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Tang KH, Blankenship RE. Neutron and light scattering studies of light-harvesting photosynthetic antenna complexes. PHOTOSYNTHESIS RESEARCH 2012; 111:205-217. [PMID: 21710338 DOI: 10.1007/s11120-011-9665-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 06/02/2011] [Indexed: 05/31/2023]
Abstract
Small-angle neutron scattering (SANS) and dynamic light scattering (DLS) have been employed in studying the structural information of various biological systems, particularly in systems without high-resolution structural information available. In this report, we briefly present some principles and biological applications of neutron scattering and DLS, compare the differences in information that can be obtained with small-angle X-ray scattering (SAXS), and then report recent studies of SANS and DLS, together with other biophysical approaches, for light-harvesting antenna complexes and reaction centers of purple and green phototrophic bacteria.
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Affiliation(s)
- Kuo-Hsiang Tang
- Department of Biology and Department of Chemistry, Washington University in St. Louis, Campus Box 1137, St. Louis, MO 63130, USA
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Cao L, Bryant DA, Schepmoes AA, Vogl K, Smith RD, Lipton MS, Callister SJ. Comparison of Chloroflexus aurantiacus strain J-10-fl proteomes of cells grown chemoheterotrophically and photoheterotrophically. PHOTOSYNTHESIS RESEARCH 2012; 110:153-168. [PMID: 22249883 DOI: 10.1007/s11120-011-9711-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 11/25/2011] [Indexed: 05/31/2023]
Abstract
Chloroflexus aurantiacus J-10-fl is a thermophilic green bacterium, a filamentous anoxygenic phototroph, and the model organism of the phylum Chloroflexi. We applied high-throughput, liquid chromatography-mass spectrometry in a global quantitative proteomics investigation of C. aurantiacus cells grown under oxic (chemoorganoheterotrophically) and anoxic (photoorganoheterotrophically) redox states. Our global analysis identified 13,524 high-confidence peptides that matched to 1,286 annotated proteins, 242 of which were either uniquely identified or significantly increased in abundance under photoheterotrophic culture condition. Fifty-four of the 242 proteins are previously characterized photosynthesis-related proteins, including chlorosome proteins, proteins involved in the bacteriochlorophyll biosynthesis, 3-hydroxypropionate (3-OHP) CO(2) fixation pathway, and components of electron transport chains. The remaining 188 proteins have not previously been reported. Of these, five proteins were found to be encoded by genes from a novel operon and observed only in photoheterotrophically grown cells. These proteins candidates may prove useful in further deciphering the phototrophic physiology of C. aurantiacus and other filamentous anoxygenic phototrophs.
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Affiliation(s)
- Li Cao
- Biological Separations and Mass Spectrometry, Pacific Northwest National Laboratory, Richland, WA 99352, USA
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Tang KH, Urban VS, Wen J, Xin Y, Blankenship RE. SANS investigation of the photosynthetic machinery of Chloroflexus aurantiacus. Biophys J 2011; 99:2398-407. [PMID: 20959079 DOI: 10.1016/j.bpj.2010.07.068] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Revised: 07/18/2010] [Accepted: 07/27/2010] [Indexed: 11/30/2022] Open
Abstract
Green photosynthetic bacteria harvest light and perform photosynthesis in low-light environments, and contain specialized antenna complexes to adapt to this condition. We performed small-angle neutron scattering (SANS) studies to obtain structural information about the photosynthetic apparatus, including the peripheral light-harvesting chlorosome complex, the integral membrane light-harvesting B808-866 complex, and the reaction center (RC) in the thermophilic green phototrophic bacterium Chloroflexus aurantiacus. Using contrast variation in SANS measurements, we found that the B808-866 complex is wrapped around the RC in Cfx. aurantiacus, and the overall size and conformation of the B808-866 complex of Cfx. aurantiacus is roughly comparable to the LH1 antenna complex of the purple bacteria. A similar size of the isolated B808-866 complex was suggested by dynamic light scattering measurements, and a smaller size of the RC of Cfx. aurantiacus compared to the RC of the purple bacteria was observed. Further, our SANS measurements indicate that the chlorosome is a lipid body with a rod-like shape, and that the self-assembly of bacteriochlorophylls, the major component of the chlorosome, is lipid-like. Finally, two populations of chlorosome particles are suggested in our SANS measurements.
