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Yu L, Min Z, Liu M, Xin Y, Liu A, Kuang J, Wu W, Wu J, He H, Xin J, Blankenship RE, Tian C, Xu X. A cytochrome c 551 mediates the cyclic electron transport chain of the anoxygenic phototrophic bacterium Roseiflexus castenholzii. PLANT COMMUNICATIONS 2024; 5:100715. [PMID: 37710959 PMCID: PMC10873879 DOI: 10.1016/j.xplc.2023.100715] [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: 02/14/2023] [Revised: 06/27/2023] [Accepted: 09/08/2023] [Indexed: 09/16/2023]
Abstract
Roseiflexus castenholzii is a gram-negative filamentous phototrophic bacterium that carries out anoxygenic photosynthesis through a cyclic electron transport chain (ETC). The ETC is composed of a reaction center (RC)-light-harvesting (LH) complex (rcRC-LH); an alternative complex III (rcACIII), which functionally replaces the cytochrome bc1/b6f complex; and the periplasmic electron acceptor auracyanin (rcAc). Although compositionally and structurally different from the bc1/b6f complex, rcACIII plays similar essential roles in oxidizing menaquinol and transferring electrons to the rcAc. However, rcACIII-mediated electron transfer (which includes both an intraprotein route and a downstream route) has not been clearly elucidated, nor have the details of cyclic ETC. Here, we identify a previously unknown monoheme cytochrome c (cyt c551) as a novel periplasmic electron acceptor of rcACIII. It reduces the light-excited rcRC-LH to complete a cyclic ETC. We also reveal the molecular mechanisms involved in the ETC using electron paramagnetic resonance (EPR), spectroelectrochemistry, and enzymatic and structural analyses. We find that electrons released from rcACIII-oxidized menaquinol are transferred to two alternative periplasmic electron acceptors (rcAc and cyt c551), which eventually reduce the rcRC to form the complete cyclic ETC. This work serves as a foundation for further studies of ACIII-mediated electron transfer in anoxygenic photosynthesis and broadens our understanding of the diversity and molecular evolution of prokaryotic ETCs.
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Affiliation(s)
- Lu Yu
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
| | - Zhenzhen Min
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Affiliated Hospital, Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University, Hangzhou 311121, China
| | - Menghua Liu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Affiliated Hospital, Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University, Hangzhou 311121, China
| | - Yueyong Xin
- Photosynthesis Research Center, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China
| | - Aokun Liu
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
| | - Jian Kuang
- The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Center for Bioanalytical Chemistry, Hefei National Laboratory of Physical Science at Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Wenping Wu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Affiliated Hospital, Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University, Hangzhou 311121, China
| | - Jingyi Wu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Affiliated Hospital, Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University, Hangzhou 311121, China
| | - Huimin He
- Photosynthesis Research Center, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China
| | - Jiyu Xin
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Affiliated Hospital, Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University, Hangzhou 311121, China
| | - Robert E Blankenship
- Departments of Biology and Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Changlin Tian
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China; The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Center for Bioanalytical Chemistry, Hefei National Laboratory of Physical Science at Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Xiaoling Xu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences and Affiliated Hospital, Key Laboratory of Aging and Cancer Biology of Zhejiang Province, Hangzhou Normal University, Hangzhou 311121, China; Photosynthesis Research Center, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China.
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Malkin R. Remembering David B. Knaff (1941-2016). PHOTOSYNTHESIS RESEARCH 2016; 129:1-12. [PMID: 27130553 DOI: 10.1007/s11120-016-0265-7] [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: 03/18/2016] [Accepted: 04/15/2016] [Indexed: 06/05/2023]
Abstract
David Knaff began his scientific career in the Department of Cell Physiology at the University of California, Berkeley. At Berkeley, he worked on chloroplast electron carriers such as the cytochromes and plastocyanin and applied redox potentiometry to characterize these carriers in situ. He moved to Texas Tech University where he made major contributions in the study of ferredoxin-mediated reactions with chloroplast enzymes, most notably nitrite reductase.
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Affiliation(s)
- Richard Malkin
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA.
