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Akutsu Y, Fujiwara T, Suzuki R, Nishigaya Y, Yamazaki T. Juglone, a plant-derived 1,4-naphthoquinone, binds to hydroxylamine oxidoreductase and inhibits the electron transfer to cytochrome c554. Appl Environ Microbiol 2023; 89:e0129123. [PMID: 38009977 PMCID: PMC10734522 DOI: 10.1128/aem.01291-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 09/20/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE Nitrification, the microbial conversion of ammonia to nitrate via nitrite, plays a pivotal role in the global nitrogen cycle. However, the excessive use of ammonium-based fertilizers in agriculture has disrupted this cycle, leading to groundwater pollution and greenhouse gas emissions. In this study, we have demonstrated the inhibitory effects of plant-derived juglone and related 1,4-naphthoquinones on the nitrification process in Nitrosomonas europaea. Notably, the inhibition mechanism is elucidated in which 1,4-naphthoquinones interact with hydroxylamine oxidoreductase, disrupting the electron transfer to cytochrome c554, a physiological electron acceptor. These findings support the notion that phytochemicals can impede nitrification by interfering with the essential electron transfer process in ammonia oxidation. The findings presented in this article offer valuable insights for the development of strategies aimed at the management of nitrification, reduction of fertilizer utilization, and mitigation of greenhouse gas emissions.
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Affiliation(s)
- Yukie Akutsu
- Research Center for Advanced Analysis, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki, Japan
| | - Takaaki Fujiwara
- Research Center for Advanced Analysis, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki, Japan
| | - Rintaro Suzuki
- Research Center for Advanced Analysis, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki, Japan
| | | | - Toshimasa Yamazaki
- Research Center for Advanced Analysis, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki, Japan
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2
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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: 92] [Impact Index Per Article: 30.7] [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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3
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Hagen WR. Very Low-Frequency Broadband Electron Paramagnetic Resonance Spectroscopy of Metalloproteins. J Phys Chem A 2021; 125:3208-3218. [PMID: 33848159 PMCID: PMC8154605 DOI: 10.1021/acs.jpca.1c01217] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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A previously developed
spectrometer for broadband electron paramagnetic
resonance (EPR) spectroscopy of dilute randomly oriented systems has
been considerably modified to extend the frequency reach down to the
hundred MHz range and to boost concentration sensitivity by 1 to 2
orders of magnitude. The instrument is now suitable for the study
of biological systems in particular metalloproteins. As a proof of
concept, examples from the class of low-spin ferric hemoproteins are
studied in terms of frequency-dependent changes in their EPR spectra.
Mono-heme cytochrome c EPR is determined by g-strain
over a wide frequency range, whereas a combination of unresolved ligand
hyperfine interaction and concentration-dependent intermolecular dipolar
interaction becomes dominant at very low frequencies. In the four
heme containing cytochrome c3, g-strain
combines with intramolecular dipolar interaction over the full-studied
frequency range of 0.23–12.0 GHz. It is concluded that the
point-dipole approach is inappropriate to describe magnetic interactions
between low-spin ferric heme systems and that a body of literature
on redox interactions in multi-heme proteins will be affected by this
conclusion.
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Affiliation(s)
- Wilfred R Hagen
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, The Netherlands
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4
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Holmes DE, Dang Y, Smith JA. Nitrogen cycling during wastewater treatment. ADVANCES IN APPLIED MICROBIOLOGY 2019; 106:113-192. [PMID: 30798802 DOI: 10.1016/bs.aambs.2018.10.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Many wastewater treatment plants in the world do not remove reactive nitrogen from wastewater prior to release into the environment. Excess reactive nitrogen not only has a negative impact on human health, it also contributes to air and water pollution, and can cause complex ecosystems to collapse. In order to avoid the deleterious effects of excess reactive nitrogen in the environment, tertiary wastewater treatment practices that ensure the removal of reactive nitrogen species need to be implemented. Many wastewater treatment facilities rely on chemicals for tertiary treatment, however, biological nitrogen removal practices are much more environmentally friendly and cost effective. Therefore, interest in biological treatment is increasing. Biological approaches take advantage of specific groups of microorganisms involved in nitrogen cycling to remove reactive nitrogen from reactor systems by converting ammonia to nitrogen gas. Organisms known to be involved in this process include autotrophic ammonia-oxidizing bacteria, heterotrophic ammonia-oxidizing bacteria, ammonia-oxidizing archaea, anaerobic ammonia oxidizing bacteria (anammox), nitrite-oxidizing bacteria, complete ammonia oxidizers, and dissimilatory nitrate reducing microorganisms. For example, in nitrifying-denitrifying reactors, ammonia- and nitrite-oxidizing bacteria convert ammonia to nitrate and then denitrifying microorganisms reduce nitrate to nonreactive dinitrogen gas. Other nitrogen removal systems (anammox reactors) take advantage of anammox bacteria to convert ammonia to nitrogen gas using NO as an oxidant. A number of promising new biological treatment technologies are emerging and it is hoped that as the cost of these practices goes down more wastewater treatment plants will start to include a tertiary treatment step.
