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Yakovlev AG, Taisova AS. Quenching of bacteriochlorophyll a triplet state by carotenoids in the chlorosome baseplate of green bacterium Chloroflexus aurantiacus. Phys Chem Chem Phys 2024; 26:8815-8823. [PMID: 38421198 DOI: 10.1039/d4cp00287c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
To capture weak light fluxes, green photosynthetic bacteria have unique structures - chlorosomes, consisting of 104-5 molecules of bacteriochlorophyll (BChl) c, d, e. Chlorosomes are attached to the cytoplasmic membrane through the baseplate, a paracrystalline protein structure containing BChl a and carotenoids (Car). The most important function of Car is the quenching of triplet states of BChl, which prevents the formation of singlet oxygen and thereby provides photoprotection. In our work, we studied the dynamics of the triplet states of BChl a and Car in the baseplate of Chloroflexus aurantiacus chlorosomes using picosecond differential spectroscopy. BChl a of the baseplate was excited into the Qy band at 810 nm, and the corresponding absorption changes were recorded in the range of 420-880 nm. It was found that the formation of the Car triplet state occurs in ∼1.3 ns, which is ∼3 times faster than the formation of this state in the peripheral antenna of C. aurantiacus according to literature data. The Car triplet state was recorded by the characteristic absorption band T1 → Tn at ∼550 nm. Simultaneously with the appearance of absorption T1 → Tn, there was a bleaching of the singlet absorption of Car in the region of 400-500 nm. Theoretical modeling made it possible to estimate the characteristic time of formation of the triplet state of BChl a as ∼0.5 ns. It is shown that the experimental data are well described by the sequential scheme of formation and quenching of the BChl a triplet state: BChl a* → BChl aT → CarT. Thus, carotenoids from green bacteria effectively protect the baseplate from possible damage by singlet oxygen.
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Affiliation(s)
- Andrei G Yakovlev
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Leninskie Gory, Moscow 119991, Russian Federation.
| | - Alexandra S Taisova
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Leninskie Gory, Moscow 119991, Russian Federation.
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2
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Tsuji JM, Shaw NA, Nagashima S, Venkiteswaran JJ, Schiff SL, Watanabe T, Fukui M, Hanada S, Tank M, Neufeld JD. Anoxygenic phototroph of the Chloroflexota uses a type I reaction centre. Nature 2024; 627:915-922. [PMID: 38480893 PMCID: PMC10972752 DOI: 10.1038/s41586-024-07180-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 02/08/2024] [Indexed: 04/01/2024]
Abstract
Scientific exploration of phototrophic bacteria over nearly 200 years has revealed large phylogenetic gaps between known phototrophic groups that limit understanding of how phototrophy evolved and diversified1,2. Here, through Boreal Shield lake water incubations, we cultivated an anoxygenic phototrophic bacterium from a previously unknown order within the Chloroflexota phylum that represents a highly novel transition form in the evolution of photosynthesis. Unlike all other known phototrophs, this bacterium uses a type I reaction centre (RCI) for light energy conversion yet belongs to the same bacterial phylum as organisms that use a type II reaction centre (RCII) for phototrophy. Using physiological, phylogenomic and environmental metatranscriptomic data, we demonstrate active RCI-utilizing metabolism by the strain alongside usage of chlorosomes3 and bacteriochlorophylls4 related to those of RCII-utilizing Chloroflexota members. Despite using different reaction centres, our phylogenomic data provide strong evidence that RCI-utilizing and RCII-utilizing Chloroflexia members inherited phototrophy from a most recent common phototrophic ancestor. The Chloroflexota phylum preserves an evolutionary record of the use of contrasting phototrophic modes among genetically related bacteria, giving new context for exploring the diversification of phototrophy on Earth.
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Affiliation(s)
- J M Tsuji
- University of Waterloo, Waterloo, Ontario, Canada.
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan.
- Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan.
| | - N A Shaw
- University of Waterloo, Waterloo, Ontario, Canada
| | - S Nagashima
- Tokyo Metropolitan University, Tokyo, Japan
- Kanagawa University, Yokohama, Japan
| | - J J Venkiteswaran
- University of Waterloo, Waterloo, Ontario, Canada
- Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - S L Schiff
- University of Waterloo, Waterloo, Ontario, Canada
| | - T Watanabe
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan
| | - M Fukui
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan
| | - S Hanada
- Tokyo Metropolitan University, Tokyo, Japan
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - M Tank
- Tokyo Metropolitan University, Tokyo, Japan
- Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany
| | - J D Neufeld
- University of Waterloo, Waterloo, Ontario, Canada.
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3
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Proteomic Time-Course Analysis of the Filamentous Anoxygenic Phototrophic Bacterium, Chloroflexus aurantiacus, during the Transition from Respiration to Phototrophy. Microorganisms 2022; 10:microorganisms10071288. [PMID: 35889008 PMCID: PMC9316378 DOI: 10.3390/microorganisms10071288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 02/05/2023] Open
Abstract
Chloroflexus aurantiacus is a filamentous anoxygenic phototrophic bacterium that grows chemotrophically under oxic conditions and phototrophically under anoxic conditions. Because photosynthesis-related genes are scattered without any gene clusters in the genome, it is still unclear how this bacterium regulates protein expression in response to environmental changes. In this study, we performed a proteomic time-course analysis of how C. aurantiacus expresses proteins to acclimate to environmental changes, namely the transition from chemoheterotrophic respiratory to photoheterotrophic growth mode. Proteomic analysis detected a total of 2520 proteins out of 3934 coding sequences in the C. aurantiacus genome from samples collected at 13 time points. Almost all proteins for reaction centers, light-harvesting chlorosomes, and carbon fixation pathways were successfully detected during the growing phases in which optical densities and relative bacteriochlorophyll c contents increased simultaneously. Combination of proteomics and pigment analysis suggests that the self-aggregation of bacteriochlorophyllide c could precede the esterification of the hydrophobic farnesyl tail in cells. Cytoplasmic subunits of alternative complex III were interchanged between oxic and anoxic conditions, although membrane-bound subunits were used for both conditions. These data highlight the protein expression dynamics of phototrophy-related genes during the transition from respiration to phototrophy.
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4
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Self-aggregation of zinc bacteriochlorophyll-d analog bearing B-ring reduced chlorin and 17-acrylate residue. Tetrahedron 2021. [DOI: 10.1016/j.tet.2020.131853] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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5
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Dabravolski SA, Isayenkov SV. Evolution of Plant Na +-P-Type ATPases: From Saline Environments to Land Colonization. PLANTS 2021; 10:plants10020221. [PMID: 33498844 PMCID: PMC7911474 DOI: 10.3390/plants10020221] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/20/2021] [Accepted: 01/21/2021] [Indexed: 11/17/2022]
Abstract
Soil salinity is one of the major factors obstructing the growth and development of agricultural crops. Eukaryotes have two main transport systems involved in active Na+ removal: cation/H+ antiporters and Na+-P-type ATPases. Key transport proteins, Na+/K+-P-ATPases, are widely distributed among the different taxa families of pumps which are responsible for keeping cytosolic Na+ concentrations below toxic levels. Na+/K+-P-ATPases are considered to be absent in flowering plants. The data presented here are a complete inventory of P-type Na+/K+-P-ATPases in the major branches of the plant kingdom. We also attempt to elucidate the evolution of these important membrane pumps in plants in comparison with other organisms. We were able to observe the gradual replacement of the Na+-binding site to the Ca2+-binding site, starting with cyanobacteria and moving to modern land plants. Our results show that the α-subunit likely evolved from one common ancestor to bacteria, fungi, plants, and mammals, whereas the β-subunit did not evolve in green algae. In conclusion, our results strongly suggest the significant differences in the domain architecture and subunit composition of plant Na+/K+-P-ATPases depending on plant taxa and the salinity of the environment. The obtained data clarified and broadened the current views on the evolution of Na+/K+-P-ATPases. The results of this work would be helpful for further research on P-type ATPase functionality and physiological roles.