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3
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Majumder ELW, King JD, Blankenship RE. Alternative Complex III from phototrophic bacteria and its electron acceptor auracyanin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1827:1383-91. [PMID: 23357331 DOI: 10.1016/j.bbabio.2013.01.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 01/12/2013] [Accepted: 01/15/2013] [Indexed: 12/30/2022]
Abstract
Alternative Complex III (ACIII) is a multisubunit integral membrane protein electron transfer complex that is proposed to be an energy-conserving functional replacement for the bacterial cytochrome bc1 or b6f complexes. Clues to the structure and function of this novel complex come from its relation to other bacterial enzyme families. The ACIII complex has menaquinone: electron acceptor oxidoreductase activity and contains protein subunits with multiple Fe-S centers and c-type hemes. ACIII is found in a diverse group of bacteria, including both phototrophic and nonphototrophic taxa. In the phototrophic filamentous anoxygenic phototrophs, the electron acceptor is the small blue copper protein auracyanin instead of a soluble cytochrome. Recent work on ACIII and the copper protein auracyanin is reviewed with focus on the photosynthetic systems and potential electron transfer pathways and mechanisms. Taken together, the ACIII complexes constitute a unique system for photosynthetic electron transfer and energy conservation. This article is part of a Special Issue entitled: Respiratory Complex III and related bc complexes.
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Affiliation(s)
- Erica L W Majumder
- Washington University in St. Louis, Departments of Biology and Chemistry, Campus Box 1137, One Brookings Dr, St. Louis, MO 63130, USA
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Xin Y, Lu YK, Fromme R, Fromme P, Blankenship RE. Purification, characterization and crystallization of menaquinol:fumarate oxidoreductase from the green filamentous photosynthetic bacterium Chloroflexus aurantiacus. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1787:86-96. [PMID: 19103151 DOI: 10.1016/j.bbabio.2008.11.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 11/20/2008] [Accepted: 11/21/2008] [Indexed: 11/17/2022]
Abstract
The integral membrane protein complex, menaquinol:fumarate oxidoreductase (mQFR) has been purified, identified and characterized from the thermophilic green filamentous anoxygenic photosynthetic bacterium Chloroflexus aurantiacus. The complex is composed of three subunits: a 74 kDa flavoprotein that contains a covalently bound flavin adenine dinucleotide, a 28 kDa iron-sulfur cluster-containing polypeptide, and a 27 kDa transmembrane polypeptide, which is also the binding site of two b-type hemes and two menaquinones. The purified complex has an apparent molecular mass of 260 kDa by blue-native PAGE, which is indicative of a native homodimeric form. The isolated complex is active in vitro in both fumarate reduction and succinate oxidation. It has been analyzed by visible absorption, redox titration, chemical analysis and EPR spectroscopy. In addition, phylogenetic analysis shows that the QFR of both C. aurantiacus and Chlorobium tepidum are most closely related to those found in the delta-proteobacteria. The purified enzyme was crystallized and X-ray diffraction data obtained up to 3.2 A resolution.
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Affiliation(s)
- Yueyong Xin
- Departments of Biology and Chemistry, Washington University, Campus Box 1137, One Brooking Drive, St. Louis, MO 63130, USA
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5
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Yanyushin MF. Fractionation of cytochromes of phototrophically grown Chloroflexus aurantiacus. Is there a cytochrome bc complex among them? FEBS Lett 2002; 512:125-8. [PMID: 11852065 DOI: 10.1016/s0014-5793(02)02236-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The cytochrome-containing membrane complexes of the phototrophically grown green non-sulfur bacterium Chloroflexus aurantiacus were fractionated by anion exchange chromatography. Three cytochrome b and four cytochrome c peaks were observed. None of the separated complexes met the features of the cytochrome bc complex. Two main cytochrome b-containing complexes were further purified: a dimer of identical subunits with unknown function and a succinate:quinone oxidoreductase containing three subunit species. Two novel multisubunit complexes, similar to each other, with two heme c-bearing subunits were also purified.
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Affiliation(s)
- Mikhail F Yanyushin
- Institute of Basic Biological Problems, Pushchino, 142 290, Moscow region, Russia.