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Affiliation(s)
- Kuo-Hsiang Tang
- Department of Biology, Washington University in St. Louis, Missouri, USA
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Collins AM, Qian P, Tang Q, Bocian DF, Hunter CN, Blankenship RE. Light-harvesting antenna system from the phototrophic bacterium Roseiflexus castenholzii. Biochemistry 2010; 49:7524-31. [PMID: 20672862 DOI: 10.1021/bi101036t] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Photosynthetic organisms have evolved diverse light-harvesting complexes to harness light of various qualities and intensities. Photosynthetic bacteria can have (bacterio)chlorophyll Q(y) antenna absorption bands ranging from approximately 650 to approximately 1100 nm. This broad range of wavelengths has allowed many organisms to thrive in unique light environments. Roseiflexus castenholzii is a niche-adapted, filamentous anoxygenic phototroph (FAP) that lacks chlorosomes, the dominant antenna found in most green bacteria, and here we describe the purification of a full complement of photosynthetic complexes: the light-harvesting (LH) antenna, reaction center (RC), and core complex (RC-LH). By high-performance liquid chromatography separation of bacteriochlorophyll and bacteriopheophytin pigments extracted from the core complex and the RC, the number of subunits that comprise the antenna was determined to be 15 +/- 1. Resonance Raman spectroscopy of the carbonyl stretching region displayed modes indicating that 3C-acetyl groups of BChl a are all involved in molecular interactions probably similar to those found in LH1 complexes from purple photosynthetic bacteria. Finally, two-dimensional projections of negatively stained core complexes and the LH antenna revealed a closed, slightly elliptical LH ring with an average diameter of 130 +/- 10 A surrounding a single RC that lacks an H-subunit but is associated with a tetraheme c-type cytochrome.
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Affiliation(s)
- Aaron M Collins
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130, USA
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Collins AM, Xin Y, Blankenship RE. Pigment organization in the photosynthetic apparatus of Roseiflexus castenholzii. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1050-6. [PMID: 19272352 DOI: 10.1016/j.bbabio.2009.02.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 02/23/2009] [Accepted: 02/26/2009] [Indexed: 10/21/2022]
Abstract
The light-harvesting-reaction center (LHRC) complex from the chlorosome-lacking filamentous anoxygenic phototroph (FAP), Roseiflexus castenholzii (R. castenholzii) was purified and characterized for overall pigment organization. The LHRC is a single complex that is comprised of light harvesting (LH) and reaction center (RC) polypeptides as well as an attached c-type cytochrome. The dominant carotenoid found in the LHRC is keto-gamma-carotene, which transfers excitation to the long wavelength antenna band with 35% efficiency. Linear dichroism and fluorescence polarization measurements indicate that the long wavelength antenna pigments absorbing around 880 nm are perpendicular to the membrane plane, with the corresponding Q(y) transition dipoles in the plane of the membrane. The antenna pigments absorbing around 800 nm, as well as the bound carotenoid, are oriented at a large angle with respect to the membrane. The antenna pigments spectroscopically resemble the well-studied LH2 complex from purple bacteria, however the close association with the RC makes the light harvesting component of this complex functionally more like LH1.
