation of electrons from the ccNiR heme pool into the empty nitrogen p orbital. In this scenario, ccNiR does not catalyze disproportionation because the electron-donating hydroxylamine does not poise the enzyme at a sufficiently low potential to stabilize the putative dehydrated hydroxylamine; presumably, a stronger reductant is required for this.
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Affiliation(s)
- Matthew Youngblut
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin 53211, United States
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39
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Paquete CM, Louro RO. Unveiling the details of electron transfer in multicenter redox proteins. Acc Chem Res 2014; 47:56-65. [PMID: 23984680 DOI: 10.1021/ar4000696] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Metalloproteins modulate the intrinsic properties of transition metals to achieve controlled catalysis, electron transfer, or structural stabilization. Those performing electron transport, redox proteins, are a diverse class of proteins with central roles in numerous metabolic and signaling pathways, including respiration and photosynthesis. Many redox proteins have applications in industry, especially biotechnology, making them the focus of intense research. Redox proteins may contain one or multiple redox centers of the same or a different type. The complexity of proteins with multiple redox centers makes it difficult to establish a detailed molecular mechanism for their activity. Thermodynamic and kinetic information can be interpreted using the molecular structure to elucidate the protein's functional mechanism. This Account reviews experimental strategies developed in recent years to determine the detailed thermodynamic properties of multicenter redox proteins and their kinetic properties during interactions with redox partners. These strategies allow the discrimination of thermodynamic and kinetic properties of each individual redox center. The thermodynamic characterization of the redox transitions results from the combined analysis of data from NMR and UV-visible spectroscopy. Meanwhile, the kinetic characterization of intermolecular electron transfer comes from stopped-flow spectrophotometry. We illustrate an application of these strategies to a particular redox protein, the small tetraheme cytochrome from the periplasmic space of Shewanella oneidensis MR-1. This protein is a convenient prototype for developing methods for the detailed analysis of multicenter electron transfer proteins because hemes have strong UV-visible absorption bands and because heme resonances have exquisite discrimination in NMR spectra. Nonetheless, the methods are fully generalizable. Ultimately, this Account highlights the relevance of detailed characterization of the thermodynamic and kinetic properties of redox proteins. These properties are responsible for the directionality and specificity of the electron transfer process in bioenergetic pathways; a more thorough characterization of these properties should allow better-designed proteins for industrial applications.
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Affiliation(s)
- Catarina M. Paquete
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República (EAN), 2780-157 Oeiras, Portugal
| | - Ricardo O. Louro
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República (EAN), 2780-157 Oeiras, Portugal
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40
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Abstract
The global biogeochemical nitrogen cycle is essential for life on Earth. Many of the underlying biotic reactions are catalyzed by a multitude of prokaryotic and eukaryotic life forms whereas others are exclusively carried out by microorganisms. The last century has seen the rise of a dramatic imbalance in the global nitrogen cycle due to human behavior that was mainly caused by the invention of the Haber-Bosch process. Its main product, ammonia, is a chemically reactive and biotically favorable form of bound nitrogen. The anthropogenic supply of reduced nitrogen to the biosphere in the form of ammonia, for example during environmental fertilization, livestock farming, and industrial processes, is mandatory in feeding an increasing world population. In this chapter, environmental ammonia pollution is linked to the activity of microbial metalloenzymes involved in respiratory energy metabolism and bioenergetics. Ammonia-producing multiheme cytochromes c are discussed as paradigm enzymes.
