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Lyratzakis A, Daskalakis V, Xie H, Tsiotis G. The synergy between the PscC subunits for electron transfer to the P 840 special pair in Chlorobaculum tepidum. PHOTOSYNTHESIS RESEARCH 2024; 160:87-96. [PMID: 38625595 PMCID: PMC11108878 DOI: 10.1007/s11120-024-01093-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 03/08/2024] [Indexed: 04/17/2024]
Abstract
The primary photochemical reaction of photosynthesis in green sulfur bacteria occurs in the homodimer PscA core proteins by a special chlorophyll pair. The light induced excited state of the special pair producing P840+ is rapidly reduced by electron transfer from one of the two PscC subunits. Molecular dynamics (MD) simulations are combined with bioinformatic tools herein to provide structural and dynamic insight into the complex between the two PscA core proteins and the two PscC subunits. The microscopic dynamic model involves extensive sampling at atomic resolution and at a cumulative time-scale of 22µs and reveals well defined protein-protein interactions. The membrane complex is composed of the two PscA and the two PscC subunits and macroscopic connections are revealed within a putative electron transfer pathway from the PscC subunit to the special pair P840 located within the PscA subunits. Our results provide a structural basis for understanding the electron transport to the homodimer RC of the green sulfur bacteria. The MD based approach can provide the basis to further probe the PscA-PscC complex dynamics and observe electron transfer therein at the quantum level. Furthermore, the transmembrane helices of the different PscC subunits exert distinct dynamics in the complex.
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Affiliation(s)
- Alexandros Lyratzakis
- Department of Chemistry, School of Science and Engineering, University of Crete, Heraklion, 70013, Greece
| | - Vangelis Daskalakis
- Department of Chemical Engineering, School of Engineering, University of Patras, Rion, Patras, 26504, Greece
| | - Hao Xie
- Max Planck Institute of Biophysics, 60438, Frankfurt am Main, Germany
| | - Georgios Tsiotis
- Department of Chemistry, School of Science and Engineering, University of Crete, Heraklion, 70013, Greece.
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2
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Kishimoto H, Azai C, Yamamoto T, Mutoh R, Nakaniwa T, Tanaka H, Miyanoiri Y, Kurisu G, Oh-oka H. Soluble domains of cytochrome c-556 and Rieske iron-sulfur protein from Chlorobaculum tepidum: Crystal structures and interaction analysis. Curr Res Struct Biol 2023; 5:100101. [PMID: 37180033 PMCID: PMC10172866 DOI: 10.1016/j.crstbi.2023.100101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 04/04/2023] [Accepted: 04/11/2023] [Indexed: 05/15/2023] Open
Abstract
In photosynthetic green sulfur bacteria, the electron transfer reaction from menaquinol:cytochrome c oxidoreductase to the P840 reaction center (RC) complex occurs directly without any involvement of soluble electron carrier protein(s). X-ray crystallography has determined the three-dimensional structures of the soluble domains of the CT0073 gene product and Rieske iron-sulfur protein (ISP). The former is a mono-heme cytochrome c with an α-absorption peak at 556 nm. The overall fold of the soluble domain of cytochrome c-556 (designated as cyt c-556sol) consists of four α-helices and is very similar to that of water-soluble cyt c-554 that independently functions as an electron donor to the P840 RC complex. However, the latter's remarkably long and flexible loop between the α3 and α4 helices seems to make it impossible to be a substitute for the former. The structure of the soluble domain of the Rieske ISP (Rieskesol protein) shows a typical β-sheets-dominated fold with a small cluster-binding and a large subdomain. The architecture of the Rieskesol protein is bilobal and belongs to those of b6f-type Rieske ISPs. Nuclear magnetic resonance (NMR) measurements revealed weak non-polar but specific interaction sites on Rieskesol protein when mixed with cyt c-556sol. Therefore, menaquinol:cytochrome c oxidoreductase in green sulfur bacteria features a Rieske/cytb complex tightly associated with membrane-anchored cyt c-556.