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Zannoni D, Daldal F. The role of c-type cytochromes in catalyzing oxidative and photosynthetic electron transport in the dual functional plasmamembrane of facultative phototrophs. Arch Microbiol 1993; 160:413-23. [PMID: 8297207 DOI: 10.1007/bf00245301] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- D Zannoni
- Department of Biology, University of Bologna, Italy
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Malkin R. Cytochrome bc 1 and b 6 f complexes of photosynthetic membranes. PHOTOSYNTHESIS RESEARCH 1992; 33:121-136. [PMID: 24408573 DOI: 10.1007/bf00039175] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/1991] [Accepted: 03/12/1992] [Indexed: 06/03/2023]
Abstract
All photosynthetic membranes contain a cytochrome bc 1 or b 6 f complex that catalyzes the oxidation of quinols and the reduction of a high-potential electron carrier, such as cytochrome c 2 or plastocyanin. The cytochrome complex also functions in the translocation of protons across the membrane and as a consequence, establishes the proton motive force that is used for the synthesis of ATP. The structure and function of the cytochrome complexes are first reviewed in this chapter. Amino acid sequence information for almost all of the protein subunits of these complexes is now available, and these allow for a detailed consideration of functional domains in the protein subunits and for a further discussion of the evolution of the cytochrome complex in photosynthetic organisms.
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Affiliation(s)
- R Malkin
- Department of Plant Biology, University of California, 94720, Berkeley, CA, USA
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Isolation, characterization, and amino acid sequences of auracyanins, blue copper proteins from the green photosynthetic bacterium Chloroflexus aurantiacus. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50460-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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9
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Heibel G, Griebenow K, Hildebrandt P. Structural studies of cytochrome c-554 from Chloroflexus aurantiacus by resonance Raman spectroscopic techniques. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1991. [DOI: 10.1016/s0005-2728(09)91007-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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van Vliet P, Zannoni D, Nitschke W, Rutherford AW. Membrane-bound cytochromes in Chloroflexus aurantiacus studied by EPR. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 199:317-23. [PMID: 1649048 DOI: 10.1111/j.1432-1033.1991.tb16127.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The heme components of chlorosome-depleted membranes of the green-gliding bacterium Chloroflexus aurantiacus were studied by EPR spectroscopy. The four major species, which are present in approximately equimolar quantities, are characterized by the following gz values, redox midpoint potentials and orientations of heme planes with respect to the plane of the membrane: gz = 3.40, Em = +280 mV, 30 degrees; gz = 3.33, Em = 0 mV, 45 degrees; gz = 3.03, Em = +95 mV, 40-50 degrees and gz = 2.95, Em = +150 mV, 90 degrees. These four hemes were attributed to cytochrome c554, the membrane-bound immediate electron donor to the photosynthetic reaction centre in Chloroflexus. All hemes except that with the highest potential were able to undergo photooxidation at 4 K. The photooxidation of the lowest potential heme was stable, whereas that of the +95 mV and the +150 mV hemes reversed on increasing the temperature to 100 K in darkness, due to charge recombination. The ability to photooxidize these hemes at 4 K was lost upon aging of samples. The results demonstrate that a reaction-centre-associated tetraheme cytochrome subunit, analogous to that of purple bacteria, is also present in C. aurantiacus.
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Affiliation(s)
- P van Vliet
- Départment de Biologie Cellulaire et Moléculaire, CE Saclay, Gif sur Yvette, France
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11
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Abstract
The cytochrome bc1 complex is the most widely occurring electron transfer complex capable of energy transduction. Cytochrome bc1 complexes are found in the plasma membranes of phylogenetically diverse photosynthetic and respiring bacteria, and in the inner mitochondrial membrane of all eucaryotic cells. In all of these species the bc1 complex transfers electrons from a low-potential quinol to a higher-potential c-type cytochrome and links this electron transfer to proton translocation. Most bacteria also possess alternative pathways of quinol oxidation capable of circumventing the bc1 complex, but these pathways generally lack the energy-transducing, protontranslocating activity of the bc1 complex. All cytochrome bc1 complexes contain three electron transfer proteins which contain four redox prosthetic groups. These are cytochrome b, which contains two b heme groups that differ in their optical and thermodynamic properties; cytochrome c1, which contains a covalently bound c-type heme; and a 2Fe-2S iron-sulfur protein. The mechanism which links proton translocation to electron transfer through these proteins is the proton motive Q cycle, and this mechanism appears to be universal to all bc1 complexes. Experimentation is currently focused on understanding selected structure-function relationships prerequisite for these redox proteins to participate in the Q-cycle mechanism. The cytochrome bc1 complexes of mitochondria differ from those of bacteria, in that the former contain six to eight supernumerary polypeptides, in addition to the three redox proteins common to bacteria and mitochondria. These extra polypeptides are encoded in the nucleus and do not contain redox prosthetic groups. The functions of the supernumerary polypeptides of the mitochondrial bc1 complexes are generally not known and are being actively explored by genetically manipulating these proteins in Saccharomyces cerevisiae.