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5
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Ponomarenko N, Niklas J, Pokkuluri PR, Poluektov O, Tiede DM. Electron Paramagnetic Resonance Characterization of the Triheme Cytochrome from Geobacter sulfurreducens. Biochemistry 2018; 57:1722-1732. [DOI: 10.1021/acs.biochem.7b00917] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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6
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Maalcke WJ, Reimann J, de Vries S, Butt JN, Dietl A, Kip N, Mersdorf U, Barends TRM, Jetten MSM, Keltjens JT, Kartal B. Characterization of Anammox Hydrazine Dehydrogenase, a Key N2-producing Enzyme in the Global Nitrogen Cycle. J Biol Chem 2016; 291:17077-92. [PMID: 27317665 PMCID: PMC5016112 DOI: 10.1074/jbc.m116.735530] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 06/07/2016] [Indexed: 11/06/2022] Open
Abstract
Anaerobic ammonium-oxidizing (anammox) bacteria derive their energy for growth from the oxidation of ammonium with nitrite as the electron acceptor. N2, the end product of this metabolism, is produced from the oxidation of the intermediate, hydrazine (N2H4). Previously, we identified N2-producing hydrazine dehydrogenase (KsHDH) from the anammox organism Kuenenia stuttgartiensis as the gene product of kustc0694 and determined some of its catalytic properties. In the genome of K. stuttgartiensis, kustc0694 is one of 10 paralogs related to octaheme hydroxylamine (NH2OH) oxidoreductase (HAO). Here, we characterized KsHDH as a covalently cross-linked homotrimeric octaheme protein as found for HAO and HAO-related hydroxylamine-oxidizing enzyme kustc1061 from K. stuttgartiensis Interestingly, the HDH trimers formed octamers in solution, each octamer harboring an amazing 192 c-type heme moieties. Whereas HAO and kustc1061 are capable of hydrazine oxidation as well, KsHDH was highly specific for this activity. To understand this specificity, we performed detailed amino acid sequence analyses and investigated the catalytic and spectroscopic (electronic absorbance, EPR) properties of KsHDH in comparison with the well defined HAO and kustc1061. We conclude that HDH specificity is most likely derived from structural changes around the catalytic heme 4 (P460) and of the electron-wiring circuit comprising seven His/His-ligated c-type hemes in each subunit. These nuances make HDH a globally prominent N2-producing enzyme, next to nitrous oxide (N2O) reductase from denitrifying microorganisms.
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Affiliation(s)
- Wouter J Maalcke
- From the Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen, 6525 AJ Nijmegen, The Netherlands
| | - Joachim Reimann
- From the Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen, 6525 AJ Nijmegen, The Netherlands
| | - Simon de Vries
- the Department of Biotechnology, Delft University of Technology, 2628 BC Delft, The Netherlands
| | - Julea N Butt
- the Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom, and
| | - Andreas Dietl
- the Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | - Nardy Kip
- From the Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen, 6525 AJ Nijmegen, The Netherlands
| | - Ulrike Mersdorf
- the Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | - Thomas R M Barends
- the Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | - Mike S M Jetten
- From the Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen, 6525 AJ Nijmegen, The Netherlands, the Department of Biotechnology, Delft University of Technology, 2628 BC Delft, The Netherlands
| | - Jan T Keltjens
- From the Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen, 6525 AJ Nijmegen, The Netherlands
| | - Boran Kartal
- From the Department of Microbiology, Institute for Water and Wetland Research, Radboud University Nijmegen, 6525 AJ Nijmegen, The Netherlands,
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7
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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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8
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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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9