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Affiliation(s)
- Hiraku Kishimoto
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Chihiro Azai
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Tomoya Yamamoto
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Risa Mutoh
- Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Tetsuko Nakaniwa
- Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Hideaki Tanaka
- Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Yohei Miyanoiri
- Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan
- Corresponding author.
| | - Genji Kurisu
- Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan
- Corresponding author.
| | - Hirozo Oh-oka
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
- Center for Education in Liberal Arts and Sciences, Osaka University, Toyonaka, Osaka, 560-0043, Japan
- Corresponding author. Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan.
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3
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Chen JH, Wang W, Wang C, Kuang T, Shen JR, Zhang X. Cryo-electron microscopy structure of the intact photosynthetic light-harvesting antenna-reaction center complex from a green sulfur bacterium. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2023; 65:223-234. [PMID: 36125941 DOI: 10.1111/jipb.13367] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Accepted: 09/19/2022] [Indexed: 06/15/2023]
Abstract
The photosynthetic reaction center complex (RCC) of green sulfur bacteria (GSB) consists of the membrane-imbedded RC core and the peripheric energy transmitting proteins called Fenna-Matthews-Olson (FMO). Functionally, FMO transfers the absorbed energy from a huge peripheral light-harvesting antenna named chlorosome to the RC core where charge separation occurs. In vivo, one RC was found to bind two FMOs, however, the intact structure of RCC as well as the energy transfer mechanism within RCC remain to be clarified. Here we report a structure of intact RCC which contains a RC core and two FMO trimers from a thermophilic green sulfur bacterium Chlorobaculum tepidum at 2.9 Å resolution by cryo-electron microscopy. The second FMO trimer is attached at the cytoplasmic side asymmetrically relative to the first FMO trimer reported previously. We also observed two new subunits (PscE and PscF) and the N-terminal transmembrane domain of a cytochrome-containing subunit (PscC) in the structure. These two novel subunits possibly function to facilitate the binding of FMOs to RC core and to stabilize the whole complex. A new bacteriochlorophyll (numbered as 816) was identified at the interspace between PscF and PscA-1, causing an asymmetrical energy transfer from the two FMO trimers to RC core. Based on the structure, we propose an energy transfer network within this photosynthetic apparatus.
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Affiliation(s)
- Jing-Hua Chen
- College of Life Science, Zhejiang University, Hangzhou, 310058, China
- Department of Pathology of Sir Run Run Shaw Hospital, and Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Weiwei Wang
- College of Life Science, Zhejiang University, Hangzhou, 310058, China
| | - Chen Wang
- Department of Pathology of Sir Run Run Shaw Hospital, and Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Tingyun Kuang
- Key Laboratory of Photobiology, Institute of Botany, Photosynthesis Research Center, the Chinese Academy of Sciences, Beijing, 100093, China
| | - Jian-Ren Shen
- Key Laboratory of Photobiology, Institute of Botany, Photosynthesis Research Center, the Chinese Academy of Sciences, Beijing, 100093, China
- Research Institute for Interdisciplinary Science, and Graduate School of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan
| | - Xing Zhang
- Department of Pathology of Sir Run Run Shaw Hospital, and Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, 310058, China
- Center of Cryo Electron Microscopy, Zhejiang University School of Medicine, Hangzhou, 310058, China
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4
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Tani K, Kanno R, Kurosawa K, Takaichi S, Nagashima KVP, Hall M, Yu LJ, Kimura Y, Madigan MT, Mizoguchi A, Humbel BM, Wang-Otomo ZY. An LH1–RC photocomplex from an extremophilic phototroph provides insight into origins of two photosynthesis proteins. Commun Biol 2022; 5:1197. [DOI: 10.1038/s42003-022-04174-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 10/26/2022] [Indexed: 11/09/2022] Open
Abstract
