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Cryo-EM structures of engineered active bc 1-cbb 3 type CIII 2CIV super-complexes and electronic communication between the complexes. Nat Commun 2021; 12:929. [PMID: 33568648 PMCID: PMC7876108 DOI: 10.1038/s41467-021-21051-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 01/06/2021] [Indexed: 01/30/2023] Open
Abstract
Respiratory electron transport complexes are organized as individual entities or combined as large supercomplexes (SC). Gram-negative bacteria deploy a mitochondrial-like cytochrome (cyt) bc1 (Complex III, CIII2), and may have specific cbb3-type cyt c oxidases (Complex IV, CIV) instead of the canonical aa3-type CIV. Electron transfer between these complexes is mediated by soluble (c2) and membrane-anchored (cy) cyts. Here, we report the structure of an engineered bc1-cbb3 type SC (CIII2CIV, 5.2 Å resolution) and three conformers of native CIII2 (3.3 Å resolution). The SC is active in vivo and in vitro, contains all catalytic subunits and cofactors, and two extra transmembrane helices attributed to cyt cy and the assembly factor CcoH. The cyt cy is integral to SC, its cyt domain is mobile and it conveys electrons to CIV differently than cyt c2. The successful production of a native-like functional SC and determination of its structure illustrate the characteristics of membrane-confined and membrane-external respiratory electron transport pathways in Gram-negative bacteria.
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Agarwal R, Chauvet AAP. Ultrafast dynamics of the photo-excited hemes b and c n in the cytochrome b 6f complex. Phys Chem Chem Phys 2017; 19:3287-3296. [PMID: 28085168 DOI: 10.1039/c6cp08077d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dynamics of hemes b and cn within the cytochrome b6f complex are investigated by means of ultrafast broad-band transient absorption spectroscopy. On the one hand, the data reveal that, subsequent to visible light excitation, part of the b hemes undergoes pulse-limited photo-oxidation, with the liberated electron supposedly being transferred to one of the adjacent aromatic amino acids. Photo-oxidation is followed by charge recombination in about 8.2 ps. Subsequent to charge recombination, heme b is promoted to a vibrationally excited ground state that relaxes in about 4.6 ps. On the other hand, heme cn undergoes ultrafast ground state recovery in about 140 fs. Interestingly, the data also show that, in contrast to previous beliefs, Chl a is involved in the photochemistry of hemes. Indeed, subsequent to heme excitation, Chl a bleaches and recovers to its ground state in 90 fs and 650 fs, respectively. Chl a bleaching allegedly corresponds to the formation of a short lived Chl a anion. Beyond the previously suggested structural role, this study provides unique evidence that Chl a is directly involved in the photochemistry of the hemes.
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Affiliation(s)
- Rachna Agarwal
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA and Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - Adrien A P Chauvet
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire de Spectroscopie Ultrarapide (LSU), ISIC, Faculté des Sciences de Base and Lausanne Centre for Ultrafast Science (LACUS), Station 6, 1015 Lausanne, Switzerland. and The University of Sheffield, Department of Chemistry, Dainton Building, Brook Hill, Sheffield S3 7HF, UK
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Chauvet AAP, Agarwal R, Haddad AA, van Mourik F, Cramer WA. Photo-induced oxidation of the uniquely liganded heme f in the cytochrome b6f complex of oxygenic photosynthesis. Phys Chem Chem Phys 2016; 18:12983-91. [PMID: 27108913 PMCID: PMC4990003 DOI: 10.1039/c6cp01592a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The ultrafast behavior of the ferrous heme f from the cytochrome b6f complex of oxygenic photosynthesis is revealed by means of transient absorption spectroscopy. Benefiting from the use of microfluidic technologies for handling the sample as well as from a complementary frame-by-frame analysis of the heme dynamics, the different relaxation mechanisms from vibrationally excited states are disentangled and monitored via the shifts of the heme α-absorption band. Under 520 nm laser excitation, about 85% of the heme f undergoes pulse-limited photo-oxidation (<100 fs), with the electron acceptor being most probably one of the adjacent aromatic amino acid residues. After charge recombination in 5.3 ps, the residual excess energy is dissipated in 3.6 ps. In a parallel pathway, the remaining 15% of the hemes directly relax from their excited state in 2.5 ps. In contrast to a vast variety of heme-proteins, including the homologous heme c1 from the cytochrome bc1 complex, there is no evidence that heme f photo-dissociates from its axial ligands. Due to its unique binding, with histidine and an unusual tyrosine as axial ligands, the heme f exemplifies a dependence of ultrafast dynamics on the structural environment.