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Subedi BP, Corder AL, Zhang S, Foss FW, Pierce BS. Steady-state kinetics and spectroscopic characterization of enzyme-tRNA interactions for the non-heme diiron tRNA-monooxygenase, MiaE. Biochemistry 2014; 54:363-76. [PMID: 25453905 DOI: 10.1021/bi5012207] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
MiaE [2-methylthio-N(6)-isopentenyl-adenosine(37)-tRNA monooxygenase] isolated from Salmonella typhimurium is a unique non-heme diiron enzyme that catalyzes the O2-dependent post-transcriptional allylic hydroxylation of a hypermodified nucleotide (ms(2)i(6)A37) at position 37 of selected tRNA molecules to produce 2-methylthio-N(6)-(4-hydroxyisopentenyl)-adenosine(37). In this work, isopentenylated tRNA substrates for MiaE were produced from small RNA oligomers corresponding to the anticodon stem loop (ACSL) region of tRNA(Trp) using recombinant MiaA and dimethylallyl pyrophosphate. Steady-state rates for MiaE-catalyzed substrate hydroxylation were determined using recombinant ferredoxin (Fd) and ferredoxin reductase (FdR) to provide a catalytic electron transport chain (ETC) using NADPH as the sole electron source. As with previously reported peroxide-shunt assays, steady-state product formation retains nearly stoichiometric (>98%) E stereoselectivity. MiaE-catalyzed i(6)A-ACSL(Trp) hydroxylation follows Michaelis-Menten saturation kinetics with kcat, KM, and V/K determined to be 0.10 ± 0.01 s(-1), 9.1 ± 1.5 μM, and ∼11000 M(-1) s(-1), respectively. While vastly slower, MiaE-catalyzed hydroxylation of free i(6)A nucleoside could also be observed using the (Fd/FdR)-ETC assay. By comparison to the V/K determined for i(6)A-ACSL substrates, an ∼6000-fold increase in enzymatic efficiency is imparted by ACSL(Trp)-MiaE interactions. The impact of substrate tRNA-MiaE interactions on protein secondary structure and active site electronic configuration was investigated using circular dichroism, dual-mode X-band electron paramagnetic resonance, and Mössbauer spectroscopies. These studies demonstrate that binding of tRNA to MiaE induces a protein conformational change that influences the electronic structure of the diiron site analogous to what has been observed for various bacterial multicomponent diiron monooxygenases upon titration with their corresponding effector proteins. These observations suggest that substrate-enzyme interactions may play a pivotal role in modulating the reactivity of the MiaE diiron active site. Moreover, the simplified monomeric (α) protein configuration exhibited by MiaE provide an unparalleled opportunity to study the impact of protein-effector interactions on non-heme diiron site geometry and reactivity.
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Affiliation(s)
- Bishnu P Subedi
- Department of Chemistry and Biochemistry, College of Sciences, The University of Texas at Arlington , Arlington, Texas 76019, United States
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10
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Ma Z, Olechnowicz F, Skorik YA, Achim C. Metal binding to ligand-containing peptide nucleic acids. Inorg Chem 2011; 50:6083-92. [PMID: 21634382 DOI: 10.1021/ic200138b] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The substitution of nucleobases in nucleic acid duplexes with ligands that have high affinity for transition metal ions creates metal-binding sites at specific locations within the duplexes. Several studies on the incorporation of metal ions into DNA and peptide nucleic acid (PNA) duplexes have suggested that the stability constant of the metal complex formed within the duplexes is a primary determinant of the thermal stability of the duplexes. To understand this relationship, we have synthesized two PNA monomers that carry the same ligand, namely 8-hydroxyquinoline, but have this ligand attached differently to the PNA backbone. The PNA monomers have been incorporated into PNA duplexes. UV and CD spectroscopy and calorimetric studies of the 8-hydroxyquinoline-PNA duplexes showed that the effect of the stability of the metal complex on the PNA duplexes was significantly modulated by the steric relationship between the complex and the duplex. This information is useful for the construction of hybrid inorganic-nucleic acid nanostructures.