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Affiliation(s)
- Jörg Simon
- Microbial Energy Conversion and Biotechnology, Department of Biology, Technische Universität Darmstadt, Schnittspahnstrasse 10, D-64287, Darmstadt, Germany,
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41
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Khalfaoui-Hassani B, Lanciano P, Daldal F. A robust genetic system for producing heterodimeric native and mutant cytochrome bc(1). Biochemistry 2013; 52:7184-95. [PMID: 24028512 DOI: 10.1021/bi400560p] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ubihydroquinone:cytochrome c oxidoreductase, or cytochrome bc1, is central to the production of ATP by oxidative phosphorylation and photophosphorylation in many organisms. Its three-dimensional structure depicts it as a homodimer with each monomer composed of the Fe-S protein, cytochrome b, and cytochrome c1 subunits. Recent genetic approaches successfully produced heterodimeric variants of this enzyme, providing insights into its mechanism of function. However, these experimental setups are inherently prone to genetic rearrangements as they carry repeated copies of cytochrome bc1 structural genes. Duplications present on a single replicon (one-plasmid system) or a double replicon (two-plasmid system) could yield heterogeneous populations via homologous recombination or other genetic events at different frequencies, especially under selective growth conditions. In this work, we assessed the origins and frequencies of genetic variations encountered in these systems and describe an improved variant of the two-plasmid system. We found that use of a recombination-deficient background (recA) minimizes spontaneous formation of co-integrant plasmids and renders the homologous recombination within the cytochrome b gene copies inconsequential. On the basis of the data, we conclude that both the newly improved RecA-deficient and the previously used RecA-proficient two-plasmid systems reliably produce native and mutant heterodimeric cytochrome bc1 variants. The two-plasmid system developed here might contribute to the study of "mitochondrial heteroplasmy"-like heterogeneous states in model bacteria (e.g., Rhodobacter species) suitable for bioenergetics studies. In the following paper (DOI 10.1021/bi400561e), we describe the use of the two-plasmid system to produce and characterize, in membranes and in purified states, an active heterodimeric cytochrome bc1 variant with unusual intermonomer electron transfer properties.
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Affiliation(s)
- Bahia Khalfaoui-Hassani
- Department of Biology, University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
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42
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Abstract
The conditions for nitrite reductase (NiRs) produced by Lactobacillus plantarum from salted fish were optimized. Enzyme activity of nitrite reductase was used as evaluation index. The results showed that the pH value had greatest influence on enzyme activity. The optimum conditions of producing nitrite reductase were inoculate quantity 4 %, pH 6.3, culture temperature 35 °C, incubation time 48 h. The enzyme activity of nitrite reductase reached to 89.672 U/mL, which increased by 71 % after optimization. This work provided the foundation for the research of enzymatic properties of nitrite reductase. This may be useful to the production of salted fish products.
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43
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Contrasting catalytic profiles of multiheme nitrite reductases containing CxxCK heme-binding motifs. J Biol Inorg Chem 2013; 18:655-67. [DOI: 10.1007/s00775-013-1011-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 06/01/2013] [Indexed: 10/26/2022]
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44
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Koebke KJ, Pauly DJ, Lerner L, Liu X, Pacheco AA. Does the Oxidation of Nitric Oxide by oxyMyoglobin Share an Intermediate with the metMyoglobin-Catalyzed Isomerization of Peroxynitrite? Inorg Chem 2013; 52:7623-32. [DOI: 10.1021/ic400697a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Karl J. Koebke
- Department of Chemistry
and Biochemistry, University of Wisconsin−Milwaukee, Milwaukee,
Wisconsin 53211, United States
| | - Daniel J. Pauly
- Department of Chemistry
and Biochemistry, University of Wisconsin−Milwaukee, Milwaukee,
Wisconsin 53211, United States
| | - Leonid Lerner
- Department of Chemistry
and Biochemistry, University of Wisconsin−Milwaukee, Milwaukee,
Wisconsin 53211, United States
| | - Xien Liu
- Department of Chemistry
and Biochemistry, University of Wisconsin−Milwaukee, Milwaukee,
Wisconsin 53211, United States
| | - A. Andrew Pacheco
- Department of Chemistry
and Biochemistry, University of Wisconsin−Milwaukee, Milwaukee,
Wisconsin 53211, United States
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45
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Bewley KD, Ellis KE, Firer-Sherwood MA, Elliott SJ. Multi-heme proteins: nature's electronic multi-purpose tool. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1827:938-48. [PMID: 23558243 DOI: 10.1016/j.bbabio.2013.03.010] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/20/2013] [Accepted: 03/25/2013] [Indexed: 02/06/2023]
Abstract
While iron is often a limiting nutrient to Biology, when the element is found in the form of heme cofactors (iron protoporphyrin IX), living systems have excelled at modifying and tailoring the chemistry of the metal. In the context of proteins and enzymes, heme cofactors are increasingly found in stoichiometries greater than one, where a single protein macromolecule contains more than one heme unit. When paired or coupled together, these protein associated heme groups perform a wide variety of tasks, such as redox communication, long range electron transfer and storage of reducing/oxidizing equivalents. Here, we review recent advances in the field of multi-heme proteins, focusing on emergent properties of these complex redox proteins, and strategies found in Nature where such proteins appear to be modular and essential components of larger biochemical pathways. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems.