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Affiliation(s)
- Aaron M Collins
- Department of Biology, Washington University, St Louis, MO 63130, USA
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van de Meene AML, Le Olson T, Collins AM, Blankenship RE. Initial characterization of the photosynthetic apparatus of "Candidatus Chlorothrix halophila," a filamentous, anoxygenic photoautotroph. J Bacteriol 2007; 189:4196-203. [PMID: 17369303 PMCID: PMC1913384 DOI: 10.1128/jb.01711-06] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
"Candidatus Chlorothrix halophila" is a recently described halophilic, filamentous, anoxygenic photoautotroph (J. A. Klappenbach and B. K. Pierson, Arch. Microbiol. 181:17-25, 2004) that was enriched from the hypersaline microbial mats at Guerrero Negro, Mexico. Analysis of the photosynthetic apparatus by negative staining, spectroscopy, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the photosynthetic apparatus in this organism has similarities to the photosynthetic apparatus in both the Chloroflexi and Chlorobi phyla of green photosynthetic bacteria. The chlorosomes were found to be ellipsoidal and of various sizes, characteristics that are comparable to characteristics of chlorosomes in other species of green photosynthetic bacteria. The absorption spectrum of whole cells was dominated by the chlorosome bacteriochlorophyll c (BChl c) peak at 759 nm, with fluorescence emission at 760 nm. A second fluorescence emission band was observed at 870 nm and was tentatively attributed to a membrane-bound antenna complex. Fluorescence emission spectra obtained at 77 K revealed another complex that fluoresced at 820 nm, which probably resulted from the chlorosome baseplate complex. All of these results suggest that BChl c is present in the chlorosomes of "Ca. Chlorothrix halophila," that BChl a is present in the baseplate, and that there is a membrane-bound antenna complex. Analysis of the proteins in the chlorosomes revealed an approximately 6-kDa band, which was found to be related to the BChl c binding protein CsmA found in other green bacteria. Overall, the absorbance and fluorescence spectra of "Ca. Chlorothrix halophila" revealed an interesting mixture of photosynthetic characteristics that seemed to have properties similar to properties of both phyla of green bacteria when they were compared to the photosynthetic characteristics of Chlorobium tepidum and Chloroflexus aurantiacus.
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Xin Y, Lin S, Montaño GA, Blankenship RE. Purification and characterization of the B808-866 light-harvesting complex from green filamentous bacterium Chloroflexus aurantiacus. PHOTOSYNTHESIS RESEARCH 2005; 86:155-63. [PMID: 16172935 DOI: 10.1007/s11120-005-5103-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2004] [Accepted: 04/06/2005] [Indexed: 05/04/2023]
Abstract
The integral membrane light-harvesting complex B808-866 from the thermophilic green filamentous bacterium Chloroflexus aurantiacus has been isolated and characterized. Reversed-phase HPLC analysis demonstrated that the number of bacteriochlorophyll (BChl) in the B808-866 antenna complex is 36 +/- 2 per reaction center. The main carotenoid type is gamma-carotene, and the molar ratio of BChl to carotenoid is 3:2. The steady-state absorption and fluorescence spectroscopy of the B808-866 complex are reminiscent of the well-studied LH2 peripheral antenna of purple bacteria, whereas the protein sequence and the circular dichroism spectrum of B808-866 is more similar to the LH1 inner core antenna. The efficiency of excitation transfer from carotenoid to BChl is about 25%. The above results combined with electron microscopy and dynamic light scattering analysis suggest that the B808-866 antenna is more like the LH1, whereas surrounds the reaction center but probably consists of 24 building blocks with a ring diameter of about 20 nm. The above results suggested that there are probably two reaction centers inside the ring of B808-866. The unique properties of this light-harvesting complex may provide insights on the protein-pigment interactions in bacterial photosynthesis.
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Affiliation(s)
- Yueyong Xin
- Department of Chemistry and Biochemistry and the Center for the Study of Early Events in Photosynthesis, Arizona State University, P.O. Box 871604, Tempe, AZ 85287-1604, USA
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Montaño GA, Xin Y, Lin S, Blankenship RE. Carotenoid and Bacteriochlorophyll Energy Transfer in the B808−866 Complex from Chloroflexus aurantiacus. J Phys Chem B 2004. [DOI: 10.1021/jp047988u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gabriel A. Montaño
- Department of Chemistry & Biochemistry, Arizona State University, Tempe, Arizona 85287-1604
| | - Yueyong Xin
- Department of Chemistry & Biochemistry, Arizona State University, Tempe, Arizona 85287-1604
| | - Su Lin
- Department of Chemistry & Biochemistry, Arizona State University, Tempe, Arizona 85287-1604
| | - Robert E. Blankenship
- Department of Chemistry & Biochemistry, Arizona State University, Tempe, Arizona 85287-1604
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A structural model for the assembly of the reaction centre and the B808-866 complex in the membranes of Chloroflexus aurantiacus based on the calculation of the triplet minus singlet spectrum of the primary donor. Chem Phys 2003. [DOI: 10.1016/s0301-0104(03)00280-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Montaño GA, Wu HM, Lin S, Brune DC, Blankenship RE. Isolation and characterization of the B798 light-harvesting baseplate from the chlorosomes of Chloroflexus aurantiacus. Biochemistry 2003; 42:10246-51. [PMID: 12939153 DOI: 10.1021/bi034350k] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The B798 light-harvesting baseplate of the chlorosome antenna complex of the thermophilic, filamentous anoxygenic phototrophic bacterium Chloroflexus aurantiacus has been isolated and characterized. Isolation was performed by using a hexanol-detergent treatment of freeze-thawed chlorosomes. The isolated baseplate consists of Bchl a, beta-carotene, and the 5.7 kDa CsmA protein with a ratio of 1.0 CsmA protein/1.6 Bchl a/4.2 beta-carotenes. The baseplate has characteristic absorbance at 798 nm as well as carotenoid absorbance maxima at 519, 489, and 462 nm. The energy transfer efficiency from the carotenoids to the Bchl a is 30% as measured by steady-state and ultrafast time-resolved fluorescence and absorption spectroscopies. Energy equilibration within the Bchl a absorbing regions exhibits ultrafast kinetics. Circular dichroism spectroscopy shows no evidence for excitonically coupled Bchl a pools within the 798 nm region.