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Affiliation(s)
- Siarhei A. Dabravolski
- Department of Clinical Diagnostics, Vitebsk State Academy of Veterinary Medicine [UO VGAVM], 21002 Vitebsk, Belarus;
| | - Stanislav V. Isayenkov
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan 528000, China
- Department of Plant Food Products and Biofortification, Institute of Food Biotechnology and Genomics NAS of Ukraine, 04123 Kyiv, Ukraine
- Correspondence: author:
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Supramolecular chlorophyll aggregates inspired from specific light-harvesting antenna “chlorosome”: Static nanostructure, dynamic construction process, and versatile application. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C: PHOTOCHEMISTRY REVIEWS 2020. [DOI: 10.1016/j.jphotochemrev.2020.100385] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Kishi M, Nakamura Y, Tamiaki H. Effect of additional hydroxy group on self-aggregation of synthetic zinc bacteriochlorophyll-c analogs. J Photochem Photobiol A Chem 2020. [DOI: 10.1016/j.jphotochem.2020.112592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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8
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Katayama A, Tamiaki H. Stereoselective self-aggregation of zinc bacteriochlorophyll-d analogs possessing an O-substituted oxime moiety at the 13-position. J Photochem Photobiol A Chem 2020. [DOI: 10.1016/j.jphotochem.2020.112554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Takeda T, Katayama A, Kinoshita Y, Tamiaki H. Synthesis of zinc 13-oxime-functionalized chlorophyll-a derivatives and their (131E/Z)-dependent self-aggregation. Tetrahedron 2020. [DOI: 10.1016/j.tet.2020.131300] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Katayama A, Tamiaki H. Synthesis of zinc bacteriochlorophyll-d analogs bearing an alkoxyimino group at the 131-position and their self-aggregation in an aqueous micelle solution. Tetrahedron Lett 2020. [DOI: 10.1016/j.tetlet.2019.151386] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Jassas M, Goodson C, Blankenship RE, Jankowiak R, Kell A. On Excitation Energy Transfer within the Baseplate BChl a-CsmA Complex of Chloroflexus aurantiacus. J Phys Chem B 2019; 123:9786-9791. [PMID: 31660744 DOI: 10.1021/acs.jpcb.9b08043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recently, a hybrid approach combining solid-state NMR spectroscopy and cryo-electron microscopy showed that the baseplate in green sulfur bacterium Chlorobaculum tepidum is a 2D lattice of BChl a-CsmA dimers [Nielsen, J. T.; et al., Nat. Commun. 2016, 7, 12454-12465]. While the existence of the BChl a-CsmA subunit was previously known, the proposed orientations of the BChl a pigments had only been elucidated from spectral data up to this point. Regarding the electronic structure of the baseplate, two models have been proposed. 2D electronic spectroscopy data were interpreted as revealing that at least four excitonically coupled BChl a might be in close contact. Conversely, spectral hole burning data suggested that the lowest energy state was localized, yet additional states are sometimes observed because of the presence of the Fenna-Matthews-Olson (FMO) antenna protein. To solve this conundrum, this work studies the chlorosome-baseplate complex from Chloroflexus aurantiacus, which does not contain the FMO protein. The results confirm that in both C. tepidum and C. aurantiacus, excitation energy is transferred to a localized low-energy trap state near 818 nm with similar rates, most likely via exciton hopping.
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Affiliation(s)
| | - Carrie Goodson
- Departments of Biology and Chemistry , Washington University in Saint Louis , Saint Louis , Missouri 63130 , United States
| | - Robert E Blankenship
- Departments of Biology and Chemistry , Washington University in Saint Louis , Saint Louis , Missouri 63130 , United States
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Fujiwara Y, Tamiaki H. Stereoselective self-aggregation of synthetic zinc 3 1-epimeric bacteriochlorophyll-d analogs possessing a methylene group at the 13 2-position as models of green photosynthetic bacterial chlorosomes. Photochem Photobiol Sci 2019; 18:1218-1227. [PMID: 30839974 DOI: 10.1039/c8pp00535d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Zinc bacteriochlorophyll-d analogs possessing a methylene group at the 132-position were prepared by chemical modification of naturally occurring chlorophyll-a. The synthetic 31-epimers were successfully separated by reverse phase HPLC to give diastereomerically pure samples. The stereochemistry of the chiral C31-center in the separated bacteriochlorophyll-d analogs was determined by HPLC analysis of the authentic stereoisomers prepared stereospecifically. Both the epimers were monomeric in tetrahydrofuran to give sharp absorption bands, while they self-aggregated to form chlorosomal oligomers with red-shifted bands in an aqueous Triton X-100 micelle solution. The resulting large oligomers deaggregated by addition of Triton X-100 to give monomeric species. Their aggregation and deaggregation were dependent on the 31-stereochemistry, indicating that each epimer produced self-aggregates that were supramolecularly different. The substitution with the 132-methylene group enhanced their self-aggregation abilities and the stability of their resulting self-aggregates.
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Affiliation(s)
- Yoshiki Fujiwara
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
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13
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Ranjbar Choubeh R, Koehorst RBM, Bína D, Struik PC, Pšenčík J, van Amerongen H. Efficiency of excitation energy trapping in the green photosynthetic bacterium Chlorobaculum tepidum. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:147-154. [PMID: 30537470 DOI: 10.1016/j.bbabio.2018.12.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 12/07/2018] [Accepted: 12/08/2018] [Indexed: 01/05/2023]
Abstract
During the millions of years of evolution, photosynthetic organisms have adapted to almost all terrestrial and aquatic habitats, although some environments are obviously more suitable for photosynthesis than others. Photosynthetic organisms living in low-light conditions require on the one hand a large light-harvesting apparatus to absorb as many photons as possible. On the other hand, the excitation trapping time scales with the size of the light-harvesting system, and the longer the distance over which the formed excitations have to be transferred, the larger the probability to lose excitations. Therefore a compromise between photon capture efficiency and excitation trapping efficiency needs to be found. Here we report results on the whole cells of the green sulfur bacterium Chlorobaculum tepidum. Its efficiency of excitation energy transfer and charge separation enables the organism to live in environments with very low illumination. Using fluorescence measurements with picosecond resolution, we estimate that despite a rather large size and complex composition of its light-harvesting apparatus, the quantum efficiency of its photochemistry is around ~87% at 20 °C, ~83% at 45 °C, and about ~81% at 77 K when part of the excitation energy is trapped by low-energy bacteriochlorophyll a molecules. The data are evaluated using target analysis, which provides further insight into the functional organization of the low-light adapted photosynthetic apparatus.
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Affiliation(s)
| | - Rob B M Koehorst
- Laboratory of Biophysics, Wageningen University, Wageningen, the Netherlands; MicroSpectroscopy Research Facility, Wageningen University, Wageningen, the Netherlands
| | - David Bína
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Paul C Struik
- Centre for Crop Systems Analysis, Wageningen University, Wageningen, the Netherlands
| | - Jakub Pšenčík
- Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
| | - Herbert van Amerongen
- Laboratory of Biophysics, Wageningen University, Wageningen, the Netherlands; MicroSpectroscopy Research Facility, Wageningen University, Wageningen, the Netherlands.
