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You Z, Li J, Wang Y, Wu D, Li F, Song H. Advances in mechanisms and engineering of electroactive biofilms. Biotechnol Adv 2023; 66:108170. [PMID: 37148984 DOI: 10.1016/j.biotechadv.2023.108170] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 03/22/2023] [Accepted: 05/02/2023] [Indexed: 05/08/2023]
Abstract
Electroactive biofilms (EABs) are electroactive microorganisms (EAMs) encased in conductive polymers that are secreted by EAMs and formed by the accumulation and cross-linking of extracellular polysaccharides, proteins, nucleic acids, lipids, and other components. EABs are present in the form of multicellular aggregates and play a crucial role in bioelectrochemical systems (BESs) for diverse applications, including biosensors, microbial fuel cells for renewable bioelectricity production and remediation of wastewaters, and microbial electrosynthesis of valuable chemicals. However, naturally occurred EABs are severely limited owing to their low electrical conductivity that seriously restrict the electron transfer efficiency and practical applications. In the recent decade, synthetic biology strategies have been adopted to elucidate the regulatory mechanisms of EABs, and to enhance the formation and electrical conductivity of EABs. Based on the formation of EABs and extracellular electron transfer (EET) mechanisms, the synthetic biology-based engineering strategies of EABs are summarized and reviewed as follows: (i) Engineering the structural components of EABs, including strengthening the synthesis and secretion of structural elements such as polysaccharides, eDNA, and structural proteins, to improve the formation of biofilms; (ii) Enhancing the electron transfer efficiency of EAMs, including optimizing the distribution of c-type cytochromes and conducting nanowire assembly to promote contact-based EET, and enhancing electron shuttles' biosynthesis and secretion to promote shuttle-mediated EET; (iii) Incorporating intracellular signaling molecules in EAMs, including quorum sensing systems, secondary messenger systems, and global regulatory systems, to increase the electron transfer flux in EABs. This review lays a foundation for the design and construction of EABs for diverse BES applications.
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Affiliation(s)
- Zixuan You
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Jianxun Li
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Beijing 100093, China
| | - Yuxuan Wang
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Deguang Wu
- Department of Brewing Engineering, Moutai Institute, Luban Ave, Renhuai 564507, Guizhou, PR China
| | - Feng Li
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
| | - Hao Song
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin 300072, China; Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
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A Cysteine Pair Controls Flavin Reduction by Extracellular Cytochromes during Anoxic/Oxic Environmental Transitions. mBio 2023; 14:e0258922. [PMID: 36645302 PMCID: PMC9973256 DOI: 10.1128/mbio.02589-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Many bacteria of the genus Shewanella are facultative anaerobes able to reduce a broad range of soluble and insoluble substrates, including Fe(III) mineral oxides. Under anoxic conditions, the bacterium Shewanella oneidensis MR-1 uses a porin-cytochrome complex (Mtr) to mediate extracellular electron transfer (EET) across the outer membrane to extracellular substrates. However, it is unclear how EET prevents generating harmful reactive oxygen species (ROS) when exposed to oxic environments. The Mtr complex is expressed under anoxic and oxygen-limited conditions and contains an extracellular MtrC subunit. This has a conserved CX8C motif that inhibits aerobic growth when removed. This inhibition is caused by an increase in ROS that kills the majority of S. oneidensis cells in culture. To better understand this effect, soluble MtrC isoforms with modified CX8C were isolated. These isoforms produced increased concentrations of H2O2 in the presence of flavin mononucleotide (FMN) and greatly increased the affinity between MtrC and FMN. X-ray crystallography revealed that the molecular structure of MtrC isoforms was largely unchanged, while small-angle X-ray scattering suggested that a change in flexibility was responsible for controlling FMN binding. Together, these results reveal that FMN reduction in S. oneidensis MR-1 is controlled by the redox-active disulfide on the cytochrome surface. In the presence of oxygen, the disulfide forms, lowering the affinity for FMN and decreasing the rate of peroxide formation. This cysteine pair consequently allows the cell to respond to changes in oxygen level and survive in a rapidly transitioning environment. IMPORTANCE Bacteria that live at the oxic/anoxic interface have to rapidly adapt to changes in oxygen levels within their environment. The facultative anaerobe Shewanella oneidensis MR-1 can use EET to respire in the absence of oxygen, but on exposure to oxygen, EET could directly reduce extracellular oxygen and generate harmful reactive oxygen species that damage the bacterium. By modifying an extracellular cytochrome called MtrC, we show how preventing a redox-active disulfide from forming causes the production of cytotoxic concentrations of peroxide. The disulfide affects the affinity of MtrC for the redox-active flavin mononucleotide, which is part of the EET pathway. Our results demonstrate how a cysteine pair exposed on the surface controls the path of electron transfer, allowing facultative anaerobic bacteria to rapidly adapt to changes in oxygen concentration at the oxic/anoxic interface.
