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Yang X, Zhou X, Qin X, Liang D, Dong X, Ji H, Wen S, Du L, Li M. Deuteration-Driven Photopharmacology: Deuterium-Labeled AzoCholine for Controlling Alpha 7 Nicotinic Acetylcholine Receptors. ACS Pharmacol Transl Sci 2024; 7:1839-1846. [PMID: 38898952 PMCID: PMC11184602 DOI: 10.1021/acsptsci.4c00058] [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: 02/04/2024] [Revised: 04/26/2024] [Accepted: 04/30/2024] [Indexed: 06/21/2024]
Abstract
Photopharmacology is a powerful approach to investigate biological processes and overcomes the common therapeutic challenges in drug development. Enhancing the photopharmacology properties of photoswitches contributes to extend their applications. Deuteration, a tiny structural modification, makes it possible to improve the photopharmacology and photophysical properties of prototype compounds, avoiding extra complex chemical changes or constructing multicomponent systems. In this work, we developed a series of D-labeled azobenzenes to expand the azobenzene photoswitchable library and introduced the D-labeled azobenzene unit into the photoagonist of α7 nicotinic acetylcholine receptors (α7 nAChRs) to investigate the effects of deuteration in photopharmacology. Spectral data indicated that deuteration maintained most of the photophysical properties of azobenzenes. The D-labeled photoagonist exhibited good control of the activity of α7 nAChRs than the prototype photoagonist. These results confirmed that deuteration is a promising strategy to improve the photopharmacological properties.
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Affiliation(s)
- Xingye Yang
- Department
of Medicinal Chemistry, Key Laboratory of Chemical Biology, School
of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
- Pharmaceutical
College, Guangxi Key Laboratory of Pharmaceutical Precision Detection
and Screening, Key Laboratory of Micro-Nanoscale Bioanalysis and Drug
Screening of Guangxi Education Department, Guangxi Key Laboratory
of Bioactive Molecules Research and Evaluation, Guangxi Medical University, Nanning, Guangxi 530021, China
| | - Xin Zhou
- Department
of Medicinal Chemistry, Key Laboratory of Chemical Biology, School
of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Xiaojun Qin
- Pharmaceutical
College, Guangxi Key Laboratory of Pharmaceutical Precision Detection
and Screening, Key Laboratory of Micro-Nanoscale Bioanalysis and Drug
Screening of Guangxi Education Department, Guangxi Key Laboratory
of Bioactive Molecules Research and Evaluation, Guangxi Medical University, Nanning, Guangxi 530021, China
| | - Dong Liang
- Department
of Medicinal Chemistry, Key Laboratory of Chemical Biology, School
of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Xuhui Dong
- Department
of Medicinal Chemistry, Key Laboratory of Chemical Biology, School
of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Huimin Ji
- Department
of Medicinal Chemistry, Key Laboratory of Chemical Biology, School
of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Siman Wen
- Pharmaceutical
College, Guangxi Key Laboratory of Pharmaceutical Precision Detection
and Screening, Key Laboratory of Micro-Nanoscale Bioanalysis and Drug
Screening of Guangxi Education Department, Guangxi Key Laboratory
of Bioactive Molecules Research and Evaluation, Guangxi Medical University, Nanning, Guangxi 530021, China
| | - Lupei Du
- Department
of Medicinal Chemistry, Key Laboratory of Chemical Biology, School
of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
| | - Minyong Li
- Department
of Medicinal Chemistry, Key Laboratory of Chemical Biology, School
of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, China
- Helmholtz
International Lab, State Key Laboratory of Microbial Technology, Shandong University, Qingdao, Shandong 266237, China
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2
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Hellmold N, Eberwein M, Phan MHT, Kümmel S, Einsle O, Deobald D, Adrian L. Dehalococcoides mccartyi strain CBDB1 takes up protons from the cytoplasm to reductively dehalogenate organohalides indicating a new modus of proton motive force generation. Front Microbiol 2023; 14:1305108. [PMID: 38192294 PMCID: PMC10772276 DOI: 10.3389/fmicb.2023.1305108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 12/07/2023] [Indexed: 01/10/2024] Open
Abstract
Proton translocation across the cytoplasmic membrane is a vital process for all organisms. Dehalococcoides strains are strictly anaerobic organohalide respiring bacteria that lack quinones and cytochromes but express a large membrane-bound protein complex (OHR complex) proposed to generate a proton gradient. However, its functioning is unclear. By using a dehalogenase-based enzyme activity assay with deuterium-labelled water in various experimental designs, we obtained evidence that the halogen atom of the halogenated electron acceptor is substituted with a proton from the cytoplasm. This suggests that the protein complex couples exergonic electron flux through the periplasmic subunits of the OHR complex to the endergonic transport of protons from the cytoplasm across the cytoplasmic membrane against the proton gradient to the halogenated electron acceptor. Using computational tools, we located two proton-conducting half-channels in the AlphaFold2-predicted structure of the OmeB subunit of the OHR complex, converging in a highly conserved arginine residue that could play a proton gatekeeper role. The cytoplasmic proton half-channel in OmeB is connected to a putative proton-conducting path within the reductive dehalogenase subunit. Our results indicate that the reductive dehalogenase and its halogenated substrate serve as both electron and proton acceptors, providing insights into the proton translocation mechanism within the OHR complex and contributing to a better understanding of energy conservation in D. mccartyi strains. Our results reveal a very simple mode of energy conservation in anaerobic bacteria, showing that proton translocation coupled to periplasmic electron flow might have importance also in other microbial processes and biotechnological applications.
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Affiliation(s)
- Nadine Hellmold
- Department Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Marie Eberwein
- Department Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - My Hanh Thi Phan
- Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | - Steffen Kümmel
- Department Isotope Biogeochemistry, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Oliver Einsle
- Institute of Biochemistry, Albert-Ludwigs-Universität Freiburg, Freiburg im Breisgau, Germany
| | - Darja Deobald
- Department Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Lorenz Adrian
- Department Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
- Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
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Yaglova NV, Timokhina EP, Obernikhin SS, Yaglov VV. Emerging Role of Deuterium/Protium Disbalance in Cell Cycle and Apoptosis. Int J Mol Sci 2023; 24:ijms24043107. [PMID: 36834518 PMCID: PMC9963022 DOI: 10.3390/ijms24043107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/21/2023] [Accepted: 02/02/2023] [Indexed: 02/09/2023] Open
Abstract
Deuterium, a stable isotope of hydrogen, is a component of water and organic compounds. It is the second most abundant element in the human body after sodium. Although the concentration of deuterium in an organism is much lower than that of protium, a wide variety of morphological, biochemical, and physiological changes are known to occur in deuterium-treated cells, including changes in fundamental processes such as cell division or energy metabolism. The mode and degree of changes in cells and tissues, both with an increase and a decrease in the concentration of deuterium, depends primarily on the time of exposure, as well as on the concentration. The reviewed data show that plant and animal cells are sensitive to deuterium content. Any shifts in the D/H balance outside or inside cells promote immediate responses. The review summarizes reported data on the proliferation and apoptosis of normal and neoplastic cells in different modes of deuteration and deuterium depletion in vivo and in vitro. The authors propose their own concept of the effects of changes in deuterium content in the body on cell proliferation and death. The altered rate of proliferation and apoptosis indicate a pivotal role of the hydrogen isotope content in living organisms and suggest the presence of a D/H sensor, which is yet to be detected.
