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Hirose M, Tsukatani Y, Harada J, Tamiaki H. In vitro reversible dehydration in C3-substituents of zinc chlorophyll analogs by BchF and BchV enzymes: Stereoselectivity and substrate specificity in the dehydration. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148959. [PMID: 36822492 DOI: 10.1016/j.bbabio.2023.148959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/14/2023] [Accepted: 02/15/2023] [Indexed: 02/25/2023]
Abstract
In the biosynthetic pathway of bacteriochlorophyll(BChl)-a/b/c/d/e molecules, BchF and BchV enzymes catalyze the hydration of a C3-vinyl to C3-1-hydroxyethyl group. In this study, the in vitro reactions catalyzed by BchF and BchV partially afforded a C31-epimeric mixture of the hydrated products (secondary alcohols), with the primary recovery of the C3-vinylated substrate. The stereoselectivity and substrate specificity for the in vitro reverse enzymatic dehydration were examined using zinc chlorophyll analogs as model substrates by BchF and BchV, which were obtained from extracts of Escherichia coli overexpressing the respective genes from Chlorobaculum tepidum and used without further purification. Both BchF and BchV preferred dehydration of the (31R)-epimers over the (31S)-epimers. The (31R)-epimer was directly dehydrated by BchF and BchV to give the C3-vinylated product. By contrast, two reaction pathways for BchF and BchV dehydrations of the (31S)-epimer were proposed: (1) the (31S)-epimer would be directly dehydrated to C3-vinyl group. (2) the (31S)-epimer would be epimerized to the (31R)-epimer, and the resulting epimer was dehydrated. The results indicated that both BchF and BchV did function as a hydratase/dehydratase and could play a role in the C31-epimerization. An increase in the alkyl size at the C8-position gradually suppressed the BchF and BchV-catalyzed dehydration in vitro, while the C121- and C20-methylation only slightly affected the reaction. Using the BchF dehydration, a large amount of 3-vinyl-bacteriochlorophyllide-a was successfully prepared, with the retention of the chemically labile, central magnesium atom.
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Affiliation(s)
- Mitsuaki Hirose
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Yusuke Tsukatani
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanagawa 237-0061, Japan
| | - Jiro Harada
- Department of Medical Biochemistry, Kurume University School of Medicine, Fukuoka 830-0011, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
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2
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Proctor MS, Sutherland GA, Canniffe DP, Hitchcock A. The terminal enzymes of (bacterio)chlorophyll biosynthesis. ROYAL SOCIETY OPEN SCIENCE 2022; 9:211903. [PMID: 35573041 PMCID: PMC9066304 DOI: 10.1098/rsos.211903] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 03/29/2022] [Indexed: 05/03/2023]
Abstract
(Bacterio)chlorophylls are modified tetrapyrroles that are used by phototrophic organisms to harvest solar energy, powering the metabolic processes that sustain most of the life on Earth. Biosynthesis of these pigments involves enzymatic modification of the side chains and oxidation state of a porphyrin precursor, modifications that differ by species and alter the absorption properties of the pigments. (Bacterio)chlorophylls are coordinated by proteins that form macromolecular assemblies to absorb light and transfer excitation energy to a special pair of redox-active (bacterio)chlorophyll molecules in the photosynthetic reaction centre. Assembly of these pigment-protein complexes is aided by an isoprenoid moiety esterified to the (bacterio)chlorin macrocycle, which anchors and stabilizes the pigments within their protein scaffolds. The reduction of the isoprenoid 'tail' and its addition to the macrocycle are the final stages in (bacterio)chlorophyll biosynthesis and are catalysed by two enzymes, geranylgeranyl reductase and (bacterio)chlorophyll synthase. These enzymes work in conjunction with photosynthetic complex assembly factors and the membrane biogenesis machinery to synchronize delivery of the pigments to the proteins that coordinate them. In this review, we summarize current understanding of the catalytic mechanism, substrate recognition and regulation of these crucial enzymes and their involvement in thylakoid biogenesis and photosystem repair in oxygenic phototrophs.
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Affiliation(s)
- Matthew S. Proctor
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - George A. Sutherland
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Daniel P. Canniffe
- Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Andrew Hitchcock
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
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3
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Abstract
Covering: up to mid-2020 Terpenoids, also called isoprenoids, are the largest and most structurally diverse family of natural products. Found in all domains of life, there are over 80 000 known compounds. The majority of characterized terpenoids, which include some of the most well known, pharmaceutically relevant, and commercially valuable natural products, are produced by plants and fungi. Comparatively, terpenoids of bacterial origin are rare. This is counter-intuitive to the fact that recent microbial genomics revealed that almost all bacteria have the biosynthetic potential to create the C5 building blocks necessary for terpenoid biosynthesis. In this review, we catalogue terpenoids produced by bacteria. We collected 1062 natural products, consisting of both primary and secondary metabolites, and classified them into two major families and 55 distinct subfamilies. To highlight the structural and chemical space of bacterial terpenoids, we discuss their structures, biosynthesis, and biological activities. Although the bacterial terpenome is relatively small, it presents a fascinating dichotomy for future research. Similarities between bacterial and non-bacterial terpenoids and their biosynthetic pathways provides alternative model systems for detailed characterization while the abundance of novel skeletons, biosynthetic pathways, and bioactivies presents new opportunities for drug discovery, genome mining, and enzymology.
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Affiliation(s)
- Jeffrey D Rudolf
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, USA.
| | - Tyler A Alsup
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, USA.
| | - Baofu Xu
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, USA.
| | - Zining Li
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, USA.
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Yoshikawa K, Ogawa K, Toya Y, Akimoto S, Matsuda F, Shimizu H. Mutations in hik26 and slr1916 lead to high-light stress tolerance in Synechocystis sp. PCC6803. Commun Biol 2021; 4:343. [PMID: 33727624 PMCID: PMC7966805 DOI: 10.1038/s42003-021-01875-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 02/19/2021] [Indexed: 01/31/2023] Open
Abstract
Increased tolerance to light stress in cyanobacteria is a desirable feature for their applications. Here, we obtained a high light tolerant (Tol) strain of Synechocystis sp. PCC6803 through an adaptive laboratory evolution, in which the cells were repeatedly sub-cultured for 52 days under high light stress conditions (7000 to 9000 μmol m-2 s-1). Although the growth of the parental strain almost stopped when exposed to 9000 μmol m-2 s-1, no growth inhibition was observed in the Tol strain. Excitation-energy flow was affected because of photosystem II damage in the parental strain under high light conditions, whereas the damage was alleviated and normal energy flow was maintained in the Tol strain. The transcriptome data indicated an increase in isiA expression in the Tol strain under high light conditions. Whole genome sequence analysis and reverse engineering revealed two mutations in hik26 and slr1916 involved in high light stress tolerance in the Tol strain.
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Affiliation(s)
- Katsunori Yoshikawa
- grid.136593.b0000 0004 0373 3971Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Suita, Osaka Japan
| | - Kenichi Ogawa
- grid.136593.b0000 0004 0373 3971Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Suita, Osaka Japan
| | - Yoshihiro Toya
- grid.136593.b0000 0004 0373 3971Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Suita, Osaka Japan
| | - Seiji Akimoto
- grid.31432.370000 0001 1092 3077Department of Chemistry, Graduate School of Science, Kobe University, Kobe, Hyogo Japan
| | - Fumio Matsuda
- grid.136593.b0000 0004 0373 3971Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Suita, Osaka Japan
| | - Hiroshi Shimizu
- grid.136593.b0000 0004 0373 3971Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, Suita, Osaka Japan
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5
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Azai C, Harada J, Fujimoto S, Masuda S, Kosumi D. Anaerobic energy dissipation by glycosylated carotenoids in the green sulfur bacterium Chlorobaculum tepidum. J Photochem Photobiol A Chem 2020. [DOI: 10.1016/j.jphotochem.2020.112828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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6
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Abstract
Modified tetrapyrroles are large macrocyclic compounds, consisting of diverse conjugation and metal chelation systems and imparting an array of colors to the biological structures that contain them. Tetrapyrroles represent some of the most complex small molecules synthesized by cells and are involved in many essential processes that are fundamental to life on Earth, including photosynthesis, respiration, and catalysis. These molecules are all derived from a common template through a series of enzyme-mediated transformations that alter the oxidation state of the macrocycle and also modify its size, its side-chain composition, and the nature of the centrally chelated metal ion. The different modified tetrapyrroles include chlorophylls, hemes, siroheme, corrins (including vitamin B12), coenzyme F430, heme d1, and bilins. After nearly a century of study, almost all of the more than 90 different enzymes that synthesize this family of compounds are now known, and expression of reconstructed operons in heterologous hosts has confirmed that most pathways are complete. Aside from the highly diverse nature of the chemical reactions catalyzed, an interesting aspect of comparative biochemistry is to see how different enzymes and even entire pathways have evolved to perform alternative chemical reactions to produce the same end products in the presence and absence of oxygen. Although there is still much to learn, our current understanding of tetrapyrrole biogenesis represents a remarkable biochemical milestone that is summarized in this review.