AbstractRhodopila globiformis is the most acidophilic of anaerobic purple phototrophs, growing optimally in culture at pH 5. Here we present a cryo-EM structure of the light-harvesting 1–reaction center (LH1–RC) complex from Rhodopila globiformis at 2.24 Å resolution. All purple bacterial cytochrome (Cyt, encoded by the gene pufC) subunit-associated RCs with known structures have their N-termini truncated. By contrast, the Rhodopila globiformis RC contains a full-length tetra-heme Cyt with its N-terminus embedded in the membrane forming an α-helix as the membrane anchor. Comparison of the N-terminal regions of the Cyt with PufX polypeptides widely distributed in Rhodobacter species reveals significant structural similarities, supporting a longstanding hypothesis that PufX is phylogenetically related to the N-terminus of the RC-bound Cyt subunit and that a common ancestor of phototrophic Proteobacteria contained a full-length tetra-heme Cyt subunit that evolved independently through partial deletions of its pufC gene. Eleven copies of a novel γ-like polypeptide were also identified in the bacteriochlorophyll a-containing Rhodopila globiformis LH1 complex; γ-polypeptides have previously been found only in the LH1 of bacteriochlorophyll b-containing species. These features are discussed in relation to their predicted functions of stabilizing the LH1 structure and regulating quinone transport under the warm acidic conditions.
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Puskar R, Du Truong C, Swain K, Chowdhury S, Chan KY, Li S, Cheng KW, Wang TY, Poh YP, Mazor Y, Liu H, Chou TF, Nannenga BL, Chiu PL. Molecular asymmetry of a photosynthetic supercomplex from green sulfur bacteria. Nat Commun 2022; 13:5824. [PMID: 36192412 PMCID: PMC9529944 DOI: 10.1038/s41467-022-33505-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 09/20/2022] [Indexed: 11/21/2022] Open
Abstract
The photochemical reaction center (RC) features a dimeric architecture for charge separation across the membrane. In green sulfur bacteria (GSB), the trimeric Fenna-Matthews-Olson (FMO) complex mediates the transfer of light energy from the chlorosome antenna complex to the RC. Here we determine the structure of the photosynthetic supercomplex from the GSB Chlorobaculum tepidum using single-particle cryogenic electron microscopy (cryo-EM) and identify the cytochrome c subunit (PscC), two accessory protein subunits (PscE and PscF), a second FMO trimeric complex, and a linker pigment between FMO and the RC core. The protein subunits that are assembled with the symmetric RC core generate an asymmetric photosynthetic supercomplex. One linker bacteriochlorophyll (BChl) is located in one of the two FMO-PscA interfaces, leading to differential efficiencies of the two energy transfer branches. The two FMO trimeric complexes establish two different binding interfaces with the RC cytoplasmic surface, driven by the associated accessory subunits. This structure of the GSB photosynthetic supercomplex provides mechanistic insight into the light excitation energy transfer routes and a possible evolutionary transition intermediate of the bacterial photosynthetic supercomplex from the primitive homodimeric RC.
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Affiliation(s)
- Ryan Puskar
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
- Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA
| | - Chloe Du Truong
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
- Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA
- Rampart Bioscience, Monrovia, CA, 91016, USA
| | - Kyle Swain
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, 85287, USA
| | - Saborni Chowdhury
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
- Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA
| | - Ka-Yi Chan
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
- Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA
| | - Shan Li
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Kai-Wen Cheng
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Ting Yu Wang
- Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Yu-Ping Poh
- Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA
- Center for Mechanisms of Evolution, Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA
| | - Yuval Mazor
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
- Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA
| | - Haijun Liu
- Department of Biology, Washington University, St. Louis, MO, 63130, USA
| | - Tsui-Fen Chou
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
- Proteome Exploration Laboratory, Beckman Institute, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Brent L Nannenga
- Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, 85287, USA
| | - Po-Lin Chiu
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA.
- Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ, 85287, USA.
