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Kis M, Smart JL, Maróti P. Probing ligands to reaction centers to limit the photocycle in photosynthetic bacterium Rubrivivax gelatinosus. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2024; 257:112969. [PMID: 38959527 DOI: 10.1016/j.jphotobiol.2024.112969] [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: 01/31/2024] [Revised: 06/19/2024] [Accepted: 06/25/2024] [Indexed: 07/05/2024]
Abstract
Light-induced electron flow between reaction center and cytochrome bc1 complexes is mediated by quinones and electron donors in purple photosynthetic bacteria. Upon high-intensity excitation, the contribution of the cytochrome bc1 complex is limited kinetically and the electron supply should be provided by the pool of reduced electron donors. The kinetic limitation of electron shuttle between reaction center and cytochrome bc1 complex and its consequences on the photocycle were studied by tracking the redox changes of the primary electron donor (BChl dimer) via absorption change and the opening of the closed reaction center via relaxation of the bacteriochlorophyll fluorescence in intact cells of wild type and pufC mutant strains of Rubrivivax gelatinosus. The results were simulated by a minimum model of reversible binding of different ligands (internal and external electron donors and inhibitors) to donor and acceptor sides of the reaction center. The calculated binding and kinetic parameters revealed that control of the rate of the photocycle is primarily due to 1) the light intensity, 2) the size and redox state of the donor pool, and 3) the unbinding rates of the oxidized donor and inhibitor from the reaction center. The similar kinetics of strains WT and pufC lacking the tetraheme cytochrome subunit attached to the reaction center raise the issue of the physiological importance of this subunit discussed from different points of view. SIGNIFICANCE: A crucial factor for the efficacy of electron donors in photosynthetic photocycle is not just the substantial size of the pool and large binding affinity (small dissociation constant KD = koff/kon) to the RC, but also the mean residence time (koff)-1 in the binding pocket. This is an important parameter that regulates the time of re-activation of the RC during multiple turnovers. The determination of koff has proven challenging and was performed by simulation of widespread experimental data on the kinetics of P+ and relaxation of fluorescence. This work is a step towards better understanding the complex pathways of electron transfer in proteins and simulation-based design of more effective electron transfer components in natural and artificial systems.
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Affiliation(s)
- M Kis
- Institute of Medical Physics, University of Szeged, Korányi Fasor 9, Szeged 6720, Hungary; HUN-REN Balaton Limnological Research Institute, Klebelsberg K. utca 3, Tihany 8237, Hungary
| | - J L Smart
- Department of Biological Sciences, University of Tennessee at Martin, Martin, TN 38238, USA
| | - P Maróti
- Institute of Medical Physics, University of Szeged, Korányi Fasor 9, Szeged 6720, Hungary.
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Chen GE, Hitchcock A, Mareš J, Gong Y, Tichý M, Pilný J, Kovářová L, Zdvihalová B, Xu J, Hunter CN, Sobotka R. Evolution of Ycf54-independent chlorophyll biosynthesis in cyanobacteria. Proc Natl Acad Sci U S A 2021; 118:e2024633118. [PMID: 33649240 PMCID: PMC7958208 DOI: 10.1073/pnas.2024633118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Chlorophylls (Chls) are essential cofactors for photosynthesis. One of the least understood steps of Chl biosynthesis is formation of the fifth (E) ring, where the red substrate, magnesium protoporphyrin IX monomethyl ester, is converted to the green product, 3,8-divinyl protochlorophyllide a In oxygenic phototrophs, this reaction is catalyzed by an oxygen-dependent cyclase, consisting of a catalytic subunit (AcsF/CycI) and an auxiliary protein, Ycf54. Deletion of Ycf54 impairs cyclase activity and results in severe Chl deficiency, but its exact role is not clear. Here, we used a Δycf54 mutant of the model cyanobacterium Synechocystis sp. PCC 6803 to generate suppressor mutations that restore normal levels of Chl. Sequencing Δycf54 revertants identified a single D219G amino acid substitution in CycI and frameshifts in slr1916, which encodes a putative esterase. Introduction of these mutations to the original Δycf54 mutant validated the suppressor effect, especially in combination. However, comprehensive analysis of the Δycf54 suppressor strains revealed that the D219G-substituted CycI is only partially active and its accumulation is misregulated, suggesting that Ycf54 controls both the level and activity of CycI. We also show that Slr1916 has Chl dephytylase activity in vitro and its inactivation up-regulates the entire Chl biosynthetic pathway, resulting in improved cyclase activity. Finally, large-scale bioinformatic analysis indicates that our laboratory evolution of Ycf54-independent CycI mimics natural evolution of AcsF in low-light-adapted ecotypes of the oceanic cyanobacteria Prochlorococcus, which lack Ycf54, providing insight into the evolutionary history of the cyclase enzyme.
