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Niedzwiedzki DM, Swainsbury DJK, Martin EC, Hunter CN, Blankenship RE. Origin of the S* Excited State Feature of Carotenoids in Light-Harvesting Complex 1 from Purple Photosynthetic Bacteria. J Phys Chem B 2017; 121:7571-7585. [PMID: 28719215 DOI: 10.1021/acs.jpcb.7b04251] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This spectroscopic study investigates the origin of the transient feature of the S* excited state of carotenoids bound in LH1 complexes from purple bacteria. The studies were performed on two RC-LH1 complexes from Rba. sphaeroides strains that bound carotenoids with different carbon-carbon double bond conjugation N, neurosporene (N = 9) and spirilloxanthin (N = 13). The S* transient spectral feature, originally associated with an elusive and optically silent excited state of spirilloxanthin in the LH1 complex, may be successfully explained and mimicked without involving any unknown electronic state. The spectral and temporal characteristics of the S* feature suggest that it is associated with triplet-triplet annihilation of carotenoid triplets formed after direct excitation of the molecule via a singlet fission mechanism. Depending on pigment homogeneity and carotenoid assembly in the LH1 complex, the spectro-temporal component associated with triplet-triplet annihilation may simply resolve a pure T-S spectrum of a carotenoid. In some cases (like spirilloxanthin), the T-S feature will also be accompanied by a carotenoid Stark spectrum and/or residual transient absorption of minor carotenoid species bound into LH1 antenna complex.
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Affiliation(s)
| | - David J K Swainsbury
- Department of Molecular Biology and Biotechnology, University of Sheffield , Sheffield S10 2TN, United Kingdom
| | - Elizabeth C Martin
- Department of Molecular Biology and Biotechnology, University of Sheffield , Sheffield S10 2TN, United Kingdom
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield , Sheffield S10 2TN, United Kingdom
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52
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Disruption of a horizontally transferred phytoene desaturase abolishes carotenoid accumulation and diapause in Tetranychus urticae. Proc Natl Acad Sci U S A 2017; 114:E5871-E5880. [PMID: 28674017 DOI: 10.1073/pnas.1706865114] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Carotenoids underlie many of the vibrant yellow, orange, and red colors in animals, and are involved in processes ranging from vision to protection from stresses. Most animals acquire carotenoids from their diets because de novo synthesis of carotenoids is primarily limited to plants and some bacteria and fungi. Recently, sequencing projects in aphids and adelgids, spider mites, and gall midges identified genes with homology to fungal sequences encoding de novo carotenoid biosynthetic proteins like phytoene desaturase. The finding of horizontal gene transfers of carotenoid biosynthetic genes to three arthropod lineages was unprecedented; however, the relevance of the transfers for the arthropods that acquired them has remained largely speculative, which is especially true for spider mites that feed on plant cell contents, a known source of carotenoids. Pigmentation in spider mites results solely from carotenoids. Using a combination of genetic approaches, we show that mutations in a single horizontally transferred phytoene desaturase result in complete albinism in the two-spotted spider mite, Tetranychus urticae, as well as in the citrus red mite, Panonychus citri Further, we show that phytoene desaturase activity is essential for photoperiodic induction of diapause in an overwintering strain of T. urticae, consistent with a role for this enzyme in provisioning provitamin A carotenoids required for light perception. Carotenoid biosynthetic genes of fungal origin have therefore enabled some mites to forgo dietary carotenoids, with endogenous synthesis underlying their intense pigmentation and ability to enter diapause, a key to the global distribution of major spider mite pests of agriculture.
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53
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Light harvesting in phototrophic bacteria: structure and function. Biochem J 2017; 474:2107-2131. [DOI: 10.1042/bcj20160753] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 04/03/2017] [Accepted: 04/06/2017] [Indexed: 12/23/2022]
Abstract
This review serves as an introduction to the variety of light-harvesting (LH) structures present in phototrophic prokaryotes. It provides an overview of the LH complexes of purple bacteria, green sulfur bacteria (GSB), acidobacteria, filamentous anoxygenic phototrophs (FAP), and cyanobacteria. Bacteria have adapted their LH systems for efficient operation under a multitude of different habitats and light qualities, performing both oxygenic (oxygen-evolving) and anoxygenic (non-oxygen-evolving) photosynthesis. For each LH system, emphasis is placed on the overall architecture of the pigment–protein complex, as well as any relevant information on energy transfer rates and pathways. This review addresses also some of the more recent findings in the field, such as the structure of the CsmA chlorosome baseplate and the whole-cell kinetics of energy transfer in GSB, while also pointing out some areas in need of further investigation.