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6
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Gisriel CJ, Azai C, Cardona T. Recent advances in the structural diversity of reaction centers. PHOTOSYNTHESIS RESEARCH 2021; 149:329-343. [PMID: 34173168 PMCID: PMC8452559 DOI: 10.1007/s11120-021-00857-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 06/10/2021] [Indexed: 06/13/2023]
Abstract
Photosynthetic reaction centers (RC) catalyze the conversion of light to chemical energy that supports life on Earth, but they exhibit substantial diversity among different phyla. This is exemplified in a recent structure of the RC from an anoxygenic green sulfur bacterium (GsbRC) which has characteristics that may challenge the canonical view of RC classification. The GsbRC structure is analyzed and compared with other RCs, and the observations reveal important but unstudied research directions that are vital for disentangling RC evolution and diversity. Namely, (1) common themes of electron donation implicate a Ca2+ site whose role is unknown; (2) a previously unidentified lipid molecule with unclear functional significance is involved in the axial ligation of a cofactor in the electron transfer chain; (3) the GsbRC features surprising structural similarities with the distantly-related photosystem II; and (4) a structural basis for energy quenching in the GsbRC can be gleaned that exemplifies the importance of how exposure to oxygen has shaped the evolution of RCs. The analysis highlights these novel avenues of research that are critical for revealing evolutionary relationships that underpin the great diversity observed in extant RCs.
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Affiliation(s)
| | - Chihiro Azai
- College of Life Sciences, Ritsumeikan University, Kusatsu, 525-8577, Japan
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, 525-8577, Japan
| | - Tanai Cardona
- Department of Life Sciences, Imperial College London, London, UK
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7
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Chen JH, Wu H, Xu C, Liu XC, Huang Z, Chang S, Wang W, Han G, Kuang T, Shen JR, Zhang X. Architecture of the photosynthetic complex from a green sulfur bacterium. Science 2021; 370:370/6519/eabb6350. [PMID: 33214250 DOI: 10.1126/science.abb6350] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 09/09/2020] [Indexed: 01/09/2023]
Abstract
The photosynthetic apparatus of green sulfur bacteria (GSB) contains a peripheral antenna chlorosome, light-harvesting Fenna-Matthews-Olson proteins (FMO), and a reaction center (GsbRC). We used cryo-electron microscopy to determine a 2.7-angstrom structure of the FMO-GsbRC supercomplex from Chlorobaculum tepidum The GsbRC binds considerably fewer (bacterio)chlorophylls [(B)Chls] than other known type I RCs do, and the organization of (B)Chls is similar to that in photosystem II. Two BChl layers in GsbRC are not connected by Chls, as seen in other RCs, but associate with two carotenoid derivatives. Relatively long distances of 22 to 33 angstroms were observed between BChls of FMO and GsbRC, consistent with the inefficient energy transfer between these entities. The structure contains common features of both type I and type II RCs and provides insight into the evolution of photosynthetic RCs.
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Affiliation(s)
- Jing-Hua Chen
- Department of Pathology of Sir Run Run Shaw Hospital and Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China.,Center of Cryo-Electron Microscopy, Zhejiang University, Hangzhou, 310058 Zhejiang, China
| | - Hangjun Wu
- Department of Pathology of Sir Run Run Shaw Hospital and Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China.,Center of Cryo-Electron Microscopy, Zhejiang University, Hangzhou, 310058 Zhejiang, China
| | - Caihuang Xu
- Department of Pathology of Sir Run Run Shaw Hospital and Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China
| | - Xiao-Chi Liu
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, 100093 Beijing, China
| | - Zihui Huang
- Department of Pathology of Sir Run Run Shaw Hospital and Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China
| | - Shenghai Chang
- Department of Pathology of Sir Run Run Shaw Hospital and Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China.,Center of Cryo-Electron Microscopy, Zhejiang University, Hangzhou, 310058 Zhejiang, China
| | - Wenda Wang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, 100093 Beijing, China
| | - Guangye Han
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, 100093 Beijing, China
| | - Tingyun Kuang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, 100093 Beijing, China.