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Shoji S, Ogawa T, Hashishin T, Tamiaki H. Self-Assemblies of Zinc Bacteriochlorophyll-d Analogues Having Amide, Ester, and Urea Groups as Substituents at 17-Position and Observation of Lamellar Supramolecular Nanostructures. Chemphyschem 2018; 19:913-920. [PMID: 29231276 DOI: 10.1002/cphc.201701044] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 12/07/2017] [Indexed: 11/05/2022]
Abstract
Chlorosomes are unique light-harvesting apparatuses in photosynthetic green bacteria. Single chlorosomes contain a large number of bacteriochlorophyll (BChl)-c, -d, -e, and -f molecules, which self-assemble without protein assistance. These BChl self-assemblies involving specific intermolecular interactions (Mg⋅⋅⋅O32 -H⋅⋅⋅O=C131 and π-π stacks of chlorin skeletons) in a chlorosome have been reported to be round-shaped rods (or tubes) with diameters of 5 or 10 nm, or lamellae with a layer spacing of approximately 2 nm. Herein, the self-assembly of synthetic zinc BChl-d analogues having ester, amide, and urea groups in the 17-substituent is reported. Spectroscopic analyses indicate that the zinc BChl-d analogues self-assemble in a nonpolar organic solvent in a similar manner to natural chlorosomal BChls with additional assistance by hydrogen-bonding of secondary amide (or urea) groups (CON-H⋅⋅⋅O=CNH). Microscopic analyses of the supramolecules of a zinc BChl-d analogue bearing amide and urea groups show round- or square-shaped rods with widths of about 65 nm. Cryogenic TEM shows a lamellar arrangement of the zinc chlorin with a layer spacing of 1.5 nm inside the rod. Similar thick rods are also visible in the micrographs of self-assemblies of zinc BChl-d analogues with one or two secondary amide moieties in the 17-substituent.
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Affiliation(s)
- Sunao Shoji
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Tetsuya Ogawa
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Takeshi Hashishin
- Faculty of Engineering, Kumamoto University, Kumamoto, Kumamoto, 860-8555, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
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Saga Y, Takahashi N, Miyatake T, Tamiaki H. Amphiphilic zinc bacteriochlorophyll a derivatives that function as artificial energy acceptors in photosynthetic antenna complexes chlorosomes of the green sulfur photosynthetic bacterium Chlorobaculum limnaeum. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2017.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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16
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Metagenomic analysis reveals a green sulfur bacterium as a potential coral symbiont. Sci Rep 2017; 7:9320. [PMID: 28839161 PMCID: PMC5571212 DOI: 10.1038/s41598-017-09032-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 07/20/2017] [Indexed: 01/27/2023] Open
Abstract
Coral reefs are ecologically significant habitats. Coral-algal symbiosis confers ecological success on coral reefs and coral-microbial symbiosis is also vital to coral reefs. However, current understanding of coral-microbial symbiosis on a genomic scale is largely unknown. Here we report a potential microbial symbiont in corals revealed by metagenomics-based genomic study. Microbial cells in coral were enriched for metagenomic analysis and a high-quality draft genome of “Candidatus Prosthecochloris korallensis” was recovered by metagenome assembly and genome binning. Phylogenetic analysis shows “Ca. P. korallensis” belongs to the Prosthecochloris clade and is clustered with two Prosthecochloris clones derived from Caribbean corals. Genomic analysis reveals “Ca. P. korallensis” has potentially important ecological functions including anoxygenic photosynthesis, carbon fixation via the reductive tricarboxylic acid (rTCA) cycle, nitrogen fixation, and sulfur oxidization. Core metabolic pathway analysis suggests “Ca. P. korallensis” is a green sulfur bacterium capable of photoautotrophy or mixotrophy. Potential host-microbial interaction reveals a symbiotic relationship: “Ca. P. korallensis” might provide organic and nitrogenous nutrients to its host and detoxify sulfide for the host; the host might provide “Ca. P. korallensis” with an anaerobic environment for survival, carbon dioxide and acetate for growth, and hydrogen sulfide as an electron donor for photosynthesis.
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Orf GS, Collins AM, Niedzwiedzki DM, Tank M, Thiel V, Kell A, Bryant DA, Montaño GA, Blankenship RE. Polymer-Chlorosome Nanocomposites Consisting of Non-Native Combinations of Self-Assembling Bacteriochlorophylls. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:6427-6438. [PMID: 28585832 DOI: 10.1021/acs.langmuir.7b01761] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Chlorosomes are one of the characteristic light-harvesting antennas from green sulfur bacteria. These complexes represent a unique paradigm: self-assembly of bacteriochlorophyll pigments within a lipid monolayer without the influence of protein. Because of their large size and reduced complexity, they have been targeted as models for the development of bioinspired light-harvesting arrays. We report the production of biohybrid light-harvesting nanocomposites mimicking chlorosomes, composed of amphiphilic diblock copolymer membrane bodies that incorporate thousands of natural self-assembling bacteriochlorophyll molecules derived from green sulfur bacteria. The driving force behind the assembly of these polymer-chlorosome nanocomposites is the transfer of the mixed raw materials from the organic to the aqueous phase. We incorporated up to five different self-assembling pigment types into single nanocomposites that mimic chlorosome morphology. We establish that the copolymer-BChl self-assembly process works smoothly even when non-native combinations of BChl homologues are included. Spectroscopic characterization revealed that the different types of self-assembling pigments participate in ultrafast energy transfer, expanding beyond single chromophore constraints of the natural chlorosome system. This study further demonstrates the utility of flexible short-chain, diblock copolymers for building scalable, tunable light-harvesting arrays for technological use and allows for an in vitro analysis of the flexibility of natural self-assembling chromophores in unique and controlled combinations.
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Affiliation(s)
| | - Aaron M Collins
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | | | - Marcus Tank
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
- Department of Biological Sciences, Tokyo Metropolitan University , Tokyo, Japan 192-0397
| | - Vera Thiel
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
- Department of Biological Sciences, Tokyo Metropolitan University , Tokyo, Japan 192-0397
| | - Adam Kell
- Department of Chemistry, Kansas State University , Manhattan, Kansas 66506, United States
| | - Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Gabriel A Montaño
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
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Light harvesting in phototrophic bacteria: structure and function. Biochem J 2017; 474:2107-2131. [DOI: 10.1042/bcj20160753] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 04/03/2017] [Accepted: 04/06/2017] [Indexed: 12/23/2022]
Abstract
This review serves as an introduction to the variety of light-harvesting (LH) structures present in phototrophic prokaryotes. It provides an overview of the LH complexes of purple bacteria, green sulfur bacteria (GSB), acidobacteria, filamentous anoxygenic phototrophs (FAP), and cyanobacteria. Bacteria have adapted their LH systems for efficient operation under a multitude of different habitats and light qualities, performing both oxygenic (oxygen-evolving) and anoxygenic (non-oxygen-evolving) photosynthesis. For each LH system, emphasis is placed on the overall architecture of the pigment–protein complex, as well as any relevant information on energy transfer rates and pathways. This review addresses also some of the more recent findings in the field, such as the structure of the CsmA chlorosome baseplate and the whole-cell kinetics of energy transfer in GSB, while also pointing out some areas in need of further investigation.