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Affiliation(s)
- Gabriel A Montaño
- Graduate Program in Molecular and Cellular Biology, Arizona State University, Tempe, Arizona 85287-1604, USA
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Blankenship RE, Matsuura K. Antenna Complexes from Green Photosynthetic Bacteria. LIGHT-HARVESTING ANTENNAS IN PHOTOSYNTHESIS 2003. [DOI: 10.1007/978-94-017-2087-8_6] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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A new possible binding site for bacteriochlorophyllbin a light-harvesting polypeptide of the bacteriumEctothiorhodospira halochloris. FEBS Lett 2001. [DOI: 10.1016/0014-5793(88)81345-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Novoderezhkin V, Fetisova Z. Exciton delocalization in the B808-866 antenna of the green bacterium Chloroflexus aurantiacus as revealed by ultrafast pump-probe spectroscopy. Biophys J 1999; 77:424-30. [PMID: 10388768 PMCID: PMC1300340 DOI: 10.1016/s0006-3495(99)76900-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
A model of pigment organization in the B808-866 bacteriochlorophyll a antenna of the green photosynthetic bacterium Chloroflexus aurantiacus based on femtosecond pump-probe studies is proposed. The building block of the antenna was assumed to be structurally similar to that of the B800-850 light-harvesting 2 (LH2) antenna of purple bacteria and to have the form of two concentric rings of N strongly coupled BChl866 pigments and of N/2 weakly coupled BChl808 monomers, where N = 24 or 32. We have shown that the Qy transition dipoles of BChl808 and BChl866 molecules form the angles 43 degrees +/- 3 degrees and 8 degrees +/- 4 degrees, respectively, with the plane of the corresponding rings. Using the exciton model, we have obtained a quantitative fit of the pump-probe spectra of the B866 and B808 bands. The anomalously high bleaching value of the B866 band with respect to the B808 monomeric band provided the direct evidence for a high degree of exciton delocalization in the BChl866 ring antenna. The coherence length of the steady-state exciton wave packet corresponds to five or six BChl866 molecules at room temperature.
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Affiliation(s)
- V Novoderezhkin
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia
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Novoderezhkin VI, Taisova AS, Fetisova ZG, Blankenship RE, Savikhin S, Buck DR, Struve WS. Energy transfers in the B808-866 antenna from the green bacterium Chloroflexus aurantiacus. Biophys J 1998; 74:2069-75. [PMID: 9545065 PMCID: PMC1299547 DOI: 10.1016/s0006-3495(98)77913-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Energy transfers within the B808-866 BChl a antenna in chlorosome-membrane complexes from the green photosynthetic bacterium Chloroflexus aurantiacus were studied in two-color pump-probe experiments at room temperature. The steady-state spectroscopy and protein sequence of the B808-866 complex are reminiscent of well-studied LH2 antennas from purple bacteria. B808-->B866 energy transfers occur with approximately 2 ps kinetics; this is slower by a factor of approximately 2 than B800-->B850 energy transfers in LH2 complexes from Rhodopseudomonas acidophila or Rhodobacter sphaeroides. Anisotropy studies show no evidence for intra-B808 energy transfers before the B808-->B866 step; intra-B866 processes are reflected in 350-550 fs anisotropy decays. Two-color anisotropies under 808 nm excitation suggest the presence of a B808-->B866 channel arising either from direct laser excitation of upper B866 exciton components that overlap the B808 absorption band or from excitation of B866 vibronic bands in nontotally symmetric modes.