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Nachliel E, Gutman M. Reaction within the coulomb-cage; science in retrospect. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184071. [PMID: 36244436 DOI: 10.1016/j.bbamem.2022.184071] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 08/01/2022] [Accepted: 09/30/2022] [Indexed: 11/06/2022]
Abstract
The Coulomb-cage is defined as the space where the electrostatic interaction between two bodies is more intensive than the thermal energy (kBT). For small molecule, the Coulomb-cage is a small sphere, extending only few water molecules towards the bulk and its radius is sensitive to the ionic strength of the solution. For charged proteins or membranal structures, the Coulomb-cage can engulf large fraction of the surface and provides a preferred pathway for ion propagation along the surface. Similarly, electrostatic potential at the inner space of a channel can form preferential trajectories passage for ions. The dynamics of ions inside the Coulomb-cage of ions was formulated by the studies of proton-anion recombination of excited photoacids. In the present article, we recount the study of intra- Coulomb-cage reaction taking place on the surface of macro-molecular bodies like micelles, membranes, proteins and intra-protein cavities. The study progressed stepwise, tracing the dynamics of a proton ejected from a photo-acid molecule located at defined sites (on membrane, inter-membrane space, active site of enzyme, inside Large Pore Channels etc.). Accumulation of experimental observations encouraged us to study of the reaction mechanism by molecular dynamics simulations of ions within the Coulomb-cage of proteins surface or inside large pores. The intra-Coulomb-cage proton transfer events follows closely the fine structure of the electrostatic field inside the cage and reflects the shape of nearby dielectric boundaries, the temporal ordering of the solvent molecules and the structural fluctuations of the charged side chains. The article sums some 40 years of research, which in retrospect clarifies the intra-Coulomb-cage reaction mechanism.
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Affiliation(s)
- E Nachliel
- Laser Laboratory for Fast Reactions, Dep. Of Biochemistry and Molecular Biology, Life Sciences, Tel Aviv University, Israel
| | - M Gutman
- Laser Laboratory for Fast Reactions, Dep. Of Biochemistry and Molecular Biology, Life Sciences, Tel Aviv University, Israel.
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Król S, Fedotovskaya O, Högbom M, Ädelroth P, Brzezinski P. Electron and proton transfer in the M. smegmatis III 2IV 2 supercomplex. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148585. [PMID: 35753381 DOI: 10.1016/j.bbabio.2022.148585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 05/25/2022] [Accepted: 06/17/2022] [Indexed: 06/15/2023]
Abstract
The M. smegmatis respiratory III2IV2 supercomplex consists of a complex III (CIII) dimer flanked on each side by a complex IV (CIV) monomer, electronically connected by a di-heme cyt. cc subunit of CIII. The supercomplex displays a quinol oxidation‑oxygen reduction activity of ~90 e-/s. In the current work we have investigated the kinetics of electron and proton transfer upon reaction of the reduced supercomplex with molecular oxygen. The data show that, as with canonical CIV, oxidation of reduced CIV at pH 7 occurs in three resolved components with time constants ~30 μs, 100 μs and 4 ms, associated with the formation of the so-called peroxy (P), ferryl (F) and oxidized (O) intermediates, respectively. Electron transfer from cyt. cc to the primary electron acceptor of CIV, CuA, displays a time constant of ≤100 μs, while re-reduction of cyt. cc by heme b occurs with a time constant of ~4 ms. In contrast to canonical CIV, neither the P → F nor the F → O reactions are pH dependent, but the P → F reaction displays a H/D kinetic isotope effect of ~3. Proton uptake through the D pathway in CIV displays a single time constant of ~4 ms, i.e. a factor of ~40 slower than with canonical CIV. The slowed proton uptake kinetics and absence of pH dependence are attributed to binding of a loop from the QcrB subunit of CIII at the D proton pathway of CIV. Hence, the data suggest that function of CIV is modulated by way of supramolecular interactions with CIII.
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Affiliation(s)
- Sylwia Król
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Olga Fedotovskaya
- 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
| | - Pia Ädelroth
- 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.
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Kselíková V, Husarčíková K, Mojzeš P, Zachleder V, Bišová K. Cultivation of the microalgae Chlamydomonas reinhardtii and Desmodesmus quadricauda in highly deuterated media: Balancing the light intensity. Front Bioeng Biotechnol 2022; 10:960862. [PMID: 36131720 PMCID: PMC9483122 DOI: 10.3389/fbioe.2022.960862] [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: 06/03/2022] [Accepted: 07/28/2022] [Indexed: 11/13/2022] Open
Abstract
The production of organic deuterated compounds in microalgal systems represents a cheaper and more versatile alternative to more complicated chemical synthesis. In the present study, we investigate the autotrophic growth of two microalgae, Chlamydomonas reinhardtii and Desmodesmus quadricauda, in medium containing high doses of deuterated water, D2O. The growth of such cultures was evaluated in the context of the intensity of incident light, since light is a critical factor in the management of autotrophic algal cultures. Deuteration increases the light sensitivity of both model organisms, resulting in increased levels of singlet oxygen and poorer photosynthetic performance. Our results also show a slowdown in growth and cell division processes with increasing D2O concentrations. At the same time, impaired cell division leads to cell enlargement and accumulation of highly deuterated compounds, especially energy-storing molecules. Thus, considering the specifics of highly deuterated cultures and using the growth conditions proposed in this study, it is possible to obtain highly deuterated algal biomass, which could be a valuable source of deuterated organic compounds.