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Shoji S, Mizoguchi T, Tamiaki H. In vitro self-assemblies of bacteriochlorophylls-c from Chlorobaculum tepidum and their supramolecular nanostructures. J Photochem Photobiol A Chem 2016. [DOI: 10.1016/j.jphotochem.2015.11.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
The grand scale, ultimate efficiency, and sustainability of natural photosynthesis have inspired generations of researchers in biomimetic light energy utilization. As an essential and ubiquitous component in all photosynthetic machinery, lipids and their assemblies have long been recognized as powerful molecular scaffolds in building artificial photosynthetic systems. Model lipid bilayers, such as black lipid membranes and liposomes (vesicles), have been extensively used to host natural as well as synthetic photo- and redox-active species, thereby enabling key photosynthetic processes, such as energy transfer and photoinduced electron transfer, to be examined in well-defined, natural-like membrane settings. Despite their long history, these lipid models remain highly relevant and still enjoy wide practice today. In this Account, we share with the reader our recent effort of introducing electrode-supported lipid nanoassemblies as new lipid models into photosynthesis biomimicking. This line of research builds off several solid-supported lipid bilayer architectures established relatively recently by workers in membrane biophysics and reveals important new features that match and sometimes exceed what earlier lipid models are capable of offering. Here, our eight-year exploration unfolds in three sections: (1) New photosynthetic mimics based on solid-supported lipid bilayers. This systematic effort has brought three solid-supported bilayers into artificial photosynthesis research: lipid bilayers supported on indium tin oxide electrodes, hybrid bilayers, and tethered lipid bilayers formed on gold. Quantitative on-electrode deposition of various photo- and redox-active agents, including fullerene, Ru(bpy)32+, and porphyrin, is realized via liposomal hosts. Vectorial electron transfer across single lipid-bilayer leaflets is achieved between electron donor/acceptor directionally organized therein, taking advantage of multiple incorporation sites offered by these bilayers as well as their sequential formation on electrodes. Supported on electrodes, these bilayers uniformly afford reliable photocurrent generation and modular system design. (2) Gold-supported hybrid bilayers as a powerful model platform for probing biomembrane-associated photoelectrochemical processes. These hybrid nanostructures consist of one alkanethiol (or substituted alkanethiol) and one lipid monolayer, whose chemical identity and makeup can be separately controlled and modified. Such precise molecular organization and flexible formation, in turn, enable a series of physicochemical parameters key to photosynthetic processes to be explicitly examined and cross-compared. A few such examples, based on donor/acceptor distance and loading, interfacial dipole, and redox level, are included here to illustrate the usefulness and versatility of this system. (3) Mimicking photosynthesis with supercomplexed lipid nanoassemblies. This research effort was motivated to address the low light absorption suffered by single-bilayer based photosynthetic mimics and has yielded a new lipid-based approach to mimicking Nature's way of organizing multiple photosynthetic subunits. Rhodamine and fullerene assembled within these lipid supercomplexes display robust electronic communication. The remarkable possibility of using lipid matrix to further improve photoconversion efficiency is revealed by cholesterol, whose addition triggers exciton formation that promotes faster energy and electron transfer in these lipid nanoassemblies.
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Affiliation(s)
- Mingming Wang
- Department of Chemistry and
Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Wei Zhan
- Department of Chemistry and
Biochemistry, Auburn University, Auburn, Alabama 36849, United States
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21
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In situ high-resolution structure of the baseplate antenna complex in Chlorobaculum tepidum. Nat Commun 2016; 7:12454. [PMID: 27534696 PMCID: PMC4992139 DOI: 10.1038/ncomms12454] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 07/05/2016] [Indexed: 01/01/2023] Open
Abstract
Photosynthetic antenna systems enable organisms harvesting light and transfer the energy to the photosynthetic reaction centre, where the conversion to chemical energy takes place. One of the most complex antenna systems, the chlorosome, found in the photosynthetic green sulfur bacterium Chlorobaculum (Cba.) tepidum contains a baseplate, which is a scaffolding super-structure, formed by the protein CsmA and bacteriochlorophyll a. Here we present the first high-resolution structure of the CsmA baseplate using intact fully functional, light-harvesting organelles from Cba. tepidum, following a hybrid approach combining five complementary methods: solid-state NMR spectroscopy, cryo-electron microscopy, isotropic and anisotropic circular dichroism and linear dichroism. The structure calculation was facilitated through development of new software, GASyCS for efficient geometry optimization of highly symmetric oligomeric structures. We show that the baseplate is composed of rods of repeated dimers of the strongly amphipathic CsmA with pigments sandwiched within the dimer at the hydrophobic side of the helix. The chlorosome of the photosynthetic bacterium C. tepidum harvests light and transfers the energy to the photosynthetic reaction centre. Here the authors determine the structure of the baseplate, a scaffolding super-structure, to show that the baseplate consists of rods of repeated CsmA dimers containing pigment molecules.
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22
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Wang M, Chen J, Lian T, Zhan W. Mimicking Photosynthesis with Supercomplexed Lipid Nanoassemblies: Design, Performance, and Enhancement Role of Cholesterol. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:7326-7338. [PMID: 27352779 DOI: 10.1021/acs.langmuir.6b01608] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report here a new approach to mimicking photosynthesis that relies on supercomplexed lipid nanoassemblies to organize small organic species for coordinated light harvesting, energy/electron transfer, and photo-to-electrochemical energy conversion. Specifically, we demonstrate efficient photoinduced electron transfer (PeT) between rhodamine and fullerene assembled together via electrostatically bound liposome and lipid bilayer hosts. The remarkable impact of the lipid matrix on the photoconversion efficiency is further revealed by cholesterol, whose addition is found to modify the distribution and organization of the coassembled rhodamine dyes and thus their photodynamics. This significantly expedites the energy transfer (ET) among rhodamine dyes, as well as the PeT between rhodamines and fullerenes. A respectable 14% photon-to-electron conversion efficiency was achieved for this supercomplexed system containing 5% rhodamines, 5% fullerenes, and 30% cholesterol. The morphology, photodynamics, and photoelectrochemical behavior of these lipid supercomplexes were thoroughly characterized using atomic force microscopy (AFM), fluorescence microscopy, steady-state and time-resolved fluorescence spectroscopy, and transient absorption (TA) and photoaction spectroscopy. A detailed discussion on enhancement mechanisms of cholesterol in this lipid-complexed photosynthesis-mimicking system is provided at the end.
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Affiliation(s)
- Mingming Wang
- Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849, United States
| | - Jinquan Chen
- Department of Chemistry, Emory University , Atlanta, Georgia 30322, United States
| | - Tianquan Lian
- Department of Chemistry, Emory University , Atlanta, Georgia 30322, United States
| | - Wei Zhan
- Department of Chemistry and Biochemistry, Auburn University , Auburn, Alabama 36849, United States
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23
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Tsukatani Y, Mizoguchi T, Thweatt J, Tank M, Bryant DA, Tamiaki H. Glycolipid analyses of light-harvesting chlorosomes from envelope protein mutants of Chlorobaculum tepidum. PHOTOSYNTHESIS RESEARCH 2016; 128:235-241. [PMID: 26869354 DOI: 10.1007/s11120-016-0228-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 01/25/2016] [Indexed: 06/05/2023]
Abstract
Chlorosomes are large and efficient light-harvesting organelles in green photosynthetic bacteria, and they characteristically contain large numbers of bacteriochlorophyll c, d, or e molecules. Self-aggregated bacteriochlorophyll pigments are surrounded by a monolayer envelope membrane comprised of glycolipids and Csm proteins. Here, we analyzed glycolipid compositions of chlorosomes from the green sulfur bacterium Chlorobaculum tepidum mutants lacking one, two, or three Csm proteins by HPLC equipped with an evaporative light-scattering detector. The ratio of monogalactosyldiacylglyceride (MGDG) to rhamnosylgalactosyldiacylglyceride (RGDG) was smaller in chlorosomes from mutants lacking two or three proteins in CsmC/D/H motif family than in chlorosomes from the wild-type, whereas chlorosomes lacking CsmIJ showed relatively less RGDG than MGDG. The results suggest that the CsmC, CsmD, CsmH, and other chlorosome proteins are involved in organizing MGDG and RGDG and thereby affect the size and shape of the chlorosome.
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Affiliation(s)
- Yusuke Tsukatani
- Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 152-8550, Japan.