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Affiliation(s)
- V I Novoderezhkin
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russia
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Watanabe Y, Feick RG, Shiozawa JA. Cloning and sequencing of the genes encoding the light-harvesting B806-866 polypeptides and initial studies on the transcriptional organization of puf2B, puf2A and puf2C in Chloroflexus aurantiacus. Arch Microbiol 1995; 163:124-30. [PMID: 7535995 DOI: 10.1007/bf00381786] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The genes encoding the alpha- and beta-polypeptide subunits of the B806-866 membrane-bound light-harvesting complex of Chloroflexus aurantiacus have been cloned and the nucleotide sequences determined. The gene puf2A, which encodes the B806-866 alpha-polypeptide, began 28 bases downstream of the stop codon of puf2B, which encodes the B806-866 beta gene. The gene-encoding cytochrome c-554, puf2C, was found about 250 bp downstream of puf2A. puf2A encoded a 13 amino acid extension at the C-terminus of the B806-866 alpha-polypeptide that was not present in the mature protein. These genes, unlike those of purple nonsulfur bacteria, did not form a contiguous operon with puf1L or puf1M, the genes encoding the L and M subunits of the photochemical reaction center. The occurrence of the two latter genes and of puf2B and puf2A in two separate operons has not been observed in purple bacteria. Under photoheterotrophic growth conditions, puf2B and puf2A were encoded on an abundant mRNA that was 0.5 kb long. Two monocistronic transcripts for puf2C were observed that had different 5'-ends. One transcript encoding all three genes was also detected. Nucleotide sequences very similar to the consensus promoter sequence of the Escherichia coli RNA polymerase sigma 70 subunit were found seven and eight bases upstream of the 5'-end of mRNA encoding puf2B and for one of the monocistronic mRNA encoding puf2C, respectively.
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Affiliation(s)
- Y Watanabe
- Max-Planck-Institut für Biochemie, Martinsried, Germany
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Müller MG, Griebenow K, Holzwarth AR. Picosecond energy transfer and trapping kinetics in living cells of the green bacterium Chloroflexus aurantiacus. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1144:161-9. [PMID: 8369334 DOI: 10.1016/0005-2728(93)90168-f] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The excitation energy transfer and trapping processes in intact cells of Chloroflexus aurantiacus were studied by picosecond time-resolved fluorescence spectroscopy. The fluorescence decay kinetics is investigated over the near infrared emission range between 730 nm and 920 nm using various excitation wavelengths and excitation intensities. The data were analyzed by global decay analysis and are presented as decay-associated spectra (DAS). The specific dependence of the decay kinetics on the excitation wavelength and on the photochemical redox state of the reaction center (RC) allows the identification of the energy transfer and trapping components. The DAS provide evidence for two chlorosomal energy transfer processes. The first one occurs between the chlorosomal bacteriochlorophyll (BChl)-c and the BChl-a792 complex (B792) in the chlorosomal baseplate with an equilibration time constant of 15-16 ps, while the second one occurs from the B792 pigments to the BChl-a806 pigments in the B806-866 complex with a time constant of 35-40 ps. The overall energy trapping process in whole cells is mainly determined by the kinetics of the primary charge separation process in the RCs. With open RCs (QA oxidized) the trapping time constant is 70-90 ps, while the trapping process with closed RCs (QA reduced) takes as long as 180-200 ps. The results on whole cells reported here are interpreted in conjunction with those reported earlier for the various isolated complexes, i.e., two different chlorosome preparations (Holzwarth, A.R., Müller, M.G. and Griebenow, K. (1990) J. Photochem. Photobiol. B 5, 457-465), the B806-866 complex (Griebenow, K., Müller, M.G. and Holzwarth, A.R. (1991) Biochim. Biophys. Acta 1059, 226-232) and isolated reaction centers (Müller, M.G., Griebenow, K. and Holzwarth, A.R. (1991) Biochim. Biophys. Acta 1098, 1-12). Based on these data, a unified and self-consistent scheme for the primary processes in the whole photosynthetic system of C. aurantiacus is presented. The BChl antenna pigment groups are arranged to form a linear energy transfer cascade with four energy transfer steps from shorter-wavelength- to longer-wavelength-absorbing antenna pools. The overall fluorescence decay kinetics of the photosynthetic system of C. aurantiacus turns out to be 'trap-limited' by the reaction center rather than 'diffusion-limited' by the energy transfer processes.
