1
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Jung H, Inaba Y, Banta S. CRISPR/dCas12a knock-down of Acidithiobacillus ferrooxidans electron transport chain bc 1 complexes enables enhanced metal sulfide bioleaching. J Biol Chem 2024:107703. [PMID: 39173952 DOI: 10.1016/j.jbc.2024.107703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2024] [Revised: 08/13/2024] [Accepted: 08/16/2024] [Indexed: 08/24/2024] Open
Abstract
Acidithiobacillus ferrooxidans is an acidophilic chemolithoautotroph that plays an important role in biogeochemical iron and sulfur cycling and is a member of the consortia used in industrial hydrometallurgical processing of copper. Metal sulfide bioleaching is catalyzed by the regeneration of ferric iron, however, bioleaching of chalcopyrite, the dominant unmined form of copper on Earth, is inhibited by surface passivation. Here, we report the implementation of CRISPR interference (CRISPRi) using the catalytically inactive Cas12a (dCas12a) in A. ferrooxidans to knockdown the expression of genes in the petI and petII operons. These operons encode bc1 complex proteins and knockdown of these genes enabled the manipulation (enhancement or repression) of iron oxidation. The petB2 gene knockdown strain enhanced iron oxidation, leading to enhanced pyrite and chalcopyrite oxidation, which correlated with reduced biofilm formation and decreased surface passivation of the minerals. These findings highlight the utility of CRISPRi/dCas12a technology for engineering A. ferrooxidans while unveiling a new strategy to manipulate and improve bioleaching efficiency.
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Affiliation(s)
- Heejung Jung
- Department of Chemical Engineering, Columbia University, New York, New York
| | - Yuta Inaba
- Department of Chemical Engineering, Columbia University, New York, New York
| | - Scott Banta
- Department of Chemical Engineering, Columbia University, New York, New York.
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2
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Riepl D, Gamiz-Hernandez AP, Kovalova T, Król SM, Mader SL, Sjöstrand D, Högbom M, Brzezinski P, Kaila VRI. Long-range charge transfer mechanism of the III 2IV 2 mycobacterial supercomplex. Nat Commun 2024; 15:5276. [PMID: 38902248 PMCID: PMC11189923 DOI: 10.1038/s41467-024-49628-9] [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: 11/16/2023] [Accepted: 06/12/2024] [Indexed: 06/22/2024] Open
Abstract
Aerobic life is powered by membrane-bound redox enzymes that shuttle electrons to oxygen and transfer protons across a biological membrane. Structural studies suggest that these energy-transducing enzymes operate as higher-order supercomplexes, but their functional role remains poorly understood and highly debated. Here we resolve the functional dynamics of the 0.7 MDa III2IV2 obligate supercomplex from Mycobacterium smegmatis, a close relative of M. tuberculosis, the causative agent of tuberculosis. By combining computational, biochemical, and high-resolution (2.3 Å) cryo-electron microscopy experiments, we show how the mycobacterial supercomplex catalyses long-range charge transport from its menaquinol oxidation site to the binuclear active site for oxygen reduction. Our data reveal proton and electron pathways responsible for the charge transfer reactions, mechanistic principles of the quinone catalysis, and how unique molecular adaptations, water molecules, and lipid interactions enable the proton-coupled electron transfer (PCET) reactions. Our combined findings provide a mechanistic blueprint of mycobacterial supercomplexes and a basis for developing drugs against pathogenic bacteria.
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Affiliation(s)
- Daniel Riepl
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Ana P Gamiz-Hernandez
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Terezia Kovalova
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Sylwia M Król
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Sophie L Mader
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Dan Sjöstrand
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Martin Högbom
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Ville R I Kaila
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden.