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54
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The C-terminus of PufX plays a key role in dimerisation and assembly of the reaction center light-harvesting 1 complex from Rhodobacter sphaeroides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2017; 1858:795-803. [PMID: 28587931 PMCID: PMC5538271 DOI: 10.1016/j.bbabio.2017.06.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 05/31/2017] [Accepted: 06/01/2017] [Indexed: 11/22/2022]
Abstract
In bacterial photosynthesis reaction center-light-harvesting 1 (RC-LH1) complexes trap absorbed solar energy by generating a charge separated state. Subsequent electron and proton transfers form a quinol, destined to diffuse to the cytochrome bc1 complex. In bacteria such as Rhodobacter (Rba.) sphaeroides and Rba. capsulatus the PufX polypeptide creates a channel for quinone/quinol traffic across the LH1 complex that surrounds the RC, and it is therefore essential for photosynthetic growth. PufX also plays a key role in dimerization of the RC-LH1-PufX core complex, and the structure of the Rba. sphaeroides complex shows that the PufX C-terminus, particularly the region from X49-X53, likely mediates association of core monomers. To investigate this putative interaction we analysed mutations PufX R49L, PufX R53L, PufX R49/53L and PufX G52L by measuring photosynthetic growth, fractionation of detergent-solubilised membranes, formation of 2-D crystals and electron microscopy. We show that these mutations do not affect assembly of PufX within the core or photosynthetic growth but they do prevent dimerization, consistent with predictions from the RC-LH1-PufX structure. We obtained low resolution structures of monomeric core complexes with and without PufX, using electron microscopy of negatively stained single particles and 3D reconstruction; the monomeric complex with PufX corresponds to one half of the dimer structure whereas LH1 completely encloses the RC if the gene encoding PufX is deleted. On the basis of the insights gained from these mutagenesis and structural analyses we propose a sequence for assembly of the dimeric RC-LH1-PufX complex.
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55
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Ashikhmin A, Makhneva Z, Bolshakov M, Moskalenko A. Incorporation of spheroidene and spheroidenone into light-harvesting complexes from purple sulfur bacteria. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2017; 170:99-107. [DOI: 10.1016/j.jphotobiol.2017.03.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Revised: 03/08/2017] [Accepted: 03/28/2017] [Indexed: 10/19/2022]
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56
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Niedzwiedzki DM, Dilbeck PL, Tang Q, Martin EC, Bocian DF, Hunter CN, Holten D. New insights into the photochemistry of carotenoid spheroidenone in light-harvesting complex 2 from the purple bacterium Rhodobacter sphaeroides. PHOTOSYNTHESIS RESEARCH 2017; 131:291-304. [PMID: 27854005 PMCID: PMC5313593 DOI: 10.1007/s11120-016-0322-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 10/24/2016] [Indexed: 06/06/2023]
Abstract
Light-harvesting complex 2 (LH2) from the semi-aerobically grown purple phototrophic bacterium Rhodobacter sphaeroides was studied using optical (static and time-resolved) and resonance Raman spectroscopies. This antenna complex comprises bacteriochlorophyll (BChl) a and the carotenoid spheroidenone, a ketolated derivative of spheroidene. The results indicate that the spheroidenone-LH2 complex contains two spectral forms of the carotenoid: (1) a minor, "blue" form with an S2 (11B u+ ) spectral origin band at 522 nm, shifted from the position in organic media simply by the high polarizability of the binding site, and (2) the major, "red" form with the origin band at 562 nm that is associated with a pool of pigments that more strongly interact with protein residues, most likely via hydrogen bonding. Application of targeted modeling of excited-state decay pathways after carotenoid excitation suggests that the high (92%) carotenoid-to-BChl energy transfer efficiency in this LH2 system, relative to LH2 complexes binding carotenoids with comparable double-bond conjugation lengths, derives mainly from resonance energy transfer from spheroidenone S2 (11B u+ ) state to BChl a via the Qx state of the latter, accounting for 60% of the total transfer. The elevated S2 (11B u+ ) → Qx transfer efficiency is apparently associated with substantially decreased energy gap (increased spectral overlap) between the virtual S2 (11B u+ ) → S0 (11A g- ) carotenoid emission and Qx absorption of BChl a. This reduced energetic gap is the ultimate consequence of strong carotenoid-protein interactions, including the inferred hydrogen bonding.
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Affiliation(s)
- Dariusz M Niedzwiedzki
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, 63130, USA.