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Affiliation(s)
- Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Martin J Warren
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, United Kingdom
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, United Kingdom
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7
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Schwieterman EW, Kiang NY, Parenteau MN, Harman CE, DasSarma S, Fisher TM, Arney GN, Hartnett HE, Reinhard CT, Olson SL, Meadows VS, Cockell CS, Walker SI, Grenfell JL, Hegde S, Rugheimer S, Hu R, Lyons TW. Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life. ASTROBIOLOGY 2018; 18:663-708. [PMID: 29727196 PMCID: PMC6016574 DOI: 10.1089/ast.2017.1729] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 12/10/2017] [Indexed: 05/04/2023]
Abstract
In the coming years and decades, advanced space- and ground-based observatories will allow an unprecedented opportunity to probe the atmospheres and surfaces of potentially habitable exoplanets for signatures of life. Life on Earth, through its gaseous products and reflectance and scattering properties, has left its fingerprint on the spectrum of our planet. Aided by the universality of the laws of physics and chemistry, we turn to Earth's biosphere, both in the present and through geologic time, for analog signatures that will aid in the search for life elsewhere. Considering the insights gained from modern and ancient Earth, and the broader array of hypothetical exoplanet possibilities, we have compiled a comprehensive overview of our current understanding of potential exoplanet biosignatures, including gaseous, surface, and temporal biosignatures. We additionally survey biogenic spectral features that are well known in the specialist literature but have not yet been robustly vetted in the context of exoplanet biosignatures. We briefly review advances in assessing biosignature plausibility, including novel methods for determining chemical disequilibrium from remotely obtainable data and assessment tools for determining the minimum biomass required to maintain short-lived biogenic gases as atmospheric signatures. We focus particularly on advances made since the seminal review by Des Marais et al. The purpose of this work is not to propose new biosignature strategies, a goal left to companion articles in this series, but to review the current literature, draw meaningful connections between seemingly disparate areas, and clear the way for a path forward. Key Words: Exoplanets-Biosignatures-Habitability markers-Photosynthesis-Planetary surfaces-Atmospheres-Spectroscopy-Cryptic biospheres-False positives. Astrobiology 18, 663-708.
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Affiliation(s)
- Edward W. Schwieterman
- Department of Earth Sciences, University of California, Riverside, California
- NASA Postdoctoral Program, Universities Space Research Association, Columbia, Maryland
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
- Blue Marble Space Institute of Science, Seattle, Washington
| | - Nancy Y. Kiang
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- NASA Goddard Institute for Space Studies, New York, New York
| | - Mary N. Parenteau
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- NASA Ames Research Center, Exobiology Branch, Mountain View, California
| | - Chester E. Harman
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- NASA Goddard Institute for Space Studies, New York, New York
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York
| | - Shiladitya DasSarma
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland
- Institute of Marine and Environmental Technology, University System of Maryland, Baltimore, Maryland
| | - Theresa M. Fisher
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona
| | - Giada N. Arney
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland
| | - Hilairy E. Hartnett
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona
- School of Molecular Sciences, Arizona State University, Tempe, Arizona
| | - Christopher T. Reinhard
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Stephanie L. Olson
- Department of Earth Sciences, University of California, Riverside, California
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
| | - Victoria S. Meadows
- NASA Astrobiology Institute, Virtual Planetary Laboratory Team, Seattle, Washington
- Astronomy Department, University of Washington, Seattle, Washington
| | - Charles S. Cockell
- University of Edinburgh School of Physics and Astronomy, Edinburgh, United Kingdom
- UK Centre for Astrobiology, Edinburgh, United Kingdom
| | - Sara I. Walker
- Blue Marble Space Institute of Science, Seattle, Washington
- School of Earth and Space Exploration, Arizona State University, Tempe, Arizona
- Beyond Center for Fundamental Concepts in Science, Arizona State University, Tempe, Arizona
- ASU-Santa Fe Institute Center for Biosocial Complex Systems, Arizona State University, Tempe, Arizona
| | - John Lee Grenfell
- Institut für Planetenforschung (PF), Deutsches Zentrum für Luft und Raumfahrt (DLR), Berlin, Germany
| | - Siddharth Hegde
- Carl Sagan Institute, Cornell University, Ithaca, New York
- Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, New York
| | - Sarah Rugheimer
- Department of Earth and Environmental Sciences, University of St. Andrews, St. Andrews, United Kingdom
| | - Renyu Hu
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California
| | - Timothy W. Lyons
- Department of Earth Sciences, University of California, Riverside, California
- NASA Astrobiology Institute, Alternative Earths Team, Riverside, California
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8
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Light-dependent accumulation of new bacteriochlorophyll-e bearing a vinyl group at the 8-position in the green sulfur bacterium Chlorobaculum limnaeum. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2017.08.071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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9
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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, Yamashita H. Effects of exogenous isoprenoid diphosphates on in vivo attachment to bacteriochlorophyllide c in the green sulfur photosynthetic bacterium Chlorobaculum tepidum. J Biosci Bioeng 2017; 124:408-413. [PMID: 28579086 DOI: 10.1016/j.jbiosc.2017.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Revised: 04/22/2017] [Accepted: 05/08/2017] [Indexed: 11/18/2022]
Abstract
Metabolic substitution of the esterifying chain in bacteriochlorophyll (BChl) c in green photosynthetic bacteria grown by supplementation of exogenous alcohols has attracted attentions to study supramolecular structures and biogenesis of major antenna complexes chlorosomes in these bacteria as well as BChl pigment biosynthesis. Actual substrates in the enzymatic attachment of the esterifying moieties to the precursor of BChl c, namely bacteriochlorophyllide (BChlide) c, in these bacteria are believed to be diphosphate esters of alcoholic substrates, although only intact alcohols have so far been supplemented in the bacterial cultures. We report herein BChl c compositions in the green sulfur photosynthetic bacterium Chlorobaculum tepidum by supplementation with geranyl and geranylgeranyl diphosphates. The supplementation of these diphosphates hardly produced BChl c derivatives esterified with geraniol and geranylgeraniol in Cba. tepidum, whereas these BChl c derivatives were accumulated by supplementation of intact geraniol and geranylgeraniol. The sharp contrast of the incorporation efficiency of the supplemental isoprenoid moieties in BChl c using the isoprenoid diphosphates to that by the isoprenoid alcohols was mainly ascribable to less penetration abilities of the diphosphate substrates into Cba. tepidum cells because of their anionic and polar diphosphate moiety.
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Affiliation(s)
- Yoshitaka Saga
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan; PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.
| | - Hayato Yamashita
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
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11
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Thweatt JL, Ferlez BH, Golbeck JH, Bryant DA. BciD Is a Radical S-Adenosyl-l-methionine (SAM) Enzyme That Completes Bacteriochlorophyllide e Biosynthesis by Oxidizing a Methyl Group into a Formyl Group at C-7. J Biol Chem 2016; 292:1361-1373. [PMID: 27994052 DOI: 10.1074/jbc.m116.767665] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 12/12/2016] [Indexed: 01/05/2023] Open
Abstract
Green bacteria are chlorophotorophs that synthesize bacteriochlorophyll (BChl) c, d, or e, which assemble into supramolecular, nanotubular structures in large light-harvesting structures called chlorosomes. The biosynthetic pathways of these chlorophylls are known except for one reaction. Null mutants of bciD, which encodes a putative radical S-adenosyl-l-methionine (SAM) protein, are unable to synthesize BChl e but accumulate BChl c; however, it is unknown whether BciD is sufficient to convert BChl c (or its precursor, bacteriochlorophyllide (BChlide) c) into BChl e (or BChlide e). To determine the function of BciD, we expressed the bciD gene of Chlorobaculum limnaeum strain DSMZ 1677T in Escherichia coli and purified the enzyme under anoxic conditions. Electron paramagnetic resonance spectroscopy of BciD indicated that it contains a single [4Fe-4S] cluster. In assays containing SAM, BChlide c or d, and sodium dithionite, BciD catalyzed the conversion of SAM into 5'-deoxyadenosine and BChlide c or d into BChlide e or f, respectively. Our analyses also identified intermediates that are proposed to be 71-OH-BChlide c and d Thus, BciD is a radical SAM enzyme that converts the methyl group of BChlide c or d into the formyl group of BChlide e or f This probably occurs by a mechanism involving consecutive hydroxylation reactions of the C-7 methyl group to form a geminal diol intermediate, which spontaneously dehydrates to produce the final products, BChlide e or BChlide f The demonstration that BciD is sufficient to catalyze the conversion of BChlide c into BChlide e completes the biosynthetic pathways for all "Chlorobium chlorophylls."
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Affiliation(s)
| | - Bryan H Ferlez
- From the Departments of Biochemistry and Molecular Biology and
| | - John H Golbeck
- From the Departments of Biochemistry and Molecular Biology and.,Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802 and
| | - Donald A Bryant
- From the Departments of Biochemistry and Molecular Biology and .,the Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717
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12
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Teramura M, Harada J, Tamiaki H. In vitro stereospecific hydration activities of the 3-vinyl group of chlorophyll derivatives by BchF and BchV enzymes involved in bacteriochlorophyll c biosynthesis of green sulfur bacteria. PHOTOSYNTHESIS RESEARCH 2016; 130:33-45. [PMID: 26816140 DOI: 10.1007/s11120-016-0220-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 01/11/2016] [Indexed: 06/05/2023]
Abstract
The photosynthetic green sulfur bacterium Chlorobaculum (Cba.) tepidum produces bacteriochlorophyll (BChl) c pigments bearing a chiral 1-hydroxyethyl group at the 3-position, which self-aggregate to construct main light-harvesting antenna complexes, chlorosomes. The secondary alcoholic hydroxy group is requisite for chlorosomal aggregation and biosynthesized by hydrating the 3-vinyl group of their precursors. Using recombinant proteins of Cba. tepidum BchF and BchV, we examined in vitro enzymatic hydration of some 3-vinyl-chlorophyll derivatives. Both the enzymes catalyzed stereoselective hydration of zinc 3-vinyl-8-ethyl-12-methyl-bacteriopheophorbide c or d to the zinc 31 R-bacteriopheophorbide c or d homolog, respectively, with a slight amount of the 31 S-epimric species. A similar R-stereoselectivity was observed in the BchF-hydration of zinc 3-vinyl-8-ethyl- and propyl-12-ethyl-bacteriopheophorbides c, while their BchV-hydration gave a relatively larger amount of the 31 S-epimers. The in vitro stereoselective hydration confirmed the in vivo production of the S-epimeric species by BchV. The enzymatic hydration for the above 8-propylated substrate proceeded more slowly than that for the 8-ethylated, and the 8-isobutylated substrate was no longer hydrated. Based on these results, biosynthetic pathways of BChl c homologs and epimers are proposed.
