Chlorosome antenna complexes from green photosynthetic bacteria

Orf, Gregory S.; Blankenship, Robert E.

doi:10.1007/s11120-013-9869-3

Cited by 234 publications

(234 citation statements)

References 114 publications

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“…The uncertainty in the structural characterization of chlorosomes stems from the large disorder in aggregates composing the chlorosome. The chlorosome is considered to be the largest and most efficient light-harvesting antenna systems found in nature [6][7][8][9][10][11]. This observation motivates a strong interest in the design of artificial light-harvesting systems that uses aggregates of pigment or dye molecules [12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Theoretical characterization of excitation energy transfer in chlorosome light-harvesting antennae from green sulfur bacteria

et al. 2014

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We present a theoretical study of excitation dynamics in the chlorosome antenna complex of green photosynthetic bacteria based on a recently proposed model for the molecular assembly. Our model for the excitation energy transfer (EET) throughout the antenna combines a stochastic time propagation of the excitonic wave function with molecular dynamics simulations of the supramolecular structure, and electronic structure calculations of the excited states. We characterized the optical properties of the chlorosome with absorption, circular dichroism and fluorescence polarization anisotropy decay spectra. The simulation results for the excitation dynamics reveal a detailed picture of the EET in the chlorosome. Coherent energy transfer is significant only for the first 50 fs after the initial excitation, and the wavelike motion of the exciton is completely damped at 100 fs. Characteristic time constants of incoherent energy transfer, subsequently, vary from 1 ps to several tens of ps. We assign the time scales of the EET to specific physical processes by comparing our results with the data obtained from time-resolved spectroscopy experiments.

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Section: Introductionmentioning

confidence: 99%

Theoretical characterization of excitation energy transfer in chlorosome light-harvesting antennae from green sulfur bacteria

et al. 2014

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“…3, lane 7). This protein was subjected to in-gel trypsin digestion, and the resulting peptides were analyzed by mass spectrometry, and the analysis confirmed that the protein was BciD-His 6 .…”

Section: Resultsmentioning

confidence: 92%

“…BciD-His 6 Activity Assay with BChlide c-Activity assays for BciD-His 6 were performed under strictly anoxic conditions at room temperature. Purified BciD-His 6 was incubated with a mixture of methylation homologs of BChlide c or BChlide d, SAM as a cofactor, and sodium dithionite as reductant.…”

Section: Resultsmentioning

confidence: 99%

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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

Thweatt

Ferlez

Golbeck

et al. 2017

Journal of Biological Chemistry

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Edited by Joseph JezGreen 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 1677 T 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 7 1 -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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“…But the structure of their light-harvesting complexes differs among phototrophic bacteria. In various GSB the light-harvesting complex can include bacteriochlorophylls b, c or e (Frigaard & Bryant, 2004;Orf & Blankenship, 2013). Members of the Chloroflexales also differ from each other in the structure of their light-harvesting complexes.…”

Section: Spectral Analysis Of O Trichoides Dg-6 Bacteriochlorophyllsmentioning

confidence: 99%

Reconstruction of bacteriochlorophyll biosynthesis pathways in the filamentous anoxygenic phototrophic bacterium Oscillochloris trichoides DG-6 and evolution of anoxygenic phototrophs of the order Chloroflexales

et al. 2015

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It is commonly accepted that green filamentous anoxygenic phototrophic (FAP) bacteria are the most ancient representatives of phototrophic micro-organisms. Modern FAPs belonging to the order Chloroflexales are divided into two suborders: Chloroflexineae and Roseiflexineae. Representatives of Roseiflexineae lack chlorosomes and synthesize bacteriochlorophyll a, whereas those of Chloroflexineae synthesize bacteriochlorophylls a and c and utilize chlorosomes for light harvesting. Though they constitute a small number of species, FAPs are quite diverse in their physiology. This bacterial group includes autotrophs and heterotrophs, thermophiles and mesophiles, aerobes and anaerobes, occupying both freshwater and halophilic environments. The anaerobic mesophilic autotroph Oscillochloris trichoides DG-6 is still not well studied in its physiology, and its evolutionary origin remains unclear. The goals of this study included identification of the reaction centre type of O. trichoides DG-6, reconstruction of its bacteriochlorophyll biosynthesis pathways, and determination of its evolutionary relationships with other FAPs. By enzymic and genomic analysis, the presence of RCII in O. trichoides DG-6 was demonstrated and the complete gene set involved in biosynthesis of bacteriochlorophylls a and c was established. We found that the bacteriochlorophyll gene sets differed between aerobic and anaerobic FAPs. The aerobic FAP genomes code oxygen-dependent AcsF cyclases, but lack the bchQ/bchR genes, which have been associated with adaptation to low light conditions in the anaerobic FAPs. A scenario of evolution of FAPs belonging to the order Chloroflexales is proposed.

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Chlorosome antenna complexes from green photosynthetic bacteria

Cited by 234 publications

References 114 publications

Theoretical characterization of excitation energy transfer in chlorosome light-harvesting antennae from green sulfur bacteria

Theoretical characterization of excitation energy transfer in chlorosome light-harvesting antennae from green sulfur bacteria

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

Reconstruction of bacteriochlorophyll biosynthesis pathways in the filamentous anoxygenic phototrophic bacterium Oscillochloris trichoides DG-6 and evolution of anoxygenic phototrophs of the order Chloroflexales

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