- Photosynthetic Antenna Research Center, Washington University in St. Louis, Campus Box 1138, St. Louis, MO, 63130, USA.
| | - Preston L Dilbeck
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Qun Tang
- Department of Chemistry, University of California Riverside, Riverside, CA, 92521, USA
| | - Elizabeth C Martin
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - David F Bocian
- Department of Chemistry, University of California Riverside, Riverside, CA, 92521, USA
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, S10 2TN, UK
| | - Dewey Holten
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, 63130, USA
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57
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Olsen JD, Martin EC, Hunter CN. The PufX quinone channel enables the light-harvesting 1 antenna to bind more carotenoids for light collection and photoprotection. FEBS Lett 2017; 591:573-580. [PMID: 28130884 PMCID: PMC5347945 DOI: 10.1002/1873-3468.12575] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 01/12/2017] [Accepted: 01/16/2017] [Indexed: 11/30/2022]
Abstract
Photosynthesis in some phototrophic bacteria requires the PufX component of the reaction centre–light‐harvesting 1–PufX (RC‐LH1‐PufX) complex, which creates a pore for quinone/quinol (Q/QH2) exchange across the LH1 barrier surrounding the RC. However, photosynthetic bacteria such as Thermochromatium (T.) tepidum do not require PufX because there are fewer carotenoid binding sites, which creates multiple pores in the LH1 ring for Q/QH2 exchange. We show that an αTrp‐24→Phe alteration of the Rhodobacter (Rba.) sphaeroides LH1 antenna impairs carotenoid binding and allows photosynthetic growth in the absence of PufX. We propose that acquisition of PufX and confining Q/QH2 traffic to a pore adjacent to the RC QB site is an evolutionary upgrade that allows increased LH1 carotenoid content for enhanced light absorption and photoprotection.
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Affiliation(s)
- John D Olsen
- Department of Molecular Biology and Biotechnology, University of Sheffield, UK
| | - Elizabeth C Martin
- Department of Molecular Biology and Biotechnology, University of Sheffield, UK
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, UK
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58
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Muzziotti D, Adessi A, Faraloni C, Torzillo G, De Philippis R. Acclimation strategy of Rhodopseudomonas palustris to high light irradiance. Microbiol Res 2017; 197:49-55. [PMID: 28219525 DOI: 10.1016/j.micres.2017.01.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 01/02/2017] [Accepted: 01/23/2017] [Indexed: 12/30/2022]
Abstract
The ability of Rhodopseudomonas palustris cells to rapidly acclimate to high light irradiance is an essential issue when cells are grown under sunlight. The aim of this study was to investigate the photo-acclimation process in Rhodopseudomonas palustris 42OL under different culturing conditions: (i) anaerobic (AnG), (ii) aerobic (AG), and (iii) under H2-producing (HP) conditions both at low (LL) and high light (HL) irradiances. The results obtained clearly showed that the photosynthetic unit was significantly affected by the light irradiance at which Rp. palustris 42OL was grown. The synthesis of carotenoids was affected by both illumination and culturing conditions. At LL, lycopene was the main carotenoid synthetized under all conditions tested, while at HL under HP conditions, it resulted the predominant carotenoid. Oppositely, under AnG and AG at HL, rhodovibrin was the major carotenoid detected. The increase in light intensity produced a deeper variation in light-harvesting complexes (LHC) ratio. These findings are important for understanding the ecological distribution of PNSB in natural environments, mostly characterized by high light intensities, and for its growth outdoors.
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Affiliation(s)
- Dayana Muzziotti
- Department of Agrifood Production and Environmental Sciences, University of Florence, via Maragliano 77, 50144, Florence, Italy.
| | - Alessandra Adessi
- Department of Agrifood Production and Environmental Sciences, University of Florence, via Maragliano 77, 50144, Florence, Italy; Institute of Chemistry of Organometallic Compounds (ICCOM), CNR, Via Madonna del Piano, 10-50019 Sesto Fiorentino, Florence, Italy.
| | - Cecilia Faraloni
- Institute of Ecosystem Study (ISE), CNR, Via Madonna del Piano, 10-50019 Sesto Fiorentino, Florence, Italy.
| | - Giuseppe Torzillo
- Institute of Ecosystem Study (ISE), CNR, Via Madonna del Piano, 10-50019 Sesto Fiorentino, Florence, Italy.
| | - Roberto De Philippis
- Department of Agrifood Production and Environmental Sciences, University of Florence, via Maragliano 77, 50144, Florence, Italy; Institute of Chemistry of Organometallic Compounds (ICCOM), CNR, Via Madonna del Piano, 10-50019 Sesto Fiorentino, Florence, Italy.