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Affiliation(s)
- Misato Teramura
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Jiro Harada
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan.
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13
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Chlorobaculum tepidum Modulates Amino Acid Composition in Response to Energy Availability, as Revealed by a Systematic Exploration of the Energy Landscape of Phototrophic Sulfur Oxidation. Appl Environ Microbiol 2016; 82:6431-6439. [PMID: 27565613 DOI: 10.1128/aem.02111-16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 08/17/2016] [Indexed: 12/26/2022] Open
Abstract
Microbial sulfur metabolism, particularly the formation and consumption of insoluble elemental sulfur (S0), is an important biogeochemical engine that has been harnessed for applications ranging from bioleaching and biomining to remediation of waste streams. Chlorobaculum tepidum, a low-light-adapted photoautolithotrophic sulfur-oxidizing bacterium, oxidizes multiple sulfur species and displays a preference for more reduced electron donors: sulfide > S0 > thiosulfate. To understand this preference in the context of light energy availability, an "energy landscape" of phototrophic sulfur oxidation was constructed by varying electron donor identity, light flux, and culture duration. Biomass and cellular parameters of C. tepidum cultures grown across this landscape were analyzed. From these data, a correction factor for colorimetric protein assays was developed, enabling more accurate biomass measurements for C. tepidum, as well as other organisms. C. tepidum's bulk amino acid composition correlated with energy landscape parameters, including a tendency toward less energetically expensive amino acids under reduced light flux. This correlation, paired with an observation of increased cell size and storage carbon production under electron-rich growth conditions, suggests that C. tepidum has evolved to cope with changing energy availability by tuning its proteome for energetic efficiency and storing compounds for leaner times. IMPORTANCE How microbes cope with and adapt to varying energy availability is an important factor in understanding microbial ecology and in designing efficient biotechnological processes. We explored the response of a model phototrophic organism, Chlorobaculum tepidum, across a factorial experimental design that enabled simultaneous variation and analysis of multiple growth conditions, what we term the "energy landscape." C. tepidum biomass composition shifted toward less energetically expensive amino acids at low light levels. This observation provides experimental evidence for evolved efficiencies in microbial proteomes and emphasizes the role that energy flux may play in the adaptive responses of organisms. From a practical standpoint, our data suggest that bulk biomass amino acid composition could provide a simple proxy to monitor and identify energy stress in microbial systems.
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Saga Y, Yamashita H, Hirota K. Introduction of perfluoroalkyl chain into the esterifying moiety of bacteriochlorophyll c in the green sulfur photosynthetic bacterium Chlorobaculum tepidum by pigment biosynthesis. Bioorg Med Chem 2016; 24:4165-4170. [PMID: 27427396 DOI: 10.1016/j.bmc.2016.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Revised: 07/02/2016] [Accepted: 07/04/2016] [Indexed: 11/27/2022]
Abstract
The green sulfur photosynthetic bacterium Chlorobaculum (Cba.) tepidum was grown in liquid cultures containing perfluoro-1-decanol, 1H,1H,2H,2H-heptadecafluoro-1-decanol [CF3(CF2)7(CH2)2OH] or 1H,1H-nonadecafluoro-1-decanol [CF3(CF2)8CH2OH], to introduce rigid and fluorophilic chains into the esterifying moiety of light-harvesting bacteriochlorophyll (BChl) c. Exogenous 1H,1H,2H,2H-heptadecafluoro-1-decanol was successfully attached to the 17(2)-carboxy group of bacteriochlorophyllide (BChlide) c in vivo: the relative ratio of the unnatural BChl c esterified with this perfluoroalcohol over the total BChl c was 10.3%. Heat treatment of the liquid medium containing 1H,1H,2H,2H-heptadecafluoro-1-decanol with β-cyclodextrin before inoculation increased the relative ratio of the BChl c derivative esterified with this alcohol in the total BChl c in Cba. tepidum. In a while, 1H,1H-nonadecafluoro-1-decanol was not attached to BChlide c in Cba. tepidum, which was grown by its supplementation. These results suggest that the rigidity close to the hydroxy group of the esterifying alcohol is not suitable for the recognition by the BChl c synthase called BchK in Cba. tepidum. The unnatural BChl c esterified with 1H,1H,2H,2H-heptadecafluoro-1-decanol participated in BChl c self-aggregates in chlorosomes.
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Affiliation(s)
- Yoshitaka Saga
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan; PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.
| | - Hayato Yamashita
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Keiya Hirota
- Department of Chemistry, Faculty of Science and Engineering, Kindai University, Higashi-Osaka, Osaka 577-8502, Japan
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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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Saga Y, Hayashi K, Hirota K, Harada J, Tamiaki H. Modification of the esterifying farnesyl chain in light-harvesting bacteriochlorophylls in green sulfur photosynthetic bacteria by supplementation of 9-decyn-1-ol, 9-decen-1-ol, and decan-1-ol. J Photochem Photobiol A Chem 2015. [DOI: 10.1016/j.jphotochem.2015.05.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Harada J, Teramura M, Mizoguchi T, Tsukatani Y, Yamamoto K, Tamiaki H. Stereochemical conversion of C3-vinyl group to 1-hydroxyethyl group in bacteriochlorophyll c by the hydratases BchF and BchV: adaptation of green sulfur bacteria to limited-light environments. Mol Microbiol 2015; 98:1184-98. [PMID: 26331578 DOI: 10.1111/mmi.13208] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2015] [Indexed: 11/28/2022]
Abstract
Photosynthetic green sulfur bacteria inhabit anaerobic environments with very low-light conditions. To adapt to such environments, these bacteria have evolved efficient light-harvesting antenna complexes called as chlorosomes, which comprise self-aggregated bacteriochlorophyll c in the model green sulfur, bacterium Chlorobaculum tepidum. The pigment possess a hydroxy group at the C3(1) position that produces a chiral center with R- or S-stereochemistry and the C3(1) -hydroxy group serves as a connecting moiety for the self-aggregation. Chlorobaculum tepidum carries the two possible homologous genes for C3-vinyl hydratase, bchF and bchV. In the present study, we constructed deletion mutants of each of these genes. Pigment analyses of the bchF-inactivated mutant, which still has BchV as a sole hydratase, showed higher ratios of S-epimeric bacteriochlorophyll c than the wild-type strain. The heightened prevalence of S-stereoisomers in the mutant was more remarkable at lower light intensities and caused a red shift of the chlorosomal Qy absorption band leading to advantages for light-energy transfer. In contrast, the bchV-mutant possessing only BchF showed a significant decrease of the S-epimers and accumulations of C3-vinyl BChl c species. As trans- criptional level of bchV was upregulated at lower light intensity, the Chlorobaculum tepidum adapted to low-light environments by control of the bchV transcription.
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Affiliation(s)
- Jiro Harada
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Misato Teramura
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Tadashi Mizoguchi
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Yusuke Tsukatani
- Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo, 152-8550, Japan.,PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, 332-0012, Japan
| | - Ken Yamamoto
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
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Saga Y, Hirota K, Harada J, Tamiaki H. In Vitro Enzymatic Activities of Bacteriochlorophyll a Synthase Derived from the Green Sulfur Photosynthetic Bacterium Chlorobaculum tepidum. Biochemistry 2015; 54:4998-5005. [PMID: 26258685 DOI: 10.1021/acs.biochem.5b00311] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The activity of an enzyme encoded by the CT1610 gene in the green sulfur photosynthetic bacterium Chlorobaculum tepidum, which was annotated as bacteriochlorophyll (BChl) a synthase, BchG (denoted as tepBchG), was examined in vitro using the lysates of Escherichia coli containing the heterologously expressed enzyme. BChl a possessing a geranylgeranyl group at the 17-propionate residue (BChl aGG) was produced from bacteriochlorophyllide (BChlide) a and geranylgeranyl pyrophosphate in the presence of tepBchG. Surprisingly, tepBchG catalyzed the formation of BChl a bearing a farnesyl group (BChl aF) as in the enzymatic production of BChl aGG, indicating loose recognition of isoprenoid pyrophosphates in tepBchG. In contrast to such loose recognition of isoprenoid substrates, BChlide c and chlorophyllide a gave no esterifying product upon being incubated with geranylgeranyl or farnesyl pyrophosphate in the presence of tepBchG. These results confirm that tepBchG undoubtedly acts as the BChl a synthase in Cba. tepidum. The enzymatic activity of tepBchG was higher than that of BchG of Rhodobacter sphaeroides at 45 °C, although the former activity was lower than the latter below 35 °C.