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3
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Das D, Miller AF. A single hydrogen bond that tunes flavin redox reactivity and activates it for modification. Chem Sci 2024; 15:7610-7622. [PMID: 38784750 PMCID: PMC11110160 DOI: 10.1039/d4sc01642d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Accepted: 04/14/2024] [Indexed: 05/25/2024] Open
Abstract
Electron bifurcation produces high-energy products based on less energetic reagents. This feat enables biological systems to exploit abundant mediocre fuel to drive vital but demanding reactions, including nitrogen fixation and CO2 capture. Thus, there is great interest in understanding principles that can be portable to man-made devices. Bifurcating electron transfer flavoproteins (Bf ETFs) employ two flavins with contrasting reactivities to acquire pairs of electrons from a modest reductant, NADH. The bifurcating flavin then dispatches the electrons individually to a high and a low reduction midpoint potential (E°) acceptor, the latter of which captures most of the energy. Maximum efficiency requires that only one electron accesses the exergonic path that will 'pay for' the production of the low-E° product. It is therefore critical that one of the flavins, the 'electron transfer' (ET) flavin, is tuned to execute single-electron (1e-) chemistry only. To learn how, and extract fundamental principles, we systematically altered interactions with the ET-flavin O2 position. Removal of a single hydrogen bond (H-bond) disfavored the formation of the flavin anionic semiquinone (ASQ) relative to the oxidized (OX) state, lowering by 150 mV and retuning the flavin's tendency for 1e-vs. 2e- reactivity. This was achieved by replacing conserved His 290 with Phe, while also replacing the supporting Tyr 279 with Ile. Although this variant binds oxidized FADs at 90% the WT level, the ASQ state of the ET-flavin is not stable in the absence of H290's H-bond, and dissociates, in contrast to the WT. Removal of this H-bond also altered the ET-flavin's covalent chemistry. While the WT ETF accumulates modified flavins whose formation is believed to rely on an anionic paraquinone methide intermediate, the FADs of the H-bond lacking variant remain unchanged over weeks. Hence the variant that destabilizes the anionic semiquinone also suppresses the anionic intermediate in flavin modification, verifying electronic similarities between these two species. These correlations suggest that the H-bond that stabilizes the crucial flavin ASQ also promotes flavin modification. The two effects may indeed be inseparable, as a Jekyll and Hydrogen bond.
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Affiliation(s)
- Debarati Das
- Department of Chemistry, University of Kentucky Lexington Kentucky USA
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4
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Montoya-Castillo A, Markland TE. A derivation of the conditions under which bosonic operators exactly capture fermionic structure and dynamics. J Chem Phys 2023; 158:094112. [PMID: 36889969 DOI: 10.1063/5.0138664] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
The dynamics of many-body fermionic systems are important in problems ranging from catalytic reactions at electrochemical surfaces to transport through nanojunctions and offer a prime target for quantum computing applications. Here, we derive the set of conditions under which fermionic operators can be exactly replaced by bosonic operators that render the problem amenable to a large toolbox of dynamical methods while still capturing the correct dynamics of n-body operators. Importantly, our analysis offers a simple guide on how one can exploit these simple maps to calculate nonequilibrium and equilibrium single- and multi-time correlation functions essential in describing transport and spectroscopy. We use this to rigorously analyze and delineate the applicability of simple yet effective Cartesian maps that have been shown to correctly capture the correct fermionic dynamics in select models of nanoscopic transport. We illustrate our analytical results with exact simulations of the resonant level model. Our work provides new insights as to when one can leverage the simplicity of bosonic maps to simulate the dynamics of many-electron systems, especially those where an atomistic representation of nuclear interactions becomes essential.
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Affiliation(s)
| | - Thomas E Markland
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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5
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Hessin C, Schleinitz J, Le Breton N, Choua S, Grimaud L, Fourmond V, Desage-El Murr M, Léger C. Assessing the Extent of Potential Inversion by Cyclic Voltammetry: Theory, Pitfalls, and Application to a Nickel Complex with Redox-Active Iminosemiquinone Ligands. Inorg Chem 2023; 62:3321-3332. [PMID: 36780646 DOI: 10.1021/acs.inorgchem.2c04365] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Potential inversion refers to the situation where a protein cofactor or a synthetic molecule can be oxidized or reduced twice in a cooperative manner; that is, the second electron transfer is easier than the first. This property is very important regarding the catalytic mechanism of enzymes that bifurcate electrons and the properties of bidirectional redox molecular catalysts that function in either direction of the reaction with no overpotential. Cyclic voltammetry is the most common technique for characterizing the thermodynamics and kinetics of electron transfer to or from these molecules. However, a gap in the literature is the absence of analytical predictions to help interpret the values of the voltammetric peak potentials when potential inversion occurs; the cyclic voltammograms are therefore often analyzed by simulating the data, with no discussion of the possibility of overfitting and often no estimation of the error on the determined parameters. Here we formulate the theory for the voltammetry of freely diffusing or surface-confined two-electron redox species in the experimentally relevant irreversible limit where the peak separation depends on the scan rate. We explain why the model is intrinsically underdetermined, and we illustrate this conclusion by analysis of the voltammetry of a nickel complex with redox-active iminosemiquinone ligands. Being able to characterize the thermodynamics of two-electron electron-transfer reactions will be crucial for designing more efficient catalysts.
