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Cryo-EM structures of the Synechocystis sp. PCC 6803 cytochrome b6f complex with and without the regulatory PetP subunit. Biochem J 2022; 479:1487-1503. [PMID: 35726684 PMCID: PMC9342900 DOI: 10.1042/bcj20220124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 06/01/2022] [Accepted: 06/21/2022] [Indexed: 11/17/2022]
Abstract
In oxygenic photosynthesis, the cytochrome b6f (cytb6f) complex links the linear electron transfer (LET) reactions occurring at photosystems I and II and generates a transmembrane proton gradient via the Q-cycle. In addition to this central role in LET, cytb6f also participates in a range of processes including cyclic electron transfer (CET), state transitions and photosynthetic control. Many of the regulatory roles of cytb6f are facilitated by auxiliary proteins that differ depending upon the species, yet because of their weak and transient nature the structural details of these interactions remain unknown. An apparent key player in the regulatory balance between LET and CET in cyanobacteria is PetP, a ∼10 kDa protein that is also found in red algae but not in green algae and plants. Here, we used cryogenic electron microscopy to determine the structure of the Synechocystis sp. PCC 6803 cytb6f complex in the presence and absence of PetP. Our structures show that PetP interacts with the cytoplasmic side of cytb6f, displacing the C-terminus of the PetG subunit and shielding the C-terminus of cytochrome b6, which binds the heme cn cofactor that is suggested to mediate CET. The structures also highlight key differences in the mode of plastoquinone binding between cyanobacterial and plant cytb6f complexes, which we suggest may reflect the unique combination of photosynthetic and respiratory electron transfer in cyanobacterial thylakoid membranes. The structure of cytb6f from a model cyanobacterial species amenable to genetic engineering will enhance future site-directed mutagenesis studies of structure-function relationships in this crucial ET complex.
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Lu C, Shen JR, Zhang L. Special issue on Regulation of the Photosynthetic Systems in honor of Tingyun Kuang. PHOTOSYNTHESIS RESEARCH 2015; 126:185-188. [PMID: 26354782 DOI: 10.1007/s11120-015-0191-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
- Congming Lu
- Photosynthesis Research Center, Key Laboratory of Photobiology Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
| | - Jian-Ren Shen
- Photosynthesis Research Center, Key Laboratory of Photobiology Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
- Department of Biology, Faculty of Science, Photosynthesis Research Center, Graduate School of Natural Science and Technology, Okayama University, 1-1, Naka 3-Chome, Tsushima, Okayama, 700-8530, Japan.
| | - Lixin Zhang
- Photosynthesis Research Center, Key Laboratory of Photobiology Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
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Vladkova R. Chlorophyllais the crucial redox sensor and transmembrane signal transmitter in the cytochromeb6fcomplex. Components and mechanisms of state transitions from the hydrophobic mismatch viewpoint. J Biomol Struct Dyn 2015; 34:824-54. [DOI: 10.1080/07391102.2015.1056551] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Sang M, Xie J, Qin XC, Wang WD, Chen XB, Wang KB, Zhang JP, Li LB, Kuang TY. High-light induced superoxide radical formation in cytochrome b₆f complex from Bryopsis corticulans as detected by EPR spectroscopy. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2010; 102:177-81. [PMID: 21277495 DOI: 10.1016/j.jphotobiol.2010.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2010] [Revised: 10/25/2010] [Accepted: 11/02/2010] [Indexed: 12/18/2022]
Abstract
The generation of superoxide radical (O₂·⁻) in Cyt b₆f of Bryopsis corticulans under high light illumination was studied using electron paramagnetic resonance (EPR) spectroscopy. This could be evidenced by the addition of SOD which specifically reacted with O₂·⁻. The generation of O₂·⁻ was lost in the absence of oxygen and was found to be suppressed in the presence of NaN₃ and be scavenged by extraneous antioxidants such as ascorbate, β-carotene and glutathione which could also scavenged ¹O₂*. These results indicated that O₂·⁻ which produced under high light illumination in Cyt b₆f of B. corticulans might rise from a reaction which ¹O₂* could participated in. Also the photo-protection mechanism to Cyt b₆f complex by antioxidants which might contain in thylakoid was speculated.