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Affiliation(s)
- Guangyu E Chen
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Andrew Hitchcock
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Jan Mareš
- Institute of Microbiology, Czech Academy of Sciences, 37901 Třeboň, Czech Republic
- Institute of Hydrobiology, Biology Centre of the Czech Academy of Sciences, 37005 České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, 37005 České Budějovice, Czech Republic
| | - Yanhai Gong
- Single-Cell Center, Chinese Academy of Sciences Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - Martin Tichý
- Institute of Microbiology, Czech Academy of Sciences, 37901 Třeboň, Czech Republic
- Faculty of Science, University of South Bohemia, 37005 České Budějovice, Czech Republic
| | - Jan Pilný
- Institute of Microbiology, Czech Academy of Sciences, 37901 Třeboň, Czech Republic
| | - Lucie Kovářová
- Institute of Microbiology, Czech Academy of Sciences, 37901 Třeboň, Czech Republic
| | - Barbora Zdvihalová
- Institute of Microbiology, Czech Academy of Sciences, 37901 Třeboň, Czech Republic
| | - Jian Xu
- Single-Cell Center, Chinese Academy of Sciences Key Laboratory of Biofuels and Shandong Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Roman Sobotka
- Institute of Microbiology, Czech Academy of Sciences, 37901 Třeboň, Czech Republic;
- Faculty of Science, University of South Bohemia, 37005 České Budějovice, Czech Republic
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Protochlorophyllide synthesis by recombinant cyclases from eukaryotic oxygenic phototrophs and the dependence on Ycf54. Biochem J 2020; 477:2313-2325. [PMID: 32469391 PMCID: PMC7319587 DOI: 10.1042/bcj20200221] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 05/22/2020] [Accepted: 05/28/2020] [Indexed: 12/20/2022]
Abstract
The unique isocyclic E ring of chlorophylls contributes to their role as light-absorbing pigments in photosynthesis. The formation of the E ring is catalyzed by the Mg-protoporphyrin IX monomethyl ester cyclase, and the O2-dependent cyclase in prokaryotes consists of a diiron protein AcsF, augmented in cyanobacteria by an auxiliary subunit Ycf54. Here, we establish the composition of plant and algal cyclases, by demonstrating the in vivo heterologous activity of O2-dependent cyclases from the green alga Chlamydomonas reinhardtii and the model plant Arabidopsis thaliana in the anoxygenic photosynthetic bacterium Rubrivivax gelatinosus and in the non-photosynthetic bacterium Escherichia coli. In each case, an AcsF homolog is the core catalytic subunit, but there is an absolute requirement for an algal/plant counterpart of Ycf54, so the necessity for an auxiliary subunit is ubiquitous among oxygenic phototrophs. A C-terminal ∼40 aa extension, which is present specifically in green algal and plant Ycf54 proteins, may play an important role in the normal function of the protein as a cyclase subunit.
