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Cordas CM, Valério GN, Stepnov A, Kommedal E, Kjendseth ÅR, Forsberg Z, Eijsink VGH, Moura JJG. Electrochemical characterization of a family AA10 LPMO and the impact of residues shaping the copper site on reactivity. J Inorg Biochem 2023; 238:112056. [PMID: 36332410 DOI: 10.1016/j.jinorgbio.2022.112056] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Revised: 10/09/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022]
Abstract
Research on enzymes for lignocellulose biomass degradation has progressively increased in recent years due to the interest in taking advantage of this natural resource. Among these enzymes are the lytic polysaccharide monooxygenases (LPMOs) that oxidatively depolymerize crystalline cellulose using a reactive oxygen species generated in a reduced mono‑copper active site. The copper site comprises of a highly conserved histidine-brace, providing three equatorial nitrogen ligands, whereas less conserved residues close to the copper contribute to shaping and confining the site. The catalytic copper site is exposed to the solvent and to the crystalline substrates, and as so, the influence of the copper environment on LPMO properties, including the redox potential, is of great interest. In the current work, a direct electrochemical study of an LPMO (ScLPMO10C) was conducted allowing to retrieve kinetic and thermodynamic data associated with the redox transition in the catalytic centre. Moreover, two residues that do not bind to the copper but shape the copper sites were mutated, and the properties of the mutants were compared with those of the wild-type enzyme. The direct electrochemical studies, using cyclic voltammetry, yielded redox potentials in the +200 mV range, well in line with LPMO redox potentials determined by other methods. Interestingly, while the mutations hardly affected the formal redox potential of the enzyme, they drastically affected the reactivity of the copper site and enzyme functionality.
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Affiliation(s)
- Cristina M Cordas
- LAQV, REQUIMTE, NOVA School of Sciences and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal.
| | - Gabriel N Valério
- LAQV, REQUIMTE, NOVA School of Sciences and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal
| | - Anton Stepnov
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway
| | - Eirik Kommedal
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway
| | - Åsmund R Kjendseth
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway
| | - Zarah Forsberg
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway.
| | - José J G Moura
- LAQV, REQUIMTE, NOVA School of Sciences and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal
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2
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Morgado L, Salgueiro CA. Elucidation of complex respiratory chains: a straightforward strategy to monitor electron transfer between cytochromes. Metallomics 2022; 14:6539350. [DOI: 10.1093/mtomcs/mfac012] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 02/17/2022] [Indexed: 11/12/2022]
Abstract
Abstract
Cytochromes are electron transfer proteins essential in various biological systems, playing crucial roles in the respiratory chains of bacteria. These proteins are particularly abundant in electrogenic microorganisms and are responsible for the efficient delivery of electrons to the cells’ exterior. The capability of sending electron outside the cells open new avenues to be explored for emerging biotechnological applications in bioremediation, microbial electrosynthesis and bioenergy fields. To develop these applications, it is critical to identify the different redox partners and elucidate the stepwise electron transfer along the respiratory paths. However, investigating direct electron transfer events between proteins with identical features in nearly all spectroscopic techniques is extremely challenging. NMR spectroscopy offers the possibility to overcome this difficulty by analysing the alterations of the spectral signatures of each protein caused by electron exchange events. The uncrowded NMR spectral regions containing the heme resonances of the cytochromes display unique and distinct signatures in the reduced and oxidized states, which can be explored to monitor electron transfer within the redox complex. In this study, we present a strategy for a fast and straightforward monitorization of electron transfer between c-type cytochromes, using as model a triheme periplasmic cytochrome (PpcA) and a membrane associated monoheme cytochrome (OmcF) from the electrogenic bacterium Geobacter sulfurreducens. The comparison between the 1D 1H NMR spectra obtained for samples containing the two cytochromes and for samples containing the individual proteins clearly demonstrated a unidirectional electron transfer within the redox complex. This strategy provides a simple and straightforward means to elucidate complex biologic respiratory electron transfer chains.