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Affiliation(s)
- M G Müller
- Max-Planck-Institut für Strahlenchemie, Mülheim a.d. Ruhr, Germany
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Brunisholz RA, Zuber H. Structure, function and organization of antenna polypeptides and antenna complexes from the three families of Rhodospirillaneae. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 1992; 15:113-40. [PMID: 1460542 DOI: 10.1016/1011-1344(92)87010-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Comparative primary structural analysis of polypeptides from antenna complexes from species of the three families of Rhodospirillaneae indicates the structural principles responsible for the formation of spectrally distinct light-harvesting complexes. In many of the characterized antenna systems the basic structural minimal unit is an alpha/beta polypeptide pair. Specific clusters of amino acid residues, in particular aromatic residues in the C-terminal domain, identify the antenna polypeptides to specific types of antenna systems, such as B880 (strong circular dichroism (CD)), B870 (weak CD), B800-850 (high), B800-850 (low) or B800-820. The core complex B880 (B1020) of species from Ectothiorhodospiraceae and Chromatiaceae apparently consists of four (alpha 1 alpha 2 beta 1 beta 2) or three (2 alpha beta 1 beta 2) chemically dissimilar antenna polypeptides respectively. There is good evidence that the so-called variable antenna complexes, such as the B800-850 (high), B800-850 (low) or B800-820 of Rp. acidophila, Rp. palustris and Cr. vinosum, are comprised of multiple forms of peripheral light-harvesting polypeptides. Structural similarities between prokaryotic and eukaryotic antenna polypeptides are discussed in terms of similar pigment organization. The structural basis for the strict organization of pigment molecules (bacteriochlorophyll (BChl) cluster) in the antenna system of purple bacteria is the hierarchical organization of the alpha- and beta-antenna polypeptides within and between the antenna complexes. On the basis of the three-domain structure of the antenna polypeptides with the central hydrophobic domain, forming a transmembrane alpha helix, possible arrangements of the antenna polypeptides in the three-dimensional structure of core and peripheral antenna complexes are discussed. Important structural and functional features of these polypeptides and therefore of the BChl cluster are the alpha/beta heterodimers, the alpha 2 beta 2 basic units and cyclic arrangements of these basic units. Equally important for the formation of the antenna complexes or the entire antenna are polypeptide-polypeptide, pigment-pigment and pigment-polypeptide interactions.
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Affiliation(s)
- R A Brunisholz
- Institut für Molekularbiologie und Biophysik, ETH-Hönggerberg, Zürich, Switzerland
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Blankenship RE. Origin and early evolution of photosynthesis. PHOTOSYNTHESIS RESEARCH 1992; 33:91-111. [PMID: 11538390 DOI: 10.1007/bf00039173] [Citation(s) in RCA: 216] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/1991] [Accepted: 03/12/1992] [Indexed: 05/24/2023]
Abstract
Photosynthesis was well-established on the earth at least 3.5 thousand million years ago, and it is widely believed that these ancient organisms had similar metabolic capabilities to modern cyanobacteria. This requires that development of two photosystems and the oxygen evolution capability occurred very early in the earth's history, and that a presumed phase of evolution involving non-oxygen evolving photosynthetic organisms took place even earlier. The evolutionary relationships of the reaction center complexes found in all the classes of currently existing organisms have been analyzed using sequence analysis and biophysical measurements. The results indicate that all reaction centers fall into two basic groups, those with pheophytin and a pair of quinones as early acceptors, and those with iron sulfur clusters as early acceptors. No simple linear branching evolutionary scheme can account for the distribution patterns of reaction centers in existing photosynthetic organisms, and lateral transfer of genetic information is considered as a likely possibility. Possible scenarios for the development of primitive reaction centers into the heterodimeric protein structures found in existing reaction centers and for the development of organisms with two linked photosystems are presented.