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Azai C, Kobayashi M, Mizoguchi T, Tamiaki H, Terauchi K, Tsukatani Y. Rapid C8-vinyl reduction of divinyl-chlorophyllide a by BciA from Rhodobacter capsulatus. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2017.09.010] [Citation(s) in RCA: 2] [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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Chen GE, Canniffe DP, Barnett SFH, Hollingshead S, Brindley AA, Vasilev C, Bryant DA, Hunter CN. Complete enzyme set for chlorophyll biosynthesis in Escherichia coli. SCIENCE ADVANCES 2018; 4:eaaq1407. [PMID: 29387799 PMCID: PMC5787379 DOI: 10.1126/sciadv.aaq1407] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 12/28/2017] [Indexed: 05/08/2023]
Abstract
Chlorophylls are essential cofactors for photosynthesis, which sustains global food chains and oxygen production. Billions of tons of chlorophylls are synthesized annually, yet full understanding of chlorophyll biosynthesis has been hindered by the lack of characterization of the Mg-protoporphyrin IX monomethyl ester oxidative cyclase step, which confers the distinctive green color of these pigments. We demonstrate cyclase activity using heterologously expressed enzyme. Next, we assemble a genetic module that encodes the complete chlorophyll biosynthetic pathway and show that it functions in Escherichia coli. Expression of 12 genes converts endogenous protoporphyrin IX into chlorophyll a, turning E. coli cells green. Our results delineate a minimum set of enzymes required to make chlorophyll and establish a platform for engineering photosynthesis in a heterotrophic model organism.
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Affiliation(s)
- Guangyu E. Chen
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Daniel P. Canniffe
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Samuel F. H. Barnett
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Sarah Hollingshead
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Amanda A. Brindley
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Cvetelin Vasilev
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Donald A. Bryant
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - C. Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
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Three classes of oxygen-dependent cyclase involved in chlorophyll and bacteriochlorophyll biosynthesis. Proc Natl Acad Sci U S A 2017; 114:6280-6285. [PMID: 28559347 DOI: 10.1073/pnas.1701687114] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The biosynthesis of (bacterio)chlorophyll pigments is among the most productive biological pathways on Earth. Photosynthesis relies on these modified tetrapyrroles for the capture of solar radiation and its conversion to chemical energy. (Bacterio)chlorophylls have an isocyclic fifth ring, the formation of which has remained enigmatic for more than 60 y. This reaction is catalyzed by two unrelated cyclase enzymes using different chemistries. The majority of anoxygenic phototrophic bacteria use BchE, an O2-sensitive [4Fe-4S] cluster protein, whereas plants, cyanobacteria, and some phototrophic bacteria possess an O2-dependent enzyme, the major catalytic component of which is a diiron protein, AcsF. Plant and cyanobacterial mutants in ycf54 display impaired function of the O2-dependent enzyme, accumulating the reaction substrate. Swapping cyclases between cyanobacteria and purple phototrophic bacteria reveals three classes of the O2-dependent enzyme. AcsF from the purple betaproteobacterium Rubrivivax (Rvi.) gelatinosus rescues the loss not only of its cyanobacterial ortholog, cycI, in Synechocystis sp. PCC 6803, but also of ycf54; conversely, coexpression of cyanobacterial cycI and ycf54 is required to complement the loss of acsF in Rvi. gelatinosus These results indicate that Ycf54 is a cyclase subunit in oxygenic phototrophs, and that different classes of the enzyme exist based on their requirement for an additional subunit. AcsF is the cyclase in Rvi. gelatinosus, whereas alphaproteobacterial cyclases require a newly discovered protein that we term BciE, encoded by a gene conserved in these organisms. These data delineate three classes of O2-dependent cyclase in chlorophototrophic organisms from higher plants to bacteria, and their evolution is discussed herein.
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Essential Genes Predicted in the Genome of Rubrivivax gelatinosus. J Bacteriol 2016; 198:2244-50. [PMID: 27274029 DOI: 10.1128/jb.00344-16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 05/30/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Rubrivivax gelatinosus is a betaproteobacterium with impressive metabolic diversity. It is capable of phototrophy, chemotrophy, two different mechanisms of sugar metabolism, fermentation, and H2 gas production. To identify core essential genes, R. gelatinosus was subjected to saturating transposon mutagenesis and high-throughput sequencing (TnSeq) analysis using nutrient-rich, aerobic conditions. Results revealed that virtually no primary metabolic genes are essential to the organism and that genomic redundancy only explains a portion of the nonessentiality, but some biosynthetic pathways are still essential under nutrient-rich conditions. Different essentialities of different portions of the Pho regulatory pathway suggest that overexpression of the regulon is toxic and hint at a larger connection between phosphate regulation and cellular health. Lastly, various essentialities of different tRNAs hint at a more complex situation than would be expected for such a core process. These results expand upon research regarding cross-organism gene essentiality and further enrich the study of purple nonsulfur bacteria. IMPORTANCE Microbial genomic data are increasing at a tremendous rate, but physiological characterization of those data lags far behind. One mechanism of high-throughput physiological characterization is TnSeq, which uses high-volume transposon mutagenesis and high-throughput sequencing to identify all of the essential genes in a given organism's genome. Here TnSeq was used to identify essential genes in the metabolically versatile betaproteobacterium Rubrivivax gelatinosus The results presented here add to the growing TnSeq field and also reveal important aspects of R. gelatinosus physiology, which are applicable to researchers working on metabolically flexible organisms.