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Affiliation(s)
- Veronika Kselíková
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
- Faculty of Science, University of South Bohemia, České Budějovice, Czechia
| | - Kamila Husarčíková
- Faculty of Food and Biochemical Technology, University of Chemistry and Technology Prague, Prague, Czechia
| | - Peter Mojzeš
- Institute of Physics, Faculty of Mathematics and Physics, Charles University, Prague, Czechia
| | - Vilém Zachleder
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
| | - Kateřina Bišová
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
- *Correspondence: Kateřina Bišová,
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7
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Nesterov SV, Smirnova EG, Yaguzhinsky LS. Mechanism of Energy Storage and Transformation in the Mitochondria at the Water-Membrane Interface. BIOCHEMISTRY. BIOKHIMIIA 2022; 87:179-190. [PMID: 35508909 DOI: 10.1134/s0006297922020092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/11/2022] [Accepted: 01/13/2022] [Indexed: 06/14/2023]
Abstract
In this review, we discuss the mechanisms of generation of membrane-bound protons using different energy sources in model and natural systems. Analysis of these mechanisms revealed that all three types of reactions include the same principal stage, which is dissociation of electrically neutral Brønsted acids at the interface during transition from the hydrophobic phase to water with a low dielectric constant. Special attention is paid to the fact that in one of the analyzed model systems, membrane-bound protons provide energy for the reaction of ATP synthesis. Similar mechanism for the generation of membrane-bound protons has been found in natural membranes involved in oxidative phosphorylation, in particular, on the membranes of mitoplasts and mitochondria. The energy of oxidative reactions required for ATP synthesis, is stored at the intermediate stage not only in the form of transmembrane electrochemical potential of protons, but also and perhaps mostly, as protons attached to the inner mitochondrial membrane. The process of energy storage in mitochondria is linked to the transfer of protons that simultaneously perform two functions. Protons on the membrane surface carry free energy and, at the same time, act as substrates facilitating the movement of F1F0-ATP-synthase biological machine.
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Affiliation(s)
- Semen V Nesterov
- National Research Center "Kurchatov Institute", Moscow, 123182, Russia
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia
| | - Elena G Smirnova
- Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Lev S Yaguzhinsky
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, 141701, Russia.
- Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
- Institute of Cytochemistry and Molecular Pharmacology, Moscow, 115404, Russia
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8
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Hua Q, Madsen KE, Esposito AM, Chen X, Woods TJ, Haasch RT, Xiang S, Frenkel AI, Fister TT, Gewirth AA. Effect of Support on Oxygen Reduction Reaction Activity of Supported Iron Porphyrins. ACS Catal 2022. [DOI: 10.1021/acscatal.1c04871] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Qi Hua
- Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Kenneth E. Madsen
- Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Anne Marie Esposito
- Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Xinyi Chen
- Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Toby J. Woods
- Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Richard T. Haasch
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Shuting Xiang
- Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, New York 11794, United States
| | - Anatoly I. Frenkel
- Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, New York 11794, United States
- Division of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Timothy T. Fister
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Andrew A. Gewirth
- Department of Chemistry, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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Supra-Optimal Temperature: An Efficient Approach for Overaccumulation of Starch in the Green Alga Parachlorella kessleri. Cells 2021; 10:cells10071806. [PMID: 34359975 PMCID: PMC8306380 DOI: 10.3390/cells10071806] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/11/2021] [Accepted: 07/12/2021] [Indexed: 11/25/2022] Open
Abstract
Green algae are fast-growing microorganisms that are considered promising for the production of starch and neutral lipids, and the chlorococcal green alga Parachlorella kessleri is a favorable model, as it can produce both starch and neutral lipids. P. kessleri commonly divides into more than two daughter cells by a specific mechanism—multiple fission. Here, we used synchronized cultures of the alga to study the effects of supra-optimal temperature. Synchronized cultures were grown at optimal (30 °C) and supra-optimal (40 °C) temperatures and incident light intensities of 110 and 500 μmol photons m−2 s−1. The time course of cell reproduction (DNA replication, cellular division), growth (total RNA, protein, cell dry matter, cell size), and synthesis of energy reserves (net starch, neutral lipid) was studied. At 40 °C, cell reproduction was arrested, but growth and accumulation of energy reserves continued; this led to the production of giant cells enriched in protein, starch, and neutral lipids. Furthermore, we examined whether the increased temperature could alleviate the effects of deuterated water on Parachlorella kessleri growth and division; results show that supra-optimal temperature can be used in algal biotechnology for the production of protein, (deuterated) starch, and neutral lipids.
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Zachleder V, Ivanov IN, Kselíková V, Bialevich V, Vítová M, Ota S, Takeshita T, Kawano S, Bišová K. Characterization of Growth and Cell Cycle Events Affected by Light Intensity in the Green Alga Parachlorella kessleri: A New Model for Cell Cycle Research. Biomolecules 2021; 11:biom11060891. [PMID: 34203860 PMCID: PMC8232753 DOI: 10.3390/biom11060891] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 06/03/2021] [Accepted: 06/05/2021] [Indexed: 11/16/2022] Open
Abstract
Multiple fission is a cell cycle variation leading to the production of more than two daughter cells. Here, we used synchronized cultures of the chlorococcal green alga Parachlorella kessleri to study its growth and pattern of cell division under varying light intensities. The time courses of DNA replication, nuclear and cellular division, cell size, total RNA, protein content, dry matter and accumulation of starch were observed at incident light intensities of 110, 250 and 500 µmol photons m−2s−1. Furthermore, we studied the effect of deuterated water on Parachlorella kessleri growth and division, to mimic the effect of stress. We describe a novel multiple fission cell cycle pattern characterized by multiple rounds of DNA replication leading to cell polyploidization. Once completed, multiple nuclear divisions were performed with each of them, immediately followed by protoplast fission, terminated by the formation of daughter cells. The multiple fission cell cycle was represented by several consecutive doublings of growth parameters, each leading to the start of a reproductive sequence. The number of growth doublings increased with increasing light intensity and led to division into more daughter cells. This study establishes the baseline for cell cycle research at the molecular level as well as for potential biotechnological applications, particularly directed synthesis of (deuterated) starch and/or neutral lipids as carbon and energy reserves.
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Affiliation(s)
- Vilém Zachleder
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 37981 Třeboň, Czech Republic; (V.Z.); (I.N.I.); (V.K.); (V.B.); (M.V.)
| | - Ivan N. Ivanov
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 37981 Třeboň, Czech Republic; (V.Z.); (I.N.I.); (V.K.); (V.B.); (M.V.)
- Faculty of Science, University of South Bohemia, 37005 České Budějovice, Czech Republic
| | - Veronika Kselíková
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 37981 Třeboň, Czech Republic; (V.Z.); (I.N.I.); (V.K.); (V.B.); (M.V.)