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Affiliation(s)
- Leonor Morgado
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, 2819-516 Caparica, Portugal
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, NOVA University Lisbon, 2819-516 Caparica, Portugal
| | - Carlos A Salgueiro
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, 2819-516 Caparica, Portugal
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, NOVA University Lisbon, 2819-516 Caparica, Portugal
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3
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Cordas CM, Nguyen GS, Valério GN, Jønsson M, Söllner K, Aune IH, Wentzel A, Moura JJG. Discovery and characterization of a novel Dyp-type peroxidase from a marine actinobacterium isolated from Trondheim fjord, Norway. J Inorg Biochem 2021; 226:111651. [PMID: 34740038 DOI: 10.1016/j.jinorgbio.2021.111651] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 10/12/2021] [Accepted: 10/20/2021] [Indexed: 12/21/2022]
Abstract
A new dye-decolorizing peroxidase (DyP) was discovered through a data mining workflow based on HMMER software and profile Hidden Markov Model (HMM) using a dataset of 1200 genomes originated from a Actinobacteria strain collection isolated from Trondheim fjord. Instead of the conserved GXXDG motif known for Dyp-type peroxidases, the enzyme contains a new conserved motif EXXDG which has been not reported before. The enzyme can oxidize an anthraquinone dye Remazol Brilliant Blue R (Reactive Blue 19) and other phenolic compounds such as ferulic acid, sinapic acid, caffeic acid, 3-methylcatechol, dopamine hydrochloride, and tannic acid. The acidic pH optimum (3 to 4) and the low temperature optimum (25 °C) were confirmed using both biochemical and electrochemical assays. Kinetic and thermodynamic parameters associated with the catalytic redox center were attained by electrochemistry.
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Affiliation(s)
- Cristina M Cordas
- LAQV-REQUIMTE, Department of Chemistry, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
| | - Giang-Son Nguyen
- Sustainable Biotechnology and Bioprospecting, Department of Biotechnology and Nanomedicine, SINTEF Industry, Norway.
| | - Gabriel N Valério
- LAQV-REQUIMTE, Department of Chemistry, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Malene Jønsson
- Sustainable Biotechnology and Bioprospecting, Department of Biotechnology and Nanomedicine, SINTEF Industry, Norway
| | - Katharina Söllner
- Sustainable Biotechnology and Bioprospecting, Department of Biotechnology and Nanomedicine, SINTEF Industry, Norway
| | - Ingvild H Aune
- Sustainable Biotechnology and Bioprospecting, Department of Biotechnology and Nanomedicine, SINTEF Industry, Norway
| | - Alexander Wentzel
- Sustainable Biotechnology and Bioprospecting, Department of Biotechnology and Nanomedicine, SINTEF Industry, Norway
| | - José J G Moura
- LAQV-REQUIMTE, Department of Chemistry, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
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4
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Di Rocco G, Battistuzzi G, Borsari M, Bortolotti CA, Ranieri A, Sola M. The enthalpic and entropic terms of the reduction potential of metalloproteins: Determinants and interplay. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2021.214071] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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5
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In Situ Electrochemical Characterization of a Microbial Fuel Cell Biocathode Running on Wastewater. Catalysts 2021. [DOI: 10.3390/catal11070839] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The electrochemical features of microbial fuel cells’ biocathodes, running on wastewater, were evaluated by cyclic voltammetry. Ex situ and in situ electrochemical assays were performed and the redox processes associated with the presence of microorganisms and/or biofilms were attained. Different controls using sterile media (abiotic cathode microbial fuel cell) and membranes covering the electrodes were performed to evaluate the source of the electrochemistry response (surface biofilms vs. biotic electrolyte). The bacteria presence, in particular when biofilms are allowed to develop, was related with the enhanced active redox processes associated with an improved catalytic activity, namely for oxygen reduction, when compared with the results attained for an abiotic microbial fuel cell cathode. The microbial main composition was also attained and is in agreement with other reported studies. The current study aims contributing to the establishment of the advantages of using biocathodes rather than abiotic, whose conditions are frequently harder to control and to contribute to a better understanding of the bioelectrochemical processes occurring on the biotic chambers and the electrode surfaces.