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Affiliation(s)
- Cheriehan Hessin
- Institut de Chimie, Université de Strasbourg, UMR CNRS 7177, Strasbourg 67000, France
| | - Jules Schleinitz
- Laboratoire des Biomolécules, Département de Chimie, Sorbonne Université, École Normale Supérieure, PSL University, CNRS, Paris 75005, France
| | - Nolwenn Le Breton
- Institut de Chimie, Université de Strasbourg, UMR CNRS 7177, Strasbourg 67000, France
| | - Sylvie Choua
- Institut de Chimie, Université de Strasbourg, UMR CNRS 7177, Strasbourg 67000, France
| | - Laurence Grimaud
- Laboratoire des Biomolécules, Département de Chimie, Sorbonne Université, École Normale Supérieure, PSL University, CNRS, Paris 75005, France
| | - Vincent Fourmond
- Laboratoire de Bioénergétique et Ingénierie des Protéines, CNRS, Aix Marseille Université, Marseille 13009, France
| | - Marine Desage-El Murr
- Institut de Chimie, Université de Strasbourg, UMR CNRS 7177, Strasbourg 67000, France
| | - Christophe Léger
- Laboratoire de Bioénergétique et Ingénierie des Protéines, CNRS, Aix Marseille Université, Marseille 13009, France
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Yu YY, Zhang Y, Peng L. Investigating the interaction between Shewanella oneidensis and phenazine 1-carboxylic acid in the microbial electrochemical processes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 838:156501. [PMID: 35667430 DOI: 10.1016/j.scitotenv.2022.156501] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 05/28/2022] [Accepted: 06/01/2022] [Indexed: 06/15/2023]
Abstract
Many exoelectrogens utilize small redox mediators for extracellular electron transfer (EET). Notable examples include Shewanella species, which synthesize flavins, and Pseudomonas species, which produce phenazines. In natural and engineered environments, redox-active metabolites from different organisms coexist. The interaction between Shewanella oneidensis and phenazine 1-carboxylic acid (PCA, a representative phenazine compound) was investigated to demonstrate exoelectrogens utilizing metabolites secreted by other organisms as redox mediators. After 24 h in a reactor with and without added PCA (1 μM), the anodic current generated by Shewanella was 235 ± 11 and 51.7 ± 2.8 μA, respectively. Shewanella produced oxidative current approximately three times as high with medium containing PCA as with medium containing the same concentration of riboflavin. PCA also stimulated inward EET in Shewanella. The strong effect of PCA on EET was attributed to its enrichment at the biofilm/electrode interface. The PCA voltammetric peak heights with a Shewanella bioanode were 25-30 times higher than under abiotic conditions. The electrochemical properties of PCA were also altered by the transition from two-electron to single-electron electrochemistry, which suggests PCA was bound between the electrode and cell surface redox proteins. This behavior would benefit electroactive bacteria, which usually dwell in open systems where mediators are present in low concentrations. Like flavins, PCA can be immobilized under both bioanode and biocathode conditions but not under metabolically inactive conditions. Shewanella rapidly transfers electrons to PCA via its Mtr pathway. Compared with wild-type Shewanella, the PCA reduction ability was decreased in gene knockout mutants lacking Mtr pathway cytochromes, especially in the mutants with severely undermined electrode-reduction capacities. These strains also lost the ability to immobilize PCA, even under current-generating conditions.
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Affiliation(s)
- Yi-Yan Yu
- School of Resources & Environment, Southwest University, Chongqing 400716, PR China
| | - Yong Zhang
- School of Resources & Environment, Southwest University, Chongqing 400716, PR China
| | - Luo Peng
- School of Resources & Environment, Southwest University, Chongqing 400716, PR China.
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7
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Site-Differentiated Iron–Sulfur Cluster Ligation Affects Flavin-Based Electron Bifurcation Activity. Metabolites 2022; 12:metabo12090823. [PMID: 36144227 PMCID: PMC9503767 DOI: 10.3390/metabo12090823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 08/25/2022] [Accepted: 08/28/2022] [Indexed: 11/16/2022] Open
Abstract
Electron bifurcation is an elegant mechanism of biological energy conversion that effectively couples three different physiologically relevant substrates. As such, enzymes that perform this function often play critical roles in modulating cellular redox metabolism. One such enzyme is NADH-dependent reduced-ferredoxin: NADP+ oxidoreductase (NfnSL), which couples the thermodynamically favorable reduction of NAD+ to drive the unfavorable reduction of ferredoxin from NADPH. The interaction of NfnSL with its substrates is constrained to strict stoichiometric conditions, which ensures minimal energy losses from non-productive intramolecular electron transfer reactions. However, the determinants for this are not well understood. One curious feature of NfnSL is that both initial acceptors of bifurcated electrons are unique iron–sulfur (FeS) clusters containing one non-cysteinyl ligand each. The biochemical impact and mechanistic roles of site-differentiated FeS ligands are enigmatic, despite their incidence in many redox active enzymes. Herein, we describe the biochemical study of wild-type NfnSL and a variant in which one of the site-differentiated ligands has been replaced with a cysteine. Results of dye-based steady-state kinetics experiments, substrate-binding measurements, biochemical activity assays, and assessments of electron distribution across the enzyme indicate that this site-differentiated ligand in NfnSL plays a role in maintaining fidelity of the coordinated reactions performed by the two electron transfer pathways. Given the commonality of these cofactors, our findings have broad implications beyond electron bifurcation and mechanistic biochemistry and may inform on means of modulating the redox balance of the cell for targeted metabolic engineering approaches.