- Faculty of Science, University of South Bohemia, 37005 České Budějovice, Czech Republic
| | - Vitali Bialevich
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 37981 Třeboň, Czech Republic; (V.Z.); (I.N.I.); (V.K.); (V.B.); (M.V.)
| | - Milada Vítová
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 37981 Třeboň, Czech Republic; (V.Z.); (I.N.I.); (V.K.); (V.B.); (M.V.)
| | - Shuhei Ota
- Center for Environmental Biology and Ecosystem Studies, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan;
| | - Tsuyoshi Takeshita
- The University of Tokyo Future Center Initiative, Wakashiba 178 4 4, Kashiwa, Chiba 277-0871, Japan; (T.T.); (S.K.)
| | - Shigeyuki Kawano
- The University of Tokyo Future Center Initiative, Wakashiba 178 4 4, Kashiwa, Chiba 277-0871, Japan; (T.T.); (S.K.)
| | - Kateřina Bišová
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 37981 Třeboň, Czech Republic; (V.Z.); (I.N.I.); (V.K.); (V.B.); (M.V.)
- Correspondence: ; Tel.: +420-384-340-480
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11
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Kselíková V, Zachleder V, Bišová K. To Divide or Not to Divide? How Deuterium Affects Growth and Division of Chlamydomonas reinhardtii. Biomolecules 2021; 11:861. [PMID: 34207920 PMCID: PMC8226696 DOI: 10.3390/biom11060861] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/31/2021] [Accepted: 06/07/2021] [Indexed: 11/16/2022] Open
Abstract
Extensive in vivo replacement of hydrogen by deuterium, a stable isotope of hydrogen, induces a distinct stress response, reduces cell growth and impairs cell division in various organisms. Microalgae, including Chlamydomonas reinhardtii, a well-established model organism in cell cycle studies, are no exception. Chlamydomonas reinhardtii, a green unicellular alga of the Chlorophyceae class, divides by multiple fission, grows autotrophically and can be synchronized by alternating light/dark regimes; this makes it a model of first choice to discriminate the effect of deuterium on growth and/or division. Here, we investigate the effects of high doses of deuterium on cell cycle progression in C. reinhardtii. Synchronous cultures of C. reinhardtii were cultivated in growth medium containing 70 or 90% D2O. We characterize specific deuterium-induced shifts in attainment of commitment points during growth and/or division of C. reinhardtii, contradicting the role of the "sizer" in regulating the cell cycle. Consequently, impaired cell cycle progression in deuterated cultures causes (over)accumulation of starch and lipids, suggesting a promising potential for microalgae to produce deuterated organic compounds.
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Affiliation(s)
- Veronika Kselíková
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 37981 Třeboň, Czech Republic; (V.K.); (V.Z.)
- Faculty of Science, University of South Bohemia, 37005 České Budějovice, Czech Republic
| | - Vilém Zachleder
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 37981 Třeboň, Czech Republic; (V.K.); (V.Z.)
| | - Kateřina Bišová
- Laboratory of Cell Cycles of Algae, Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, 37981 Třeboň, Czech Republic; (V.K.); (V.Z.)
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12
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Klenner MA, Pascali G, Fraser BH, Darwish TA. Kinetic isotope effects and synthetic strategies for deuterated carbon-11 and fluorine-18 labelled PET radiopharmaceuticals. Nucl Med Biol 2021; 96-97:112-147. [PMID: 33892374 DOI: 10.1016/j.nucmedbio.2021.03.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 03/19/2021] [Accepted: 03/30/2021] [Indexed: 11/22/2022]
Abstract
The deuterium labelling of pharmaceuticals is a useful strategy for altering pharmacokinetic properties, particularly for improving metabolic resistance. The pharmacological effects of such metabolites are often assumed to be negligible during standard drug discovery and are factored in later at the clinical phases of development, where the risks and benefits of the treatment and side-effects can be wholly assessed. This paradigm does not translate to the discovery of radiopharmaceuticals, however, as the confounding effects of radiometabolites can inevitably show in preliminary positron emission tomography (PET) scans and thus complicate interpretation. Consequently, the formation of radiometabolites is crucial to take into consideration, compared to non-radioactive metabolites, and the application of deuterium labelling is a particularly attractive approach to minimise radiometabolite formation. Herein, we provide a comprehensive overview of the deuterated carbon-11 and fluorine-18 radiopharmaceuticals employed in PET imaging experiments. Specifically, we explore six categories of deuterated radiopharmaceuticals used to investigate the activities of monoamine oxygenase (MAO), choline, translocator protein (TSPO), vesicular monoamine transporter 2 (VMAT2), neurotransmission and the diagnosis of Alzheimer's disease; from which we derive four prominent deuteration strategies giving rise to a kinetic isotope effect (KIE) for reducing the rate of metabolism. Synthetic approaches for over thirty of these deuterated radiopharmaceuticals are discussed from the perspective of deuterium and radioisotope incorporation, alongside an evaluation of the deuterium labelling and radiolabelling efficacies across these independent studies. Clinical and manufacturing implications are also discussed to provide a more comprehensive overview of how deuterated radiopharmaceuticals may be introduced to routine practice.
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Affiliation(s)
- Mitchell A Klenner
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia; Department of Nuclear Medicine and PET, Liverpool Hospital, Liverpool, NSW 2170, Australia.
| | - Giancarlo Pascali
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia; Department of Nuclear Medicine and PET, Prince of Wales Hospital, Randwick, NSW 2031, Australia; School of Chemistry, University of New South Wales (UNSW), Kensington, NSW 2052, Australia
| | - Benjamin H Fraser
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
| | - Tamim A Darwish
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
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13
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Deuterium and its impact on living organisms. Folia Microbiol (Praha) 2019; 64:673-681. [DOI: 10.1007/s12223-019-00740-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 07/15/2019] [Indexed: 12/12/2022]
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14
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Control of transmembrane charge transfer in cytochrome c oxidase by the membrane potential. Nat Commun 2018; 9:3187. [PMID: 30093670 PMCID: PMC6085328 DOI: 10.1038/s41467-018-05615-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 07/09/2018] [Indexed: 11/08/2022] Open
Abstract
The respiratory chain in mitochondria is composed of membrane-bound proteins that couple electron transfer to proton translocation across the inner membrane. These charge-transfer reactions are regulated by the proton electrochemical gradient that is generated and maintained by the transmembrane charge transfer. Here, we investigate this feedback mechanism in cytochrome c oxidase in intact inner mitochondrial membranes upon generation of an electrochemical potential by hydrolysis of ATP. The data indicate that a reaction step that involves proton uptake to the catalytic site and presumably proton translocation is impaired by the potential, but electron transfer is not affected. These results define the order of electron and proton-transfer reactions and suggest that the proton pump is regulated by the transmembrane electrochemical gradient through control of internal proton transfer rather than by control of electron transfer.