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Exchange and complementation of genes coding for photosynthetic reaction center core subunits among purple bacteria. J Mol Evol 2014; 79:52-62. [PMID: 25080366 DOI: 10.1007/s00239-014-9634-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 07/11/2014] [Indexed: 10/25/2022]
Abstract
A mutant of the phototrophic species belonging to the β-proteobacteria, Rubrivivax gelatinosus, lacking the photosynthetic growth ability was constructed by the removal of genes coding for the L, M, and cytochrome subunits of the photosynthetic reaction center complex. The L, M, and cytochrome genes derived from five other species of proteobacteria, Acidiphilium rubrum, Allochromatium vinosum, Blastochloris viridis, Pheospirillum molischianum, and Roseateles depolymerans, and the L and M subunits from two other species, Rhodobacter sphaeroides and Rhodopseudomonas palustris, respectively, have been introduced into this mutant. Introduction of the genes from three of these seven species, Rte. depolymerans, Ach. vinosum, and Psp. molischianum, restored the photosynthetic growth ability of the mutant of Rvi. gelatinosus, although the growth rates were 1.5, 9.4, and 10.7 times slower, respectively, than that of the parent strain. Flash-induced kinetic measurements for the intact cells of these three mutants showed that the photo-oxidized cytochrome c bound to the introduced reaction center complex could be rereduced by electron donor proteins of Rvi. gelatinosus with a t1/2 of less than 10 ms. The reaction center core subunits of photosynthetic proteobacteria appear to be exchangeable if the sequence identities of the LM core subunits between donor and acceptor species are high enough, i.e., 70% or more.
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Verméglio A, Nagashima S, Alric J, Arnoux P, Nagashima KVP. Photo-induced electron transfer in intact cells of Rubrivivax gelatinosus mutants deleted in the RC-bound tetraheme cytochrome: insight into evolution of photosynthetic electron transport. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:689-96. [PMID: 22305913 DOI: 10.1016/j.bbabio.2012.01.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 01/18/2012] [Accepted: 01/18/2012] [Indexed: 11/25/2022]
Abstract
Deletion of two of the major electron carriers, the reaction center-bound tetrahemic cytochrome and the HiPIP, involved in the light-induced cyclic electron transfer pathway of the purple photosynthetic bacterium, Rubrivivax gelatinosus, significantly impairs its anaerobic photosynthetic growth. Analysis on the light-induced absorption changes of the intact cells of the mutants shows, however, a relatively efficient photo-induced cyclic electron transfer. For the single mutant lacking the reaction center-bound cytochrome, we present evidence that the electron carrier connecting the reaction center and the cytochrome bc(1) complex is the High Potential Iron-sulfur Protein. In the double mutant lacking both the reaction center-bound cytochrome and the High Potential Iron-sulfur Protein, this connection is achieved by the high potential cytochrome c(8). Under anaerobic conditions, the halftime of re-reduction of the photo-oxidized primary donor by these electron donors is 3 to 4 times faster than the back reaction between P(+) and the reduced primary quinone acceptor. This explains the photosynthetic growth of these two mutants. The results are discussed in terms of evolution of the type II RCs and their secondary electron donors.
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Affiliation(s)
- André Verméglio
- CEA, DSV, IBEB, Laboratoire de Bioénergétique Cellulaire, Saint-Paul-lez-Durance, France.