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Affiliation(s)
- Zhijie Ma
- Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, USA
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11
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Kim HJ, Zatsman A, Upadhyay AK, Whittaker M, Bergmann D, Hendrich MP, Hooper AB. Membrane tetraheme cytochrome c(m552) of the ammonia-oxidizing nitrosomonas europaea: a ubiquinone reductase. Biochemistry 2010; 47:6539-51. [PMID: 18505274 DOI: 10.1021/bi8001264] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cytochrome c(m552) (cyt c(m552)) from the ammonia-oxidizing Nitrosomonas europaea is encoded by the cycB gene, which is preceded in a gene cluster by three genes encoding proteins involved in the oxidation of hydroxylamine: hao, hydroxylamine oxidoreductase; orf2, a putative membrane protein; cycA, cyt c(554). By amino acid sequence alignment of the core tetraheme domain, cyt c(m552) belongs to the NapC/TorC family of tetra- or pentaheme cytochrome c species involved in electron transport from membrane quinols to a variety of periplasmic electron shuttles leading to terminal reductases. However, cyt c(m552) is thought to reduce quinone with electrons originating from HAO. In this work, the tetrahemic 27 kDa cyt c(m552) from N. europaea was purified after extraction from membranes using Triton X-100 with subsequent exchange into n-dodecyl beta-d-maltoside. The cytochrome had a propensity to form strong SDS-resistant dimers likely mediated by a conserved GXXXG motif present in the putative transmembrane segment. Optical spectra of the ferric protein contained a broad ligand-metal charge transfer band at approximately 625 nm indicative of a high-spin heme. Mossbauer spectroscopy of the reduced (57)Fe-enriched protein revealed the presence of high-spin and low-spin hemes in a 1:3 ratio. Multimode EPR spectroscopy of the native state showed signals from an electronically interacting high-spin/low-spin pair of hemes. Upon partial reduction, a typical high-spin heme EPR signal was observed. No EPR signals were observed from the other two low-spin hemes, indicating an electronic interaction between these hemes as well. UV-vis absorption data indicate that CO (ferrous enzyme) or CN(-) (ferric or ferrous enzyme) bound to more than one and possibly all hemes. Other anionic ligands did not bind. The four ferrous hemes of the cytochrome were rapidly oxidized in the presence of oxygen. Comparative modeling, based on the crystal structure and conserved residues of the homologous NrfH protein from Desulfovibrio of cyt c(m552), predicted some structural elements, including a Met-ligated high-spin heme in a quinone-binding pocket, and likely axial ligands to all four hemes.
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Affiliation(s)
- Hyung J Kim
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, St. Paul, Minnesota 55106, USA
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12
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Abstract
Ammonia oxidizing bacteria extract energy for growth from the oxidation of ammonia to nitrite. Ammonia monooxygenase, which initiates ammonia oxidation, remains enigmatic given the lack of purified preparations. Genetic and biochemical studies support a model for the enzyme consisting of three subunits and metal centers of copper and iron. Knowledge of hydroxylamine oxidoreductase, which oxidizes hydroxylamine formed by ammonia monooxygenase to nitrite, is informed by a crystal structure and detailed spectroscopic and catalytic studies. Other inorganic nitrogen compounds, including NO, N2O, NO2, and N2 can be consumed and/or produced by ammonia-oxidizing bacteria. NO and N2O can be produced as byproducts of hydroxylamine oxidation or through nitrite reduction. NO2 can serve as an alternative oxidant in place of O2 in some ammonia-oxidizing strains. Our knowledge of the diversity of inorganic N metabolism by ammonia-oxidizing bacteria continues to grow. Nonetheless, many questions remain regarding the enzymes and genes involved in these processes and the role of these pathways in ammonia oxidizers.
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Affiliation(s)
- Daniel J Arp
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA.
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13
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Belock CW, Cetin A, Barone NV, Ziegler CJ. Transition metal coordination chemistry ofN,N-bis(2-{pyrid-2-ylethyl})hydroxylamine. Inorg Chem 2008; 47:7114-20. [PMID: 18646844 DOI: 10.1021/ic702406n] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although directly relevant to metal mediated biological nitrification as well as the coordination chemistry of peroxide, the metal complexes of hydroxylamines and their functionalized variants remain largely unexplored. The chelating hydroxylamine ligand N,N-bis(2-{pyrid-2-ylethyl})hydroxylamine can be readily generated via a solvent free reaction in high purity; however, the ligand is prone to decomposition which can hamper metal reaction. N,N-bis(2-{pyrid-2-ylethyl})hydroxylamine forms stable complexes with chromium(III), manganese(II), nickel(II), and cadmium(II) ions, coordinating in a side-on mode in the case of chromium and via the nitrogen in the case of the latter three metal ions. The hydroxylamine ligand can also be reduced to form N,N-bis(2-{pyrid-2-ylethyl})amine upon exposure to a stoichiometric amount of the metal salts cobalt(II) nitrate, vanadium(III) chloride, and iron(II) chloride. In the reaction with cobalt nitrate, the reduced ligand then chelates to the metal to form [N,N-bis(2-{pyrid-2-ylethyl})amine]dinitrocobalt(II). Upon reaction with vanadium(III) chloride and iron(III) chloride, the reduced ligand is isolated as the protonated free base, resulting from a metal-mediated decomposition reaction.