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15
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Multiscale simulations reveal key features of the proton-pumping mechanism in cytochrome c oxidase. Proc Natl Acad Sci U S A 2016; 113:7420-5. [PMID: 27339133 DOI: 10.1073/pnas.1601982113] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cytochrome c oxidase (CcO) reduces oxygen to water and uses the released free energy to pump protons across the membrane. We have used multiscale reactive molecular dynamics simulations to explicitly characterize (with free-energy profiles and calculated rates) the internal proton transport events that enable proton pumping during first steps of oxidation of the fully reduced enzyme. Our results show that proton transport from amino acid residue E286 to both the pump loading site (PLS) and to the binuclear center (BNC) are thermodynamically driven by electron transfer from heme a to the BNC, but that the former (i.e., pumping) is kinetically favored whereas the latter (i.e., transfer of the chemical proton) is rate-limiting. The calculated rates agree with experimental measurements. The backflow of the pumped proton from the PLS to E286 and from E286 to the inside of the membrane is prevented by large free-energy barriers for the backflow reactions. Proton transport from E286 to the PLS through the hydrophobic cavity and from D132 to E286 through the D-channel are found to be strongly coupled to dynamical hydration changes in the corresponding pathways and, importantly, vice versa.
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16
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Samkov AA, Dzhimak SS, Barishev MG, Volchenko NN, Khudokormov AA, Samkova SM, Karaseva EV. The effect of water isotopic composition on Rhodococcus erythropolis biomass production. Biophysics (Nagoya-shi) 2015. [DOI: 10.1134/s0006350915010212] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Affiliation(s)
- Shinya Yoshikawa
- Picobiology Institute, Graduate
School of Life Science, University of Hyogo, Kamigohri Akoh Hyogo, 678-1297, Japan
| | - Atsuhiro Shimada
- Picobiology Institute, Graduate
School of Life Science, University of Hyogo, Kamigohri Akoh Hyogo, 678-1297, Japan
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18
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Näsvik Öjemyr L, Maréchal A, Vestin H, Meunier B, Rich PR, Brzezinski P. Reaction of wild-type and Glu243Asp variant yeast cytochrome c oxidase with O2. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1012-8. [PMID: 24685432 DOI: 10.1016/j.bbabio.2014.03.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 03/07/2014] [Accepted: 03/21/2014] [Indexed: 11/29/2022]
Abstract
We have studied internal electron transfer during the reaction of Saccharomyces cerevisiae mitochondrial cytochrome c oxidase with dioxygen. Similar absorbance changes were observed with this yeast oxidase as with the previously studied Rhodobacter sphaeroides and bovine mitochondrial oxidases, which suggests that the reaction proceeds along the same trajectory. However, notable differences were observed in rates and electron-transfer equilibrium constants of specific reaction steps, for example the ferryl (F) to oxidized (O) reaction was faster with the yeast (0.4ms) than with the bovine oxidase (~1ms) and a larger fraction CuA was oxidized with the yeast than with the bovine oxidase in the peroxy (PR) to F reaction. Furthermore, upon replacement of Glu243, located at the end of the so-called D proton pathway, by Asp the PR→F and F→O reactions were slowed by factors of ~3 and ~10, respectively, and electron transfer from CuA to heme a during the PR→F reaction was not observed. These data indicate that during reduction of dioxygen protons are transferred through the D pathway, via Glu243, to the catalytic site in the yeast mitochondrial oxidase. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.
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Affiliation(s)
- Linda Näsvik Öjemyr
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Amandine Maréchal
- Glynn Laboratory of Bioenergetics, Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Henrik Vestin
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Brigitte Meunier
- Centre de Génétique Moléculaire du CNRS, UPR 3404, avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France
| | - Peter R Rich
- Glynn Laboratory of Bioenergetics, Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
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19
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Gyöngyi Z, Budán F, Szabó I, Ember I, Kiss I, Krempels K, Somlyai I, Somlyai G. Deuterium depleted water effects on survival of lung cancer patients and expression of Kras, Bcl2, and Myc genes in mouse lung. Nutr Cancer 2013; 65:240-6. [PMID: 23441611 PMCID: PMC3613976 DOI: 10.1080/01635581.2013.756533] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Although advances in cancer therapies continue to develop, the shortness of the survival of lung cancer patients is still disappointing. Therefore, finding new adjuvant strategies is within the focus of cancer cure. Based on observations that deuterium depletion inhibits the growth of cancer cell lines and suppresses certain proto-oncogenes, we have conducted a clinical study in 129 patients with small cell and nonsmall cell lung cancers who consumed deuterium-depleted drinking water (DDW) as a nontoxic agent in addition to conventional chemotherapy and radiotherapy. Median survival time (MST) was 25.9 mo in males and 74.1 mo in female patients; the difference between genders was statistically significant (p < 0.05). Median survival of subjects with brain metastasis was 27.1 mo. Cumulative 5-yr survival probabilities were 19%, 52%, and 33% in males, females, and all patients with brain metastasis, respectively. Gene expression analysis in mouse lung indicated that DDW attenuates 7,12-dimethylbenz(a)anthracene (DMBA)-induced expression of Bcl2, Kras, and Myc in females. In conclusion, DDW counteracts the DMBA-induced overexpression of Bcl2, Kras and Myc genes in mouse lung, and it may extend survival of lung cancer patients as a nontoxic anticancer dietary supplement, especially for women with tumors overexpressing cancer-related genes, because MST of DDW-consuming group was 2-4 times longer than it is generally observed in lung cancer patients.
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Affiliation(s)
- Zoltán Gyöngyi
- Department of Public Health, Medical School, University of Pécs, Pécs, Hungary.
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20
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Current advances in research of cytochrome c oxidase. Amino Acids 2013; 45:1073-87. [PMID: 23999646 DOI: 10.1007/s00726-013-1585-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 08/21/2013] [Indexed: 12/13/2022]
Abstract
The function of cytochrome c oxidase as a biomolecular nanomachine that transforms energy of redox reaction into protonmotive force across a biological membrane has been subject of intense research, debate, and controversy. The structure of the enzyme has been solved for several organisms; however details of its molecular mechanism of proton pumping still remain elusive. Particularly, the identity of the proton pumping site, the key element of the mechanism, is still open to dispute. The pumping mechanism has been for a long time one of the key unsolved issues of bioenergetics and biochemistry, but with the accelerating progress in this field many important details and principles have emerged. Current advances in cytochrome oxidase research are reviewed here, along with a brief discussion of the most complete proton pumping mechanism proposed to date, and a molecular basis for control of its efficiency.