- PRESTO, Japan Science and Technology Agency, Saitama, 332-0012, Japan.
| | - Tadashi Mizoguchi
- Graduate School of Life Sciences, Ritsumeikan University, Shiga, 525-8577, Japan
| | - Jennifer Thweatt
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, Pennsylvania, 16802, USA
| | - Marcus Tank
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, Pennsylvania, 16802, USA
| | - Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, Pennsylvania, 16802, USA
- Department of Chemistry and Biochemistry, Montana State University, Montana, 59717, USA
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Shiga, 525-8577, Japan
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24
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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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25
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Bína D, Gardian Z, Vácha F, Litvín R. Native FMO-reaction center supercomplex in green sulfur bacteria: an electron microscopy study. PHOTOSYNTHESIS RESEARCH 2016; 128:93-102. [PMID: 26589322 DOI: 10.1007/s11120-015-0205-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/12/2015] [Indexed: 06/05/2023]
Abstract
Chlorobaculum tepidum is a representative of green sulfur bacteria, a group of anoxygenic photoautotrophs that employ chlorosomes as the main light-harvesting structures. Chlorosomes are coupled to a ferredoxin-reducing reaction center by means of the Fenna-Matthews-Olson (FMO) protein. While the biochemical properties and physical functioning of all the individual components of this photosynthetic machinery are quite well understood, the native architecture of the photosynthetic supercomplexes is not. Here we report observations of membrane-bound FMO and the analysis of the respective FMO-reaction center complex. We propose the existence of a supercomplex formed by two reaction centers and four FMO trimers based on the single-particle analysis of the complexes attached to native membrane. Moreover, the structure of the photosynthetic unit comprising the chlorosome with the associated pool of RC-FMO supercomplexes is proposed.
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Affiliation(s)
- David Bína
- Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic.
- Institute of Plant Molecular Biology, Biology Centre CAS, Branišovská 31, 370 05, České Budějovice, Czech Republic.
| | - Zdenko Gardian
- Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
- Institute of Plant Molecular Biology, Biology Centre CAS, Branišovská 31, 370 05, České Budějovice, Czech Republic
| | - František Vácha
- Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
- Institute of Plant Molecular Biology, Biology Centre CAS, Branišovská 31, 370 05, České Budějovice, Czech Republic
| | - Radek Litvín
- Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, České Budějovice, Czech Republic
- Institute of Plant Molecular Biology, Biology Centre CAS, Branišovská 31, 370 05, České Budějovice, Czech Republic
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26
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Watanabe H, Mizoguchi T, Tamiaki H. Stereoselective Self-Aggregation of 3 1 -Epimerically Pure Amino Analogs of Zinc Bacteriochlorophyll-d in an Aqueous Micelle Solution. Photochem Photobiol 2016; 92:276-285. [PMID: 26757057 DOI: 10.1111/php.12562] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 11/25/2015] [Indexed: 12/12/2022]
Abstract
Zinc bacteriochlorophyll-d analogs possessing an amino group instead of the original hydroxy group at the C31 position were prepared by chemical modification of naturally occurring chlorophyll-a. The synthetic 31 -epimers were successfully separated by reverse phase HPLC to give diastereomerically pure samples. The stereochemistry of the chiral C31 -center in the separated amines was determined by NMR analysis of their diastereomeric amides as well as by their asymmetric synthesis from authentic stereoisomers. Both the epimers were monomeric in tetrahydrofuran to give sharp electronic absorption bands, while they self-aggregated to form chlorosomal oligomers with the redshifted bands in an aqueous Triton X-100 micelle solution (pH = 6.9). The resulting oligomers deaggregated by addition of p-toluenesulfonic acid to give monomeric N-protonated ammonium species. The aggregation and deaggregation were dependent on the 31 -stereochemistry, indicating that each epimer produced supramolecularly different self-aggregates.
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Affiliation(s)
- Hiroaki Watanabe
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Tadashi Mizoguchi
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
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27
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Yakovlev A, Novoderezhkin V, Taisova A, Shuvalov V, Fetisova Z. Orientation of B798 BChl a Q y transition dipoles in Chloroflexus aurantiacus chlorosomes: polarized transient absorption spectroscopy studies. PHOTOSYNTHESIS RESEARCH 2015; 125:31-42. [PMID: 25515768 DOI: 10.1007/s11120-014-0060-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 11/16/2014] [Indexed: 06/04/2023]
Abstract
Isotropic and anisotropic pump-probe spectra of Cfx. aurantiacus chlorosomes were measured on the fs-through ps-time scales for the B798 BChl a Q y band upon direct excitation of the B798 band at T = 293 K and T = 90 K. Upon direct excitation of the B798 band, the anisotropy parameter value r(λ) was constant within the whole BChl a Q y band at any delay time at both temperatures. The value of the anisotropy parameter r decayed from r = 0.4 at both temperatures (at 200 fs delay time after excitation) to the steady-state values r = 0.1 at T = 293 K and to r = 0.09 at T = 90 K (at 30 ÷ 100 ps delay time after excitation). The results were considered within the framework of the model of uniaxial orientation distribution of BChl-a transition dipoles within a single Cfx. aurantiacus chlorosome. This implies that the B798 BChl a Q y transition dipoles, randomly distributed around the normal to the baseplate plane, form the angle θ with the plane. For this model, the theoretical dependence of the steady-state anisotropy parameter r on the angle θ was derived. According to the theoretical dependence r(θ), the angle θ corresponding to the experimental steady-state value r = 0.1 at T = 293 K was found to equal 55°. As the temperature drops to 90 K, the angle θ decreases to 54°.
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Affiliation(s)
- Andrei Yakovlev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, 119991, Moscow, Russian Federation
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28
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Kell A, Chen J, Jassas M, Tang JKH, Jankowiak R. Alternative Excitonic Structure in the Baseplate (BChl a-CsmA Complex) of the Chlorosome from Chlorobaculum tepidum. J Phys Chem Lett 2015; 6:2702-2707. [PMID: 26266851 DOI: 10.1021/acs.jpclett.5b01074] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In the photosynthetic green sulfur bacterium Chlorobaculum tepidum, the baseplate mediates excitation energy transfer from the light-harvesting chlorosome to the Fenna-Matthews-Olson (FMO) complex and subsequently toward the reaction center (RC). Literature data suggest that the baseplate is a 2D lattice of BChl a-CsmA dimers. However, recently, it has been proposed, using 2D electronic spectroscopy (2DES) at 77 K, that at least four excitonically coupled BChl a are in close contact within the baseplate structure [ Dostál , J. ; et al., J. Phys. Chem. Lett. 2014 , 5 , 1743 ]. This finding is tested via hole burning (HB) spectroscopy (5 K). Our results indicate that the four excitonic states identified by 2DES likely correspond to contamination of the baseplate with the FMO antenna and possibly the RC. In contrast, HB reveals a different excitonic structure of the baseplate chromophores, where excitation is transferred to a localized trap state near 818 nm via exciton hopping, which leads to emission near 826 nm.