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Affiliation(s)
- Christopher W Belock
- Department of Chemistry, Knight Chemical Laboratory, University of Akron, Akron, Ohio 44325-3601, USA
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14
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Kostera J, Youngblut MD, Slosarczyk JM, Pacheco AA. Kinetic and product distribution analysis of NO* reductase activity in Nitrosomonas europaea hydroxylamine oxidoreductase. J Biol Inorg Chem 2008; 13:1073-83. [PMID: 18553112 DOI: 10.1007/s00775-008-0393-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2007] [Accepted: 05/25/2008] [Indexed: 10/22/2022]
Abstract
Hydroxylamine oxidoreductase (HAO) from the ammonia-oxidizing bacterium Nitrosomonas europaea normally catalyzes the four-electron oxidation of hydroxylamine to nitrite, which is the second step in ammonia-dependent respiration. Here we show that, in the presence of methyl viologen monocation radical (MV(red)), HAO can catalyze the reduction of nitric oxide to ammonia. The process is analogous to that catalyzed by cytochrome c nitrite reductase, an enzyme found in some bacteria that use nitrite as a terminal electron acceptor during anaerobic respiration. The availability of a reduction pathway to ammonia is an important factor to consider when designing in vitro studies of HAO, and may also have some physiological relevance. The reduction of nitric oxide to ammonia proceeds in two kinetically distinct steps: nitric oxide is first reduced to hydroxylamine, and then hydroxylamine is reduced to ammonia at a tenfold slower rate. The second step was investigated independently in solutions initially containing hydroxylamine, MV(red), and HAO. Both steps show first-order dependence on nitric oxide and HAO concentrations, and zero-order dependence on MV(red) concentration. The rate constants governing each reduction step were found to have values of (4.7 +/- 0.3) x 10(5) and (2.06 +/- 0.04) x 10(4) M(-1) s(-1), respectively. A second reduction pathway, with second-order dependence on nitric oxide, may become available as the concentration of nitric oxide is increased. Such a pathway might lead to production of nitrous oxide. We estimate a maximum value of (1.5 +/- 0.05) x 10(10) M(-2) s(-1) for the rate constant of the alternative pathway, which is small and suggests that the pathway is not physiologically important.
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Affiliation(s)
- Joshua Kostera
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
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Zatsman AI, Zhang H, Gunderson WA, Cramer WA, Hendrich MP. Heme-heme interactions in the cytochrome b6f complex: EPR spectroscopy and correlation with structure. J Am Chem Soc 2007; 128:14246-7. [PMID: 17076484 PMCID: PMC2812023 DOI: 10.1021/ja065798m] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytochrome b6f of oxygenic photosynthesis was studied using multifrequency, multimode EPR Spectroscopy. Frequency dependent signals above g = 4.3, and the observation of parallel-mode signals, are indicative of spin interactions in the complex. We demonstrate the presence of an exchange interaction between the unique high-spin heme cn and a nearby low-spin heme bn, and show that a quinone analog NQNO binds at or near to heme cn. The two hemes remain spin coupled upon the binding of NQNO, though strength of interaction decreases significantly. The electronic coupling implies that the heme bn/cn pair could function as a unit to facilitate 2-electron reduction of plastoquionone without generation of an energetically unfavorable semiquinone intermediate.
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16
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Hartshorne RS, Jepson BN, Clarke TA, Field SJ, Fredrickson J, Zachara J, Shi L, Butt JN, Richardson DJ. Characterization of Shewanella oneidensis MtrC: a cell-surface decaheme cytochrome involved in respiratory electron transport to extracellular electron acceptors. J Biol Inorg Chem 2007; 12:1083-94. [PMID: 17701062 DOI: 10.1007/s00775-007-0278-y] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Accepted: 07/09/2007] [Indexed: 10/23/2022]
Abstract
MtrC is a decaheme c-type cytochrome associated with the outer cell membrane of Fe(III)-respiring species of the Shewanella genus. It is proposed to play a role in anaerobic respiration by mediating electron transfer to extracellular mineral oxides that can serve as terminal electron acceptors. The present work presents the first spectropotentiometric and voltammetric characterization of MtrC, using protein purified from Shewanella oneidensis MR-1. Potentiometric titrations, monitored by UV-vis absorption and electron paramagnetic resonance (EPR) spectroscopy, reveal that the hemes within MtrC titrate over a broad potential range spanning between approximately +100 and approximately -500 mV (vs. the standard hydrogen electrode). Across this potential window the UV-vis absorption spectra are characteristic of low-spin c-type hemes and the EPR spectra reveal broad, complex features that suggest the presence of magnetically spin-coupled low-spin c-hemes. Non-catalytic protein film voltammetry of MtrC demonstrates reversible electrochemistry over a potential window similar to that disclosed spectroscopically. The voltammetry also allows definition of kinetic properties of MtrC in direct electron exchange with a solid electrode surface and during reduction of a model Fe(III) substrate. Taken together, the data provide quantitative information on the potential domain in which MtrC can operate.