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8
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An uncharacteristically low-potential flavin governs the energy landscape of electron bifurcation. Proc Natl Acad Sci U S A 2022; 119:e2117882119. [PMID: 35290111 PMCID: PMC8944662 DOI: 10.1073/pnas.2117882119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Nature has long been an inspiration for materials design, as it exemplifies exquisite control of both matter and energy. Electron bifurcation, a mechanism employed in biological systems to drive thermodynamically unfavorable and energetically challenging chemical reactions, is one such example. A key feature of bifurcating enzymes is the ability of a single redox cofactor to distribute a pair of electrons across two spatially separated electron transfer pathways. Here, we report on the empirical determination of both the one-electron potential and two-electron potential of the bifurcating flavin cofactor in the NADH-dependent ferredoxin-NADP+ oxidoreductase I (NfnSL) enzyme. Insights arising from the defined energy landscape of this bifurcation site may underlie the design of synthetic catalysts capable of generating high-energy intermediates. Electron bifurcation, an energy-conserving process utilized extensively throughout all domains of life, represents an elegant means of generating high-energy products from substrates with less reducing potential. The coordinated coupling of exergonic and endergonic reactions has been shown to operate over an electrochemical potential of ∼1.3 V through the activity of a unique flavin cofactor in the enzyme NADH-dependent ferredoxin-NADP+ oxidoreductase I. The inferred energy landscape has features unprecedented in biochemistry and presents novel energetic challenges, the most intriguing being a large thermodynamically uphill step for the first electron transfer of the bifurcation reaction. However, ambiguities in the energy landscape at the bifurcating site deriving from overlapping flavin spectral signatures have impeded a comprehensive understanding of the specific mechanistic contributions afforded by thermodynamic and kinetic factors. Here, we elucidate an uncharacteristically low two-electron potential of the bifurcating flavin, resolving the energetic challenge of the first bifurcation event.
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9
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Agarwal RG, Coste SC, Groff BD, Heuer AM, Noh H, Parada GA, Wise CF, Nichols EM, Warren JJ, Mayer JM. Free Energies of Proton-Coupled Electron Transfer Reagents and Their Applications. Chem Rev 2021; 122:1-49. [PMID: 34928136 DOI: 10.1021/acs.chemrev.1c00521] [Citation(s) in RCA: 140] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We present an update and revision to our 2010 review on the topic of proton-coupled electron transfer (PCET) reagent thermochemistry. Over the past decade, the data and thermochemical formalisms presented in that review have been of value to multiple fields. Concurrently, there have been advances in the thermochemical cycles and experimental methods used to measure these values. This Review (i) summarizes those advancements, (ii) corrects systematic errors in our prior review that shifted many of the absolute values in the tabulated data, (iii) provides updated tables of thermochemical values, and (iv) discusses new conclusions and opportunities from the assembled data and associated techniques. We advocate for updated thermochemical cycles that provide greater clarity and reduce experimental barriers to the calculation and measurement of Gibbs free energies for the conversion of X to XHn in PCET reactions. In particular, we demonstrate the utility and generality of reporting potentials of hydrogenation, E°(V vs H2), in almost any solvent and how these values are connected to more widely reported bond dissociation free energies (BDFEs). The tabulated data demonstrate that E°(V vs H2) and BDFEs are generally insensitive to the nature of the solvent and, in some cases, even to the phase (gas versus solution). This Review also presents introductions to several emerging fields in PCET thermochemistry to give readers windows into the diversity of research being performed. Some of the next frontiers in this rapidly growing field are coordination-induced bond weakening, PCET in novel solvent environments, and reactions at material interfaces.
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Affiliation(s)
- Rishi G Agarwal
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Scott C Coste
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Benjamin D Groff
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Abigail M Heuer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Hyunho Noh
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Giovanny A Parada
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States.,Department of Chemistry, The College of New Jersey, Ewing, New Jersey 08628, United States
| | - Catherine F Wise
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Eva M Nichols
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - James M Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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10
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Song Z, Wei C, Li C, Gao X, Mao S, Lu F, Qin HM. Customized exogenous ferredoxin functions as an efficient electron carrier. BIORESOUR BIOPROCESS 2021; 8:109. [PMID: 38650207 PMCID: PMC10992505 DOI: 10.1186/s40643-021-00464-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 10/28/2021] [Indexed: 11/10/2022] Open
Abstract
Ferredoxin (Fdx) is regarded as the main electron carrier in biological electron transfer and acts as an electron donor in metabolic pathways of many organisms. Here, we screened a self-sufficient P450-derived reductase PRF with promising production yield of 9OHAD (9α-hydroxy4-androstene-3,17-dione) from AD, and further proved the importance of [2Fe-2S] clusters of ferredoxin-oxidoreductase in transferring electrons in steroidal conversion. The results of truncated Fdx domain in all oxidoreductases and mutagenesis data elucidated the indispensable role of [2Fe-2S] clusters in the electron transfer process. By adding the independent plant-type Fdx to the reaction system, the AD (4-androstene-3,17-dione) conversion rate have been significantly improved. A novel efficient electron transfer pathway of PRF + Fdx + KshA (KshA, Rieske-type oxygenase of 3-ketosteroid-9-hydroxylase) in the reaction system rather than KshAB complex system was proposed based on analysis of protein-protein interactions and redox potential measurement. Adding free Fdx created a new conduit for electrons to travel from reductase to oxygenase. This electron transfer pathway provides new insight for the development of efficient exogenous Fdx as an electron carrier.