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Xu B, Li Z, Jiang Y, Chen M, Chen B, Xin F, Dong W, Jiang M. Recent advances in the improvement of bi-directional electron transfer between abiotic/biotic interfaces in electron-assisted biosynthesis system. Biotechnol Adv 2021; 54:107810. [PMID: 34333092 DOI: 10.1016/j.biotechadv.2021.107810] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 07/06/2021] [Accepted: 07/26/2021] [Indexed: 12/18/2022]
Abstract
As an important biosynthesis technology, electron-assisted biosynthesis (EABS) system can utilize exogenous electrons to regulate the metabolic network of microorganisms, realizing the biosynthesis of high value-added chemicals and CO2 fixation. Electrons play crucial roles as the energy carriers in the EABS process. In fact, efficient interfacial electron transfer (ET) is the decisive factor to realize the rapid energy exchange, thus stimulating the biosynthesis of target metabolic products. However, due to the interfacial resistance of ET between the abiotic solid electrode and biotic microbial cells, the low efficiency of interfacial ET has become a major bottleneck, further limiting the practical application of EABS system. As the cell membrane is insulated, even the cell membrane embedded electron conduit (no matter cytochromes or channel protein for shuttle transferring) to increase the cell membrane conductivity, the ET between membrane electron conduit and electrode surface is kinetically restricted. In this review, the pathway of bi-directional interfacial ET in EABS system was summarized. Furthermore, we reviewed representative milestones and advances in both the anode outward interfacial ET (from organism to electrode) and cathode inward interfacial ET (from electrode to organism). Here, new insights from the perspectives of material science and synthetic biology were also proposed, which were expected to provide some innovative opinions and ideas for the following in-depth studies.
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Affiliation(s)
- Bin Xu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China
| | - Zhe Li
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 211800, PR China
| | - Yujia Jiang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China
| | - Minjiao Chen
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China
| | - Boryann Chen
- Department of Chemical and Materials Engineering, National I-Lan University, I-Lan 26047, Taiwan
| | - Fengxue Xin
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800, PR China
| | - Weiliang Dong
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800, PR China.
| | - Min Jiang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing, 211800, PR China.
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4
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Gong Z, Yu H, Zhang J, Li F, Song H. Microbial electro-fermentation for synthesis of chemicals and biofuels driven by bi-directional extracellular electron transfer. Synth Syst Biotechnol 2020; 5:304-313. [PMID: 32995586 PMCID: PMC7490822 DOI: 10.1016/j.synbio.2020.08.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/23/2020] [Accepted: 08/25/2020] [Indexed: 11/16/2022] Open
Abstract
Electroactive bacteria could perform bi-directional extracellular electron transfer (EET) to exchange electrons and energy with extracellular environments, thus playing a central role in microbial electro-fermentation (EF) process. Unbalanced fermentation and microbial electrosynthesis are the main pathways to produce value-added chemicals and biofuels. However, the low efficiency of the bi-directional EET is a dominating bottleneck in these processes. In this review, we firstly demonstrate the main bi-directional EET mechanisms during EF, including the direct EET and the shuttle-mediated EET. Then, we review representative milestones and progresses in unbalanced fermentation via anode outward EET and microbial electrosynthesis via inward EET based on these two EET mechanisms in detail. Furthermore, we summarize the main synthetic biology strategies in improving the bi-directional EET and target products synthesis, thus to enhance the efficiencies in unbalanced fermentation and microbial electrosynthesis. Lastly, a perspective on the applications of microbial electro-fermentation is provided.