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Affiliation(s)
- Yoshitaka Saga
- †Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan.,‡PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Keiya Hirota
- †Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Jiro Harada
- §Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka 830-0011, Japan
| | - Hitoshi Tamiaki
- ∥Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
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Wang Y, Freund DM, Magdaong NM, Urban VS, Frank HA, Hegeman AD, Tang JKH. Impact of esterified bacteriochlorophylls on the biogenesis of chlorosomes in Chloroflexus aurantiacus. PHOTOSYNTHESIS RESEARCH 2014; 122:69-86. [PMID: 24880610 DOI: 10.1007/s11120-014-0017-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 05/19/2014] [Indexed: 06/03/2023]
Abstract
A chlorosome is an antenna complex located on the cytoplasmic side of the inner membrane in green photosynthetic bacteria that contains tens of thousands of self-assembled bacteriochlorophylls (BChls). Green bacteria are known to incorporate various esterifying alcohols at the C-17 propionate position of BChls in the chlorosome. The effect of these functional substitutions on the biogenesis of the chlorosome has not yet been fully explored. In this report, we address this question by investigating various esterified bacteriochlorophyll c (BChl c) homologs in the thermophilic green non-sulfur bacterium Chloroflexus aurantiacus. Cultures were supplemented with exogenous long-chain alcohols at 52 °C (an optimal growth temperature) and 44 °C (a suboptimal growth temperature), and the morphology, optical properties and exciton transfer characteristics of chlorosomes were investigated. Our studies indicate that at 44 °C Cfl. aurantiacus synthesizes more carotenoids, incorporates more BChl c homologs with unsaturated and rigid polyisoprenoid esterifying alcohols and produces more heterogeneous BChl c homologs in chlorosomes. Substitution of phytol for stearyl alcohol of BChl c maintains similar morphology of the intact chlorosome and enhances energy transfer from the chlorosome to the membrane-bound photosynthetic apparatus. Different morphologies of the intact chlorosome versus in vitro BChl aggregates are suggested by small-angle neutron scattering. Additionally, phytol cultures and 44 °C cultures exhibit slow assembly of the chlorosome. These results suggest that the esterifying alcohol of BChl c contributes to long-range organization of BChls, and that interactions between BChls with other components are important to the assembly of the chlorosome. Possible mechanisms for how esterifying alcohols affect the biogenesis of the chlorosome are discussed.
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Affiliation(s)
- Yaya Wang
- Department of Chemistry and Biochemistry, Clark University, Worcester, MA, 01610, USA
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21
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Luo SC, Khin Y, Huang SJ, Yang Y, Hou TY, Cheng YC, Chen HM, Chin YY, Chen CT, Lin HJ, Tang JKH, Chan JCC. Probing the Spatial Organization of Bacteriochlorophyll c by Solid-State Nuclear Magnetic Resonance. Biochemistry 2014; 53:5515-25. [DOI: 10.1021/bi500755r] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
| | - Yadana Khin
- Department
of Chemistry and Biochemistry, Clark University, Worcester, Massachusetts 01610, United States,
| | | | - Yanshen Yang
- Department
of Chemistry and Biochemistry, Clark University, Worcester, Massachusetts 01610, United States,
| | | | | | | | - Yi-Ying Chin
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Chien-Te Chen
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Hong-Ji Lin
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Joseph Kuo-Hsiang Tang
- Department
of Chemistry and Biochemistry, Clark University, Worcester, Massachusetts 01610, United States,
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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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Saga Y, Hayashi K, Mizoguchi T, Tamiaki H. Biosynthesis of bacteriochlorophyll c derivatives possessing chlorine and bromine atoms at the terminus of esterifying chains in the green sulfur bacterium Chlorobaculum tepidum. J Biosci Bioeng 2014; 118:82-7. [PMID: 24495924 DOI: 10.1016/j.jbiosc.2013.12.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 12/26/2013] [Accepted: 12/27/2013] [Indexed: 11/26/2022]
Abstract
The green sulfur photosynthetic bacterium Chlorobaculum tepidum newly produced BChl c derivatives possessing a chlorine or bromine atom at the terminus of the esterifying chain in the 17-propionate residue by cultivation with exogenous ω-halo-1-alkanols. The relative ratios of BChl c derivatives esterified with 8-chloro-1-octanol and 10-chloro-1-decanol were estimated to be 26.5% and 33.3% by cultivation with these ω-chloro-1-alkanols at the final concentrations of 300 and 150 μM, respectively. In contrast, smaller amounts of unnatural BChls c esterified with ω-bromo-1-alkanols were biosynthesized than those esterified with ω-chloro-1-alkanols: the ratios of BChl c derivatives esterified with 8-bromo-1-octanol and 10-bromo-1-decanol were 11.3% and 12.2% at the concentrations of 300 and 150 μM, respectively. These indicate that ω-chloro-1-alkanols can be incorporated into bacteriochlorophyllide c more than ω-bromo-1-alkanols in the BChl c biosynthetic pathway. The homolog compositions of the novel BChl c derivatives possessing a halogen atom were analogous to those of coexisting natural BChl c esterified with farnesol. These results demonstrate unique properties of BChl c synthase, BchK, which can utilize unnatural substrates containing halogen in the BChl c biosynthesis of Cba. tepidum.
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Affiliation(s)
- Yoshitaka Saga
- Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan.
| | - Keisuke Hayashi
- Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Tadashi Mizoguchi
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
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Harada J, Mizoguchi T, Satoh S, Tsukatani Y, Yokono M, Noguchi M, Tanaka A, Tamiaki H. Specific gene bciD for C7-methyl oxidation in bacteriochlorophyll e biosynthesis of brown-colored green sulfur bacteria. PLoS One 2013; 8:e60026. [PMID: 23560066 PMCID: PMC3613366 DOI: 10.1371/journal.pone.0060026] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 02/20/2013] [Indexed: 11/18/2022] Open
Abstract
The gene named bciD, which encodes the enzyme involved in C7-formylation in bacteriochlorophyll e biosynthesis, was found and investigated by insertional inactivation in the brown-colored green sulfur bacterium Chlorobaculum limnaeum (previously called Chlorobium phaeobacteroides). The bciD mutant cells were green in color, and accumulated bacteriochlorophyll c homologs bearing the 7-methyl group, compared to C7-formylated BChl e homologs in the wild type. BChl-c homolog compositions in the mutant were further different from those in Chlorobaculum tepidum which originally produced BChl c: (3(1) S)-8-isobutyl-12-ethyl-BChl c was unusually predominant.
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Affiliation(s)
- Jiro Harada
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, Japan
- * E-mail: (JH); (HT)
| | - Tadashi Mizoguchi
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Souichirou Satoh
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Yusuke Tsukatani
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
- Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Makio Yokono
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Masato Noguchi
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, Japan
| | - Ayumi Tanaka
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Hokkaido, Japan
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Sapporo, Hokkaido, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
- * E-mail: (JH); (HT)
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Kulminskaya NV, Pedersen MØ, Bjerring M, Underhaug J, Miller M, Frigaard NU, Nielsen JT, Nielsen NC. In Situ Solid-State NMR Spectroscopy of Protein in Heterogeneous Membranes: The Baseplate Antenna Complex of Chlorobaculum tepidum. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201201160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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26
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Kulminskaya NV, Pedersen MØ, Bjerring M, Underhaug J, Miller M, Frigaard NU, Nielsen JT, Nielsen NC. In situ solid-state NMR spectroscopy of protein in heterogeneous membranes: the baseplate antenna complex of Chlorobaculum tepidum. Angew Chem Int Ed Engl 2012; 51:6891-5. [PMID: 22685072 DOI: 10.1002/anie.201201160] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2012] [Revised: 05/16/2012] [Indexed: 11/06/2022]
Abstract
A clever combination: an in situ solid-state NMR analysis of CsmA proteins in the heterogeneous environment of the photoreceptor of Chlorobaculum tepidum is reported. Using different combinations of 2D and 3D solid-state NMR spectra, 90 % of the CsmA resonances are assigned and provide on the basis of chemical shift data information about the structure and conformation of CsmA in the CsmA-bacteriochlorophyll a complex.
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Garcia Costas AM, Tsukatani Y, Rijpstra WIC, Schouten S, Welander PV, Summons RE, Bryant DA. Identification of the bacteriochlorophylls, carotenoids, quinones, lipids, and hopanoids of "Candidatus Chloracidobacterium thermophilum". J Bacteriol 2012; 194:1158-68. [PMID: 22210764 PMCID: PMC3294765 DOI: 10.1128/jb.06421-11] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 12/19/2011] [Indexed: 11/20/2022] Open
Abstract
"Candidatus Chloracidobacterium thermophilum" is a recently discovered chlorophototroph from the bacterial phylum Acidobacteria, which synthesizes bacteriochlorophyll (BChl) c and chlorosomes like members of the green sulfur bacteria (GSB) and the green filamentous anoxygenic phototrophs (FAPs). The pigments (BChl c homologs and carotenoids), quinones, lipids, and hopanoids of cells and chlorosomes of this new chlorophototroph were characterized in this study. "Ca. Chloracidobacterium thermophilum" methylates its antenna BChls at the C-8(2) and C-12(1) positions like GSB, but these BChls were esterified with a variety of isoprenoid and straight-chain alkyl alcohols as in FAPs. Unlike the chlorosomes of other green bacteria, "Ca. Chloracidobacterium thermophilum" chlorosomes contained two major xanthophyll carotenoids, echinenone and canthaxanthin. These carotenoids may confer enhanced protection against reactive oxygen species and could represent a specific adaptation to the highly oxic natural environment in which "Ca. Chloracidobacterium thermophilum" occurs. Dihydrogenated menaquinone-8 [menaquinone-8(H(2))], which probably acts as a quencher of energy transfer under oxic conditions, was an abundant component of both cells and chlorosomes of "Ca. Chloracidobacterium thermophilum." The betaine lipid diacylglycerylhydroxymethyl-N,N,N-trimethyl-β-alanine, esterified with 13-methyl-tetradecanoic (isopentadecanoic) acid, was a prominent polar lipid in the membranes of both "Ca. Chloracidobacterium thermophilum" cells and chlorosomes. This lipid may represent a specific adaptive response to chronic phosphorus limitation in the mats. Finally, three hopanoids, diploptene, bacteriohopanetetrol, and bacteriohopanetetrol cyclitol ether, which may help to stabilize membranes during diel shifts in pH and other physicochemical conditions in the mats, were detected in the membranes of "Ca. Chloracidobacterium thermophilum."