| | - Jian-Ren Shen
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, 100093 Beijing, China. .,Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University, 700-8530 Okayama, Japan
| | - Xing Zhang
- Department of Pathology of Sir Run Run Shaw Hospital and Department of Biophysics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China. .,Center of Cryo-Electron Microscopy, Zhejiang University, Hangzhou, 310058 Zhejiang, China.,Zhejiang Laboratory for System and Precision Medicine, Zhejiang University Medical Center, 1369 West Wenyi Road, Hangzhou, 311121 Zhejiang, China
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Nowicka B, Kruk J. Powered by light: Phototrophy and photosynthesis in prokaryotes and its evolution. Microbiol Res 2016; 186-187:99-118. [PMID: 27242148 DOI: 10.1016/j.micres.2016.04.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 02/12/2016] [Accepted: 04/01/2016] [Indexed: 11/29/2022]
Abstract
Photosynthesis is a complex metabolic process enabling photosynthetic organisms to use solar energy for the reduction of carbon dioxide into biomass. This ancient pathway has revolutionized life on Earth. The most important event was the development of oxygenic photosynthesis. It had a tremendous impact on the Earth's geochemistry and the evolution of living beings, as the rise of atmospheric molecular oxygen enabled the development of a highly efficient aerobic metabolism, which later led to the evolution of complex multicellular organisms. The mechanism of photosynthesis has been the subject of intensive research and a great body of data has been accumulated. However, the evolution of this process is not fully understood, and the development of photosynthesis in prokaryota in particular remains an unresolved question. This review is devoted to the occurrence and main features of phototrophy and photosynthesis in prokaryotes. Hypotheses concerning the origin and spread of photosynthetic traits in bacteria are also discussed.
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Affiliation(s)
- Beatrycze Nowicka
- Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Jerzy Kruk
- Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
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9
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He G, Zhang H, King JD, Blankenship RE. Structural analysis of the homodimeric reaction center complex from the photosynthetic green sulfur bacterium Chlorobaculum tepidum. Biochemistry 2014; 53:4924-30. [PMID: 25014729 PMCID: PMC4372062 DOI: 10.1021/bi5006464] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
![]()
The reaction center (RC) complex
of the green sulfur bacterium Chlorobaculum tepidum is composed of the Fenna–Matthews–Olson
antenna protein (FMO) and the reaction center core (RCC) complex.
The RCC complex has four subunits: PscA, PscB, PscC, and PscD. We
studied the FMO/RCC complex by chemically cross-linking the purified
sample followed by biochemical and spectroscopic analysis. Blue-native
gels showed that there were two types of FMO/RCC complexes, which
are consistent with complexes with one copy of FMO per RCC and two
copies of FMO per RCC. Sodium dodecyl sulfate–polyacrylamide
gel electrophoresis analysis of the samples after cross-linking showed
that all five subunits of the RC can be linked by three different
cross-linkers: bissulfosuccinimidyl suberate, disuccinimidyl suberate,
and 3,3-dithiobis-sulfosuccinimidyl propionate. The interaction sites
of the cross-linked complex were also studied using liquid chromatography
coupled to tandem mass spectrometry. The results indicated that FMO,
PscB, PscD, and part of PscA are exposed on the cytoplasmic side of
the membrane. PscD helps stabilize FMO to the reaction center and
may facilitate transfer of the electron from the RC to ferredoxin.
The soluble domain of the heme-containing cytochrome subunit PscC
and part of the core subunit PscA are located on the periplasmic side
of the membrane. There is a close relationship between the periplasmic
portions of PscA and PscC, which is needed for the efficient transfer
of the electron between PscC and P840.