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Affiliation(s)
- Zhan Song
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
- National Engineering Laboratory for Industrial Enzymes, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
| | - Cancan Wei
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
- National Engineering Laboratory for Industrial Enzymes, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
| | - Chao Li
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
- National Engineering Laboratory for Industrial Enzymes, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
| | - Xin Gao
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
- National Engineering Laboratory for Industrial Enzymes, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China
| | - Shuhong Mao
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
- National Engineering Laboratory for Industrial Enzymes, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
| | - Fuping Lu
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
- National Engineering Laboratory for Industrial Enzymes, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
| | - Hui-Min Qin
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
- National Engineering Laboratory for Industrial Enzymes, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
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11
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Valdiviezo J, Zhang P, Beratan DN. Electron ratcheting in self-assembled soft matter. J Chem Phys 2021; 155:055102. [PMID: 34364335 DOI: 10.1063/5.0044420] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Ratcheted multi-step hopping electron transfer systems can plausibly produce directional charge transport over very large distances without requiring a source-drain voltage bias. We examine molecular strategies to realize ratcheted charge transport based on multi-step charge hopping, and we illustrate two ratcheting mechanisms with examples based on DNA structures. The charge transport times and currents that may be generated in these assemblies are also estimated using kinetic simulations. The first ratcheting mechanism described for nanoscale systems requires local electric fields on the 109 V/m scale to realize nearly 100% population transport. The second ratcheting mechanism for even larger systems, based on electrochemical gating, is estimated to generate currents as large as 0.1 pA for DNA structures that are a few μm in length with a gate voltage of about 5 V, a magnitude comparable to currents measured in DNA wires at the nanoscale when a source-drain voltage bias of similar magnitude is applied, suggesting an approach to considerably extend the distance range over which DNA charge transport devices may operate.
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Affiliation(s)
- Jesús Valdiviezo
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - Peng Zhang
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
| | - David N Beratan
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
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12
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Yuly JL, Zhang P, Ru X, Terai K, Singh N, Beratan DN. Efficient and reversible electron bifurcation with either normal or inverted potentials at the bifurcating cofactor. Chem 2021. [DOI: 10.1016/j.chempr.2021.03.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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13
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Duan HD, Khan SA, Miller AF. Photogeneration and reactivity of flavin anionic semiquinone in a bifurcating electron transfer flavoprotein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148415. [PMID: 33727071 DOI: 10.1016/j.bbabio.2021.148415] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 02/15/2021] [Accepted: 03/10/2021] [Indexed: 02/04/2023]
Abstract
Electron transfer bifurcation allows production of a strongly reducing carrier at the expense of a weaker one, by redistributing energy among a pair of electrons. Thus, two weakly-reducing electrons from NADH are consumed to produce a strongly reducing ferredoxin or flavodoxin, paid for by reduction of an oxidizing acceptor. The prevailing mechanism calls for participation of a strongly reducing flavin semiquinone which has been difficult to observe with site-certainly in multi-flavin systems. Using blue light (450 nm) to photoexcite the flavins of bifurcating electron transfer flavoprotein (ETF), we demonstrate accumulation of anionic flavin semiquinone in excess of what is observed in equilibrium titrations, and establish its ability to reduce the low-potential electron acceptor benzyl viologen. This must occur at the bifurcating flavin because the midpoint potentials of the electron transfer (ET) flavin are not sufficiently negative. We show that bis-tris propane buffer is an effective electron donor to the flavin photoreduction, but that if the system is prepared with the ET flavin chemically reduced, so that only the bifurcating flavin is oxidized and photochemically active, flavin anionic semiquinone is formed more rapidly. Thus, excited bifurcating flavin is able to draw on an electron stored at the ET flavin. Flavin semiquinone photogenerated at the bifurcation site must therefore be accompanied by additional semiquinone formation by oxidation of the ET flavin. Consistent with the expected instability of bifurcating flavin semiquinone, it subsides immediately upon cessation of illumination. However comparison with yields of semiquinone in equilibrium titrations suggest that during continuous illumination at pH 9 a steady state population of 0.3 equivalents of bifurcating flavin semiquinone accumulates, and then undergoes further photoreduction to the hydroquinone. Although transient, the population of bifurcating flavin semiquinone explains the system's ability to conduct light-driven electron transfer from bis-tris propane to benzyl viologen, in effect trapping energy from light.