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Affiliation(s)
- Amaya M. Garcia Costas
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Yusuke Tsukatani
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - W. Irene C. Rijpstra
- NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Organic Biogeochemistry, Den Burg, The Netherlands
| | - Stefan Schouten
- NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Organic Biogeochemistry, Den Burg, The Netherlands
| | - Paula V. Welander
- Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Roger E. Summons
- Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Donald A. Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
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Garcia Costas AM, Tsukatani Y, Romberger SP, Oostergetel GT, Boekema EJ, Golbeck JH, Bryant DA. Ultrastructural analysis and identification of envelope proteins of "Candidatus Chloracidobacterium thermophilum" chlorosomes. J Bacteriol 2011; 193:6701-11. [PMID: 21965575 PMCID: PMC3232888 DOI: 10.1128/jb.06124-11] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 09/23/2011] [Indexed: 11/20/2022] Open
Abstract
Chlorosomes are sac-like, light-harvesting organelles that characteristically contain very large numbers of bacteriochlorophyll (BChl) c, d, or e molecules. These antenna structures occur in chlorophototrophs belonging to some members of the Chlorobi and Chloroflexi phyla and are also found in a recently discovered member of the phylum Acidobacteria, "Candidatus Chloracidobacterium thermophilum." "Ca. Chloracidobacterium thermophilum" is the first aerobic organism discovered to possess chlorosomes as light-harvesting antennae for phototrophic growth. Chlorosomes were isolated from "Ca. Chloracidobacterium thermophilum" and subjected to electron microscopic, spectroscopic, and biochemical analyses. The chlorosomes of "Ca. Chloracidobacterium thermophilum" had an average size of ∼100 by 30 nm. Cryo-electron microscopy showed that the BChl c molecules formed folded or twisted, sheet-like structures with a lamellar spacing of ∼2.3 nm. Unlike the BChls in the chlorosomes of the green sulfur bacterium Chlorobaculum tepidum, concentric cylindrical nanotubes were not observed. Chlorosomes of "Ca. Chloracidobacterium thermophilum" contained a homolog of CsmA, the BChl a-binding, baseplate protein; CsmV, a protein distantly related to CsmI, CsmJ, and CsmX of C. tepidum, which probably binds a single [2Fe-2S] cluster; and five unique polypeptides (CsmR, CsmS, CsmT, CsmU, and a type II NADH dehydrogenase homolog). Although "Ca. Chloracidobacterium thermophilum" is an aerobe, energy transfer among the BChls in these chlorosomes was very strongly quenched in the presence of oxygen (as measured by quenching of fluorescence emission). The combined analyses showed that the chlorosomes of "Ca. Chloracidobacterium thermophilum" possess a number of unique features but also share some properties with the chlorosomes found in anaerobic members of other phyla.
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Affiliation(s)
| | | | | | - Gert T. Oostergetel
- Groningen Biomolecular Sciences and Biotechnology Institute, 9747 AG Groningen, The Netherlands
| | - Egbert J. Boekema
- Groningen Biomolecular Sciences and Biotechnology Institute, 9747 AG Groningen, The Netherlands
| | - John H. Golbeck
- Department of Biochemistry and Molecular Biology
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Donald A. Bryant
- Department of Biochemistry and Molecular Biology
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717
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Nishimori R, Mizoguchi T, Tamiaki H, Kashimura S, Saga Y. Biosynthesis of Unnatural Bacteriochlorophyll c Derivatives Esterified with α,ω-Diols in the Green Sulfur Photosynthetic Bacterium Chlorobaculum tepidum. Biochemistry 2011; 50:7756-64. [DOI: 10.1021/bi200994h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Risato Nishimori
- Department of Chemistry, Faculty
of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Tadashi Mizoguchi
- Department of Bioscience and
Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Hitoshi Tamiaki
- Department of Bioscience and
Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Shigenori Kashimura
- Department of Chemistry, Faculty
of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
| | - Yoshitaka Saga
- Department of Chemistry, Faculty
of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
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Multiple types of 8-vinyl reductases for (bacterio)chlorophyll biosynthesis occur in many green sulfur bacteria. J Bacteriol 2011; 193:4996-8. [PMID: 21764919 DOI: 10.1128/jb.05520-11] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two 8-vinyl reductases, BciA and BciB, have been identified in chlorophototrophs. The bciA gene of Chlorobaculum tepidum was replaced with genes similar to bciB from other green sulfur bacteria. Pigment analyses of the complemented strains showed that the bciB homologs encode 8-vinyl reductases similar to those of cyanobacteria.
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31
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Tang KH, Barry K, Chertkov O, Dalin E, Han CS, Hauser LJ, Honchak BM, Karbach LE, Land ML, Lapidus A, Larimer FW, Mikhailova N, Pitluck S, Pierson BK, Blankenship RE. Complete genome sequence of the filamentous anoxygenic phototrophic bacterium Chloroflexus aurantiacus. BMC Genomics 2011; 12:334. [PMID: 21714912 PMCID: PMC3150298 DOI: 10.1186/1471-2164-12-334] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 06/29/2011] [Indexed: 11/16/2022] Open
Abstract
Background Chloroflexus aurantiacus is a thermophilic filamentous anoxygenic phototrophic (FAP) bacterium, and can grow phototrophically under anaerobic conditions or chemotrophically under aerobic and dark conditions. According to 16S rRNA analysis, Chloroflexi species are the earliest branching bacteria capable of photosynthesis, and Cfl. aurantiacus has been long regarded as a key organism to resolve the obscurity of the origin and early evolution of photosynthesis. Cfl. aurantiacus contains a chimeric photosystem that comprises some characters of green sulfur bacteria and purple photosynthetic bacteria, and also has some unique electron transport proteins compared to other photosynthetic bacteria. Methods The complete genomic sequence of Cfl. aurantiacus has been determined, analyzed and compared to the genomes of other photosynthetic bacteria. Results Abundant genomic evidence suggests that there have been numerous gene adaptations/replacements in Cfl. aurantiacus to facilitate life under both anaerobic and aerobic conditions, including duplicate genes and gene clusters for the alternative complex III (ACIII), auracyanin and NADH:quinone oxidoreductase; and several aerobic/anaerobic enzyme pairs in central carbon metabolism and tetrapyrroles and nucleic acids biosynthesis. Overall, genomic information is consistent with a high tolerance for oxygen that has been reported in the growth of Cfl. aurantiacus. Genes for the chimeric photosystem, photosynthetic electron transport chain, the 3-hydroxypropionate autotrophic carbon fixation cycle, CO2-anaplerotic pathways, glyoxylate cycle, and sulfur reduction pathway are present. The central carbon metabolism and sulfur assimilation pathways in Cfl. aurantiacus are discussed. Some features of the Cfl. aurantiacus genome are compared with those of the Roseiflexus castenholzii genome. Roseiflexus castenholzii is a recently characterized FAP bacterium and phylogenetically closely related to Cfl. aurantiacus. According to previous reports and the genomic information, perspectives of Cfl. aurantiacus in the evolution of photosynthesis are also discussed. Conclusions The genomic analyses presented in this report, along with previous physiological, ecological and biochemical studies, indicate that the anoxygenic phototroph Cfl. aurantiacus has many interesting and certain unique features in its metabolic pathways. The complete genome may also shed light on possible evolutionary connections of photosynthesis.
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Affiliation(s)
- Kuo-Hsiang Tang
- Department of Biology and Department of Chemistry, Campus Box 1137, Washington University in St. Louis, St. Louis, MO 63130, USA
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32
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Liu Z, Bryant DA. Identification of a gene essential for the first committed step in the biosynthesis of bacteriochlorophyll c. J Biol Chem 2011; 286:22393-402. [PMID: 21550979 DOI: 10.1074/jbc.m111.249433] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacteriochlorophylls (BChls) c, d, and e are the major chlorophylls in chlorosomes, which are the largest and one of the most efficient antennae produced by chlorophototrophic organisms. In the biosynthesis of these three BChls, a C-13(2)-methylcarboxyl group found in all other chlorophylls (Chls) must be removed. This reaction is postulated to be the first committed step in the synthesis of these BChls. Analyses of gene neighborhoods of (B)Chl biosynthesis genes and distribution patterns in organisms producing chlorosomes helped to identify a gene (bciC) that appeared to be a good candidate to produce the enzyme involved in this biochemical reaction. To confirm that this was the case, a deletion mutant of an open reading frame orthologous to bciC, CT1077, was constructed in Chlorobaculum tepidum, a genetically tractible green sulfur bacterium. The CT1077 deletion mutant was unable to synthesize BChl c but still synthesized BChl a and Chl a. The deletion mutant accumulated large amounts of various (bacterio)pheophorbides, all of which still had C-13(2)-methylcarboxyl groups. A C. tepidum strain in which CT1077 was replaced by an orthologous gene, Cabther_B0081 [corrected] from "Candidatus Chloracidobacterium thermophilum" was constructed. Although the product of Cabther_B0081 [corrected] was only 28% identical to the product of CT1077, this strain synthesized BChl c, BChl a, and Chl a in amounts similar to wild-type C. tepidum cells. To indicate their roles in the first committed step of BChl c, d, and e biosynthesis, open reading frames CT1077 and Cabther_B0081 [corrected] have been redesignated bciC. The potential mechanism by which BciC removes the C-13(2)-methylcarboxyl moiety of chlorophyllide a is discussed.
