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Günter Hauska - One of the best experts on this subject based on the ideXlab platform.
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the bound electron acceptors in green sulfur bacteria resolution of the g tensor for the fx iron sulfur cluster in chlorobium tepidum
Biophysical Journal, 2000Co-Authors: Ilya R Vassiliev, Günter Hauska, Michael T Ronan, John H GolbeckAbstract:The photosynthetic reaction center (RC) of green sulfur bacteria contains two [4Fe-4S] clusters named F(A) and F(B), by analogy with photosystem I (PS I). PS I also contains an interpolypeptide [4Fe-4S] cluster named F(X); however, spectroscopic evidence for an analogous iron-sulfur cluster in green sulfur bacteria remains equivocal. To minimize oxidative damage to the iron-sulfur clusters, we studied the sensitivity of F(A) and F(B) to molecular oxygen in whole cells of Chlorobium vibrioforme and Chlorobium tepidum and obtained highly photoactive membranes and RCs from Cb. tepidum by adjusting isolation conditions to maximize the amplitude of the F(A)(-)/F(B)(-) electron paramagnetic resonance signal at g = 1.89 (measured at 126 mW of microwave power and 14 K) relative to the P840(+) signal at g = 2.0028 (measured at 800 microW of microwave power and 14 K). In these optimized preparations we were able to differentiate F(X)(-) from F(A)(-)/F(B)(-) by their different relaxation properties. At temperatures between 4 and 9 K, isolated membranes and RCs of Cb. tepidum show a broad peak at g = 2.12 and a prominent high-field trough at g = 1.76 (measured at 126 mW of microwave power). The complete g-tensor of F(X)(-), extracted by numerical simulation, yields principal values of 2.17, 1.92, and 1. 77 and is similar to F(X) in PS I. An important difference from PS I is that because the bound cytochrome is available as a fast electron donor in Chlorobium, it is not necessary to prereduce F(A) and F(B) to photoaccumulate F(X)(-).
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P840-reaction centers from Chlorobium tepidum-quinone analysis and functional reconstitution into lipid vesicles
Photochemistry and Photobiology, 1996Co-Authors: Nicole Frankenberg, Nathan Nelson, Christine Hager-braun, Ute Feiler, Markus Fuhrmann, Hans Rogl, Nikolaus Schneebauer, Günter HauskaAbstract:Membranes of Chlorobium tepidum contain about 35, 45 and2–10 molecules of menaquinone-7, chlorobium quinone (1′-oxo-menaquinone-7) and of the polar menaquinone (probably 1′-OH-menaquinone-7) per reaction center, respectively. None of these quinones was retained during the isolation of P840-reaction centers beyond the detection limit of about 0.2 quinones per reaction center, neither in the core complex nor in functionally intact reaction center preparations. The latter is shown to catalyze the formation of an electrochemical proton gradient in the presence of ascorbate and phenazinium methosulfate, when it is incorporated into lipid vesicles.
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stable photobleaching of p840 in chlorobium reaction center preparations presence of the 42 kda bacteriochlorophyll a protein and a 17 kda polypeptide
Biochemistry, 1995Co-Authors: Christine Hagerbraun, Günter Hauska, Dian-lin Xie, Michael Büttner, R. Deutzmann, U Jarosch, E Herold, R Zimmermann, Nathan NelsonAbstract:Simple procedures for the anaerobic preparation of photoactive and stable P840 reaction centers from Chlorobium tepidum and Chlorobium limicola in good yield are presented and quantitated. The subunit composition was tested by cosedimentation in sucrose density gradients. For C. limicola, it minimally comprises four subunits: the P840 reaction center protein PscA, the BChla antenna protein FMO, the FeS protein PscB with centers A and B, and a positively charged 17-kDa protein denoted PscD. The preparation from Chlorobium tepidum additionally contained PscC, a cytochrome c-551. The BChla absorption peak of the purified complexes was at 810 nm, with a shoulder at 835 nm. The ratio of the shoulder to the peak was 0.25, which corresponds to 1 reaction center per 70 BChla molecules if a uniform extinction coefficient of BChla is assumed. However, bleaching at 610 nm in continuous light corresponded up to 1 photoactive reaction center per 50 BChla molecules. Therefore, either the extinction coefficient of BChla in the reaction center is overestimated or the one for photobleaching is underestimated. In any case, the major portion of the reaction center was photoactive in the preparations. A P840 reaction center subcomplex, lacking PscD and deficient in FMO and PscB, but retaining the cytochrome c subunit, was obtained as a side product. It was photoinactive and had an absorption peak at 814 nm and a 835/814 absorbance ratio of 0.42. FMO and PscB show the tendency to form a complementary subcomplex. FMO and PscD are apparently required to stabilize the photoactive reaction center, while the cytochrome c subunit is not.