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Affiliation(s)
- Robert S Hartshorne
- Centre for Metalloprotein Spectroscopy and Biology, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
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17
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Pearson AR, Elmore BO, Yang C, Ferrara JD, Hooper AB, Wilmot CM. The crystal structure of cytochrome P460 of Nitrosomonas europaea reveals a novel cytochrome fold and heme-protein cross-link. Biochemistry 2007; 46:8340-9. [PMID: 17583915 PMCID: PMC2527454 DOI: 10.1021/bi700086r] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have determined the 1.8 A X-ray crystal structure of a monoheme c-type cytochrome, cytochrome P460, from Nitrosomonas europea. The chromophore possesses unusual spectral properties analogous to those of the catalytic heme P460 of hydroxylamine oxidoreductase (HAO), the only known heme in biology to withdraw electrons from an iron-coordinated substrate. The analysis reveals a homodimeric structure and elucidates a new c-type cytochrome fold that is predominantly beta-sheet. In addition to the two cysteine thioether links to the porphyrin typical of c-type hemes, there is a third proteinaceous link involving a conserved lysine. The covalent bond is between the lysine side-chain nitrogen and the 13'-meso carbon of the heme, which, following cross-link formation, is sp3-hybridized, demonstrating the loss of conjugation at this position within the porphyrin. The structure has implications for the analogous tyrosine-heme meso carbon cross-link observed in HAO.
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Affiliation(s)
- Arwen R. Pearson
- Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota, Minneapolis, MN, 55455, U. S. A
| | - Bradley O. Elmore
- Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota, Minneapolis, MN, 55455, U. S. A
| | - Cheng Yang
- Rigaku Americas Corp. 9009 New Trails Drive, The Woodlands, TX, 77381, U. S. A
| | - Joseph D. Ferrara
- Rigaku Americas Corp. 9009 New Trails Drive, The Woodlands, TX, 77381, U. S. A
| | - Alan B. Hooper
- Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota, Minneapolis, MN, 55455, U. S. A
| | - Carrie M. Wilmot
- Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota, Minneapolis, MN, 55455, U. S. A
- Corresponding Author: Carrie M. Wilmot, e-mail: , tel: +1-612-624-2406, fax: +1-612-624-5121
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Upadhyay AK, Hooper AB, Hendrich MP. NO reductase activity of the tetraheme cytochrome C554 of Nitrosomonas europaea. J Am Chem Soc 2006; 128:4330-7. [PMID: 16569009 PMCID: PMC2806813 DOI: 10.1021/ja055183+] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The tetraheme cytochrome c(554) (cyt c(554)) from Nitrosomonas europaea is believed to function as an electron-transfer protein from hydroxylamine oxidoreductase (HAO). We show here that cyt c(554) also has significant NO reductase activity. The protein contains one high-spin and three low-spin c-type hemes. HAO catalyzed reduction of the cyt c(554), ligand binding, intermolecular electron transfer, and kinetics of NO reduction by cyt c(554) have been investigated. We detect the formation of a NO-bound ferrous heme species in cyt c(554) by EPR and Mössbauer spectroscopies during the HAO catalyzed oxidation of hydroxylamine, indicating that N-oxide intermediates produced from HAO readily bind to cyt c(554). In the half-reduced state of cyt c(554), we detect a spin interaction between the [FeNO](7) state of heme 2 and the low-spin ferric state of heme 4. We find that ferrous cyt c(554) will reduce NO at a rate greater than 16 s(-1), which is comparable to rates of other known NO reductases. Carbon monoxide or nitrite are shown not to bind to the reduced protein, and previous results indicate the reactions with O(2) are slow and that a variety of ligands will not bind in the oxidized state. Thus, the enzymatic site is highly selective for NO. The NO reductase activity of cyt c(554) may be important during ammonia oxidation in N. europaea at low oxygen concentrations to detoxify NO produced by reduction of nitrite or incomplete oxidation of hydroxylamine.