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Affiliation(s)
| | | | | | - Joseph Kuo-Hsiang Tang
- ‡Department of Chemistry and Biochemistry, Clark University, Worcester, Massachusetts 01610, United States
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29
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Grouzdev DS, Kuznetsov BB, Keppen OI, Krasil’nikova EN, Lebedeva NV, Ivanovsky RN. Reconstruction of bacteriochlorophyll biosynthesis pathways in the filamentous anoxygenic phototrophic bacterium Oscillochloris trichoides DG-6 and evolution of anoxygenic phototrophs of the order Chloroflexales. Microbiology (Reading) 2015; 161:120-130. [DOI: 10.1099/mic.0.082313-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Denis S. Grouzdev
- Faculty of Biology, Moscow State University, Moscow, Russia
- Bioengineering Center, Russian Academy of Sciences, Moscow, Russia
| | | | - Olga I. Keppen
- Faculty of Biology, Moscow State University, Moscow, Russia
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30
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Bína D, Gardian Z, Vácha F, Litvín R. Supramolecular organization of photosynthetic membrane proteins in the chlorosome-containing bacterium Chloroflexus aurantiacus. PHOTOSYNTHESIS RESEARCH 2014; 122:13-21. [PMID: 24760483 DOI: 10.1007/s11120-014-0006-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 04/08/2014] [Indexed: 06/03/2023]
Abstract
The arrangement of core antenna complexes (B808-866-RC) in the cytoplasmic membrane of filamentous phototrophic bacterium Chloroflexus aurantiacus was studied by electron microscopy in cultures from different light conditions. A typical nearest-neighbor center-to-center distance of ~18 nm was found, implying less protein crowding compared to membranes of purple bacteria. A mean RC:chlorosome ratio of 11 was estimated for the occupancy of the membrane directly underneath each chlorosome, based on analysis of chlorosome dimensions and core complex distribution. Also presented are results of single-particle analysis of core complexes embedded in the native membrane.
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Affiliation(s)
- David Bína
- Faculty of Science, University of South Bohemia, Branišovská 31, 37005, České Budějovice, Czech Republic,
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31
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Kudryashev M, Aktoudianaki A, Dedoglou D, Stahlberg H, Tsiotis G. The ultrastructure of Chlorobaculum tepidum revealed by cryo-electron tomography. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1635-42. [DOI: 10.1016/j.bbabio.2014.06.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 06/04/2014] [Accepted: 06/10/2014] [Indexed: 11/28/2022]
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32
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León-Montiel RDJ, Kassal I, Torres JP. Importance of Excitation and Trapping Conditions in Photosynthetic Environment-Assisted Energy Transport. J Phys Chem B 2014; 118:10588-94. [DOI: 10.1021/jp505179h] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Roberto de J. León-Montiel
- ICFO−Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain
| | - Ivan Kassal
- Centre
for Engineered Quantum Systems, Centre for Quantum Computation and
Communication Technology, and School of Mathematics and Physics, The University of Queensland, Brisbane QLD 4072, Australia
| | - Juan P. Torres
- ICFO−Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain
- Department
of Signal Theory and Communications, Campus Nord D3, Universitat Politecnica de Catalunya, 08034 Barcelona, Spain
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Fujita T, Huh J, Saikin SK, Brookes JC, Aspuru-Guzik A. Theoretical characterization of excitation energy transfer in chlorosome light-harvesting antennae from green sulfur bacteria. PHOTOSYNTHESIS RESEARCH 2014; 120:273-289. [PMID: 24504540 DOI: 10.1007/s11120-014-9978-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 01/23/2014] [Indexed: 06/03/2023]
Abstract
We present a theoretical study of excitation dynamics in the chlorosome antenna complex of green photosynthetic bacteria based on a recently proposed model for the molecular assembly. Our model for the excitation energy transfer (EET) throughout the antenna combines a stochastic time propagation of the excitonic wave function with molecular dynamics simulations of the supramolecular structure and electronic structure calculations of the excited states. We characterized the optical properties of the chlorosome with absorption, circular dichroism and fluorescence polarization anisotropy decay spectra. The simulation results for the excitation dynamics reveal a detailed picture of the EET in the chlorosome. Coherent energy transfer is significant only for the first 50 fs after the initial excitation, and the wavelike motion of the exciton is completely damped at 100 fs. Characteristic time constants of incoherent energy transfer, subsequently, vary from 1 ps to several tens of ps. We assign the time scales of the EET to specific physical processes by comparing our results with the data obtained from time-resolved spectroscopy experiments.
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Affiliation(s)
- Takatoshi Fujita
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA,
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34
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Chromatic acclimation and population dynamics of green sulfur bacteria grown with spectrally tailored light. Sci Rep 2014; 4:5057. [PMID: 24862580 PMCID: PMC4033924 DOI: 10.1038/srep05057] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 05/06/2014] [Indexed: 11/08/2022] Open
Abstract
Living organisms have to adjust to their surrounding in order to survive in stressful conditions. We study this mechanism in one of most primitive creatures – photosynthetic green sulfur bacteria. These bacteria absorb photons very efficiently using the chlorosome antenna complexes and perform photosynthesis in extreme low-light environments. How the chlorosomes in green sulfur bacteria are acclimated to the stressful light conditions, for instance, if the spectrum of light is not optimal for absorption, is unknown. Studying Chlorobaculumtepidum cultures with far-red to near-infrared light-emitting diodes, we found that these bacteria react to changes in energy flow by regulating the amount of light-absorbing pigments and the size of the chlorosomes. Surprisingly, our results indicate that the bacteria can survive in near-infrared lights capturing low-frequency photons by the intermediate units of the light-harvesting complex. The latter strategy may be used by the species recently found near hydrothermal vents in the Pacific Ocean.
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35
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Dostál J, Vácha F, Pšenčík J, Zigmantas D. 2D Electronic Spectroscopy Reveals Excitonic Structure in the Baseplate of a Chlorosome. J Phys Chem Lett 2014; 5:1743-1747. [PMID: 26270377 DOI: 10.1021/jz5005279] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In green photosynthetic bacteria, the chlorosome baseplate mediates excitation energy transfer from the interior of the light-harvesting chlorosome toward the reaction centers. However, the electronic states of the baseplate remain unexplored, hindering the mechanistic understanding of the baseplate as an excitation energy collector and mediator. Here we use two-dimensional spectroscopy to study the excited state structure and internal energy relaxation in the baseplate of green sulfur bacterium Chlorobaculum tepidum. We resolved an exciton system with four energy states, indicating that the organization of the pigments in the baseplate is more complex than was thought before and constitutes at least four bacteriochlorophyll molecules in a close contact. Based on the finding that the energy of the baseplate states is in the same range as in the adjacent Fenna-Matthews-Olson complex, we propose a "lateral" energy transfer pathway, where excitation energy can flow through the photosynthetic unit via all the states of individual complexes.
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Affiliation(s)
- Jakub Dostál
- †Department of Chemical Physics, Lund University, P.O. Box 124, 221 00 Lund, Sweden
- ‡Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague, Czech Republic
| | - František Vácha
- §Faculty of Science, University of South Bohemia, Branišovská 31, 370 05 České Budějovice, Czech Republic
| | - Jakub Pšenčík
- ‡Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, 121 16 Prague, Czech Republic
| | - Donatas Zigmantas
- †Department of Chemical Physics, Lund University, P.O. Box 124, 221 00 Lund, Sweden
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36
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Furumaki S, Vacha F, Hirata S, Vacha M. Bacteriochlorophyll aggregates self-assembled on functionalized gold nanorod cores as mimics of photosynthetic chlorosomal antennae: a single molecule study. ACS NANO 2014; 8:2176-2182. [PMID: 24559170 DOI: 10.1021/nn500224v] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We prepare artificial aggregates that mimic the structure and function of natural chlorosomal light harvesting complexes of green photosynthetic bacteria. Gold nanorods functionalized with hydroxyl groups and immobilized on a substrate serve as cores for the growth of bacteriochlorophyll (BChl) aggregates from a buffer solution. The BChl pigments form large self-assembled aggregate particles with sizes more than twice that of natural chlorosomes. The size is controllable by the aggregation time. The aggregates are characterized on a single-particle level by atomic force microscopy, electron microscopy, and single-molecule spectroscopy. The absorption and fluorescence spectral properties which reflect the molecular level arrangement of the BChl aggregates closely resemble those of the natural chlorosomes of the photosynthetic bacterium Chlorobaculum tepidum. On the other hand, the results of linear dichroism and circular dichroism are different from those of the chlorosomes and indicate a different mesoscopic structure for the artificial aggregates. These results emphasize the structural role played by the baseplate pigment-protein complex in natural chlorosomes.