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Affiliation(s)
- H Diessel Duan
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Sharique A Khan
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
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14
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Tyburski R, Liu T, Glover SD, Hammarström L. Proton-Coupled Electron Transfer Guidelines, Fair and Square. J Am Chem Soc 2021; 143:560-576. [PMID: 33405896 PMCID: PMC7880575 DOI: 10.1021/jacs.0c09106] [Citation(s) in RCA: 201] [Impact Index Per Article: 67.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Indexed: 12/23/2022]
Abstract
Proton-coupled electron transfer (PCET) reactions are fundamental to energy transformation reactions in natural and artificial systems and are increasingly recognized in areas such as catalysis and synthetic chemistry. The interdependence of proton and electron transfer brings a mechanistic richness of reactivity, including various sequential and concerted mechanisms. Delineating between different PCET mechanisms and understanding why a particular mechanism dominates are crucial for the design and optimization of reactions that use PCET. This Perspective provides practical guidelines for how to discern between sequential and concerted mechanisms based on interpretations of thermodynamic data with temperature-, pressure-, and isotope-dependent kinetics. We present new PCET-zone diagrams that show how a mechanism can switch or even be eliminated by varying the thermodynamic (ΔGPT° and ΔGET°) and coupling strengths for a PCET system. We discuss the appropriateness of asynchronous concerted PCET to rationalize observations in organic reactions, and the distinction between hydrogen atom transfer and other concerted PCET reactions. Contemporary issues and future prospects in PCET research are discussed.
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Affiliation(s)
- Robin Tyburski
- Ångström
Laboratory, Department of Chemistry, Uppsala
University, Box 523, SE75120 Uppsala, Sweden
| | - Tianfei Liu
- Department
of Chemistry, University of North Carolina
at Chapel Hill, Chapel
Hill, North Carolina 27599-3290, United States
| | - Starla D. Glover
- Ångström
Laboratory, Department of Chemistry, Uppsala
University, Box 523, SE75120 Uppsala, Sweden
| | - Leif Hammarström
- Ångström
Laboratory, Department of Chemistry, Uppsala
University, Box 523, SE75120 Uppsala, Sweden
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15
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Appel L, Willistein M, Dahl C, Ermler U, Boll M. Functional diversity of prokaryotic HdrA(BC) modules: Role in flavin-based electron bifurcation processes and beyond. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148379. [PMID: 33460586 DOI: 10.1016/j.bbabio.2021.148379] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 10/22/2022]
Abstract
In methanogenic archaea, the archetypical complex of heterodisulfide reductase (HdrABC) and hydrogenase (MvhAGD) couples the endergonic reduction of CO2 by H2 to the exergonic reduction of the CoB-S-S-CoM heterodisulfide by H2 via flavin-based electron bifurcation. Presently known enzymes containing HdrA(BC)-like components play key roles in methanogenesis, acetogenesis, respiratory sulfate reduction, lithotrophic reduced sulfur compound oxidation, aromatic compound degradation, fermentations, and probably many further processes. This functional diversity is achieved by a modular architecture of HdrA(BC) enzymes, where a big variety of electron input/output modules may be connected either directly or via adaptor modules to the HdrA(BC) components. Many, but not all HdrA(BC) complexes are proposed to catalyse a flavin-based electron bifurcation/confurcation. Despite the availability of HdrA(BC) crystal structures, fundamental questions of electron transfer and energy coupling processes remain. Here, we address the common properties and functional diversity of HdrA(BC) core modules integrated into electron-transfer machineries of outstanding complexity.
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Affiliation(s)
- Lena Appel
- Fakultät für Biologie - Mikrobiologie, Universität Freiburg, Freiburg, Germany
| | - Max Willistein
- Fakultät für Biologie - Mikrobiologie, Universität Freiburg, Freiburg, Germany
| | - Christiane Dahl
- Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - Ulrich Ermler
- Max-Planck-Institut für Biophysik, Frankfurt, Germany
| | - Matthias Boll
- Fakultät für Biologie - Mikrobiologie, Universität Freiburg, Freiburg, Germany.