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Affiliation(s)
- Anup K. Upadhyay
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Alan B. Hooper
- Department of Biochemistry, University of Minnesota, St. Paul, Minnesota 55108
| | - Michael P. Hendrich
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
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Elmore BO, Pearson AR, Wilmot CM, Hooper AB. Expression, purification, crystallization and preliminary X-ray diffraction of a novel Nitrosomonas europaea cytochrome, cytochrome P460. Acta Crystallogr Sect F Struct Biol Cryst Commun 2006; 62:395-8. [PMID: 16582494 PMCID: PMC2222571 DOI: 10.1107/s1744309106008785] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Accepted: 03/08/2006] [Indexed: 11/11/2022]
Abstract
Cytochrome P460 from Nitrosomonas europaea, a novel mono-heme protein containing an unusual cross-link between a conserved lysine and the porphyrin ring, has been recombinantly expressed and purified from Escherichia coli. The protein crystallizes readily and diffraction to 1.7 angstroms has been obtained in-house. The crystals belong to the trigonal space group P3(1/2)21, with unit-cell parameters a = b = 53.3, c = 127.1 angstroms, and contain one monomer in the asymmetric unit.
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Affiliation(s)
- Bradley O. Elmore
- Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota, Minneapolis, Minnesota, USA
| | - Arwen R. Pearson
- Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota, Minneapolis, Minnesota, USA
| | - Carrie M. Wilmot
- Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota, Minneapolis, Minnesota, USA
| | - Alan B. Hooper
- Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota, Minneapolis, Minnesota, USA
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Abstract
Heme is one of the most pervasive cofactors in nature and the c-type cytochromes represent one of the largest families of heme-containing proteins. Recent progress in bacterial genomic analysis has revealed a vast range of genes encoding novel c-type cytochromes that contain multiple numbers of heme cofactors. The genome sequence of Geobacter sulfurreducens, for example, includes some one hundred genes encoding c-type cytochromes, with around seventy of these containing two, or more, heme groups and with one protein containing an astonishing twenty seven heme groups. This wealth of cytochromes is of great significance in the respiratory flexibility shown by bacteria such as Geobacter. In addition, we are now discovering that many of these multi-heme cytochromes have associated enzymatic activities and in some cases this is revealing new chemistries. The purpose of this perspective is to describe recent progress in the structural and functional analyses of these new multi-heme cytochromes. To illustrate this we have chosen to focus on three of these cytochromes which exhibit catalytic activities; nitrite reductase, hydroxylamine oxidoreductase and tetrathionate reductase. In addition we consider the multi-heme cytochromes from Geobacter and Desulfovibrio species. Finally, we consider and contrast the repeating structural modules found in these multi-heme cytochromes.
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Affiliation(s)
- Christopher G Mowat
- EaStCHEM, School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, UK EH9 3JJ.
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OLABE JOSÉA. REDOX REACTIVITY OF COORDINATED LIGANDS IN PENTACYANO(L)FERRATE COMPLEXES. ADVANCES IN INORGANIC CHEMISTRY 2004. [DOI: 10.1016/s0898-8838(03)55002-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Pires RH, Lourenço AI, Morais F, Teixeira M, Xavier AV, Saraiva LM, Pereira IAC. A novel membrane-bound respiratory complex from Desulfovibrio desulfuricans ATCC 27774. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1605:67-82. [PMID: 12907302 DOI: 10.1016/s0005-2728(03)00065-3] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In the anaerobic respiration of sulfate, performed by sulfate-reducing prokaryotes, reduction of the terminal electron acceptor takes place in the cytoplasm. The membrane-associated electron transport chain that feeds electrons to the cytoplasmic reductases is still very poorly characterized. In this study we report the isolation and characterization of a novel membrane-bound redox complex from Desulfovibrio desulfuricans ATCC 27774. This complex is formed by three subunits, and contains two hemes b, two FAD groups and several iron-sulfur centers. The two hemes b are low-spin, with macroscopic redox potentials of +75 and -20 mV at pH 7.6. Both hemes are reduced by menadiol, a menaquinone analogue, indicating a function for this complex in the respiratory electron-transport chain. EPR studies of the as-isolated and dithionite-reduced complex support the presence of a [3Fe-4S](1+/0) center and at least four [4Fe-4S](2+/1+) centers. Cloning of the genes coding for the complex subunits revealed that they form a putative transcription unit and have homology to subunits of heterodisulfide reductases (Hdr). The first and second genes code for soluble proteins that have homology to HdrA, whereas the third gene codes for a novel type of membrane-associated protein that contains both a hydrophobic domain with homology to the heme b protein HdrE and a hydrophilic domain with homology to the iron-sulfur protein HdrC. Homologous operons are found in the genomes of other sulfate-reducing organisms and in the genome of the green-sulfur bacterium Chlorobium tepidum TLS. The isolated complex is the first example of a new family of respiratory complexes present in anaerobic prokaryotes.