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Ohmine M, Matsuura K, Shimada K, Alric J, Verméglio A, Nagashima KVP. Cytochrome c4 can be involved in the photosynthetic electron transfer system in the purple bacterium Rubrivivax gelatinosus. Biochemistry 2009; 48:9132-9. [PMID: 19697907 DOI: 10.1021/bi901202m] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Three periplasmic electron carriers, HiPIP and two cytochromes c8 with low- and high-midpoint potentials, are present in the purple photosynthetic bacterium Rubrivivax gelatinosus. Comparison of the growth rates of mutants lacking one, two, or all three electron carrier proteins showed that HiPIP is the main electron donor to the photochemical reaction center and that high-potential cytochrome c8 plays a subsidiary role in the electron donation in photosynthetically growing cells. However, the triple deletion mutant was still capable of photosynthetic growth, indicating that another electron donor could be present. A new soluble cytochrome c, which can reduce the photooxidized reaction center in vitro, was purified. Based on amino acid sequence comparisons to known cytochromes, this cytochrome was identified as a diheme cytochrome c of the family of cytochromes c4. The quadruple mutant lacking this cytochrome and three other electron carriers showed about three times slower growth than the triple mutant under photosynthetic growth conditions. In conclusion, cytochrome c4 can function as a physiological electron carrier in the photosynthetic electron transport chain in R. gelatinosus.
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Affiliation(s)
- Makito Ohmine
- Department of Biological Science, Tokyo Metropolitan University, Minamiohsawa 1-1, Hachioji, Tokyo 192-0397, Japan
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Jones MR. Structural Plasticity of Reaction Centers from Purple Bacteria. THE PURPLE PHOTOTROPHIC BACTERIA 2009. [DOI: 10.1007/978-1-4020-8815-5_16] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Mizoguchi T, Isaji M, Harada J, Tamiaki H. Identification of 3,4-didehydrorhodopin as major carotenoid in Rhodopseudomonas species. Photochem Photobiol Sci 2008; 7:492-7. [PMID: 18385894 DOI: 10.1039/b719272j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Recently we isolated the purple photosynthetic bacterium, Rhodopseudomonas sp. Rits, which was phylogenetically related to Rhodopseudomonas (Rps.) palustris. In this study, the light-dependent and time-dependent changes in the carotenoid composition were investigated by HPLC analysis of extracts from the cultures. All seven carotenoids in the biosynthetic pathway from lycopene to spirilloxanthin were detected. Especially, 3,4-didehydrorhodopin, having twelve conjugated double bonds as well as one terminal hydroxy group, was isolated in a remarkably large amount and fully characterized for the first time. The biosynthetic intermediate was commonly found in the Rps. palustris strains (CGA009, Morita and NBRC100419).
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Affiliation(s)
- Tadashi Mizoguchi
- Department of Bioscience and Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
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Harada J, Mizoguchi T, Yoshida S, Isaji M, Oh-Oka H, Tamiaki H. Composition and localization of bacteriochlorophyll a intermediates in the purple photosynthetic bacterium Rhodopseudomonas sp. Rits. PHOTOSYNTHESIS RESEARCH 2008; 95:213-21. [PMID: 17912605 DOI: 10.1007/s11120-007-9254-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Accepted: 09/07/2007] [Indexed: 05/17/2023]
Abstract
Rhodopseudomonas sp. Rits is a recently isolated new species of photosynthetic bacteria and found to accumulate a significantly high amount of bacteriochlorophyll (BChl) a intermediates possessing non-, di- and tetra-hydrogenated geranylgeranyl groups at the 17-propionate as well as normal phytylated BChl a (Mizoguchi T et al. (2006) FEBS Lett 580:137-143). A phylogenetic analysis showed that this bacterium was closely related to Rhodopseudomonas palustris. The strain Rits synthesizes light-harvesting complexes 2 and 4 (LH2/4), as peripheral antennas, as well as the reaction center and light-harvesting 1 core complex (RC-LH1 core). The amounts of these complexes were dependent upon the incident light intensities, which was also a typical behavior of Rhodopseudomonas palustris. HPLC analyses of extracted pigments indicated that all four BChls a were associated with the purified photosynthetic pigment-protein, as complexes described above. The results suggested that this bacterium could use these pigments as functional molecules within the LH2/4 and RC-LH1 core. Pigment compositional analyses in several purple photosynthetic bacteria showed that such BChl a intermediates were always detected and were more widely distributed than expected. Long chains in the propionate moiety of BChl a would be one of the important factors for assembly of LH systems in purple photosynthetic bacteria.