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21
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Brzezinski P, Öjemyr LN, Ädelroth P. Intermediates generated during the reaction of reduced Rhodobacter sphaeroides cytochrome c oxidase with dioxygen. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1827:843-7. [DOI: 10.1016/j.bbabio.2013.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 04/18/2013] [Accepted: 04/23/2013] [Indexed: 10/26/2022]
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22
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Role of aspartate 132 at the orifice of a proton pathway in cytochrome c oxidase. Proc Natl Acad Sci U S A 2013; 110:8912-7. [PMID: 23674679 DOI: 10.1073/pnas.1303954110] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Proton transfer across biological membranes underpins central processes in biological systems, such as energy conservation and transport of ions and molecules. In the membrane proteins involved in these processes, proton transfer takes place through specific pathways connecting the two sides of the membrane via control elements within the protein. It is commonly believed that acidic residues are required near the orifice of such proton pathways to facilitate proton uptake. In cytochrome c oxidase, one such pathway starts near a conserved Asp-132 residue. Results from earlier studies have shown that replacement of Asp-132 by, e.g., Asn, slows proton uptake by a factor of ∼5,000. Here, we show that proton uptake at full speed (∼10(4) s(-1)) can be restored in the Asp-132-Asn oxidase upon introduction of a second structural modification further inside the pathway (Asn-139-Thr) without compensating for the loss of the negative charge. This proton-uptake rate was insensitive to Zn(2+) addition, which in the wild-type cytochrome c oxidase slows the reaction, indicating that Asp-132 is required for Zn(2+) binding. Furthermore, in the absence of Asp-132 and with Thr at position 139, at high pH (>9), proton uptake was significantly accelerated. Thus, the data indicate that Asp-132 is not strictly required for maintaining rapid proton uptake. Furthermore, despite the rapid proton uptake in the Asn-139-Thr/Asp-132-Asn mutant cytochrome c oxidase, proton pumping was impaired, which indicates that the segment around these residues is functionally linked to pumping.
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23
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Johansson AL, Carlsson J, Högbom M, Hosler JP, Gennis RB, Brzezinski P. Proton uptake and pKa changes in the uncoupled Asn139Cys variant of cytochrome c oxidase. Biochemistry 2013; 52:827-36. [PMID: 23305515 DOI: 10.1021/bi301597a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cytochrome c oxidase (CytcO) is a membrane-bound enzyme that links electron transfer from cytochrome c to O(2) to proton pumping across the membrane. Protons are transferred through specific pathways that connect the protein surface with the catalytic site as well as the proton input with the proton output sides. Results from earlier studies have shown that one site within the so-called D proton pathway, Asn139, located ~10 Å from the protein surface, is particularly sensitive to mutations that uncouple the O(2) reduction reaction from the proton pumping activity. For example, none of the Asn139Asp (charged) or Asn139Thr (neutral) mutant CytcOs pump protons, although the proton-uptake rates are unaffected. Here, we have investigated the Asn139Cys and Asn139Cys/Asp132Asn mutant CytcOs. In contrast to other structural variants investigated to date, the Cys side chain may be either neutral or negatively charged in the experimentally accessible pH range. The data show that the Asn139Cys and Asn139Asp mutations result in the same changes of the kinetic and thermodynamic parameters associated with the proton transfer. The similarity is not due to introduction of charge at position 139, but rather introduction of a protonatable group that modulates the proton connectivity around this position. These results illuminate the mechanism by which CytcO couples electron transfer to proton pumping.
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Affiliation(s)
- Ann-Louise Johansson
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, Sweden
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24
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Siletsky SA, Konstantinov AA. Cytochrome c oxidase: Charge translocation coupled to single-electron partial steps of the catalytic cycle. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:476-88. [DOI: 10.1016/j.bbabio.2011.08.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 08/09/2011] [Accepted: 08/10/2011] [Indexed: 11/28/2022]
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25
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Proton transfer in ba3 cytochrome c oxidase from Thermus thermophilus. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:650-7. [DOI: 10.1016/j.bbabio.2011.11.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 11/15/2011] [Accepted: 11/16/2011] [Indexed: 11/23/2022]
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26
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Johansson AL, Chakrabarty S, Berthold CL, Högbom M, Warshel A, Brzezinski P. Proton-transport mechanisms in cytochrome c oxidase revealed by studies of kinetic isotope effects. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:1083-94. [PMID: 21463601 DOI: 10.1016/j.bbabio.2011.03.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 03/25/2011] [Accepted: 03/28/2011] [Indexed: 10/18/2022]
Abstract
Cytochrome c oxidase (CytcO) is a membrane-bound enzyme, which catalyzes the reduction of di-oxygen to water and uses a major part of the free energy released in this reaction to pump protons across the membrane. In the Rhodobacter sphaeroides aa₃ CytcO all protons that are pumped across the membrane, as well as one half of the protons that are used for O₂ reduction, are transferred through one specific intraprotein proton pathway, which holds a highly conserved Glu286 residue. Key questions that need to be addressed in order to understand the function of CytcO at a molecular level are related to the timing of proton transfers from Glu286 to a "pump site" and the catalytic site, respectively. Here, we have investigated the temperature dependencies of the H/D kinetic-isotope effects of intramolecular proton-transfer reactions in the wild-type CytcO as well as in two structural CytcO variants, one in which proton uptake from solution is delayed and one in which proton pumping is uncoupled from O₂ reduction. These processes were studied for two specific reaction steps linked to transmembrane proton pumping, one that involves only proton transfer (peroxy-ferryl, P→F, transition) and one in which the same sequence of proton transfers is also linked to electron transfer to the catalytic site (ferryl-oxidized, F→O, transition). An analysis of these reactions in the framework of theory indicates that that the simpler, P→F reaction is rate-limited by proton transfer from Glu286 to the catalytic site. When the same proton-transfer events are also linked to electron transfer to the catalytic site (F→O), the proton-transfer reactions might well be gated by a protein structural change, which presumably ensures that the proton-pumping stoichiometry is maintained also in the presence of a transmembrane electrochemical gradient. Furthermore, the present study indicates that a careful analysis of the temperature dependence of the isotope effect should help us in gaining mechanistic insights about CytcO.