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Affiliation(s)
- Ziying Gong
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, China.,Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Huan Yu
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, China.,Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Junqi Zhang
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, China.,Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Feng Li
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, China.,Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Hao Song
- Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, 300072, China.,Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
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Chong GW, Karbelkar AA, El-Naggar MY. Nature's conductors: what can microbial multi-heme cytochromes teach us about electron transport and biological energy conversion? Curr Opin Chem Biol 2018; 47:7-17. [PMID: 30015234 DOI: 10.1016/j.cbpa.2018.06.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 06/04/2018] [Indexed: 10/28/2022]
Abstract
Microorganisms can acquire energy from the environment by extending their electron transport chains to external solid electron donors or acceptors. This process, known as extracellular electron transfer (EET), is now being heavily pursued for wiring microbes to electrodes in bioelectrochemical renewable energy technologies. Recent studies highlight the crucial role of multi-heme cytochromes in facilitating biotic-abiotic EET both for cellular electron export and uptake. Here we explore progress in understanding the range and function of these biological electron conduits in the context of fuel-to-electricity and electricity-to-bioproduct conversion. We also highlight emerging topics, including the role of multi-heme cytochromes in inter-species electron transfer and in inspiring the design and synthesis of a new generation of protein-based bioelectronic components.
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Affiliation(s)
- Grace W Chong
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-2910, USA
| | - Amruta A Karbelkar
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089-1062, USA
| | - Mohamed Y El-Naggar
- Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-2910, USA; Department of Chemistry, University of Southern California, Los Angeles, CA 90089-1062, USA; Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484, USA.
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6
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Xu F, Lu C, Wu Q, Gu W, Chen J, Fang F, Zhao B, Du W, You M. Studies on the lipid-regulating mechanism of alisol-based compounds on lipoprotein lipase. Bioorg Chem 2018; 80:347-360. [PMID: 29986183 DOI: 10.1016/j.bioorg.2018.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 06/10/2018] [Accepted: 07/01/2018] [Indexed: 01/02/2023]
Abstract
Studies on the lipid-regulating effects of alisol compounds are reported that include alisol B, alisol A 24-acetate (24A), alisol A and an alisol B - 24A - alisol A mixture (content ratio = 1:1:1). The effects on the activity of lipoprotein lipase (LPL), a key lipid-modulating enzyme, were studied to investigate the molecular mechanism of lipid-regulating activity of alisols. The effects of alisols on regulating blood lipids and the activities of LPL were determined using a reagent kit method. The structure of LPL was obtained by homology modeling and the interactive mechanism of alisol monomers and the mixture with LPL was investigated by molecular simulation. The alisol monomer and mixture were shown to regulate blood lipids, suggesting that alisols may decrease the level of triglyceride (TG) by improving the activity of LPL. The order of intensity was: mixture > alisol A > alisol B > 24A, indicating that alisols of alismatis rhizoma feature a synergistic effect on LPL. The N- and C-terminus of LPL both represented the catalytic active domains of this lipid-regulating effect. Cys306, Gln129 and Ser166 were the key amino acid residues resulting in the lipid-regulating effect of the alisol monomer while Ser166 and Arg18 were found to be responsible for the lipid-regulating effect of the mixture. The C-terminus of LPL was indirectly involved in the enzymatic process. A folded side chain of alisols or the parent ring was found to bind somewhat weaker to LPL than an open side chain or parent ring. The hydroxyl groups on the C14-, C22-, C28-, C30- and C31-terminus in the side chain, the ring ether structure in C23-position, and the acetyl group in C29-position represented the key sites for the lipid-regulating action of alisols. Meanwhile, the C30-site hydroxyl group played an important role in the synergistic effect of the alisol mixture.