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Affiliation(s)
- Jiro Harada
- Department of Bioscience and Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
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Mizoguchi T, Harada J, Tamiaki H. Structural determination of dihydro- and tetrahydrogeranylgeranyl groups at the 17-propionate of bacteriochlorophylls-a. FEBS Lett 2006; 580:6644-8. [PMID: 17123518 DOI: 10.1016/j.febslet.2006.11.020] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2006] [Revised: 11/08/2006] [Accepted: 11/08/2006] [Indexed: 11/23/2022]
Abstract
In the final stage of bacteriochlorophyll (BChl) biosynthesis, the presence of BChl-a molecules possessing dihydrogeranylgeranyl and tetrahydrogeranylgeranyl groups at the 17-propionate has been reported. However, the molecular structures of such BChls-a have not yet been determined in terms of the positions of CC double bonds in the 17(2)-ester. In this study, we isolated significant amounts of such pure BChls-a from Rhodopseudomonas palustris and determined their structures by both mass spectrometry and (1)H and (13)C NMR spectroscopy. The determined structures enable us to discuss a stepwise reduction from a geranylgeranyl to phytyl substituent.
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Affiliation(s)
- Tadashi Mizoguchi
- Department of Bioscience and Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
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Nogi T, Hirano Y, Miki K. Structural and functional studies on the tetraheme cytochrome subunit and its electron donor proteins: the possible docking mechanisms during the electron transfer reaction. PHOTOSYNTHESIS RESEARCH 2005; 85:87-99. [PMID: 15977061 DOI: 10.1007/s11120-004-2416-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2004] [Accepted: 08/30/2004] [Indexed: 05/03/2023]
Abstract
The photosynthetic reaction centers (RCs) classified as the group II possess a peripheral cytochrome (Cyt) subunit, which serves as the electron mediator to the special-pair. In the cycle of the photosynthetic electron transfer reactions, the Cyt subunit accepts electrons from soluble electron carrier proteins, and re-reduces the photo-oxidized special-pair of the bacteriochlorophyll. Physiologically, high-potential cytochromes such as the cytochrome c2 and the high-potential iron-sulfur protein (HiPIP) function as the electron donors to the Cyt subunit. Most of the Cyt subunits possess four heme c groups, and it was unclear which heme group first accepts the electron from the electron donor. The most distal heme to the special-pair, the heme-1, has a lower redox potential than the electron donors, which makes it difficult to understand the electron transfer mechanism mediated by the Cyt subunit. Extensive mutagenesis combined with kinetic studies has made a great contribution to our understanding of the molecular interaction mechanisms, and has demonstrated the importance of the region close to the heme-1 in the electron transfer. Moreover, crystallographic studies have elucidated two high-resolution three-dimensional structures for the RCs containing the Cyt subunit, the Blastochloris viridis and Thermochromatium tepidum RCs, as well as the structures of their electron donors. An examination of the structural data also suggested that the binding sites for both the cytochrome c2 and the HiPIP are located adjacent to the solvent-accessible edge of the heme-1. In addition, it is also indicated by the structural and biochemical data that the cytochrome c2 and the HiPIP dock with the Cyt subunit by c2 is recognized through electrostatic interactions while hydrophobic interactions are important in the HiPIP docking.
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Affiliation(s)
- Terukazu Nogi
- Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita, 565-0871, Japan
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Alric J, Cuni A, Maki H, Nagashima KVP, Verméglio A, Rappaport F. Electrostatic Interaction between Redox Cofactors in Photosynthetic Reaction Centers. J Biol Chem 2004; 279:47849-55. [PMID: 15347641 DOI: 10.1074/jbc.m408888200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Intramolecular electron transfer within proteins is an essential process in bioenergetics. Redox cofactors are embedded in proteins, and this matrix strongly influences their redox potential. Several cofactors are usually found in these complexes, and they are structurally organized in a chain with distances between the electron donor and acceptor short enough to allow rapid electron tunneling. Among the different interactions that contribute to the determination of the redox potential of these cofactors, electrostatic interactions are important but restive to direct experimental characterization. The influence of interaction between cofactors is evidenced here experimentally by means of redox titrations and time-resolved spectroscopy in a chimeric bacterial reaction center (Maki, H., Matsuura, K., Shimada, K., and Nagashima, K. V. P. (2003) J. Biol. Chem. 278, 3921-3928) composed of the core subunits of Rubrivivax gelatinosus and the tetraheme cytochrome of Blastochloris viridis. The absorption spectra and orientations of the various cofactors of this chimeric reaction center are similar to those found in their respective native protein, indicating that their local environment is conserved. However, the redox potentials of both the primary electron donor and its closest heme are changed. The redox potential of the primary electron donor is downshifted in the chimeric reaction center when compared with the wild type, whereas, conversely, that of its closet heme is upshifted. We propose a model in which these reciprocal shifts in the midpoint potentials of two electron transfer partners are explained by an electrostatic interaction between them.