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Affiliation(s)
- B L Trumpower
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03756
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12
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Freeman JC, Blankenship RE. Isolation and characterization of the membrane-bound cytochrome c-554 from the thermophilic green photosynthetic bacterium Chloroflexus aurantiacus. PHOTOSYNTHESIS RESEARCH 1990; 23:29-38. [PMID: 24420989 DOI: 10.1007/bf00030060] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/1988] [Accepted: 11/21/1988] [Indexed: 06/03/2023]
Abstract
The membrane-bound photooxidizable cytochrome c-554 from Chloroflexus aurantiacus has been purified. The purified protein runs as a single heme staining band on SDS-PAGE with an apparent molecular mass of 43 000 daltons. An extinction coefficient of 28 ± 1 mM(-1) cm(-1) per heme at 554 nm was found for the dithionite-reduced protein. The potentiometric titration of the hemes takes place over an extended range, showing clearly that the protein does not contain a single heme in a well-defined site. The titration can be fit to a Nernst curve with midpoint potentials at 0, +120, +220 and +300 mV vs the standard hydrogen electrode. Pyridine hemochrome analysis combined with a Lowry protein assay and the SDS-PAGE molecular weight indicates that there are a minimum of three, and probably four hemes per peptide. Amino acid analysis shows 5 histidine residues and 29% hydrophobic residues in the protein. This cytochrome appears to be functionally similar to the bound cytochrome from Rhodopseudomonas viridis. Both cytochrome c-554 from C. aurantiacus and the four-heme cytochrome c-558-553 from R. viridis appear to act as direct electron donors to the special bacteriochlorophyll pair of the photosynthetic reaction center. They have a similar content of hydrophobic amino acids, but differ in isoelectric point, thermodynamic characteristics, spectral properties, and in their ability to be photooxidized at low temperature.
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Affiliation(s)
- J C Freeman
- Department of Chemistry, Arizona State University, 85287-1604, Tempe, AZ, USA
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Meyer TE, Tollin G, Cusanovich MA, Freeman JC, Blankenship RE. In vitro kinetics of reduction of cytochrome c554 isolated from the reaction center of the green phototrophic bacterium, Chloroflexus aurantiacus. Arch Biochem Biophys 1989; 272:254-61. [PMID: 2544143 DOI: 10.1016/0003-9861(89)90217-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The photochemical reaction center in the green bacterium Chloroflexus aurantiacus is similar to that found in purple phototrophic bacteria and interacts with a multiheme membrane-bound cytochrome. We have examined the kinetics of reduction of the pure solubilized reaction center cytochrome by laser flash photolysis of solutions containing lumiflavin or FMN. Reduction by lumiflavin semiquinone followed single exponential kinetics and the observed rate constant (kobs) was linearly dependent on protein concentration (k = 1.8 X 10(7) M-1s-1 heme-1). This result suggests either that the four hemes have similar reduction rate constants which cannot be resolved or that there are large differences in rate constant and only the most reactive heme (or hemes) was observed under these conditions. To determine the relative reactivities of the four hemes, we varied the extent of heme reduction at a single total protein concentration. As the hemes were progressively reduced by steady-state illumination prior to laser flash photolysis, kobs for the reaction with fully reduced lumiflavin decreased nonlinearly. Second-order rate constants for the four hemes were assigned by nonlinear least-squares analysis of kobs vs oxidized heme concentration data. The second-order rate constants obtained in this way for the highest and lowest potential hemes differed by a factor of about 20, which is larger than expected for c-type cytochromes based on redox potential alone (a factor of about 3 would be expected). This is interpreted as being due to differences in steric accessibility. Relative to the highest potential heme, which is as reactive as a typical c-type cytochrome, we estimated a steric effect of approximately twofold for heme 2, and steric effects of approximately fivefold for hemes 3 and 4. Using fully reduced FMN as reductant of oxidized cytochrome, ionic strength effects indicate a minus-minus interaction, with approximately a -2 charge near the site of reduction of the highest potential heme.
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Affiliation(s)
- T E Meyer
- Department of Biochemistry, University of Arizona, Tucson 85721
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14
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Functional and spectral characterization of the respiratory chain of Chloroflexus aurantiacus grown in the dark under oxygen-saturated conditions. Arch Microbiol 1988. [DOI: 10.1007/bf00408309] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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