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59
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Augmenting light coverage for photosynthesis through YFP-enhanced charge separation at the Rhodobacter sphaeroides reaction centre. Nat Commun 2017; 8:13972. [PMID: 28054547 PMCID: PMC5512671 DOI: 10.1038/ncomms13972] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 11/17/2016] [Indexed: 12/31/2022] Open
Abstract
Photosynthesis uses a limited range of the solar spectrum, so enhancing spectral coverage could improve the efficiency of light capture. Here, we show that a hybrid reaction centre (RC)/yellow fluorescent protein (YFP) complex accelerates photosynthetic growth in the bacterium Rhodobacter sphaeroides. The structure of the RC/YFP-light-harvesting 1 (LH1) complex shows the position of YFP attachment to the RC-H subunit, on the cytoplasmic side of the RC complex. Fluorescence lifetime microscopy of whole cells and ultrafast transient absorption spectroscopy of purified RC/YFP complexes show that the YFP–RC intermolecular distance and spectral overlap between the emission of YFP and the visible-region (QX) absorption bands of the RC allow energy transfer via a Förster mechanism, with an efficiency of 40±10%. This proof-of-principle study demonstrates the feasibility of increasing spectral coverage for harvesting light using non-native genetically-encoded light-absorbers, thereby augmenting energy transfer and trapping in photosynthesis. Photosynthesis uses only a limited range of solar radiation. Here, Grayson et al. genetically incorporated the yellow fluorescent protein (YFP) chromophore into a bacterial photosystem, and show that energy harvested by reaction centre–YFP complexes can augment photosynthesis in vivo.
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60
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Eltsova Z, Bolshakov M, Tsygankov A. Effect of light intensity and various organic acids on the growth of Rhodobacter sphaeroides LHII-deficient mutant in a turbidostat culture. PHOTOSYNTHESIS RESEARCH 2016; 130:307-316. [PMID: 27034065 DOI: 10.1007/s11120-016-0254-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 03/21/2016] [Indexed: 06/05/2023]
Abstract
The composition of photosynthetic apparatus of Rhodobacter sphaeroides wild strain 2.4.1 and its LHII-deficient mutant DBCΩ was compared. The absence of LHII in the mutant was confirmed by comparison of chromatophores spectra and by the absence of electrophoretic band corresponding to LHII complex. Continuous turbidostat cultures of wild strain and its LHII-deficient mutant were compared in response to different light intensities. Cultures were grown using lactate, mixture of lactate and acetate or succinate as carbon source. For comparative analysis, an approximation of experimental data by Monod and Gompertz equations were used. Cultures of DBCΩ had lower growth rates than wild strain when grown on lactate as electron donor and carbon source. Cultures of both strains grown on lactate and acetate or on succinate had similar growth rates. The cultures showed maximum growth rates when grown with succinate. Bacteriochlorophyll a content increased in both strains with decrease of incident light intensity. However, the variation of Bchl a content in wild strain was much more significant. Under light-limiting conditions, bacteriochlorophyll a content in DBCΩ was 4-5 times lower than in the wild strain. Under light-saturating conditions, it was only 1.5-2.5 times lower. Growing with lactate or with lactate and acetate, the mutant switched from light limitation under low light intensities to limitation by organic acids under higher light, whereas the parental strain had similar switch of limiting factor only when growing with lactate and acetate mixture. DBCΩ mutant has higher minimal light intensity enabling growth on any organic acid as a substrate. When growing with lactate or with lactate and acetate, the mutant reached maximum growth rate at lower light intensities than the wild strain. This phenomenon was observed for the first time. Taking into account the concentration of BChl a under light-limiting conditions, the thickness of the suspension capable of effective light absorption could be increased by 4-5 times, which is favorable for intensive cultivation.
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Affiliation(s)
- Zinaida Eltsova
- Institute of Basic Biological Problems, Russian Academy of Sciences, 2, Institutskaya str, Pushchino, Moscow region, Russia, 142290.
| | - Maxim Bolshakov
- Institute of Basic Biological Problems, Russian Academy of Sciences, 2, Institutskaya str, Pushchino, Moscow region, Russia, 142290
| | - Anatoly Tsygankov
- Institute of Basic Biological Problems, Russian Academy of Sciences, 2, Institutskaya str, Pushchino, Moscow region, Russia, 142290
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61
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Tsargorodska A, Cartron ML, Vasilev C, Kodali G, Mass OA, Baumberg JJ, Dutton PL, Hunter CN, Törmä P, Leggett GJ. Strong Coupling of Localized Surface Plasmons to Excitons in Light-Harvesting Complexes. NANO LETTERS 2016; 16:6850-6856. [PMID: 27689237 PMCID: PMC5135229 DOI: 10.1021/acs.nanolett.6b02661] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 09/28/2016] [Indexed: 05/24/2023]
Abstract
Gold nanostructure arrays exhibit surface plasmon resonances that split after attaching light harvesting complexes 1 and 2 (LH1 and LH2) from purple bacteria. The splitting is attributed to strong coupling between the localized surface plasmon resonances and excitons in the light-harvesting complexes. Wild-type and mutant LH1 and LH2 from Rhodobacter sphaeroides containing different carotenoids yield different splitting energies, demonstrating that the coupling mechanism is sensitive to the electronic states in the light harvesting complexes. Plasmon-exciton coupling models reveal different coupling strengths depending on the molecular organization and the protein coverage, consistent with strong coupling. Strong coupling was also observed for self-assembling polypeptide maquettes that contain only chlorins. However, it is not observed for monolayers of bacteriochlorophyll, indicating that strong plasmon-exciton coupling is sensitive to the specific presentation of the pigment molecules.