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Affiliation(s)
- Adrien A P Chauvet
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire de Spectroscopie Ultrarapide (LSU), ISIC, Faculté des Sciences de Base and Lausanne Centre for Ultrafast Science (LACUS), Station 6, 1015 Lausanne, Switzerland.
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Infante-Rodriguez C, Domon L, Breuilles P, Uguen D. Asymmetric Synthesis of Stigmatellin and Crocacin C. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2015. [DOI: 10.1246/bcsj.20140271] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Carolina Infante-Rodriguez
- Laboratoire de Synthèse Organique (associé au CNRS; UMR 7509), Ecole Européenne de Chimie, Polymères et Matériaux, Université de Strasbourg
| | - Lisianne Domon
- Laboratoire de Synthèse Organique (associé au CNRS; UMR 7509), Ecole Européenne de Chimie, Polymères et Matériaux, Université de Strasbourg
| | - Pascal Breuilles
- Laboratoire de Synthèse Organique (associé au CNRS; UMR 7509), Ecole Européenne de Chimie, Polymères et Matériaux, Université de Strasbourg
| | - Daniel Uguen
- Laboratoire de Synthèse Organique (associé au CNRS; UMR 7509), Ecole Européenne de Chimie, Polymères et Matériaux, Université de Strasbourg
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5
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Qu Y, Dong F. New methods for determining proton pumping ability and electron transfer activity of the cytochrome bc1 complex. Acta Biochim Biophys Sin (Shanghai) 2015; 47:114-20. [PMID: 25543120 DOI: 10.1093/abbs/gmu126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
It is important to determine the electron transfer activity and proton pumping ability of the cytochrome bc1 complex for better understanding its structure and function. In this study, several methods for determining the electron transfer and proton pumping of the bc1 complex, including the traditional and the new methods, are presented and evaluated. For determining the proton pumping ability of the bc1 complex, the new stopped-flow method has a higher accuracy than the traditional pH meter method, and the new spectrophotometer method is more convenient than the traditional pH meter method. In measuring the electron transfer activity of the bc1 complex, the new stopped-flow method is more accurate and has a higher separating capacity than the traditional spectrophotometer method.
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Affiliation(s)
- Yuangang Qu
- College of Life Sciences, Linyi University, Linyi 276000, China Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater 74078, USA
| | - Fang Dong
- College of Life Sciences, Linyi University, Linyi 276000, China
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Hasan SS, Zakharov SD, Chauvet A, Stadnytskyi V, Savikhin S, Cramer WA. A map of dielectric heterogeneity in a membrane protein: the hetero-oligomeric cytochrome b6f complex. J Phys Chem B 2014; 118:6614-25. [PMID: 24867491 PMCID: PMC4067154 DOI: 10.1021/jp501165k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
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The
cytochrome b6f complex,
a member of the cytochrome bc family that
mediates energy transduction in photosynthetic and respiratory membranes,
is a hetero-oligomeric complex that utilizes two pairs of b-hemes in a symmetric dimer to accomplish trans-membrane
electron transfer, quinone oxidation–reduction, and generation
of a proton electrochemical potential. Analysis of electron storage
in this pathway, utilizing simultaneous measurement of heme reduction,
and of circular dichroism (CD) spectra, to assay heme–heme
interactions, implies a heterogeneous distribution of the dielectric
constants that mediate electrostatic interactions between the four
hemes in the complex. Crystallographic information was used to determine
the identity of the interacting hemes. The Soret band CD signal is
dominated by excitonic interaction between the intramonomer b-hemes, bn and bp, on the electrochemically negative and positive sides
of the complex. Kinetic data imply that the most probable pathway
for transfer of the two electrons needed for quinone oxidation–reduction
utilizes this intramonomer heme pair, contradicting the expectation
based on heme redox potentials and thermodynamics, that the two higher
potential hemes bn on different monomers
would be preferentially reduced. Energetically preferred intramonomer
electron storage of electrons on the intramonomer b-hemes is found to require heterogeneity of interheme dielectric
constants. Relative to the medium separating the two higher potential
hemes bn, a relatively large dielectric
constant must exist between the intramonomer b-hemes,
allowing a smaller electrostatic repulsion between the reduced hemes.