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Affiliation(s)
- Ricardo H Pires
- Instituto de Tecnologia Qui;mica e Biológica, Universidade Nova de Lisboa, R. da Quinta Grande 6, Oeiras 2780-156, Portugal
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Pitts KE, Dobbin PS, Reyes-Ramirez F, Thomson AJ, Richardson DJ, Seward HE. Characterization of the Shewanella oneidensis MR-1 decaheme cytochrome MtrA: expression in Escherichia coli confers the ability to reduce soluble Fe(III) chelates. J Biol Chem 2003; 278:27758-65. [PMID: 12732647 DOI: 10.1074/jbc.m302582200] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Shewanella oneidensis MR-1 has the metabolic capacity to grow anaerobically using Fe(III) as a terminal electron acceptor. Growth under these conditions results in the de novo synthesis of a number of periplasmic c-type cytochromes, many of which are multiheme in nature and are thought to be involved in the Fe(III) respiratory process. To begin a biochemical study of these complex cytochromes, the mtrA gene that encodes an approximate 32-kDa periplasmic decaheme cytochrome has been heterologously expressed in Escherichia coli. Co-expression of mtrA with a plasmid that contains cytochrome c maturation genes leads to the assembly of a correctly targeted holoprotein, which covalently binds ten hemes. The recombinant MtrA protein has been characterized by magnetic circular dichroism, which shows that all ten hemes have bis-histidine axial ligation. EPR spectroscopy detected only eight of these hemes, all of which are low spin and provides evidence for a spin-coupled pair of hemes in the oxidized state. Redox titrations of MtrA have been carried out with optical- and EPR-monitored methods, and the hemes are shown to reduce over the potential range -100 to -400 mV. In intact cells of E. coli, MtrA is shown to obtain electrons from the host electron transport chain and pass these onto host oxidoreductases or a range of soluble Fe(III) species. This demonstrates the promiscuous nature of this decaheme cytochrome and its potential to serve as a soluble Fe(III) reductase in intact cells.
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Affiliation(s)
- Katy E Pitts
- Centre for Metalloprotein Spectroscopy and Biology, School of Biological Sciences and School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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Bergmann DJ, Hooper AB. Cytochrome P460 of Nitrosomonas europaea. Formation of the heme-lysine cross-link in a heterologous host and mutagenic conversion to a non-cross-linked cytochrome c'. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:1935-41. [PMID: 12709052 DOI: 10.1046/j.1432-1033.2003.03550.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The heme of cytochrome P460 of Nitrosomonas europaea, which is covalently crosslinked to two cysteines of the polypeptide as with all c-type cytochromes, has an additional novel covalent crosslink to lysine 70 of the polypeptide [Arciero, D.M. & Hooper, A.B. (1997) FEBS Lett.410, 457-460]. The protein can catalyze the oxidation of hydroxylamine. The gene for this protein, cyp, was expressed in Pseudomonas aeruginosa strain PAO lacI, resulting in formation of a holo-cytochrome P460 which closely resembled native cytochrome P460 purified from N. europaea in its UV-visible spectroscopic, ligand binding and catalytic properties. Mutant versions of cytochrome P460 of N. europaea in which Lys70 70 was replaced by Arg, Ala, or Tyr, retained ligand-binding ability but lost catalytic ability and differed in optical spectra which, instead, closely resembled those of cytochromes c'. Tryptic fragments containing the c-heme joined only by two thioether linkages were observed by MALDI-TOF for the mutant cytochromes P460 K70R and K70A but not in wild-type cytochrome P460, consistent with the structural modification of the c-heme only in the wild-type cytochrome. The present observations support the hypothesized evolutionary relationship between cytochromes P460 and cytochromes c' in N. europaea and M. capsulatus[Bergmann, D.J., Zahn, J.A., & DiSpirito, A.A. (2000) Arch. Microbiol. 173, 29-34], confirm the importance of a heme-crosslink to the spectroscopic properties and catalysis and suggest that the crosslink might form auto-catalytically.
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Affiliation(s)
- David J Bergmann
- Department of Biology, Black Hills State University, Spearfish, SD, USA
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Metzler DE, Metzler CM, Sauke DJ. Electron Transport, Oxidative Phosphorylation, and Hydroxylation. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50021-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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