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Affiliation(s)
- R E Blankenship
- Department of Chemistry and Biochemistry, Arizona State University, Tempe 85287-1604, USA
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Localization of polypeptides in isolated chlorosomes from green phototrophic bacteria by immuno-gold labeling electron microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1991. [DOI: 10.1016/s0005-2728(05)80124-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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22
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Pigment organization and energy transfer in green bacteria. 3. Picosecond energy transfer kinetics within the B806-866 bacteriochlorophyll a antenna complex isolated from Chloroflexus aurantiacus. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1991. [DOI: 10.1016/s0005-2728(05)80207-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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23
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Liebetanz R, Hornberger U, Drews G. Organization of the genes coding for the reaction-centre L and M subunits and B870 antenna polypeptides alpha and beta from the aerobic photosynthetic bacterium Erythrobacter species OCH114. Mol Microbiol 1991; 5:1459-68. [PMID: 1787796 DOI: 10.1111/j.1365-2958.1991.tb00792.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In the aerobic photosynthetic bacterium Erythrobacter species OCH114 the structural genes coding for the light-harvesting (LH) complex B870 and the reaction-centre (RC) polypeptides (the gene products of the pufB, pufA, pufL and pufM genes) are mapped on a 2.728 kbp EcoRI fragment. Sequencing of this fragment revealed that the deduced amino acid sequences contain 50 (B870 beta), 52 (B850 alpha), 283 (RCL) and 331 (RCM) residues with the corresponding molecular weights of 5592, 5814, 31364, and 37671, respectively. In the corresponding mRNA a 'hairpin' structure (delta G degrees = -26.6 kcal) is predicted to be located immediately downstream of pufA. The RC and LH polypeptides are highly homologous to those of the purple photosynthetic bacteria Rhodobacter capsulatus, Rhodobacter sphaeroides and Rhodopseudomonas viridis. Directly downstream of pufM there is an open reading frame (ORF) of unknown size. Partial sequencing indicates that this ORF is highly homologous to the cytochrome subunit of the photosynthetic reaction centre from R. viridis. In the puf operon no pufQ or pufX genes could be found, but the bchA gene is located upstream of that operon. Plasmid pESS8.9 containing the 2.728 kbp EcoRI fragment reconstituted a photoinactive mutant of Erythrobacter species OCH114. Comparative analysis of the DNA region upstream of the puf operon and of bacteriochlorophyll (Bchl) synthesis indicated that Bchl synthesis and puf gene expression are regulated differently in Erythrobacter and purple bacteria, respectively.
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Affiliation(s)
- R Liebetanz
- Institute of Biology II, Albert-Ludwigs-University Freiburg, Germany
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Wechsler TD, Brunisholz RA, Frank G, Zuber H. Isolation and protein chemical characterization of the B806-866 antenna complex of the green thermophilic bacterium Chloroflexus aurantiacus. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 1991; 8:189-97. [PMID: 1904920 DOI: 10.1016/1011-1344(91)80058-p] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The B806-866 antenna complex was isolated from cytoplasmic membranes of the green thermophilic bacterium Chloroflexus aurantiacus. The membranes were treated with 7 M urea at 50 degrees C, the B806-866 antenna complex was solubilized with a mixture of Noni-fjdet P-40 (octylphenoxypolyethoxyethanol (Sigma)) and sodium dodecylsulphate (2:1) and isolated by sucrose density gradient centrifugation. This antenna complex was characterized by reversed-phase chromatography (fast polypeptide and polynucleotide liquid chromatography), amino acid and sequence analyses. The B806-866 antenna of Chloroflexus aurantiacus consists of two polypeptides: the B806-866-alpha and B806-866-beta polypeptides in an apparent stoichiometric ratio of 1:1, which may be equivalent to the structural elementary unit found in the antenna systems of many species of Rhodospirillaceae.
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Affiliation(s)
- T D Wechsler
- Institut für Molekularbiologie und Biophysik, Zürich, Switzerland
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