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16
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Wise CE, Ledinina AE, Yuly JL, Artz JH, Lubner CE. The role of thermodynamic features on the functional activity of electron bifurcating enzymes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148377. [PMID: 33453185 DOI: 10.1016/j.bbabio.2021.148377] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 01/05/2021] [Accepted: 01/06/2021] [Indexed: 11/25/2022]
Abstract
Electron bifurcation is a biological mechanism to drive a thermodynamically unfavorable redox reaction through direct coupling with an exergonic reaction. This process allows microorganisms to generate high energy reducing equivalents in order to sustain life and is often found in anaerobic metabolism, where the energy economy of the cell is poor. Recent work has revealed details of the redox energy landscapes for a variety of electron bifurcating enzymes, greatly expanding the understanding of how energy is transformed by this unique mechanism. Here we highlight the plasticity of these emerging landscapes, what is known regarding their mechanistic underpinnings, and provide a context for interpreting their biochemical activity within the physiological framework. We conclude with an outlook for propelling the field toward an integrative understanding of the impact of electron bifurcation.
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Affiliation(s)
| | | | | | - Jacob H Artz
- National Renewable Energy Laboratory, Golden, CO, USA
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17
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Pérez-Mejías G, Olloqui-Sariego JL, Guerra-Castellano A, Díaz-Quintana A, Calvente JJ, Andreu R, De la Rosa MA, Díaz-Moreno I. Physical contact between cytochrome c1 and cytochrome c increases the driving force for electron transfer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148277. [DOI: 10.1016/j.bbabio.2020.148277] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 06/29/2020] [Accepted: 07/09/2020] [Indexed: 01/09/2023]
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18
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Kirschning A. The coenzyme/protein pair and the molecular evolution of life. Nat Prod Rep 2020; 38:993-1010. [PMID: 33206101 DOI: 10.1039/d0np00037j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Covering: up to 2020What was first? Coenzymes or proteins? These questions are archetypal examples of causal circularity in living systems. Classically, this "chicken-and-egg" problem was discussed for the macromolecules RNA, DNA and proteins. This report focuses on coenzymes and cofactors and discusses the coenzyme/protein pair as another example of causal circularity in life. Reflections on the origin of life and hypotheses on possible prebiotic worlds led to the current notion that RNA was the first macromolecule, long before functional proteins and hence DNA. So these causal circularities of living systems were solved by a time travel into the past. To tackle the "chicken-and-egg" problem of the protein-coenzyme pair, this report addresses this problem by looking for clues (a) in the first hypothetical biotic life forms such as protoviroids and the last unified common ancestor (LUCA) and (b) in considerations and evidence of the possible prebiotic production of amino acids and coenzymes before life arose. According to these considerations, coenzymes and cofactors can be regarded as very old molecular players in the origin and evolution of life, and at least some of them developed independently of α-amino acids, which here are evolutionarily synonymous with proteins. Discussions on "chicken-and-egg" problems open further doors to the understanding of evolution.
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Affiliation(s)
- Andreas Kirschning
- Institut für Organische Chemie und Zentrum für Biomolekulare Wirkstoffchemie (BMWZ), Leibniz Universität Hannover, Schneiderberg 1B, D-30167 Hannover, Germany.
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19
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Das A, Hessin C, Ren Y, Desage-El Murr M. Biological concepts for catalysis and reactivity: empowering bioinspiration. Chem Soc Rev 2020; 49:8840-8867. [PMID: 33107878 DOI: 10.1039/d0cs00914h] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Biological systems provide attractive reactivity blueprints for the design of challenging chemical transformations. Emulating the operating mode of natural systems may however not be so easy and direct translation of structural observations does not always afford the anticipated efficiency. Metalloenzymes rely on earth-abundant metals to perform an incredibly wide range of chemical transformations. To do so, enzymes in general have evolved tools and tricks to enable control of such reactivity. The underlying concepts related to these tools are usually well-known to enzymologists and bio(inorganic) chemists but may be a little less familiar to organometallic chemists. So far, the field of bioinspired catalysis has greatly focused on the coordination sphere and electronic effects for the design of functional enzyme models but might benefit from a paradigm shift related to recent findings in biological systems. The goal of this review is to bring these fields closer together as this could likely result in the development of a new generation of highly efficient bioinspired systems. This contribution covers the fields of redox-active ligands, entatic state reactivity, energy conservation through electron bifurcation, and quantum tunneling for C-H activation.
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Affiliation(s)
- Agnideep Das
- Université de Strasbourg, Institut de Chimie, UMR CNRS 7177, 67000 Strasbourg, France.