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Affiliation(s)
- Jean Alric
- Laboratoire de Génétique et Biophysique des Plantes, UMR 6191 CNRS-CEA-Aix-Marseille II, 163 avenue de Luminy, Marseille 13288, France
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Alric J, Yoshida M, Nagashima KVP, Hienerwadel R, Parot P, Verméglio A, Chen SWW, Pellequer JL. Two distinct binding sites for high potential iron-sulfur protein and cytochrome c on the reaction center-bound cytochrome of Rubrivivax gelatinosus. J Biol Chem 2004; 279:32545-53. [PMID: 15155756 DOI: 10.1074/jbc.m401784200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The photosynthetic cyclic electron transfer of the purple bacterium Rubrivivax gelatinosus, involving the cytochrome bc(1) complex and the reaction center, can be carried out via two pathways. A high potential iron-sulfur protein (HiPIP) acts as the in vivo periplasmic electron donor to the reaction center (RC)-bound cytochrome when cells are grown under anaerobic conditions in the light, while cytochrome c is the soluble electron carrier for cells grown under (8)aerobic conditions in the dark. A spontaneous reversion of R. gelatinosus C244, a defective mutant in synthesis of the RC-bound cytochrome by insertion of a Km(r) cassette leading to gene disruption with a slow growth rate, restores the normal photosynthetic growth. This revertant, designated C244-P1, lost the Km(r) cassette but synthesized a RC-bound cytochrome with an external 77-amino acid insertion derived from the cassette. We characterized the RC-bound cytochrome of this mutant by EPR, time-resolved optical spectroscopy, and structural analysis. We also investigated the in vivo electron transfer rates between the two soluble electron donors and this RC-bound cytochrome. Our results demonstrated that the C244-P1 RC-bound cytochrome is still able to receive electrons from HiPIP, but it is no longer reducible by cytochrome c(8). Combining these experimental and theoretical protein-protein docking results, we conclude that cytochrome c(8) and HiPIP bind the RC-bound cytochrome at two distinct but partially overlapping sites.
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Affiliation(s)
- Jean Alric
- Laboratoire de Génétique et Biophysique des Plantes, UMR 6191 CNRS-Commissariat à l'Energie Atomique-Aix-Marseille II, 163 avenue de Luminy, Marseille 13288, France
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Maki H, Matsuura K, Shimada K, Nagashima KVP. Chimeric photosynthetic reaction center complex of purple bacteria composed of the core subunits of Rubrivivax gelatinosus and the cytochrome subunit of Blastochloris viridis. J Biol Chem 2003; 278:3921-8. [PMID: 12464624 DOI: 10.1074/jbc.m209069200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A gene coding for the photosynthetic reaction center-bound cytochrome subunit, pufC, of Blastochloris viridis, which belongs to the alpha-purple bacteria, was introduced into Rubrivivax gelatinosus, which belongs to the beta-purple bacteria. The cytochrome subunit of B. viridis was synthesized in the R. gelatinosus cells, in which the native pufC gene was knocked out, and formed a chimeric reaction center (RC) complex together with other subunits of R. gelatinosus. The transformant was able to grow photosynthetically. Rapid photo-oxidization of the hemes in the cytochrome subunit was observed in the membrane of the transformant. The soluble electron carrier, cytochrome c(2), isolated from B. viridis was a good electron donor to the chimeric RC. The redox midpoint potentials and the redox difference spectra of four hemes in the cytochrome subunit of the chimeric RC were almost identical with those in the B. viridis RC. The cytochrome subunit of B. viridis seems to retain its structure and function in the R. gelatinosus cell. The chimeric RC and its mutagenesis system should be useful for further studies about the cytochrome subunit of B. viridis.