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Affiliation(s)
- Fei Xu
- College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China.
| | - Cai Lu
- College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China.
| | - Qinan Wu
- College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing 210023, China; National and LocalCollaborative Engineering Center of Chinese Medicinal Resources Industrialization and Formulae Innovative Medicine, Nanjing 210023, China.
| | - Wei Gu
- College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China.
| | - Jun Chen
- College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing 210023, China.
| | - Fang Fang
- College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China.
| | - Bo Zhao
- College of Chemistry and Environmental Science, Nanjing Normal University, Nnanjing 210097, China.
| | - Wenjia Du
- College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China.
| | - Min You
- College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China.
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Costa NL, Clarke TA, Philipp LA, Gescher J, Louro RO, Paquete CM. Electron transfer process in microbial electrochemical technologies: The role of cell-surface exposed conductive proteins. BIORESOURCE TECHNOLOGY 2018; 255:308-317. [PMID: 29444758 DOI: 10.1016/j.biortech.2018.01.133] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 01/26/2018] [Accepted: 01/27/2018] [Indexed: 06/08/2023]
Abstract
Electroactive microorganisms have attracted significant interest for the development of novel biotechnological systems of low ecological footprint. These can be used for the sustainable production of energy, bioremediation of metal-contaminated environments and production of added-value products. Currently, almost 100 microorganisms from the Bacterial and Archaeal domains are considered electroactive, given their ability to efficiently interact with electrodes in microbial electrochemical technologies. Cell-surface exposed conductive proteins are key players in the electron transfer between cells and electrodes. Interestingly, it seems that among the electroactive organisms identified so far, these cell-surface proteins fall into one of four groups. In this review, the different types of cell-surface conductive proteins found in electroactive organisms will be overviewed, focusing on their structural and functional properties.
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Affiliation(s)
- Nazua L Costa
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Av. da República-EAN, 2780-157, Oeiras, Portugal
| | - Thomas A Clarke
- Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Laura-Alina Philipp
- Department of Applied Biology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (CS), Karlsruhe, Germany
| | - Johannes Gescher
- Department of Applied Biology, Institute for Applied Biosciences, Karlsruhe Institute of Technology (CS), Karlsruhe, Germany; Institute for Biological Interfaces, Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
| | - Ricardo O Louro
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Av. da República-EAN, 2780-157, Oeiras, Portugal
| | - Catarina M Paquete
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade NOVA de Lisboa, Av. da República-EAN, 2780-157, Oeiras, Portugal.
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Khrenova MG, Meteleshko YI, Nemukhin AV. Mutants of the Flavoprotein iLOV as Prospective Red-Shifted Fluorescent Markers. J Phys Chem B 2017; 121:10018-10025. [DOI: 10.1021/acs.jpcb.7b07533] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Maria G. Khrenova
- Department
of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Yulia I. Meteleshko
- Department
of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Alexander V. Nemukhin
- Department
of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
- Emanuel
Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119334, Russia
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Outer membrane cytochromes/flavin interactions in Shewanella spp.-A molecular perspective. Biointerphases 2017; 12:021004. [PMID: 28565913 DOI: 10.1116/1.4984007] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Extracellular electron transfer (EET) is intrinsically associated with the core phenomena of energy harvesting/energy conversion in natural ecosystems and biotechnology applications. However, the mechanisms associated with EET are complex and involve molecular interactions that take place at the "bionano interface" where biotic/abiotic interactions are usually explored. This work provides molecular perspective on the electron transfer mechanism(s) employed by Shewanella oneidensis MR-1. Molecular docking simulations were used to explain the interfacial relationships between two outer-membrane cytochromes (OMC) OmcA and MtrC and riboflavin (RF) and flavin mononucleotide (FMN), respectively. OMC-flavin interactions were analyzed by studying the electrostatic potential, the hydrophilic/hydrophobic surface properties, and the van der Waals surface of the OMC proteins. As a result, it was proposed that the interactions between flavins and OMCs are based on geometrical recognition event. The possible docking positions of RF and FMN to OmcA and MtrC were also shown.