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Affiliation(s)
- Guannan He
- Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States
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10
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Yu LJ, Unno M, Kimura Y, Yanagimoto K, Oh-oka H, Wang-Otomo ZY. Structure analysis and characterization of the cytochrome c-554 from thermophilic green sulfur photosynthetic bacterium Chlorobaculum tepidum. PHOTOSYNTHESIS RESEARCH 2013; 118:249-258. [PMID: 24052268 DOI: 10.1007/s11120-013-9922-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 09/03/2013] [Indexed: 06/02/2023]
Abstract
The cytochrome (Cyt) c-554 in thermophilic green photosynthetic bacterium Chlorobaculum tepidum serves as an intermediate electron carrier, transferring electrons to the membrane-bound Cyt c z from various enzymes involved in the oxidations of sulfide, thiosulfate, and sulfite compounds. Spectroscopically, this protein exhibits an asymmetric α-absorption band for the reduced form and particularly large paramagnetic (1)H NMR shifts for the heme methyl groups with an unusual shift pattern in the oxidized form. The crystal structure of the Cyt c-554 has been determined at high resolution. The overall fold consists of four α-helices and is characterized by a remarkably long and flexible loop between the α3 and α4 helices. The axial ligand methionine has S-chirality at the sulfur atom with its C(ε)H3 group pointing toward the heme pyrrole ring I. This configuration corresponds to an orientation of the lone-pair orbital of the sulfur atom directed at the pyrrole ring II and explains the lowest-field (1)H NMR shift arising from the 18(1) heme methyl protons. Differing from most other class I Cyts c, no hydrogen bond was formed between the methionine sulfur atom and polypeptide chain. Lack of this hydrogen bond may account for the observed large paramagnetic (1)H NMR shifts of the heme methyl protons. The surface-exposed heme pyrrole ring II edge is in a relatively hydrophobic environment surrounded by several electronically neutral residues. This portion is considered as an electron transfer gateway. The structure of the Cyt c-554 is compared with those of other Cyts c, and possible interactions of this protein with its electron transport partners are discussed.
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Affiliation(s)
- Long-Jiang Yu
- Faculty of Science, Ibaraki University, Bunkyo 2-1-1, Mito, 310-8512, Japan
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11
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A heterogeneous tag-attachment to the homodimeric type 1 photosynthetic reaction center core protein in the green sulfur bacterium Chlorobaculum tepidum. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:803-12. [DOI: 10.1016/j.bbabio.2011.03.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 03/10/2011] [Accepted: 03/15/2011] [Indexed: 01/26/2023]
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12
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Higuchi M, Hirano Y, Kimura Y, Oh-oka H, Miki K, Wang ZY. Overexpression, characterization, and crystallization of the functional domain of cytochrome c(z) from Chlorobium tepidum. PHOTOSYNTHESIS RESEARCH 2009; 102:77-84. [PMID: 19731072 DOI: 10.1007/s11120-009-9492-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Accepted: 08/17/2009] [Indexed: 05/28/2023]
Abstract
Cytochrome c(z) is found in green sulfur photosynthetic bacteria, and is considered to be the only electron donor to the special pair P840 of the reaction center. It consists of an N-terminal transmembrane domain and a C-terminal soluble domain that binds a single heme group. Large scale expression of the C-terminal functional domain of the cytochrome c(z) (C-cyt c(z)) from the thermophilic bacterium Chlorobium tepidum has been achieved using the Escherichia coli expression system. The C-cyt c(z) expressed has been highly purified, and is stable at room temperature over 10 days of incubation for both reduced and oxidized forms. Spectroscopic measurements indicate that the heme iron in C-cyt c(z) is in a low-spin state and this does not change with the redox state. (1)H-NMR spectra of the oxidized C-cyt c(z) exhibited unusually large paramagnetic chemical shifts for the heme methyl protons in comparison with those of other Class I ferric cytochromes c. Differences in the (1)H-NMR linewidth were observed for some resonances, indicating different dynamic environments for these protons. Crystals of the oxidized C-cyt c(z) were obtained using ammonium sulfate as a precipitant. The crystals diffracted X-rays to a maximum resolution of 1.2 A, and the diffraction data were collected to 1.3 A resolution.
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