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Affiliation(s)
- Anna Tsargorodska
- Department
of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, U.K.
| | - Michaël L. Cartron
- Department
of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, U.K.
| | - Cvetelin Vasilev
- Department
of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, U.K.
| | - Goutham Kodali
- The
Johnson Research Foundation and Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 10104, United States
| | - Olga A. Mass
- Department
of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Jeremy J. Baumberg
- Cavendish
Laboratory, Dept. of Physics, University
of Cambridge, J. J. Thomson
Ave, Cambridge, CB3 0HE, U.K.
| | - P. Leslie Dutton
- The
Johnson Research Foundation and Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 10104, United States
| | - C. Neil Hunter
- Department
of Molecular Biology and Biotechnology, University of Sheffield, Western Bank, Sheffield S10 2TN, U.K.
| | - Päivi Törmä
- COMP Centre
of Excellence, Department of Applied Physics, Aalto University, School of Science,
P.O. Box 15100, 00076 Aalto, Finland
| | - Graham J. Leggett
- Department
of Chemistry, University of Sheffield, Brook Hill, Sheffield S3 7HF, U.K.
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62
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Niedzwiedzki DM, Hunter CN, Blankenship RE. Evaluating the Nature of So-Called S*-State Feature in Transient Absorption of Carotenoids in Light-Harvesting Complex 2 (LH2) from Purple Photosynthetic Bacteria. J Phys Chem B 2016; 120:11123-11131. [PMID: 27726397 PMCID: PMC5098231 DOI: 10.1021/acs.jpcb.6b08639] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Carotenoids
are a class of natural pigments present in all phototrophic
organisms, mainly in their light-harvesting proteins in which they
play roles of accessory light absorbers and photoprotectors. Extensive
time-resolved spectroscopic studies of these pigments have revealed
unexpectedly complex photophysical properties, particularly for carotenoids
in light-harvesting LH2 complexes from purple bacteria. An ambiguous,
optically forbidden electronic excited state designated as S* has
been postulated to be involved in carotenoid excitation relaxation
and in an alternative carotenoid-to-bacteriochlorophyll energy transfer
pathway, as well as being a precursor of the carotenoid triplet state.
However, no definitive and satisfactory origin of the carotenoid S*
state in these complexes has been established, despite a wide-ranging
series of studies. Here, we resolve the ambiguous origin of the carotenoid
S* state in LH2 complex from Rba. sphaeroides by
showing that the S* feature can be seen as a combination of ground
state absorption bleaching of the carotenoid pool converted to cations
and the Stark spectrum of neighbor neutral carotenoids, induced by
temporal electric field brought by the carotenoid cation–bacteriochlorophyll
anion pair. These findings remove the need to assign an S* state,
and thereby significantly simplify the photochemistry of carotenoids
in these photosynthetic antenna complexes.
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Affiliation(s)
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield , Sheffield S10 2TN, United Kingdom
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63
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Hitchcock A, Jackson PJ, Chidgey JW, Dickman MJ, Hunter CN, Canniffe DP. Biosynthesis of Chlorophyll a in a Purple Bacterial Phototroph and Assembly into a Plant Chlorophyll-Protein Complex. ACS Synth Biol 2016; 5:948-54. [PMID: 27171912 DOI: 10.1021/acssynbio.6b00069] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Improvements to photosynthetic efficiency could be achieved by manipulating pigment biosynthetic pathways of photosynthetic organisms in order to increase the spectral coverage for light absorption. The development of organisms that can produce both bacteriochlorophylls and chlorophylls is one way to achieve this aim, and accordingly we have engineered the bacteriochlorophyll-utilizing anoxygenic phototroph Rhodobacter sphaeroides to make chlorophyll a. Bacteriochlorophyll and chlorophyll share a common biosynthetic pathway up to the precursor chlorophyllide. Deletion of genes responsible for the bacteriochlorophyll-specific modifications of chlorophyllide and replacement of the native bacteriochlorophyll synthase with a cyanobacterial chlorophyll synthase resulted in the production of chlorophyll a. This pigment could be assembled in vivo into the plant water-soluble chlorophyll protein, heterologously produced in Rhodobacter sphaeroides, which represents a proof-of-principle for the engineering of novel antenna complexes that enhance the spectral range of photosynthesis.