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Affiliation(s)
- Ann-Louise Johansson
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, Sweden
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27
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Chakrabarty S, Namslauer I, Brzezinski P, Warshel A. Exploration of the cytochrome c oxidase pathway puzzle and examination of the origin of elusive mutational effects. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:413-26. [PMID: 21232525 DOI: 10.1016/j.bbabio.2011.01.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 12/22/2010] [Accepted: 01/05/2011] [Indexed: 10/18/2022]
Abstract
Gaining detailed understanding of the energetics of the proton-pumping process in cytochrome c oxidase (CcO) is a problem of great current interest. Despite promising mechanistic proposals, so far, a physically consistent model that would reproduce all the relevant barriers needed to create a working pump has not been presented. In addition, there are major problems in elucidating the origin of key mutational effects and in understanding the nature of the apparent pK(a) values associated with the pH dependencies of specific proton transfer (PT) reactions in CcO. This work takes a key step in resolving the above problems, by considering mutations, such as the Asn139Asp replacement, that blocks proton pumping without affecting PT to the catalytic site. We first introduce a formulation that makes it possible to relate the apparent pK(a) of Glu286 to different conformational states of this residue. We then use the new formulation along with the calculated pK(a) values of Glu286 at these different conformations to reproduce the experimentally observed apparent pK(a) of the residue. Next, we take the X-ray structures of the native and Asn139Asp mutant of the Paracoccus denitrificans CcO (N131D in this system) and reproduce for the first time the change in the primary PT pathways (and other key features) based on simulations that start with the observed structural changes. We also consider the competition between proton transport to the catalytic site and the pump site, as a function of the bulk pH, as well as the H/D isotope effect, and use this information to explore the relative height of the two barriers. The paper emphasizes the crucial role of energy-based considerations that include the PT process, and the delicate control of PT in CcO.
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Affiliation(s)
- Suman Chakrabarty
- Department of Chemistry, University of Southern California, 418 SGM Building, 3620 McClintock Avenue, Los Angeles, CA 90089-1062, USA
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28
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Lee HJ, Svahn E, Swanson JMJ, Lepp H, Voth GA, Brzezinski P, Gennis RB. Intricate role of water in proton transport through cytochrome c oxidase. J Am Chem Soc 2010; 132:16225-39. [PMID: 20964330 DOI: 10.1021/ja107244g] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytochrome c oxidase (CytcO), the final electron acceptor in the respiratory chain, catalyzes the reduction of O(2) to H(2)O while simultaneously pumping protons across the inner mitochondrial or bacterial membrane to maintain a transmembrane electrochemical gradient that drives, for example, ATP synthesis. In this work mutations that were predicted to alter proton translocation and enzyme activity in preliminary computational studies are characterized with extensive experimental and computational analysis. The mutations were introduced in the D pathway, one of two proton-uptake pathways, in CytcO from Rhodobacter sphaeroides . Serine residues 200 and 201, which are hydrogen-bonded to crystallographically resolved water molecules halfway up the D pathway, were replaced by more bulky hydrophobic residues (Ser200Ile, Ser200Val/Ser201Val, and Ser200Val/Ser201Tyr) to query the effects of changing the local structure on enzyme activity as well as proton uptake, release, and intermediate transitions. In addition, the effects of these mutations on internal proton transfer were investigated by blocking proton uptake at the pathway entrance (Asp132Asn replacement in addition to the above-mentioned mutations). Even though the overall activities of all mutant CytcO's were lowered, both the Ser200Ile and Ser200Val/Ser201Val variants maintained the ability to pump protons. The lowered activities were shown to be due to slowed oxidation kinetics during the P(R) → F and F → O transitions (P(R) is the "peroxy" intermediate formed at the catalytic site upon reaction of the four-electron-reduced CytcO with O(2), F is the oxoferryl intermediate, and O is the fully oxidized CytcO). Furthermore, the P(R) → F transition is shown to be essentially pH independent up to pH 12 (i.e., the apparent pK(a) of Glu286 is increased from 9.4 by at least 3 pK(a) units) in the Ser200Val/Ser201Val mutant. Explicit simulations of proton transport in the mutated enzymes revealed that the solvation dynamics can cause intriguing energetic consequences and hence provide mechanistic insights that would never be detected in static structures or simulations of the system with fixed protonation states (i.e., lacking explicit proton transport). The results are discussed in terms of the proton-pumping mechanism of CytcO.
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Affiliation(s)
- Hyun Ju Lee
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
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29
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Brzezinski P, Johansson AL. Variable proton-pumping stoichiometry in structural variants of cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:710-23. [DOI: 10.1016/j.bbabio.2010.02.020] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Revised: 02/15/2010] [Accepted: 02/17/2010] [Indexed: 10/19/2022]
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30
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Siletsky SA, Zhu J, Gennis RB, Konstantinov AA. Partial steps of charge translocation in the nonpumping N139L mutant of Rhodobacter sphaeroides cytochrome c oxidase with a blocked D-channel. Biochemistry 2010; 49:3060-73. [PMID: 20192226 DOI: 10.1021/bi901719e] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The N139L substitution in the D-channel of cytochrome oxidase from Rhodobacter sphaeroides results in an approximately 15-fold decrease in the turnover number and a loss of proton pumping. Time-resolved absorption and electrometric assays of the F --> O transition in the N139L mutant oxidase result in three major findings. (1) Oxidation of the reduced enzyme by O(2) shows approximately 200-fold inhibition of the F --> O step (k approximately 2 s(-1) at pH 8) which is not compatible with enzyme turnover ( approximately 30 s(-1)). Presumably, an abnormal intermediate F(deprotonated) is formed under these conditions, one proton-deficient relative to a normal F state. In contrast, the F --> O transition in N139L oxidase induced by single-electron photoreduction of intermediate F, generated by reaction of the oxidized enzyme with H(2)O(2), decelerates to an extent compatible with enzyme turnover. (2) In the N139L mutant, the protonic phase of Deltapsi generation coupled to the flash-induced F --> O transition greatly decreases in rate and magnitude and can be assigned to the movement of a proton from E286 to the binuclear site, required for reduction of heme a(3) from the Fe(4+) horizontal lineO(2-) state to the Fe(3+)-OH(-) state. Electrogenic reprotonation of E286 from the inner aqueous phase is missing from the F --> O step in the mutant. (3) In the N139L mutant, the KCN-insensitive rapid electrogenic phase may be composed of two components with lifetimes of approximately 10 and approximately 40 mus and a magnitude ratio of approximately 3:2. The 10 mus phase matches vectorial electron transfer from Cu(A) to heme a, whereas the 40 mus component is assigned to intraprotein proton displacement across approximately 20% of the membrane dielectric thickness. This proton displacement might be triggered by rotation of the charged K362 side chain coupled to heme a reduction. The two components of the rapid electrogenic phase have been resolved subsequently with other D-channel mutants as well as with cyanide-inhibited wild-type oxidase. The finding helps to reconcile the unusually high relative contribution of the microsecond electrogenic phase in the bacterial enzyme ( approximately 30%) with the net electrogenicity of the F --> O transition coupled to transmembrane transfer of two charges per electron.