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Affiliation(s)
- Min Sang
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, P.R. China; Institute of Hydrobiology, Ji' nan University, Guangzhou 510632, P.R.China
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Weiss TL, Chun HJ, Okada S, Vitha S, Holzenburg A, Laane J, Devarenne TP. Raman spectroscopy analysis of botryococcene hydrocarbons from the green microalga Botryococcus braunii. J Biol Chem 2010; 285:32458-66. [PMID: 20705610 DOI: 10.1074/jbc.m110.157230] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Botryococcus braunii, B race is a unique green microalga that produces large amounts of liquid hydrocarbons known as botryococcenes that can be used as a fuel for internal combustion engines. The simplest botryococcene (C(30)) is metabolized by methylation to give intermediates of C(31), C(32), C(33), and C(34), with C(34) being the predominant botryococcene in some strains. In the present work we have used Raman spectroscopy to characterize the structure of botryococcenes in an attempt to identify and localize botryococcenes within B. braunii cells. The spectral region from 1600-1700 cm(-1) showed ν(C=C) stretching bands specific for botryococcenes. Distinct botryococcene Raman bands at 1640 and 1647 cm(-1) were assigned to the stretching of the C=C bond in the botryococcene branch and the exomethylene C=C bonds produced by the methylations, respectively. A Raman band at 1670 cm(-1) was assigned to the backbone C=C bond stretching. Density function theory calculations were used to determine the Raman spectra of all botryococcenes to compare computed theoretical values with those observed. The analysis showed that the ν(C=C) stretching bands at 1647 and 1670 cm(-1) are actually composed of several closely spaced bands arising from the six individual C=C bonds in the molecule. We also used confocal Raman microspectroscopy to map the presence and location of methylated botryococcenes within a colony of B. braunii cells based on the methylation-specific 1647 cm(-1) botryococcene Raman shift.
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Affiliation(s)
- Taylor L Weiss
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128, USA
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Sang M, Ma F, Xie J, Chen XB, Wang KB, Qin XC, Wang WD, Zhao JQ, Li LB, Zhang JP, Kuang TY. High-light induced singlet oxygen formation in cytochrome b(6)f complex from Bryopsis corticulans as detected by EPR spectroscopy. Biophys Chem 2009; 146:7-12. [PMID: 19861232 DOI: 10.1016/j.bpc.2009.09.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Revised: 09/24/2009] [Accepted: 09/26/2009] [Indexed: 11/16/2022]
Abstract
Electron paramagnetic resonance (EPR) spectroscopy was used to detect the light-induced formation of singlet oxygen ((1)O(2)*) in the intact and the Rieske-depleted cytochrome b(6)f complexes (Cyt b(6)f) from Bryopsis corticulans, as well as in the isolated Rieske Fe-S protein. It is shown that, under white-light illumination and aerobic conditions, chlorophyll a (Chl a) bound in the intact Cyt b(6)f can be bleached by light-induced (1)O(2)*, and that the (1)O(2)* production can be promoted by D(2)O or scavenged by extraneous antioxidants such as l-histidine, ascorbate, beta-carotene and glutathione. Under similar experimental conditions, (1)O(2)* was also detected in the Rieske-depleted Cyt b(6)f complex, but not in the isolated Rieske Fe-S protein. The results prove that Chl a cofactor, rather than Rieske Fe-S protein, is the specific site of (1)O(2)* formation, a conclusion which draws further support from the generation of (1)O(2)* with selective excitation of Chl a using monocolor red light.