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Affiliation(s)
- Shu Furumaki
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology , Ookayama 2-12-1-S8, Meguro-ku, Tokyo 152-8552, Japan
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37
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Huh J, Saikin SK, Brookes JC, Valleau S, Fujita T, Aspuru-Guzik A. Atomistic study of energy funneling in the light-harvesting complex of green sulfur bacteria. J Am Chem Soc 2014; 136:2048-57. [PMID: 24405318 DOI: 10.1021/ja412035q] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Phototrophic organisms such as plants, photosynthetic bacteria, and algae use microscopic complexes of pigment molecules to absorb sunlight. Within the light-harvesting complexes, which frequently have several functional and structural subunits, the energy is transferred in the form of molecular excitations with very high efficiency. Green sulfur bacteria are considered to be among the most efficient light-harvesting organisms. Despite multiple experimental and theoretical studies of these bacteria, the physical origin of the efficient and robust energy transfer in their light-harvesting complexes is not well understood. To study excitation dynamics at the systems level, we introduce an atomistic model that mimics a complete light-harvesting apparatus of green sulfur bacteria. The model contains approximately 4000 pigment molecules and comprises a double wall roll for the chlorosome, a baseplate, and six Fenna-Matthews-Olson trimer complexes. We show that the fast relaxation within functional subunits combined with the transfer between collective excited states of pigments can result in robust energy funneling to the initial excitation conditions and temperature changes. Moreover, the same mechanism describes the coexistence of multiple time scales of excitation dynamics frequently observed in ultrafast optical experiments. While our findings support the hypothesis of supertransfer, the model reveals energy transport through multiple channels on different length scales.
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Affiliation(s)
- Joonsuk Huh
- Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States
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Pšenčík J, Butcher SJ, Tuma R. Chlorosomes: Structure, Function and Assembly. THE STRUCTURAL BASIS OF BIOLOGICAL ENERGY GENERATION 2014. [DOI: 10.1007/978-94-017-8742-0_5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Kovács SÁ, Bricker WP, Niedzwiedzki DM, Colletti PF, Lo CS. Computational determination of the pigment binding motif in the chlorosome protein a of green sulfur bacteria. PHOTOSYNTHESIS RESEARCH 2013; 118:231-247. [PMID: 24078352 DOI: 10.1007/s11120-013-9920-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Accepted: 08/31/2013] [Indexed: 06/02/2023]
Abstract
We present a molecular-scale model of Bacteriochlorophyll a (BChl a) binding to the chlorosome protein A (CsmA) of Chlorobaculum tepidum, and the aggregated pigment–protein dimer, as determined from protein–ligand docking and quantum chemistry calculations. Our calculations provide strong evidence that the BChl a molecule is coordinated to the His25 residue of CsmA, with the magnesium center of the bacteriochlorin ring situated\3 A° from the imidazole nitrogen atom of the histidine sidechain, and the phytyl tail aligned along the nonpolar residues of the a-helix of CsmA. We also confirm that the Qy band in the absorption spectra of BChl a experiences a large (?16 to ?43 nm) redshift when aggregated with another BChl a molecule in the CsmA dimer, compared to the BChl a in solvent; this redshift has been previously established by experimental researchers. We propose that our model of the BChl a–CsmA binding motif, where the dimer contains parallel aligned N-terminal regions, serves as the smallest repeating unit in a larger model of the para-crystalline chlorosome baseplate protein.
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Orf GS, Blankenship RE. Chlorosome antenna complexes from green photosynthetic bacteria. PHOTOSYNTHESIS RESEARCH 2013; 116:315-31. [PMID: 23761131 DOI: 10.1007/s11120-013-9869-3] [Citation(s) in RCA: 176] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 06/06/2013] [Indexed: 05/18/2023]
Abstract
Chlorosomes are the distinguishing light-harvesting antenna complexes that are found in green photosynthetic bacteria. They contain bacteriochlorophyll (BChl) c, d, e in natural organisms, and recently through mutation, BChl f, as their principal light-harvesting pigments. In chlorosomes, these pigments self-assemble into large supramolecular structures that are enclosed inside a lipid monolayer to form an ellipsoid. The pigment assembly is dictated mostly by pigment-pigment interactions as opposed to protein-pigment interactions. On the bottom face of the chlorosome, the CsmA protein aggregates into a paracrystalline baseplate with BChl a, and serves as the interface to the next energy acceptor in the system. The exceptional light-harvesting ability at very low light conditions of chlorosomes has made them an attractive subject of study for both basic and applied science. This review, incorporating recent advancements, considers several important aspects of chlorosomes: pigment biosynthesis, organization of pigments and proteins, spectroscopic properties, and applications to bio-hybrid and bio-inspired devices.
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Affiliation(s)
- Gregory S Orf
- Departments of Chemistry and Biology, Washington University in St. Louis, Campus Box 1137, One Brookings Drive, St. Louis, MO, 63130, USA
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41
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Linnanto JM, Korppi-Tommola JEI. Exciton Description of Chlorosome to Baseplate Excitation Energy Transfer in Filamentous Anoxygenic Phototrophs and Green Sulfur Bacteria. J Phys Chem B 2013; 117:11144-61. [DOI: 10.1021/jp4011394] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Juha M. Linnanto
- Department of Chemistry, P.O.
Box 35, University of Jyväskylä, FIN-40014, Finland
- University of Tartu, Institute of Physics, Riia 142,
EE-51014 Tartu, Estonia
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Fluorescent epibiotic microbial community on the carapace of a Bahamian ostracod. Arch Microbiol 2013; 195:595-604. [PMID: 23861150 DOI: 10.1007/s00203-013-0911-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 06/19/2013] [Accepted: 06/26/2013] [Indexed: 10/26/2022]
Abstract
Ostracods collected from shallow coral reefs in the Bahamas were found to exhibit blue light-stimulated orange fluorescence at night. Fluorescent spectra revealed the presence of orange fluorescence with a maximum emission at ~595 nm on the carapace of these ostracods, while scanning electron microscopy revealed a morphologically diverse microbial community covering the entire carapace of these ostracods. Pyrosequencing and cyanobacterial-specific 16S rRNA sequencing reveals that this epibiont community is highly diverse and highly variable between individual ostracods. Many species of Cyanobacteria in the orders Oscillatoriales and Chroococcales, as well as other Proteobacteria and diatom chloroplast sequences, were identified using the cyanobacterial-specific primers. While no fluorescent proteins or phycoerythrin were detected in these ostracods, it is possible that the observed orange fluorescence is the result of carotenoid fluorescence from Cyanobacteria. The microbial consortium forms an epibiotic biofilm on the carapace of these ostracods whose functions are unknown.