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Affiliation(s)
- Kathryn D Bewley
- Department of Chemistry, Boston University, Boston, MA 02215, USA
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46
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Judd ET, Youngblut M, Pacheco AA, Elliott SJ. Direct electrochemistry of Shewanella oneidensis cytochrome c nitrite reductase: evidence of interactions across the dimeric interface. Biochemistry 2012; 51:10175-85. [PMID: 23210513 DOI: 10.1021/bi3011708] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Shewanella oneidensis cytochrome c nitrite reductase (soNrfA), a dimeric enzyme that houses five c-type hemes per protomer, conducts the six-electron reduction of nitrite and the two-electron reduction of hydroxylamine. Protein film voltammetry (PFV) has been used to study the cytochrome c nitrite reductase from Escherichia coli (ecNrfA) previously, revealing catalytic reduction of both nitrite and hydroxylamine substrates by ecNrfA adsorbed to a graphite electrode that is characterized by "boosts" and attenuations in activity depending on the applied potential. Here, we use PFV to investigate the catalytic properties of soNrfA during both nitrite and hydroxylamine turnover and compare those properties to the properties of ecNrfA. Distinct differences in both the electrochemical and kinetic characteristics of soNrfA are observed; e.g., all detected electron transfer steps are one-electron in nature, contrary to what has been observed in ecNrfA [Angove, H. C., Cole, J. A., Richardson, D. J., and Butt, J. N. (2002) J. Biol. Chem. 277, 23374-23381]. Additionally, we find evidence of substrate inhibition during nitrite turnover and negative cooperativity during hydroxylamine turnover, neither of which has previously been observed in any cytochrome c nitrite reductase. Collectively, these data provide evidence that during catalysis, potential pathways of communication exist between the individual soNrfA monomers comprising the native homodimer.
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Affiliation(s)
- Evan T Judd
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA
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47
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Schmidt M, Šrajer V, Purwar N, Tripathi S. The kinetic dose limit in room-temperature time-resolved macromolecular crystallography. JOURNAL OF SYNCHROTRON RADIATION 2012; 19:264-73. [PMID: 22338689 PMCID: PMC3284346 DOI: 10.1107/s090904951105549x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 12/23/2011] [Indexed: 05/16/2023]
Abstract
Protein X-ray structures are determined with ionizing radiation that damages the protein at high X-ray doses. As a result, diffraction patterns deteriorate with the increased absorbed dose. Several strategies such as sample freezing or scavenging of X-ray-generated free radicals are currently employed to minimize this damage. However, little is known about how the absorbed X-ray dose affects time-resolved Laue data collected at physiological temperatures where the protein is fully functional in the crystal, and how the kinetic analysis of such data depends on the absorbed dose. Here, direct evidence for the impact of radiation damage on the function of a protein is presented using time-resolved macromolecular crystallography. The effect of radiation damage on the kinetic analysis of time-resolved X-ray data is also explored.
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Affiliation(s)
- M Schmidt
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
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