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Affiliation(s)
- Min Sang
- Institute of Botany, Chinese Academy of Sciences, Beijing, PR China
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Chen XB, Zhao XH, Zhu Y, Gong YD, Li LB, Zhang JP, Kuang TY. Hydrogen peroxide-induced chlorophyll a bleaching in the cytochrome b6f complex: a simple and effective assay for stability of the complex in detergent solutions. PHOTOSYNTHESIS RESEARCH 2006; 90:205-14. [PMID: 17235492 DOI: 10.1007/s11120-006-9118-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2006] [Accepted: 11/20/2006] [Indexed: 05/10/2023]
Abstract
The instability of cytochrome b ( 6 ) f complex in detergent solutions is a well-known problem that has been studied extensively, but without finding a satisfactory solution. One of the important reasons can be short of the useful method to verify whether the complex suspended in different detergent is in an intact state or not. In this article, a simple and effective assay for stability of the complex was proposed based on the investigation on the different effects of the two detergents, n-octyl-beta-D: -glucopyranoside (OG) and dodecyl-beta-D: -maltoside (DDM), on the properties of the complex. DDM stabilizes the complex preparation more effectively whereas OG denatures the interactions of the heme groups and pigment molecules with the protein environment, leading to the bleaching of chlorophyll a induced by addition of hydrogen peroxide. The assay of the use of hydrogen peroxide to characterize the complex by studying the bleaching of chlorophyll induced by hydrogen peroxide and the peroxidase activity of the complex was discussed. This simple method will probably be useful to study the stability of the complex.
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Affiliation(s)
- Xiao-Bo Chen
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Nan Xincun 20, Xiangshan, 100093, Beijing, P.R. China
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Li BX, Zuo P, Chen XB, Li LB, Zhang JP, Zhang JP, Kuang TY. Study on energy transfer between carotenoid and chlorophyll a in cytochrome b6f complex from Bryopsis corticulans. PHOTOSYNTHESIS RESEARCH 2006; 88:43-50. [PMID: 16688490 DOI: 10.1007/s11120-005-9020-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2005] [Accepted: 09/19/2005] [Indexed: 05/09/2023]
Abstract
The excitation energy transfer between carotenoid and chlorophyll (Chl) in the cytochrome b ( 6 ) f complex from Bryopsis corticulans (B. corticulans), in which the carotenoid is 9-cis-alpha-carotene, was investigated by means of fluorescence excitation and sub-microsecond time-resolved absorption spectroscopies. The presence of efficient singlet excitation transfer from alpha-carotene to Chl a was found with an overall efficiency as high as approximately approximately 24%, meanwhile the Chl a-to-alpha-carotene triplet excitation transfer was also evidenced. Circular dichroism spectroscopy showed that alpha-carotene molecule existed in an asymmetric environment and Chl a molecule had a certain orientation in this complex.
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Affiliation(s)
- Bin-Xing Li
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Nan Xincun 20, Xiangshan, 100093, Beijing, P.R. China.
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Zuo P, Li BX, Zhao XH, Wu YS, Ai XC, Zhang JP, Li LB, Kuang TY. Ultrafast carotenoid-to-chlorophyll singlet energy transfer in the cytochrome b6f complex from Bryopsis corticulans. Biophys J 2006; 90:4145-54. [PMID: 16565047 PMCID: PMC1459505 DOI: 10.1529/biophysj.105.076612] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ultrafast carotenoid-to-chlorophyll (Car-to-Chl) singlet excitation energy transfer in the cytochrome b(6)f (Cyt b(6)f) complex from Bryopsis corticulans is investigated by the use of femtosecond time-resolved absorption spectroscopy. For all-trans-alpha-carotene free in n-hexane, the lifetimes of the two low-lying singlet excited states, S(1)(2A(g)(-)) and S(2)(1B(u)(+)), are determined to be 14.3 +/- 0.4 ps and 230 +/- 10 fs, respectively. For the Cyt b(6)f complex, to which 9-cis-alpha-carotene is bound, the lifetime of the S(1)(2A(g)(-)) state remains unchanged, whereas that of the S(2)(1B(u)(+)) state is significantly reduced. In addition, a decay-to-rise correlation between the excited-state dynamics of alpha-carotene and Chl a is clearly observed. This spectroscopic evidence proves that the S(2)(1B(u)(+)) state is able to transfer electronic excitations to the Q(x) state of Chl a, whereas the S(1)(2A(g)(-)) state remains inactive. The time constant and the partial efficiency of the energy transfer are determined to be 240 +/- 40 fs and (49 +/- 4)%, respectively, which supports the overall efficiency of 24% determined with steady-state fluorescence spectroscopy. A scheme of the alpha-carotene-to-Chl a singlet energy transfer is proposed based on the excited-state dynamics of the pigments.
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Affiliation(s)
- Ping Zuo
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, People's Republic of China
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