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Affiliation(s)
- Zhenfeng Liu
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Wen J, Zhang H, Gross ML, Blankenship RE. Native electrospray mass spectrometry reveals the nature and stoichiometry of pigments in the FMO photosynthetic antenna protein. Biochemistry 2011; 50:3502-11. [PMID: 21449539 DOI: 10.1021/bi200239k] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The nature and stoichiometry of pigments in the Fenna-Matthews-Olson (FMO) photosynthetic antenna protein complex were determined by native electrospray mass spectrometry. The FMO antenna complex was the first chlorophyll-containing protein that was crystallized. Previous results indicate that the FMO protein forms a trimer with seven bacteriochlorophyll a in each monomer. This model has long been a working basis to understand the molecular mechanism of energy transfer through pigment/pigment and pigment/protein coupling. Recent results have suggested, however, that an eighth bacteriochlorophyll is present in some subunits. In this report, a direct mass spectrometry measurement of the molecular weight of the intact FMO protein complex clearly indicates the existence of an eighth pigment, which is assigned as a bacteriochlorophyll a by mass analysis of the complex and HPLC analysis of the pigment. The eighth pigment is found to be easily lost during purification, which results in its partial occupancy in the mass spectra of the intact complex prepared by different procedures. The results are consistent with the recent X-ray structural models. The existence of the eighth bacteriochlorophyll a in this model antenna protein gives new insights into the functional role of the FMO protein and motivates the need for new theoretical and spectroscopic assignments of spectral features of the FMO protein.
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Affiliation(s)
- Jianzhong Wen
- Department of Biology, Washington University in St. Louis, Missouri 63130, United States
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Tamiaki H, Komada J, Kunieda M, Fukai K, Yoshitomi T, Harada J, Mizoguchi T. In vitro synthesis and characterization of bacteriochlorophyll-f and its absence in bacteriochlorophyll-e producing organisms. PHOTOSYNTHESIS RESEARCH 2011; 107:133-138. [PMID: 21161597 DOI: 10.1007/s11120-010-9603-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Accepted: 12/01/2010] [Indexed: 05/30/2023]
Abstract
Bacteriochlorophyll(BChl)-f which has not yet been found in natural phototrophs was prepared by chemically modifying chlorophyll-b. The retention time of reverse-phase high-performance liquid chromatography of the synthetic monomeric BChl-f as well as its visible absorption and fluorescence emission spectra in a solution were identified and compared with other naturally occurring chlorophyll pigments obtained from the main light-harvesting antenna systems of green sulfur bacteria, BChls-c/d/e. Based on the above data, BChl-f was below the level of detection in three strains of green photosynthetic bacteria producing BChl-e.
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Affiliation(s)
- Hitoshi Tamiaki
- Department of Bioscience and Biotechnology, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
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Abstract
Mounting evidence in recent years has challenged the dogma that prokaryotes are simple and undefined cells devoid of an organized subcellular architecture. In fact, proteins once thought to be the purely eukaryotic inventions, including relatives of actin and tubulin control prokaryotic cell shape, DNA segregation, and cytokinesis. Similarly, compartmentalization, commonly noted as a distinguishing feature of eukaryotic cells, is also prevalent in the prokaryotic world in the form of protein-bounded and lipid-bounded organelles. In this article we highlight some of these prokaryotic organelles and discuss the current knowledge on their ultrastructure and the molecular mechanisms of their biogenesis and maintenance.
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Affiliation(s)
- Dorothee Murat
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California 94720-3102, USA
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36
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Envelope proteins of the CsmB/CsmF and CsmC/CsmD motif families influence the size, shape, and composition of chlorosomes in Chlorobaculum tepidum. J Bacteriol 2009; 191:7109-20. [PMID: 19749040 DOI: 10.1128/jb.00707-09] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The chlorosome envelope of Chlorobaculum tepidum contains 10 proteins that belong to four structural motif families. A previous mutational study (N.-U. Frigaard, H. Li, K. J. Milks, and D. A. Bryant, J. Bacteriol. 186:646-653, 2004) suggested that some of these proteins might have redundant functions. Six multilocus mutants were constructed to test the effects of eliminating the proteins of the CsmC/CsmD and CsmB/CsmF motif families, and the resulting strains were characterized physiologically and biochemically. Mutants lacking all proteins of either motif family still assembled functional chlorosomes, and as measured by growth rates of the mutant strains, light harvesting was affected only at the lowest light intensities tested (9 and 32 micromol photons m(-2) s(-1)). The size, composition, and biogenesis of the mutant chlorosomes differed from those of wild-type chlorosomes. Mutants lacking proteins of the CsmC/CsmD motif family produced smaller chlorosomes than did the wild type, and the Q(y) absorbance maximum for the bacteriochlorophyll c aggregates in these chlorosomes was strongly blueshifted. Conversely, the chlorosomes of mutants lacking proteins of the CsmB/CsmF motif family were larger than wild-type chlorosomes, and the Q(y) absorption for their bacteriochlorophyll c aggregates was redshifted. When CsmH was eliminated in addition to other proteins of either motif family, chlorosomes had smaller diameters. These data show that the chlorosome envelope proteins of the CsmB/CsmF and CsmC/CsmD families play important roles in determining chlorosome size as well as the assembly and supramolecular organization of the bacteriochlorophyll c aggregates within the chlorosome.
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Gomez Maqueo Chew A, Frigaard NU, Bryant DA. Mutational analysis of three bchH paralogs in (bacterio-)chlorophyll biosynthesis in Chlorobaculum tepidum. PHOTOSYNTHESIS RESEARCH 2009; 101:21-34. [PMID: 19568953 DOI: 10.1007/s11120-009-9460-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Accepted: 06/10/2009] [Indexed: 05/28/2023]
Abstract
The first committed step in the biosynthesis of (bacterio-)chlorophyll is the insertion of Mg2+ into protoporphyrin IX by Mg-chelatase. In all known (B)Chl-synthesizing organisms, Mg-chelatase is encoded by three genes that are homologous to bchH, bchD, and bchI of Rhodobacter spp. The genomes of all sequenced strains of green sulfur bacteria (Chlorobi) encode multiple bchH paralogs, and in the genome of Chlorobaculum tepidum, there are three bchH paralogs, denoted CT1295 (bchT), CT1955 (bchS), and CT1957 (bchH). Cba. tepidum mutants lacking one or two of these paralogs were constructed and characterized. All of the mutants lacking only one of these BchH homologs, as well as bchS bchT and bchH bchT double mutants, which can only produce BchH or BchS, respectively, were viable. However, attempts to construct a bchH bchS double mutant, in which only BchT was functional, were consistently unsuccessful. This result suggested that BchT alone is unable to support the minimal (B)Chl synthesis requirements of cells required for viability. The pigment compositions of the various mutant strains varied significantly. The BChl c content of the bchS mutant was only approximately 10% of that of the wild type, and this mutant excreted large amounts of protoporphyrin IX into the growth medium. The observed differences in BChl c production of the mutant strains were consistent with the hypothesis that the three BchH homologs function in end product regulation and/or substrate channeling of intermediates in the BChl c biosynthetic pathway.
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Affiliation(s)
- Aline Gomez Maqueo Chew
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, S-235 Frear Building, PA 16802, University Park, USA
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The biosynthetic pathway for myxol-2' fucoside (myxoxanthophyll) in the cyanobacterium Synechococcus sp. strain PCC 7002. J Bacteriol 2009; 191:3292-300. [PMID: 19304845 DOI: 10.1128/jb.00050-09] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Synechococcus sp. strain PCC 7002 produces a variety of carotenoids, which comprise predominantly dicylic beta-carotene and two dicyclic xanthophylls, zeaxanthin and synechoxanthin. However, this cyanobacterium also produces a monocyclic myxoxanthophyll, which was identified as myxol-2' fucoside. Compared to the carotenoid glycosides produced by diverse microorganisms, cyanobacterial myxoxanthophyll and closely related compounds are unusual because they are glycosylated on the 2'-OH rather than on the 1'-OH position of the psi end of the molecule. In this study, the genes encoding two enzymes that modify the psi end of myxoxanthophyll in Synechococcus sp. strain PCC 7002 were identified. Mutational and biochemical studies showed that open reading frame SynPCC7002_A2032, renamed cruF, encodes a 1',2'-hydroxylase [corrected] and that open reading frame SynPCC7002_A2031, renamed cruG, encodes a 2'-O-glycosyltransferase. The enzymatic activity of CruF was verified by chemical characterization of the carotenoid products synthesized when cruF was expressed in a lycopene-producing strain of Escherichia coli. Database searches showed that homologs of cruF and cruG occur in the genomes of all sequenced cyanobacterial strains that are known to produce myxol or the acylic xanthophyll oscillaxanthin. The genomes of many other bacteria that produce hydroxylated carotenoids but do not contain crtC homologs also contain cruF orthologs. Based upon observable intermediates, a complete biosynthetic pathway for myxoxanthophyll is proposed. This study expands the suite of enzymes available for metabolic engineering of carotenoid biosynthetic pathways for biotechnological applications.
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The Biosynthetic pathway for synechoxanthin, an aromatic carotenoid synthesized by the euryhaline, unicellular cyanobacterium Synechococcus sp. strain PCC 7002. J Bacteriol 2008; 190:7966-74. [PMID: 18849428 DOI: 10.1128/jb.00985-08] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The euryhaline, unicellular cyanobacterium Synechococcus sp. strain PCC 7002 produces the dicyclic aromatic carotenoid synechoxanthin (chi,chi-caroten-18,18'-dioic acid) as a major pigment (>15% of total carotenoid) and when grown to stationary phase also accumulates small amounts of renierapurpurin (chi,chi-carotene) (J. E. Graham, J. T. J. Lecomte, and D. A. Bryant, J. Nat. Prod. 71:1647-1650, 2008). Two genes that were predicted to encode enzymes involved in the biosynthesis of synechoxanthin were identified by comparative genomics, and these genes were insertionally inactivated in Synechococcus sp. strain PCC 7002 to verify their function. The cruE gene (SYNPCC7002_A1248) encodes beta-carotene desaturase/methyltransferase, which converts beta-carotene to renierapurpurin. The cruH gene (SYNPCC7002_A2246) encodes an enzyme that is minimally responsible for the hydroxylation/oxidation of the C-18 and C-18' methyl groups of renierapurpurin. Based on observed and biochemically characterized intermediates, a complete pathway for synechoxanthin biosynthesis is proposed.