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Affiliation(s)
- Andrew Hitchcock
- Department
of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, U.K
| | - Philip J. Jackson
- Department
of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, U.K
- ChELSI
Institute, Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, U.K
| | - Jack W. Chidgey
- Department
of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, U.K
| | - Mark J. Dickman
- ChELSI
Institute, Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD, U.K
| | - C. Neil Hunter
- Department
of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, U.K
| | - Daniel P. Canniffe
- Department
of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, U.K
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64
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Freiberg A, Chenchiliyan M, Rätsep M, Timpmann K. Spectral and kinetic effects accompanying the assembly of core complexes of Rhodobacter sphaeroides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1727-1733. [PMID: 27514285 DOI: 10.1016/j.bbabio.2016.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 08/03/2016] [Accepted: 08/06/2016] [Indexed: 11/19/2022]
Abstract
In the present work, spectral and kinetic changes accompanying the assembly of the light-harvesting 1 (LH1) complex with the reaction center (RC) complex into monomeric RC-LH1 and dimeric RC-LH1-PufX core complexes of the photosynthetic purple bacterium Rhodobacter sphaeroides are systematically studied over the temperature range of 4.5-300K. The samples were interrogated with a combination of optical absorption, hole burning, fluorescence excitation, steady state and picosecond time resolved fluorescence spectroscopy. Fair additivity of the LH1 and RC absorption spectra suggests rather weak electronic coupling between them. A low-energy tail revealed at cryogenic temperatures in the absorption spectra of both monomeric and dimeric core complexes is proved to be due to the special pair of the RC. At selected excitation intensity and temperature, the fluorescence decay time of core complexes is shown to be a function of multiple factors, most importantly of the presence/absence of RCs, the supramolecular architecture (monomeric or dimeric) of the complexes, and whether the complexes were studied in a native membrane environment or in a detergent - purified state.
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Affiliation(s)
- Arvi Freiberg
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu, Estonia; Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
| | - Manoop Chenchiliyan
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu, Estonia
| | - Margus Rätsep
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu, Estonia
| | - Kõu Timpmann
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu, Estonia
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Bol’shakov MA, Ashikhmin AA, Makhneva ZK, Moskalenko AA. Effect of illumination intensity and inhibition of carotenoid biosynthesis on assembly of peripheral light-harvesting complexes in purple sulfur bacteria Allochromatium vinosum ATCC 17899. Microbiology (Reading) 2016. [DOI: 10.1134/s0026261716040020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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66
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Dilbeck PL, Tang Q, Mothersole DJ, Martin EC, Hunter CN, Bocian DF, Holten D, Niedzwiedzki DM. Quenching Capabilities of Long-Chain Carotenoids in Light-Harvesting-2 Complexes from Rhodobacter sphaeroides with an Engineered Carotenoid Synthesis Pathway. J Phys Chem B 2016; 120:5429-43. [PMID: 27285777 PMCID: PMC4921951 DOI: 10.1021/acs.jpcb.6b03305] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Six light-harvesting-2 complexes
(LH2) from genetically modified
strains of the purple photosynthetic bacterium Rhodobacter
(Rb.) sphaeroides were studied using static and ultrafast
optical methods and resonance Raman spectroscopy. These strains were
engineered to incorporate carotenoids for which the number of conjugated
groups (N = NC=C + NC=O) varies from 9 to 15.
The Rb. sphaeroides strains incorporate their native
carotenoids spheroidene (N = 10) and spheroidenone
(N = 11), as well as longer-chain analogues including
spirilloxanthin (N = 13) and diketospirilloxantion
(N = 15) normally found in Rhodospirillum
rubrum. Measurements of the properties of the carotenoid
first singlet excited state (S1) in antennas from the Rb. sphaeroides set show that carotenoid-bacteriochlorophyll a (BChl a) interactions are similar to
those in LH2 complexes from various other bacterial species and thus
are not significantly impacted by differences in polypeptide composition.
Instead, variations in carotenoid-to-BChl a energy
transfer are primarily regulated by the N-determined
energy of the carotenoid S1 excited state, which for long-chain
(N ≥ 13) carotenoids is not involved in energy
transfer. Furthermore, the role of the long-chain carotenoids switches
from a light-harvesting supporter (via energy transfer to BChl a) to a quencher of the BChl a S1 excited state B850*. This quenching is manifested as a substantial
(∼2-fold) reduction of the B850* lifetime and the B850* fluorescence
quantum yield for LH2 housing the longest carotenoids.