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Ren Y, Lv Y, Wang Y, Li X. Effect of heterotrophic anodic denitrification on anolyte pH control and bioelectricity generation enhancement of bufferless microbial fuel cells. CHEMOSPHERE 2020; 257:127251. [PMID: 32512336 DOI: 10.1016/j.chemosphere.2020.127251] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 05/22/2020] [Accepted: 05/28/2020] [Indexed: 06/11/2023]
Abstract
Heterotrophic anodic denitrification (HAD) in the single-chamber microbial fuel cell (MFC) is a promising nitrogen removal technology. In this paper, the benefit (anolyte pH increase) and challenge (substrate consumption) brought by the heterotrophic anodic denitrification process for the electricity generation of bufferless MFCs were studied for the first time. Substrate anaerobic hydrolysis dramatically decreased the anolyte pH to 5.1, which seriously restricted the electric power output of the Control. The anolyte pH of the heterotrophic anodic denitrification MFCs (HADMFCs) with 60 mg/L (HADMFC-60), 90 mg/L (HADMFC-90), and 120 mg/L (HADMFC-120) nitrate nitrogen (NO3--N), retained above 6.0, 6.5, and 6.8 in every running cycles, due to the protons (H+) consumption by nitrate reduction. In the HADMFC-60 and HADMFC-90, 17.6% and 26.1% of the total organic carbons (TOC) were used for the nitrate reduction, but their electric power output significantly increased. The maximum power densities of the HADMFC-60 and HADMFC-90 were 3.3 and 5.4 times higher than that of the Control. However, when the proportion of TOC consumption for nitrate reduction increased to 35.8%, substrate insufficiency became a serious limitation for the electricity generation. The Pmax of the HADMFC-120 dramatically decreased to 17.3 mW/m2. Dysgonomonas was the dominant electro-active genus, and Petrimonas, Acidovorax and Devosia appeared as the denitrifying bacteria genera.
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Affiliation(s)
- Yueping Ren
- School of Environmental and Civil Engineering, Jiangnan University, Wuxi, Jiangsu, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Wuxi, Jiangsu, China; State Key Laboratory of Pollution Control and Resource Reuse, Nanjing, Jiangsu, China.
| | - Ying Lv
- School of Environmental and Civil Engineering, Jiangnan University, Wuxi, Jiangsu, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Wuxi, Jiangsu, China
| | - Yue Wang
- School of Environmental and Civil Engineering, Jiangnan University, Wuxi, Jiangsu, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Wuxi, Jiangsu, China
| | - Xiufen Li
- School of Environmental and Civil Engineering, Jiangnan University, Wuxi, Jiangsu, China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Wuxi, Jiangsu, China; Jiangsu Cooperative Innovation Center of Technology and Material of Water Treatment, Suzhou, China.
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7
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Teixeira LR, Cordas CM, Fonseca MP, Duke NEC, Pokkuluri PR, Salgueiro CA. Modulation of the Redox Potential and Electron/Proton Transfer Mechanisms in the Outer Membrane Cytochrome OmcF From Geobacter sulfurreducens. Front Microbiol 2020; 10:2941. [PMID: 32010071 PMCID: PMC6971198 DOI: 10.3389/fmicb.2019.02941] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 12/06/2019] [Indexed: 11/13/2022] Open
Abstract
The monoheme outer membrane cytochrome F (OmcF) from Geobacter sulfurreducens plays an important role in Fe(III) reduction and electric current production. The electrochemical characterization of this cytochrome has shown that its redox potential is modulated by the solution pH (redox-Bohr effect) endowing the protein with the necessary properties to couple electron and proton transfer in the physiological range. The analysis of the OmcF structures in the reduced and oxidized states showed that with the exception of the side chain of histidine 47 (His47), all other residues with protonatable side chains are distant from the heme iron and, therefore, are unlikely to affect the redox potential of the protein. The protonatable site at the imidazole ring of His47 is in the close proximity to the heme and, therefore, this residue was suggested as the redox-Bohr center. In the present work, we tested this hypothesis by replacing the His47 with non-protonatable residues (isoleucine – OmcFH47I and phenylalanine – OmcFH47F). The structure of the mutant OmcFH47I was determined by X-ray crystallography to 1.13 Å resolution and showed only minimal changes at the site of the mutation. Both mutants were 15N-labeled and their overall folding was confirmed to be the same as the wild-type by NMR spectroscopy. The pH dependence of the redox potential of the mutants was measured by cyclic voltammetry. Compared to the wild-type protein, the magnitude of the redox-Bohr effect in the mutants was smaller, but not fully abolished, confirming the role of His47 on the pH modulation of OmcF’s redox potential. However, the pH effect on the heme substituents’ NMR chemical shifts suggested that the heme propionate P13 also contributes to the overall redox-Bohr effect in OmcF. In physiological terms, the contribution of two independent acid–base centers to the observed redox-Bohr effect confers OmcF a higher versatility to environmental changes by coupling electron/proton transfer within a wider pH range.