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Affiliation(s)
- Sergey A Siletsky
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119991, Russia
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31
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Yoshioka Y, Mitani M. B3LYP study on reduction mechanisms from O2 to H2O at the catalytic sites of fully reduced and mixed-valence bovine cytochrome c oxidases. Bioinorg Chem Appl 2010; 2010:182804. [PMID: 20396396 PMCID: PMC2852611 DOI: 10.1155/2010/182804] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 11/27/2009] [Accepted: 01/05/2010] [Indexed: 11/26/2022] Open
Abstract
Reduction mechanisms of oxygen molecule to water molecules in the fully reduced (FR) and mixed-valence (MV) bovine cytochrome c oxidases (CcO) have been systematically examined based on the B3LYP calculations. The catalytic cycle using four electrons and four protons has been also shown consistently. The MV CcO catalyses reduction to produce one water molecule, while the FR CcO catalyses to produce two water molecules. One water molecule is added into vacant space between His240 and His290 in the catalytic site. This water molecule constructs the network of hydrogen bonds of Tyr244, farnesyl ethyl, and Thr316 that is a terminal residue of the K-pathway. It plays crucial roles for the proton transfer to the dioxygen to produce the water molecules in both MV and FR CcOs. Tyr244 functions as a relay of the proton transfer from the K-pathway to the added water molecule, not as donors of a proton and an electron to the dioxygen. The reduction mechanisms of MV and FR CcOs are strictly distinguished. In the FR CcO, the Cu atom at the Cu(B) site maintains the reduced state Cu(I) during the process of formation of first water molecule and plays an electron storage. At the final stage of formation of first water molecule, the Cu(I) atom releases an electron to Fe-O. During the process of formation of second water molecule, the Cu atom maintains the oxidized state Cu(II). In contrast with experimental proposals, the K-pathway functions for formation of first water molecule, while the D-pathway functions for second water molecule. The intermediates, P(M), P(R), F, and O, obtained in this work are compared with those proposed experimentally.
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Affiliation(s)
- Yasunori Yoshioka
- Chemistry Department for Materials, Graduate School of Engineering, Mie University, Kurima-machiya 1577, Tsu, Mie 514-8507, Japan.
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Egawa T, Lee HJ, Gennis RB, Yeh SR, Rousseau DL. Critical structural role of R481 in cytochrome c oxidase from Rhodobacter sphaeroides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1272-5. [PMID: 19463779 DOI: 10.1016/j.bbabio.2009.05.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Revised: 05/05/2009] [Accepted: 05/11/2009] [Indexed: 10/20/2022]
Abstract
The R481 residue in cytochrome c oxidase from Rhodobacter sphaeroides forms hydrogen bonds with the propionate groups of both heme a and heme a(3). It has been postulated that R481 is the proton loading site in the proton exit pathway essential for proton translocation. A recent functional study showed that the mutations of R481 to His, Leu and Gln cause the reduction of the activity to approximately 5-18% of the native level, and the absence of proton pumping in R481Q but retention of approximately 40% efficiency in R481H and R481L (H.J. Lee, L. Ojemyr, A. Vakkasoglu, P. Brzezinski and R. B. Gennis, manuscript submitted). To decipher the molecular mechanism underlying the perturbed functionalities, we have used resonance Raman spectroscopy to examine the structural properties of the three mutants. The data show that the frequencies of the formyl CO stretching modes of both the heme a and a(3) in the mutants are characteristic of formyl groups exposed to an aqueous environment, indicating that the mutations disrupt the native H-bonding interaction between the formyl group of heme a and R52, as well as the hydrophobic environment surrounding the formyl group of heme a(3). In addition to the change in the environments of heme a and a(3), the Raman data show that the mutations induce a partial conversion of the heme a(3) from a high-spin to a low-spin state, suggesting that the mutations are associated with the rearrangement of the Cu(B)-heme a(3) binuclear center. The Raman results reported here demonstrate that R481 plays a critical role in supporting efficient proton pumping, by holding the heme groups in a proper environment.
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Affiliation(s)
- Tsuyoshi Egawa
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York, USA
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Abstract
The history of research on voltage-gated proton channels is recounted, from their proposed existence in dinoflagellates by Hastings in 1972 and their demonstration in snail neurons by Thomas and Meech in 1982 to the discovery in 2006 (after a decade of controversy) of genes that unequivocally code for proton channels. Voltage-gated proton channels are perfectly selective for protons, conduct deuterons half as well, and the conductance is strongly temperature dependent. These properties are consistent with a conduction mechanism involving hydrogen-bonded-chain transfer, in which the selectivity filter is a titratable amino acid residue. Channel opening is regulated stringently by pH such that only outward current is normally activated. Main functions of proton channels include acid extrusion from cells and charge compensation for the electrogenic activity of the phagocyte NADPH oxidase. Genetic approaches hold the promise of rapid progress in the near future.
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Affiliation(s)
- T E DeCoursey
- Department of Molecular Biophysics and Physiology, Rush University Medical Center, 1750 W. Harrison, Chicago, Illinois 60612, USA.
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Electrostatic basis for the unidirectionality of the primary proton transfer in cytochrome c oxidase. Proc Natl Acad Sci U S A 2008; 105:7726-31. [PMID: 18509049 DOI: 10.1073/pnas.0800580105] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Gaining detailed understanding of the energetics of the proton-pumping process in cytochrome c oxidase (CcO) is one of the challenges of modern biophysics. Despite promising mechanistic proposals, most works have not related the activation barriers of the different assumed steps to the protein structure, and there has not been a physically consistent model that reproduced the barriers needed to create a working pump. This work reevaluates the activation barriers for the primary proton transfer (PT) steps by calculations that reflect all relevant free energy contributions, including the electrostatic energies of the generated charges, the energies of water insertion, and large structural rearrangements of the donor and acceptor. The calculations have reproduced barriers that account for the directionality and sequence of events in the primary PT in CcO. It has also been found that the PT from Glu-286 (E) to the propionate of heme a(3) (Prd) provides a gate for an initial back leakage from the high pH side of the membrane. Interestingly, the rotation of E that brings it closer to Prd appears to provide a way for blocking competing pathways in the primary PT. Our study elucidates and quantifies the nature of the control of the directionality in the primary PT in CcO and provides instructive insight into the role of the water molecules in biological PT, showing that "bridges" of several water molecules in hydrophobic regions present a problem (rather than a solution) that is minimized in the primary PT.
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