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Identification of the bchP gene, encoding geranylgeranyl reductase in Chlorobaculum tepidum. J Bacteriol 2007; 190:747-9. [PMID: 17993528 DOI: 10.1128/jb.01430-07] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Chlorobaculum tepidum genome contains two paralogous genes, CT2256 and CT1232, whose products are members of the FixC dehydrogenase superfamily and have sequence similarity to geranylgeranyl reductases. Each gene was insertionally inactivated, and the resulting mutants were characterized. CT2256 encodes geranylgeranyl reductase (BchP); CT1232 is not involved in bacteriochlorophyll or chlorophyll biosynthesis.
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Chew AGM, Bryant DA. Chlorophyll Biosynthesis in Bacteria: The Origins of Structural and Functional Diversity. Annu Rev Microbiol 2007; 61:113-29. [PMID: 17506685 DOI: 10.1146/annurev.micro.61.080706.093242] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The use of photochemical reaction centers to convert light energy into chemical energy, chlorophototrophy, occurs in organisms belonging to only five eubacterial phyla: Cyanobacteria, Proteobacteria, Chlorobi, Chloroflexi, and Firmicutes. All chlorophototrophs synthesize two types of pigments: (a) chlorophylls and bacteriochlorophylls, which function in both light harvesting and uniquely in photochemistry; and (b) carotenoids, which function primarily as photoprotective pigments but can also participate in light harvesting. Although hundreds of carotenoids have been identified, only 12 types of chlorophylls (Chl a, b, d; divinyl-Chl a and b; and 8(1)-hydroxy-Chl a) and bacteriochlorophylls (BChl a, b, c, d, e, and g) are currently known to occur in bacteria. This review summarizes recent progress in the identification of genes and enzymes in the biosynthetic pathways leading to Chls and BChls, the essential tetrapyrrole cofactors of photosynthesis, and addresses the mechanisms for generating functional diversity for solar energy capture and conversion in chlorophototrophs.
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Affiliation(s)
- Aline Gomez Maqueo Chew
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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Maresca JA, Graham JE, Wu M, Eisen JA, Bryant DA. Identification of a fourth family of lycopene cyclases in photosynthetic bacteria. Proc Natl Acad Sci U S A 2007; 104:11784-9. [PMID: 17606904 PMCID: PMC1905924 DOI: 10.1073/pnas.0702984104] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A fourth and large family of lycopene cyclases was identified in photosynthetic prokaryotes. The first member of this family, encoded by the cruA gene of the green sulfur bacterium Chlorobium tepidum, was identified in a complementation assay with a lycopene-producing strain of Escherichia coli. Orthologs of cruA are found in all available green sulfur bacterial genomes and in all cyanobacterial genomes that lack genes encoding CrtL- or CrtY-type lycopene cyclases. The cyanobacterium Synechococcus sp. PCC 7002 has two homologs of CruA, denoted CruA and CruP, and both were shown to have lycopene cyclase activity. Although all characterized lycopene cyclases in plants are CrtL-type proteins, genes orthologous to cruP also occur in plant genomes. The CruA- and CruP-type carotenoid cyclases are members of the FixC dehydrogenase superfamily and are distantly related to CrtL- and CrtY-type lycopene cyclases. Identification of these cyclases fills a major gap in the carotenoid biosynthetic pathways of green sulfur bacteria and cyanobacteria.
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Affiliation(s)
- Julia A. Maresca
- *Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802; and
| | - Joel E. Graham
- *Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802; and
| | - Martin Wu
- The Institute for Genomic Research (TIGR), Rockville, MD 20850
| | | | - Donald A. Bryant
- *Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802; and
- To whom correspondence should be addressed at:
Department of Biochemistry and Molecular Biology, Pennsylvania State University, S-235 Frear Building, University Park, PA 16802. E-mail:
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Gomez Maqueo Chew A, Frigaard NU, Bryant DA. Bacteriochlorophyllide c C-8(2) and C-12(1) methyltransferases are essential for adaptation to low light in Chlorobaculum tepidum. J Bacteriol 2007; 189:6176-84. [PMID: 17586634 PMCID: PMC1951906 DOI: 10.1128/jb.00519-07] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteriochlorophyll (BChl) c is the major photosynthetic pigment in the green sulfur bacterium Chlorobaculum tepidum, in which it forms protein-independent aggregates that function in light harvesting. BChls c, d, and e are found only in chlorosome-producing bacteria and are unique among chlorophylls because of methylations that occur at the C-8(2) and C-12(1) carbons. Two genes required for these methylation reactions were identified and designated bchQ (CT1777) and bchR (CT1320). BchQ and BchR are members of the radical S-adenosylmethionine (SAM) protein superfamily; each has sequence motifs to ligate a [4Fe-4S] cluster, and we propose that they catalyze the methyl group transfers. bchQ, bchR, and bchQ bchR mutants of C. tepidum were constructed and characterized. The bchQ mutant produced BChl c that was not methylated at C-8(2), the bchR mutant produced BChl c that was not methylated at C-12(1), and the double mutant produced [8-ethyl, 12-methyl]-BChl c that lacked methylation at both the C-8(2) and C-12(1) positions. Compared to the wild type, the Qy absorption bands for BChl c in the mutant cells were narrower and blue shifted to various extents. All three mutants grew slower and had a lower cellular BChl c content than the wild type, an effect that was especially pronounced at low light intensities. These observations show that the C-8(2) and C-12(1) methylations of BChl c play important roles in the adaptation of C. tepidum to low light intensity. The data additionally suggest that these methylations also directly or indirectly affect the regulation of the BChl c biosynthetic pathway.
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Affiliation(s)
- Aline Gomez Maqueo Chew
- Department of Biochemistry and Molecular Biology, S-235 Frear Building, The Pennsylvania State University, University Park, PA 16802, USA
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Olson TL, van de Meene AML, Francis JN, Pierson BK, Blankenship RE. Pigment analysis of "Candidatus Chlorothrix halophila," a green filamentous anoxygenic phototrophic bacterium. J Bacteriol 2007; 189:4187-95. [PMID: 17369304 PMCID: PMC1913391 DOI: 10.1128/jb.01712-06] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Accepted: 02/27/2007] [Indexed: 11/20/2022] Open
Abstract
The pigment composition of "Candidatus Chlorothrix halophila," a filamentous anoxygenic phototrophic bacterium found in Baja California Sur, Mexico, was determined. Previous work showed that bacteriochlorophyll c (BChl c) was the major pigment in "Ca. Chlorothrix halophila," but it was not clear if this bacterium also contains BChl a (J. A. Klappenbach and B. K. Pierson, Arch. Microbiol. 181:17-25, 2004). Here we show that in addition to BChl c, a small amount of a pigment that is spectrally indistinguishable from BChl a is present in cell extracts of "Ca. Chlorothrix halophila." Nevertheless, the BChl a-like pigment from "Ca. Chlorothrix halophila" has a different molecular weight and a different high-performance liquid chromatography elution time than BChl a from other photosynthetic bacteria. Based on mass spectrometry and other spectroscopic analysis, we determined that the BChl a-like pigment in "Ca. Chlorothrix halophila" contains a tetrahydrogeranylgeraniol tail rather than the phytol tail that is present in BChl a. The carotenoids and major BChl c homologs in "Ca. Chlorothrix halophila" were also identified. BChls c were found to be farnesol esterified and geranylgeraniol esterified.
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Affiliation(s)
- Tien Le Olson
- Department of Biology and Chemistry, Arizona State University, Tempe, AZ 85287, USA
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Ikonen TP, Li H, Pšenčík J, Laurinmäki PA, Butcher SJ, Frigaard NU, Serimaa RE, Bryant DA, Tuma R. X-ray scattering and electron cryomicroscopy study on the effect of carotenoid biosynthesis to the structure of Chlorobium tepidum chlorosomes. Biophys J 2007; 93:620-8. [PMID: 17468163 PMCID: PMC1896238 DOI: 10.1529/biophysj.106.101444] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chlorosomes, the main antenna complexes of green photosynthetic bacteria, were isolated from null mutants of Chlorobium tepidum, each of which lacked one enzyme involved in the biosynthesis of carotenoids. The effects of the altered carotenoid composition on the structure of the chlorosomes were studied by means of x-ray scattering and electron cryomicroscopy. The chlorosomes from each mutant strain exhibited a lamellar arrangement of the bacteriochlorophyll c aggregates, which are the major constituents of the chlorosome interior. However, the carotenoid content and composition had a pronounced effect on chlorosome biogenesis and structure. The results indicate that carotenoids with a sufficiently long conjugated system are important for the biogenesis of the chlorosome baseplate. Defects in the baseplate structure affected the shape of the chlorosomes and were correlated with differences in the arrangement of lamellae and spacing between the lamellar planes of bacteriochlorophyll aggregates. In addition, comparisons among the various mutants enabled refinement of the assignments of the x-ray scattering peaks. While the main scattering peaks come from the lamellar structure of bacteriochlorophyll c aggregates, some minor peaks may originate from the paracrystalline arrangement of CsmA in the baseplate.