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The Cholesterol-Lowering Effect of Alisol Acetates Based on HMG-CoA Reductase and Its Molecular Mechanism. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2016; 2016:4753852. [PMID: 27872650 PMCID: PMC5107224 DOI: 10.1155/2016/4753852] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 09/24/2016] [Accepted: 10/09/2016] [Indexed: 01/11/2023]
Abstract
This study measured the impact of alisol B 23-acetate and alisol A 24-acetate, the main active ingredients of the traditional Chinese medicine Alismatis rhizoma, on total cholesterol (TC), triglyceride (TG), high density lipoprotein-cholesterol (HDL-C), and low density lipoprotein-cholesterol (LDL-C) levels of hyperlipidemic mice. The binding of alisol B 23-acetate and alisol A 24-acetate to the key enzyme involved in the metabolism of TC, 3-hydroxy-3-methylglutary-coenzyme A (HMG-CoA) reductase, was studied using the reagent kit method and the western blotting technique combined with a molecular simulation technique. According to the results, alisol acetates significantly lower the TC, TG, and LDL-C concentrations of hyperlipidemic mice, while raising HDL-C concentrations. Alisol acetates lower HMG-CoA reductase activity in a dose-dependent fashion, both in vivo and in vitro. Neither of these alisol acetates significantly lower the protein expression of HMG-CoA. This suggests that alisol acetates lower the TC level via inhibiting the activity of HMG-CoA reductase by its prototype drug, which may exhibit an inhibition effect via directly and competitively binding to HMG-CoA. The side chain of the alisol acetate was the steering group via molecular simulation.
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Hong G, Pachter R. Bound Flavin-Cytochrome Model of Extracellular Electron Transfer in Shewanella oneidensis: Analysis by Free Energy Molecular Dynamics Simulations. J Phys Chem B 2016; 120:5617-24. [PMID: 27266856 DOI: 10.1021/acs.jpcb.6b03851] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Flavins are known to enhance extracellular electron transfer (EET) in Shewanella oneidensis MR-1 bacteria, which reduce electron acceptors through outer-membrane (OM) cytochromes c. Free-shuttle and bound-redox cofactor mechanisms were proposed to explain this enhancement, but recent electrochemical reports favor a flavin-bound model, proposing two one-electron reductions of flavin, namely, oxidized (Ox) to semiquinone (Sq) and semiquinone to hydroquinone (Hq), at anodic and cathodic conditions, respectively. In this work, to provide a mechanistic understanding of riboflavin (RF) binding at the multiheme OM cytochrome OmcA, we explored binding configurations at hemes 2, 5, 7, and 10. Subsequently, on the basis of molecular dynamics (MD) simulations, binding free energies and redox potential shifts upon RF binding for the Ox/Sq and Sq/Hq reductions were analyzed. Our results demonstrated an upshift in the Ox/Sq and a downshift in the Sq/Hq redox potentials, consistent with a bound RF-OmcA model. Furthermore, binding free energy MD simulations indicated an RF binding preference at heme 7. MD simulations of the OmcA-MtrC complex interfacing at hemes 5 revealed a small interprotein redox potential difference with an electron transfer rate of 10(7)-10(8)/s.
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Affiliation(s)
- Gongyi Hong
- Air Force Research Laboratory , Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Ruth Pachter
- Air Force Research Laboratory , Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, United States
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