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Adams PG, Cadby AJ, Robinson B, Tsukatani Y, Tank M, Wen J, Blankenship RE, Bryant DA, Hunter CN. Comparison of the physical characteristics of chlorosomes from three different phyla of green phototrophic bacteria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1827:1235-44. [PMID: 23867748 DOI: 10.1016/j.bbabio.2013.07.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/05/2013] [Accepted: 07/08/2013] [Indexed: 11/18/2022]
Abstract
Chlorosomes, the major antenna complexes in green sulphur bacteria, filamentous anoxygenic phototrophs, and phototrophic acidobacteria, are attached to the cytoplasmic side of the inner cell membrane and contain thousands of bacteriochlorophyll (BChl) molecules that harvest light and channel the energy to membrane-bound reaction centres. Chlorosomes from phototrophs representing three different phyla, Chloroflexus (Cfx.) aurantiacus, Chlorobaculum (Cba.) tepidum and the newly discovered "Candidatus (Ca.) Chloracidobacterium (Cab.) thermophilum" were analysed using PeakForce Tapping atomic force microscopy (PFT-AFM). Gentle PFT-AFM imaging in buffered solutions that maintained the chlorosomes in a near-native state revealed ellipsoids of variable size, with surface bumps and undulations that differ between individual chlorosomes. Cba. tepidum chlorosomes were the largest (133×57×36nm; 141,000nm(3) volume), compared with chlorosomes from Cfx. aurantiacus (120×44×30nm; 84,000nm(3)) and Ca. Cab. thermophilum (99×40×31nm; 65,000nm(3)). Reflecting the contributions of thousands of pigment-pigment stacking interactions to the stability of these supramolecular assemblies, analysis by nanomechanical mapping shows that chlorosomes are highly stable and that their integrity is disrupted only by very strong forces of 1000-2000pN. AFM topographs of Ca. Cab. thermophilum chlorosomes that had retained their attachment to the cytoplasmic membrane showed that this membrane dynamically changes shape and is composed of protrusions of up to 30nm wide and 6nm above the mica support, possibly representing different protein domains. Spectral imaging revealed significant heterogeneity in the fluorescence emission of individual chlorosomes, likely reflecting the variations in BChl c homolog composition and internal arrangements of the stacked BChls within each chlorosome.
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Affiliation(s)
- Peter G Adams
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
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Reconstruction of rod self-aggregates of natural bacteriochlorophylls-c from Chloroflexus aurantiacus. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.06.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Cyclopropane-ring formation in the acyl groups of chlorosome glycolipids is crucial for acid resistance of green bacterial antenna systems. Bioorg Med Chem 2013; 21:3689-94. [DOI: 10.1016/j.bmc.2013.04.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 04/15/2013] [Accepted: 04/16/2013] [Indexed: 11/21/2022]
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Li H, Frigaard NU, Bryant DA. [2Fe-2S] Proteins in Chlorosomes: CsmI and CsmJ Participate in Light-Dependent Control of Energy Transfer in Chlorosomes of Chlorobaculum tepidum. Biochemistry 2013; 52:1321-30. [DOI: 10.1021/bi301454g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hui Li
- Department of Biochemistry and
Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Niels-Ulrik Frigaard
- Department of Biochemistry and
Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Donald A. Bryant
- Department of Biochemistry and
Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry and
Biochemistry, Montana State University,
Bozeman, Montana 59717, United States
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Johnson TW, Li H, Frigaard NU, Golbeck JH, Bryant DA. [2Fe-2S] proteins in Chlorosomes: redox properties of CsmI, CsmJ, and CsmX of the Chlorosome envelope of Chlorobaculum tepidum. Biochemistry 2013; 52:1331-43. [PMID: 23368794 DOI: 10.1021/bi301455k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The chlorosome envelope of Chlorobaculum tepidum contains 10 polypeptides, three of which, CsmI, CsmJ, and CsmX, have an adrenodoxin-like domain harboring a single [2Fe-2S] cluster. Mutants that produced chlorosomes containing two, one, or none of these Fe-S proteins were constructed [Li, H., et al. (2013) Biochemistry 52, preceding paper in this issue ( DOI: 10.1021/bi301454g )]. The electron paramagnetic resonance (EPR) spectra, g values, and line widths of the Fe-S clusters in individual CsmI, CsmJ, and CsmX proteins were obtained from studies with isolated chlorosomes. The Fe-S clusters in these proteins were characterized by EPR and could be differentiated on the basis of their g values and line widths. The EPR spectrum of wild-type chlorosomes could be simulated by a 1:1 admixture of the CsmI and CsmJ spectra. No contribution of CsmX to the EPR spectrum of chlorosomes was observed because of its low abundance. In chlorosomes that contained only CsmI or CsmJ, the midpoint potential of the [2Fe-2S] clusters was -205 or 8 mV, respectively; the midpoint potential of the [2Fe-2S] cluster in CsmX was estimated to be more oxidizing than -180 mV. In wild-type chlorosomes, the midpoint potentials of the [2Fe-2S] clusters were -348 mV for CsmI and 92 mV for CsmJ. The lower potential for CsmI in the presence of CsmJ, and the higher potential for CsmJ in the presence of CsmI, were attributed to interactions that occur when these proteins form complexes in the chlorosome envelope. The redox properties of CsmI and CsmJ are consistent with their proposed participation in the transfer of electrons to and from quenchers of energy transfer in chlorosomes.
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Affiliation(s)
- T Wade Johnson
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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48
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Abstract
Chlorosomes are large light-harvesting complexes found in three phyla of anoxygenic photosynthetic bacteria. Chlorosomes are primarily composed of self-assembling pigment aggregates. In addition to the main pigment, bacteriochlorophyll c, d, or e, chlorosomes also contain variable amounts of carotenoids. Here, we use X-ray scattering and electron cryomicroscopy, complemented with absorption spectroscopy and pigment analysis, to compare the morphologies, structures, and pigment compositions of chlorosomes from Chloroflexus aurantiacus grown under two different light conditions and Chlorobaculum tepidum. High-purity chlorosomes from C. aurantiacus contain about 20% more carotenoid per bacteriochlorophyll c molecule when grown under low light than when grown under high light. This accentuates the light-harvesting function of carotenoids, in addition to their photoprotective role. The low-light chlorosomes are thicker due to the overall greater content of pigments and contain domains of lamellar aggregates. Experiments where carotenoids were selectively extracted from intact chlorosomes using hexane proved that they are located in the interlamellar space, as observed previously for species belonging to the phylum Chlorobi. A fraction of the carotenoids are localized in the baseplate, where they are bound differently and cannot be removed by hexane. In C. tepidum, carotenoids cannot be extracted by hexane even from the chlorosome interior. The chemical structure of the pigments in C. tepidum may lead to π-π interactions between carotenoids and bacteriochlorophylls, preventing carotenoid extraction. The results provide information about the nature of interactions between bacteriochlorophylls and carotenoids in the protein-free environment of the chlorosome interior.
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Shoji S, Hashishin T, Tamiaki H. Construction of Chlorosomal Rod Self-Aggregates in the Solid State on Any Substrates from Synthetic Chlorophyll Derivatives Possessing an Oligomethylene Chain at the 17-Propionate Residue. Chemistry 2012; 18:13331-41. [DOI: 10.1002/chem.201201935] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Indexed: 11/09/2022]
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50
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Fujita T, Brookes JC, Saikin SK, Aspuru-Guzik A. Memory-Assisted Exciton Diffusion in the Chlorosome Light-Harvesting Antenna of Green Sulfur Bacteria. J Phys Chem Lett 2012; 3:2357-2361. [PMID: 26292114 DOI: 10.1021/jz3008326] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Chlorosomes are likely the largest and most efficient natural light-harvesting photosynthetic antenna systems. They are composed of large numbers of bacteriochlorophylls organized into supramolecular aggregates. We explore the microscopic origin of the fast excitation energy transfer in the chlorosome using the recently resolved structure and atomistic-detail simulations. Despite the dynamical disorder effects on the electronic transitions of the bacteriochlorophylls, our simulations show that the exciton delocalizes over the entire aggregate in about 200 fs. The memory effects associated to the dynamical disorder assist the exciton diffusion through the aggregates and enhance the diffusion coefficients as a factor of 2 as compared to the model without memory. Furthermore, exciton diffusion in the chlorosome is found to be highly anisotropic with the preferential transfer toward the baseplate, which is the next functional element in the photosynthetic system.
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Affiliation(s)
- Takatoshi Fujita
- †Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Jennifer C Brookes
- †Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
- ‡Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT
| | - Semion K Saikin
- †Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Alán Aspuru-Guzik
- †Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
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