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Affiliation(s)
| | - Qun Tang
- Department of Chemistry, University of California Riverside , Riverside, California 92521, United States
| | - David J Mothersole
- Department of Molecular Biology and Biotechnology, University of Sheffield , Sheffield S10 2TN, United Kingdom
| | - Elizabeth C Martin
- Department of Molecular Biology and Biotechnology, University of Sheffield , Sheffield S10 2TN, United Kingdom
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield , Sheffield S10 2TN, United Kingdom
| | - David F Bocian
- Department of Chemistry, University of California Riverside , Riverside, California 92521, United States
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67
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Chenchiliyan M, Timpmann K, Jalviste E, Adams PG, Hunter CN, Freiberg A. Dimerization of core complexes as an efficient strategy for energy trapping in Rhodobacter sphaeroides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:634-42. [DOI: 10.1016/j.bbabio.2016.03.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 03/16/2016] [Accepted: 03/18/2016] [Indexed: 11/24/2022]
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68
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Nowicka B, Kruk J. Powered by light: Phototrophy and photosynthesis in prokaryotes and its evolution. Microbiol Res 2016; 186-187:99-118. [PMID: 27242148 DOI: 10.1016/j.micres.2016.04.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 02/12/2016] [Accepted: 04/01/2016] [Indexed: 11/29/2022]
Abstract
Photosynthesis is a complex metabolic process enabling photosynthetic organisms to use solar energy for the reduction of carbon dioxide into biomass. This ancient pathway has revolutionized life on Earth. The most important event was the development of oxygenic photosynthesis. It had a tremendous impact on the Earth's geochemistry and the evolution of living beings, as the rise of atmospheric molecular oxygen enabled the development of a highly efficient aerobic metabolism, which later led to the evolution of complex multicellular organisms. The mechanism of photosynthesis has been the subject of intensive research and a great body of data has been accumulated. However, the evolution of this process is not fully understood, and the development of photosynthesis in prokaryota in particular remains an unresolved question. This review is devoted to the occurrence and main features of phototrophy and photosynthesis in prokaryotes. Hypotheses concerning the origin and spread of photosynthetic traits in bacteria are also discussed.
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Affiliation(s)
- Beatrycze Nowicka
- Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Jerzy Kruk
- Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
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69
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Mothersole DJ, Jackson PJ, Vasilev C, Tucker JD, Brindley AA, Dickman MJ, Hunter CN. PucC and LhaA direct efficient assembly of the light-harvesting complexes in Rhodobacter sphaeroides. Mol Microbiol 2015; 99:307-27. [PMID: 26419219 PMCID: PMC4949548 DOI: 10.1111/mmi.13235] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2015] [Indexed: 01/21/2023]
Abstract
The mature architecture of the photosynthetic membrane of the purple phototroph Rhodobacter sphaeroides has been characterised to a level where an atomic-level membrane model is available, but the roles of the putative assembly proteins LhaA and PucC in establishing this architecture are unknown. Here we investigate the assembly of light-harvesting LH2 and reaction centre-light-harvesting1-PufX (RC-LH1-PufX) photosystem complexes using spectroscopy, pull-downs, native gel electrophoresis, quantitative mass spectrometry and fluorescence lifetime microscopy to characterise a series of lhaA and pucC mutants. LhaA and PucC are important for specific assembly of LH1 or LH2 complexes, respectively, but they are not essential; the few LH1 subunits found in ΔlhaA mutants assemble to form normal RC-LH1-PufX core complexes showing that, once initiated, LH1 assembly round the RC is cooperative and proceeds to completion. LhaA and PucC form oligomers at sites of initiation of membrane invagination; LhaA associates with RCs, bacteriochlorophyll synthase (BchG), the protein translocase subunit YajC and the YidC membrane protein insertase. These associations within membrane nanodomains likely maximise interactions between pigments newly arriving from BchG and nascent proteins within the SecYEG-SecDF-YajC-YidC assembly machinery, thereby co-ordinating pigment delivery, the co-translational insertion of LH polypeptides and their folding and assembly to form photosynthetic complexes.