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Affiliation(s)
- Hideaki Maki
- Department of Biology, Tokyo Metropolitan University, Minamiohsawa 1-1, Hachioji, Japan
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Harada J, Nagashima KV, Takaichi S, Misawa N, Matsuura K, Shimada K. Phytoene desaturase, CrtI, of the purple photosynthetic bacterium, Rubrivivax gelatinosus, produces both neurosporene and lycopene. PLANT & CELL PHYSIOLOGY 2001; 42:1112-8. [PMID: 11673627 DOI: 10.1093/pcp/pce140] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Biosynthetic pathways for carotenoids in the purple photosynthetic bacterium, Rubrivivax gelatinosus, which synthesizes spirilloxanthin in addition to spheroidene and OH-spheroidene, were investigated by means of genetic manipulation. A phytoene desaturase gene (crtI) found in the photosynthesis gene cluster of this bacterium was expressed in an Escherichia coli strain that can produce phytoene. Both neurosporene and lycopene were synthesized in the recombinant, probably by three- and four-step desaturation reactions of CrtI. A mutant of RVI: gelatinosus lacking the crtI gene produced only phytoene, indicating that this organism had no other phytoene desaturases. When the crtI deletion mutant was complemented by the three-step phytoene desaturase of Rhodobacter capsulatus, spirilloxanthin and its precursors were not synthesized, although spheroidene and OH-spheroidene were accumulated. It was concluded that neurosporene and lycopene are produced by a single phytoene desaturase in RVI: gelatinosus resulting in the synthesis of spheroidene and spirilloxanthin, and that there are no pathways for spirilloxanthin synthesis via spheroidene.
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Affiliation(s)
- J Harada
- Department of Biology, Tokyo Metropolitan University, Minami-ohsawa 1-1, Hachioji, Tokyo, 192-0397 Japan.
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Masuda S, Yoshida M, Nagashima KV, Shimada K, Matsuura K. A new cytochrome subunit bound to the photosynthetic reaction center in the purple bacterium, Rhodovulum sulfidophilum. J Biol Chem 1999; 274:10795-801. [PMID: 10196154 DOI: 10.1074/jbc.274.16.10795] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The nucleotide sequence of the puf operon, which contains the genes encoding the B870 light-harvesting protein and the reaction center complex of the purple photosynthetic bacterium, Rhodovulum sulfidophilum, was determined. The operon, which consisted of six genes, pufQ, pufB, pufA, pufL, pufM, and pufC, is a new variety in photosynthetic bacteria in the sense that pufQ and pufC coexist. The amino acid sequence of the cytochrome subunit of the reaction center deduced from the pufC sequence revealed that this cytochrome contains only three possible heme-binding motifs; the heme-1-binding motif of the corresponding tetraheme cytochrome subunits was not present. This is the first exception of the "tetraheme" cytochrome family in purple bacteria and green filamentous bacteria. The pufC sequence also revealed that the sixth axial ligands to heme-1 and heme-2 irons were not present in the cytochrome either. This cytochrome was actually detected in membrane preparation as a 43-kDa protein and shown to associate functionally with the photosynthetic reaction center as the immediate electron donor to the photo-oxidized special pair of bacteriochlorophyll. This new cytochrome should be useful for studies on the role of each heme in the cytochrome subunit of the bacterial reaction center and the evolution of proteins in photosynthetic electron transfer systems.
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Affiliation(s)
- S Masuda
- Department of Biology, Tokyo Metropolitan University, Minamiohsawa, Hachioji, Tokyo 192-0397, Japan.
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Osyczka A, Yoshida M, Nagashima KV, Shimada K, Matsuura K. Electron transfer from high-potential iron-sulfur protein and low-potential cytochrome c-551 to the primary donor of Rubrivivax gelatinosus reaction center mutationally devoid of the bound cytochrome subunit. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1997. [DOI: 10.1016/s0005-2728(97)00041-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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