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20
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Arrigoni F, Rizza F, Vertemara J, Breglia R, Greco C, Bertini L, Zampella G, De Gioia L. Rational Design of Fe 2 (μ-PR 2 ) 2 (L) 6 Coordination Compounds Featuring Tailored Potential Inversion. Chemphyschem 2020; 21:2279-2292. [PMID: 32815583 DOI: 10.1002/cphc.202000623] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/19/2020] [Indexed: 01/04/2023]
Abstract
It was recently discovered that some redox proteins can thermodynamically and spatially split two incoming electrons towards different pathways, resulting in the one-electron reduction of two different substrates, featuring reduction potential respectively higher and lower than the parent reductant. This energy conversion process, referred to as electron bifurcation, is relevant not only from a biochemical perspective, but also for the ground-breaking applications that electron-bifurcating molecular devices could have in the field of energy conversion. Natural electron-bifurcating systems contain a two-electron redox centre featuring potential inversion (PI), i. e. with second reduction easier than the first. With the aim of revealing key factors to tailor the span between first and second redox potentials, we performed a systematic density functional study of a 26-molecule set of models with the general formula Fe2 (μ-PR2 )2 (L)6 . It turned out that specific features such as i) a Fe-Fe antibonding character of the LUMO, ii) presence of electron-donor groups and iii) low steric congestion in the Fe's coordination sphere, are key ingredients for PI. In particular, the synergic effects of i)-iii) can lead to a span between first and second redox potentials larger than 700 mV. More generally, the "molecular recipes" herein described are expected to inspire the synthesis of Fe2 P2 systems with tailored PI, of primary relevance to the design of electron-bifurcating molecular devices.
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Affiliation(s)
- Federica Arrigoni
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, Piazza della Scienza 2, 20126, Milan, Italy
| | - Fabio Rizza
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, Piazza della Scienza 2, 20126, Milan, Italy
| | - Jacopo Vertemara
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, Piazza della Scienza 2, 20126, Milan, Italy
| | - Raffaella Breglia
- Department of Earth and Environmental Sciences, University of Milano - Bicocca, Piazza della Scienza 1, 20126, Milan, Italy
| | - Claudio Greco
- Department of Earth and Environmental Sciences, University of Milano - Bicocca, Piazza della Scienza 1, 20126, Milan, Italy
| | - Luca Bertini
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, Piazza della Scienza 2, 20126, Milan, Italy
| | - Giuseppe Zampella
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, Piazza della Scienza 2, 20126, Milan, Italy
| | - Luca De Gioia
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, Piazza della Scienza 2, 20126, Milan, Italy
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21
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Universal free-energy landscape produces efficient and reversible electron bifurcation. Proc Natl Acad Sci U S A 2020; 117:21045-21051. [PMID: 32801212 DOI: 10.1073/pnas.2010815117] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
For decades, it was unknown how electron-bifurcating systems in nature prevented energy-wasting short-circuiting reactions that have large driving forces, so synthetic electron-bifurcating molecular machines could not be designed and built. The underpinning free-energy landscapes for electron bifurcation were also enigmatic. We predict that a simple and universal free-energy landscape enables electron bifurcation, and we show that it enables high-efficiency bifurcation with limited short-circuiting (the EB scheme). The landscape relies on steep free-energy slopes in the two redox branches to insulate against short-circuiting using an electron occupancy blockade effect, without relying on nuanced changes in the microscopic rate constants for the short-circuiting reactions. The EB scheme thus unifies a body of observations on biological catalysis and energy conversion, and the scheme provides a blueprint to guide future campaigns to establish synthetic electron bifurcation machines.
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22
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Mandal A, Krauss TD, Huo P. Polariton-Mediated Electron Transfer via Cavity Quantum Electrodynamics. J Phys Chem B 2020; 124:6321-6340. [PMID: 32589846 DOI: 10.1021/acs.jpcb.0c03227] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigate the polariton-mediated electron transfer reaction in a model system with analytic rate constant theory and direct quantum dynamical simulations. We demonstrate that the photoinduced charge transfer reaction between a bright donor state and dark acceptor state can be significantly enhanced or suppressed by coupling the molecular system to the quantized radiation field inside an optical cavity. This is because the quantum light-matter interaction can influence the effective driving force and electronic couplings between the donor state, which is the hybrid light-matter excitation, and the molecular acceptor state. Under the resonance condition between the photonic and electronic excitations, the effective driving force can be tuned by changing the light-matter coupling strength; for an off-resonant condition, the same effect can be accomplished by changing the molecule-cavity detuning. We further demonstrate that using both the electronic coupling and light-matter coupling helps to extend the effective couplings across the entire system, even for the dark state that carries a zero transition dipole. Theoretically, we find that both the counter-rotating terms and the dipole self-energy in the quantum electrodynamics Hamiltonian are important for obtaining an accurate polariton eigenspectrum as well as the polariton-mediated charge transfer rate constant, especially in the ultrastrong coupling regime.
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Affiliation(s)
- Arkajit Mandal
- Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, New York 14627, United States
| | - Todd D Krauss
- Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, New York 14627, United States
| | - Pengfei Huo
- Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, New York 14627, United States
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23
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Onuchic JN, Rubtsov IV, Therien MJ. Tribute to David N. Beratan. J Phys Chem B 2020; 124:3437-3440. [DOI: 10.1021/acs.jpcb.0c02606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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