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Affiliation(s)
- David J Mothersole
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK
| | - Philip J Jackson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK.,ChELSI Institute, Department of Chemical and Biological Engineering, University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK
| | - Cvetelin Vasilev
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK
| | - Jaimey D Tucker
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK
| | - Amanda A Brindley
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK
| | - Mark J Dickman
- ChELSI Institute, Department of Chemical and Biological Engineering, University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK
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70
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Niedzwiedzki DM, Dilbeck PL, Tang Q, Mothersole DJ, Martin EC, Bocian DF, Holten D, Hunter CN. Functional characteristics of spirilloxanthin and keto-bearing Analogues in light-harvesting LH2 complexes from Rhodobacter sphaeroides with a genetically modified carotenoid synthesis pathway. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1847:640-55. [PMID: 25871644 DOI: 10.1016/j.bbabio.2015.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 04/01/2015] [Accepted: 04/03/2015] [Indexed: 11/24/2022]
Abstract
Light-harvesting 2 (LH2) complexes from a genetically modified strain of the purple photosynthetic bacterium Rhodobacter (Rba.) sphaeroides were studied using static and ultrafast optical methods and resonance Raman spectroscopy. Carotenoid synthesis in the Rba. sphaeroides strain was engineered to redirect carotenoid production away from spheroidene into the spirilloxanthin synthesis pathway. The strain assembles LH2 antennas with substantial amounts of spirilloxanthin (total double-bond conjugation length N=13) if grown anaerobically and of keto-bearing long-chain analogs [2-ketoanhydrorhodovibrin (N=13), 2-ketospirilloxanthin (N=14) and 2,2'-diketospirilloxanthin (N=15)] if grown semi-aerobically (with ratios that depend on growth conditions). We present the photophysical, electronic, and vibrational properties of these carotenoids, both isolated in organic media and assembled within LH2 complexes. Measurements of excited-state energy transfer to the array of excitonically coupled bacteriochlorophyll a molecules (B850) show that the mean lifetime of the first singlet excited state (S1) of the long-chain (N≥13) carotenoids does not change appreciably between organic media and the protein environment. In each case, the S1 state appears to lie lower in energy than that of B850. The energy-transfer yield is ~0.4 in LH2 (from the strain grown aerobically or semi-aerobically), which is less than half that achieved for LH2 that contains short-chain (N≤11) analogues. Collectively, the results suggest that the S1 excited state of the long-chain (N≥13) carotenoids participates little if at all in carotenoid-to-BChl a energy transfer, which occurs predominantly via the carotenoid S2 excited state in these antennas.
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Affiliation(s)
- Dariusz M Niedzwiedzki
- Photosynthetic Antenna Research Center, Washington University, St. Louis, MO 63130, USA.
| | - Preston L Dilbeck
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
| | - Qun Tang
- Department of Chemistry, University of California Riverside, Riverside, CA 92521, USA
| | - David J Mothersole
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Elizabeth C Martin
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - David F Bocian
- Department of Chemistry, University of California Riverside, Riverside, CA 92521, USA
| | - Dewey Holten
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
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71
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Khan NE, Nybo SE, Chappell J, Curtis WR. Triterpene hydrocarbon production engineered into a metabolically versatile host--Rhodobacter capsulatus. Biotechnol Bioeng 2015; 112:1523-32. [PMID: 25728701 DOI: 10.1002/bit.25573] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/14/2015] [Accepted: 02/11/2015] [Indexed: 11/08/2022]
Abstract
Triterpene hydrocarbon biosynthesis of the ancient algae Botryococcus braunii was installed into Rhodobacter capsulatus to explore the production of C30 hydrocarbon in a host capable of diverse growth habits-utilizing carbohydrate, sunlight or hydrogen (with CO2 fixation) as alternative energy feedstocks. Engineering an enhanced MEP pathway was also used to augment triterpene accumulation. Despite dramatically different sources of carbon and reducing power, nearly the same level of botryococcene or squalene (∼5 mg oil/g-dry-weight [gDW]) was achieved in small-scale aerobic heterotrophic, anaerobic photoheterotrophic, and aerobic chemoautotrophic growth conditions. A glucose fed-batch bioreactor reached 40 mg botryococcene/L (∼12 mg/gDW), while autotrophic bioreactor performance with CO2 , H2 , and O2 reached 110 mg/L (16.7 mg/gDW) during batch and 60 mg/L (23 mg/gDW) during continuous operation at a dilution rate corresponding to about 10% of μ(max). Batch and continuous autotrophic specific productivity was found to reach 0.5 and 0.32 mg triterpene/g DW/h, comparable to prior reports for terpene production driven by heterotrophic growth conditions. This demonstrates the feasibility of alternative feedstocks and trophic modes to provide comparable routes to biochemicals that do not rely on sugar.
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Affiliation(s)
- Nymul E Khan
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, 16802
| | - S Eric Nybo
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky, 40536
| | - Joe Chappell
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky, 40536
| | - Wayne R Curtis
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania, 16802.
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