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Affiliation(s)
- T. P. Ikonen
- Department of Physical Sciences, University of Helsinki, Helsinki, Finland; Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, Pennsylvania; Department of Chemical Physics and Optics, Charles University, Prague, Czech Republic; Institute of Biotechnology and Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland; and Department of Molecular Biology, University of Copenhagen, Denmark
| | - H. Li
- Department of Physical Sciences, University of Helsinki, Helsinki, Finland; Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, Pennsylvania; Department of Chemical Physics and Optics, Charles University, Prague, Czech Republic; Institute of Biotechnology and Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland; and Department of Molecular Biology, University of Copenhagen, Denmark
| | - J. Pšenčík
- Department of Physical Sciences, University of Helsinki, Helsinki, Finland; Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, Pennsylvania; Department of Chemical Physics and Optics, Charles University, Prague, Czech Republic; Institute of Biotechnology and Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland; and Department of Molecular Biology, University of Copenhagen, Denmark
| | - P. A. Laurinmäki
- Department of Physical Sciences, University of Helsinki, Helsinki, Finland; Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, Pennsylvania; Department of Chemical Physics and Optics, Charles University, Prague, Czech Republic; Institute of Biotechnology and Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland; and Department of Molecular Biology, University of Copenhagen, Denmark
| | - S. J. Butcher
- Department of Physical Sciences, University of Helsinki, Helsinki, Finland; Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, Pennsylvania; Department of Chemical Physics and Optics, Charles University, Prague, Czech Republic; Institute of Biotechnology and Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland; and Department of Molecular Biology, University of Copenhagen, Denmark
| | - N.-U. Frigaard
- Department of Physical Sciences, University of Helsinki, Helsinki, Finland; Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, Pennsylvania; Department of Chemical Physics and Optics, Charles University, Prague, Czech Republic; Institute of Biotechnology and Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland; and Department of Molecular Biology, University of Copenhagen, Denmark
| | - R. E. Serimaa
- Department of Physical Sciences, University of Helsinki, Helsinki, Finland; Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, Pennsylvania; Department of Chemical Physics and Optics, Charles University, Prague, Czech Republic; Institute of Biotechnology and Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland; and Department of Molecular Biology, University of Copenhagen, Denmark
| | - D. A. Bryant
- Department of Physical Sciences, University of Helsinki, Helsinki, Finland; Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, Pennsylvania; Department of Chemical Physics and Optics, Charles University, Prague, Czech Republic; Institute of Biotechnology and Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland; and Department of Molecular Biology, University of Copenhagen, Denmark
| | - R. Tuma
- Department of Physical Sciences, University of Helsinki, Helsinki, Finland; Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, Pennsylvania; Department of Chemical Physics and Optics, Charles University, Prague, Czech Republic; Institute of Biotechnology and Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland; and Department of Molecular Biology, University of Copenhagen, Denmark
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Chew AGM, Bryant DA. Characterization of a plant-like protochlorophyllide a divinyl reductase in green sulfur bacteria. J Biol Chem 2006; 282:2967-75. [PMID: 17148453 DOI: 10.1074/jbc.m609730200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The green sulfur bacterium Chlorobium tepidum synthesizes three types of (bacterio)chlorophyll ((B)Chl): BChl a(P), Chl a(PD), and BChl c(F). During the synthesis of all three molecules, a C-8 vinyl substituent is reduced to an ethyl group, and in the case of BChl c(F), the C-8(2) carbon of this ethyl group is subsequently methylated once or twice by the radical S-adenosylmethionine enzyme BchQ. The C. tepidum genome contains homologs of two genes, bchJ (CT2014) and CT1063, that are highly homologous to genes, bchJ and AT5G18660, and that have been reported to encode C-8 vinyl reductases in Rhodobacter capsulatus and Arabidopsis thaliana, respectively. To determine which gene product actually encodes a C-8 vinyl reductase activity, the bchJ and CT1063 genes were insertionally inactivated in C. tepidum. All three Chls synthesized by the CT1063 mutant of C. tepidum have a C-8 vinyl group. Using NADPH but not NADH as reductant, recombinant BciA reduces the C-8 vinyl group of 3,8-divinyl-protochlorophyllide in vitro. These data demonstrate that CT1063, renamed bciA, encodes a C-8 divinyl reductase in C. tepidum. The bchJ mutant produces detectable amounts of Chl a(PD), BChl a(P), and BChl c(F), all of which have reduced C-8 substituents, but the mutant cells secrete large amounts of 3,8-divinyl-protochlorophyllide a into the growth medium and have a greatly reduced BChl c(F) content. The results suggest that BchJ may play an important role in substrate channeling and/or regulation of Chl biosynthesis but show that it is not a vinyl reductase. Because only some Chl-synthesizing organisms possess homologs of bciA, at least two types of C-8 vinyl reductases must occur.
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Affiliation(s)
- Aline Gomez Maqueo Chew
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Tsukatani Y, Miyamoto R, Itoh S, Oh-oka H. Soluble cytochrome c-554, CycA, is not essential for photosynthetic electron transfer in Chlorobium tepidum. FEBS Lett 2006; 580:2191-4. [PMID: 16579991 DOI: 10.1016/j.febslet.2006.03.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2006] [Revised: 03/02/2006] [Accepted: 03/03/2006] [Indexed: 11/18/2022]
Abstract
We constructed a mutant lacking soluble cytochrome c-554 (CycA) by disruption of the cycA gene in the green sulfur bacterium Chlorobium tepidum. The mutant grew phototrophically with a growth rate slower than that of the wild type, suggesting that CycA is not essential for photosynthetic electron transfer even though CycA is known to work as an electron donor to the reaction center. The re-reduction of photo-oxidized cytochrome c(z) by quinol oxidoreductase was inhibited almost completely by the addition of stigmatellin in the mutant cells. This result indicates that, in the mutant cells, the linear electron transfer can occur from the quinol oxidoreductase to cytochrome c(z), and to reaction center P840 with no participation of CycA.
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Affiliation(s)
- Yusuke Tsukatani
- Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
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48
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Frigaard NU, Bryant DA. Chlorosomes: Antenna Organelles in Photosynthetic Green Bacteria. MICROBIOLOGY MONOGRAPHS 2006. [DOI: 10.1007/7171_021] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Frigaard NU, Li H, Martinsson P, Das SK, Frank HA, Aartsma TJ, Bryant DA. Isolation and characterization of carotenosomes from a bacteriochlorophyll c-less mutant of Chlorobium tepidum. PHOTOSYNTHESIS RESEARCH 2005; 86:101-11. [PMID: 16172929 DOI: 10.1007/s11120-005-1331-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2004] [Accepted: 01/27/2005] [Indexed: 05/04/2023]
Abstract
Chlorosomes are the light-harvesting organelles in photosynthetic green bacteria and typically contain large amounts of bacteriochlorophyll (BChl) c in addition to smaller amounts of BChl a, carotenoids, and several protein species. We have isolated vestigial chlorosomes, denoted carotenosomes, from a BChl c-less, bchK mutant of the green sulfur bacterium Chlorobium tepidum. The physical shape of the carotenosomes (86 +/- 17 nm x 66 +/- 13 nm x 4.3 +/- 0.8 nm on average) was reminiscent of a flattened chlorosome. The carotenosomes contained carotenoids, BChl a, and the proteins CsmA and CsmD in ratios to each other comparable to their ratios in wild-type chlorosomes, but all other chlorosome proteins normally found in wild-type chlorosomes were found only in trace amounts or were not detected. Similar to wild-type chlorosomes, the CsmA protein in the carotenosomes formed oligomers at least up to homo-octamers as shown by chemical cross-linking and immunoblotting. The absorption spectrum of BChl a in the carotenosomes was also indistinguishable from that in wild-type chlorosomes. Energy transfer from the bulk carotenoids to BChl a in carotenosomes was poor. The results indicate that the carotenosomes have an intact baseplate made of remarkably stable oligomeric CsmA-BChl a complexes but are flattened in structure due to the absence of BChl c. Carotenosomes thus provide a valuable material for studying the biogenesis, structure, and function of the photosynthetic antennae in green bacteria.
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Affiliation(s)
- Niels-Ulrik Frigaard
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.
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Tsukatani Y, Miyamoto R, Itoh S, Oh-Oka H. Function of a PscD subunit in a homodimeric reaction center complex of the photosynthetic green sulfur bacterium Chlorobium tepidum studied by insertional gene inactivation. Regulation of energy transfer and ferredoxin-mediated NADP+ reduction on the cytoplasmic side. J Biol Chem 2004; 279:51122-30. [PMID: 15371432 DOI: 10.1074/jbc.m410432200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The PscD subunit in the homodimeric "type I" photosynthetic reaction center (RC) complex of the green sulfur bacterium Chlorobium tepidum was disrupted by insertional mutagenesis of its relevant pscD gene. This is the first report on the use of the direct mutagenic approach into the RC-related genes in green sulfur bacteria. The RC complex of C. tepidum is supposed to form a homodimer of two identical PscA subunits together with three other subunits: PscB (FA/FB-containing protein), PscC (cytochrome cz), and PscD. PscD shows a relatively low but significant similarity in its amino acid sequence to PsaD in the photosystem I of plants and cyanobacteria. We studied the biochemical and spectroscopic properties of a mutant lacking PscD in order to elucidate its unknown function. 1) The RC complex isolated from the mutant cells showed no band corresponding to PscD on SDS-PAGE analysis. 2) The growth rate of the PscD-less mutant was slower than that of the wild-type cells at low light intensities. 3) Time-resolved fluorescence spectra at 77 K revealed prolonged decay times of the fluorescence from bacteriochlorophyll c on the antenna chlorosome and from bacteriochlorophyll a on the Fenna-Matthews-Olson antenna protein in the mutant cells. The loss of PscD led to a much slower energy transfer from the antenna pigments to the special pair bacteriochlorophyll a (P840). 4) The mutant strain exhibited slightly less activity of ferredoxin-mediated NADP+ photoreduction compared with that in the wild-type strain. The extent of suppression, however, was less significant than that reported in the PsaD-less mutants of cyanobacterial photosystem I. The evolutionary relationship between PscD and PsaD was also discussed based on a structural homology modeling of the former.
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Affiliation(s)
- Yusuke Tsukatani
- Department of Biology, Graduate School of Science, Osaka University, Machikaneyama 1-1, Toyonaka, Osaka 560-0043, Japan.
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