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Affiliation(s)
- Liliana R Teixeira
- UCIBIO-Requimte, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Cristina M Cordas
- LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Marta P Fonseca
- UCIBIO-Requimte, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Norma E C Duke
- Biosciences Division, Argonne National Laboratory, Lemont, IL, United States
| | - Phani Raj Pokkuluri
- Biosciences Division, Argonne National Laboratory, Lemont, IL, United States
| | - Carlos A Salgueiro
- UCIBIO-Requimte, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
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8
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Edwards MJ, Richardson DJ, Paquete CM, Clarke TA. Role of multiheme cytochromes involved in extracellular anaerobic respiration in bacteria. Protein Sci 2019; 29:830-842. [PMID: 31721352 PMCID: PMC7096707 DOI: 10.1002/pro.3787] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 11/05/2019] [Accepted: 11/05/2019] [Indexed: 01/08/2023]
Abstract
Heme containing proteins are involved in a broad range of cellular functions, from oxygen sensing and transport to catalyzing oxidoreductive reactions. The two major types of cytochrome (b-type and c-type) only differ in their mechanism of heme attachment, but this has major implications for their cellular roles in both localization and mechanism. The b-type cytochromes are commonly cytoplasmic, or are within the cytoplasmic membrane, while c-type cytochromes are always found outside of the cytoplasm. The mechanism of heme attachment allows for complex c-type multiheme complexes, having the capacity to hold multiple electrons, to be assembled. These are increasingly being identified as secreted into the extracellular environment. For organisms that respire using extracellular substrates, these large multiheme cytochromes allow for electron transfer networks from the cytoplasmic membrane to the cell exterior for the reduction of extracellular electron acceptors. In this review the structures and functions of these networks and the mechanisms by which electrons are transferred to extracellular substrates is described.
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Affiliation(s)
- Marcus J Edwards
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, UK
| | - David J Richardson
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, UK
| | - Catarina M Paquete
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Oeiras, Portugal
| | - Thomas A Clarke
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich, UK
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9
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Zeng D, Yin Q, Du Q, Wu G. System performance and microbial community in ethanol-fed anaerobic reactors acclimated with different organic carbon to sulfate ratios. BIORESOURCE TECHNOLOGY 2019; 278:34-42. [PMID: 30669029 DOI: 10.1016/j.biortech.2019.01.047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 01/09/2019] [Accepted: 01/11/2019] [Indexed: 06/09/2023]
Abstract
Sulfate influences the organics removal and methanogenic performance during anaerobic wastewater treatment. System performance, microbial community and metabolic pathways in ethanol-fed anaerobic reactors were investigated under different COD/SO42- ratios (2, 1 and 0.67) and control without sulfate addition. The sulfate removal percentages declined (99%, 60% and 49%) with decreasing COD/SO42- ratios, and methanogenesis was completely inhibited. Acetate accumulated to 903-734 mg/L, though propionate was constantly lower than 30 mg/L. Without sulfate, acetate and propionate did not accumulate, despite the extended time for propionate degradation. Incomplete oxidizing sulfate reducing bacteria (Desulfobulbus and Desulfomicrobium) and hydrolysis-acidification genera (Treponema and Bacteroidales) predominated but could not degrade acetate. Desulfobulbus was the key genus for propionate degradation through the pyruvate & propanoate metabolism pathway. Pseudomonas and Desulfobulbus, possessing genes encoding Type IV pili and cytochrome c6 OmcF, respectively, potentially participated in the direct interspecies electron transfer in sulfate-rich conditions.
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Affiliation(s)
- Danfei Zeng
- Guangdong Province Engineering Research Center for Urban Water Recycling and Environmental Safety, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, Guangdong, China
| | - Qidong Yin
- Guangdong Province Engineering Research Center for Urban Water Recycling and Environmental Safety, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, Guangdong, China
| | - Qing Du
- Guangdong Province Engineering Research Center for Urban Water Recycling and Environmental Safety, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, Guangdong, China
| | - Guangxue Wu
- Guangdong Province Engineering Research Center for Urban Water Recycling and Environmental Safety, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, Guangdong, China.
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