Heterogeneity of dielectric constants is an additional structure–function
parameter of membrane protein complexes.
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Affiliation(s)
- S Saif Hasan
- Department of Biological Sciences and ‡Department of Physics, Purdue University , West Lafayette, Indiana 47907, United States
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Xia D, Esser L, Tang WK, Zhou F, Zhou Y, Yu L, Yu CA. Structural analysis of cytochrome bc1 complexes: implications to the mechanism of function. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1827:1278-94. [PMID: 23201476 PMCID: PMC3593749 DOI: 10.1016/j.bbabio.2012.11.008] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 11/13/2012] [Accepted: 11/19/2012] [Indexed: 01/18/2023]
Abstract
The cytochrome bc1 complex (bc1) is the mid-segment of the cellular respiratory chain of mitochondria and many aerobic prokaryotic organisms; it is also part of the photosynthetic apparatus of non-oxygenic purple bacteria. The bc1 complex catalyzes the reaction of transferring electrons from the low potential substrate ubiquinol to high potential cytochrome c. Concomitantly, bc1 translocates protons across the membrane, contributing to the proton-motive force essential for a variety of cellular activities such as ATP synthesis. Structural investigations of bc1 have been exceedingly successful, yielding atomic resolution structures of bc1 from various organisms and trapped in different reaction intermediates. These structures have confirmed and unified results of decades of experiments and have contributed to our understanding of the mechanism of bc1 functions as well as its inactivation by respiratory inhibitors. This article is part of a Special Issue entitled: Respiratory complex III and related bc complexes.
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Affiliation(s)
- Di Xia
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Al-Attar S, de Vries S. Energy transduction by respiratory metallo-enzymes: From molecular mechanism to cell physiology. Coord Chem Rev 2013. [DOI: 10.1016/j.ccr.2012.05.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Kurosu M, Begari E. Vitamin K2 in electron transport system: are enzymes involved in vitamin K2 biosynthesis promising drug targets? Molecules 2010; 15:1531-53. [PMID: 20335999 PMCID: PMC6257245 DOI: 10.3390/molecules15031531] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Revised: 02/11/2010] [Accepted: 03/03/2010] [Indexed: 01/01/2023] Open
Abstract
Aerobic and anaerobic respiratory systems allow cells to transport the electrons to terminal electron acceptors. The quinone (ubiquinone or menaquinone) pool is central to the electron transport chain. In the majority of gram-positive bacteria, vitamin K2 (menaquinone) is the sole quinone in the electron transport chain, and thus, the bacterial enzymes catalyzing the synthesis of menaquinone are potential targets for the development of novel antibacterial drugs. This manuscript reviews the role of vitamin K in bacteria and humans, and especially emphasizes on recent aspects of menaquinones in bacterial electron transport chain and on discoveries of inhibitor molecules targeting bacterial electron transport systems for new antibacterial agents.
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Affiliation(s)
- Michio Kurosu
- Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 1682 Campus Delivery, Fort Collins, CO 80523-1682, USA.
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Scheuring S, Sturgis JN. Atomic force microscopy of the bacterial photosynthetic apparatus: plain pictures of an elaborate machinery. PHOTOSYNTHESIS RESEARCH 2009; 102:197-211. [PMID: 19266309 DOI: 10.1007/s11120-009-9413-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Accepted: 02/10/2009] [Indexed: 05/27/2023]
Abstract
Photosynthesis both in the past and present provides the vast majority of the energy used on the planet. The purple photosynthetic bacteria are a group of organisms that are able to perform photosynthesis using a particularly simple system that has been much studied. The main molecular constituents required for photosynthesis in these organisms are a small number of transmembrane pigment-protein complexes. These are able to function together with a high quantum efficiency (about 95%) to convert light energy into chemical potential energy. While the structure of the various proteins have been solved for several years, direct studies of the supramolecular assembly of these complexes in native membranes needed maturity of the atomic force microscope (AFM). Here, we review the novel findings and the direct conclusions that could be drawn from high-resolution AFM analysis of photosynthetic membranes. These conclusions rely on the possibility that the AFM brings of obtaining molecular resolution images of large membrane areas and thereby bridging the resolution gap between atomic structures and cellular ultrastructure.
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Affiliation(s)
- Simon Scheuring
- Institut Curie, UMR168-CNRS, 26 Rue d’Ulm, 75248 Paris, France.
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