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A transcription unit for the Rieske FeS-protein and cytochrome b in Chlorobium limicola.
Photosynthesis research, 1994Co-Authors: Michael Schütz, Dian-lin Xie, Nathan Nelson, S. Zirngibl, J. Le Coutre, Michael Büttner, R. Deutzmann, Günter HauskaAbstract:A transcription unit petCB from Chlorobium limicola is described. The leading gene petC codes for a Rieske FeS-protein of 19.04 kDa with 181 amino acid residues. The following gene petB codes for a cytochrome b of 47.48 kDa with 428 amino acid residues. The transcription unit lacks a third gene pet-A for cytochrome c1 or-f, which is found in the fbc-operons of gram-negative bacteria. In the derived amino acid sequence for the Rieske FeS-protein the four cysteines and the 2 histidines are conserved in the peptides binding the 2Fe2S-cluster, although the redox potential of the cluster is about 150 mV more negative in Chlorobium. The gene for cytochrome b includes the coding region for an N-terminal, positively charged extension which is typical for Chlorobium. The gene is not split into two parts for cytochrome b6 and subunit IV. However, a fourteenth amino acid between the two histidines in the fourth, putative transmembrane helix, and the lack of an eighth transmembrane helix at the C-terminus, among other features, clearly resemble the cytochrome b6f-complexes. Therefore, the separation into b6f- and bc1-type complexes during evolution must have occurred before the split of the gene.
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photosynthetic reaction center genes in green sulfur bacteria and in photosystem 1 are related
Proceedings of the National Academy of Sciences of the United States of America, 1992Co-Authors: Michael Büttner, Günter Hauska, Dian-lin Xie, Hannah Nelson, Wilfried Pinther, Nathan NelsonAbstract:Oxygenic photosynthesis of chloroplasts and cyanobacteria involves two photosystems, which originate from different prokaryotic ancestors. The reaction center of photo-system 2 (PS2) is related to the well-characterized reaction center of purple bacteria, while the reaction center of photosystem 1 (PS1) is related to the green sulfur bacteria, as is convincingly documented here. An operon encoding the P840 reaction center of Chlorobium limicola f.sp. thiosulfatophilum has been cloned and sequenced. It contains two structural genes, coding for proteins of 730 and 232 amino acids. The first protein resembles the large subunits of the PS1 reaction center. Putative binding elements for the primary donor, P840 in Chlorobium and P700 in PS1, and for the acceptors A0, A1, and FeS center X are conserved. The second protein is related to the PS1 subunit carrying the FeS centers A and B. An adjacent third gene, not belonging to the reaction center, encodes a protein related to dolichyl-phosphate-D-mannose synthase from yeast. The different origins of PS1 and PS2 are discussed.
Nathan Nelson - One of the best experts on this subject based on the ideXlab platform.
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P840-reaction centers from Chlorobium tepidum-quinone analysis and functional reconstitution into lipid vesicles
Photochemistry and Photobiology, 1996Co-Authors: Nicole Frankenberg, Nathan Nelson, Christine Hager-braun, Ute Feiler, Markus Fuhrmann, Hans Rogl, Nikolaus Schneebauer, Günter HauskaAbstract:Membranes of Chlorobium tepidum contain about 35, 45 and2–10 molecules of menaquinone-7, chlorobium quinone (1′-oxo-menaquinone-7) and of the polar menaquinone (probably 1′-OH-menaquinone-7) per reaction center, respectively. None of these quinones was retained during the isolation of P840-reaction centers beyond the detection limit of about 0.2 quinones per reaction center, neither in the core complex nor in functionally intact reaction center preparations. The latter is shown to catalyze the formation of an electrochemical proton gradient in the presence of ascorbate and phenazinium methosulfate, when it is incorporated into lipid vesicles.
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stable photobleaching of p840 in chlorobium reaction center preparations presence of the 42 kda bacteriochlorophyll a protein and a 17 kda polypeptide
Biochemistry, 1995Co-Authors: Christine Hagerbraun, Günter Hauska, Dian-lin Xie, Michael Büttner, R. Deutzmann, U Jarosch, E Herold, R Zimmermann, Nathan NelsonAbstract:Simple procedures for the anaerobic preparation of photoactive and stable P840 reaction centers from Chlorobium tepidum and Chlorobium limicola in good yield are presented and quantitated. The subunit composition was tested by cosedimentation in sucrose density gradients. For C. limicola, it minimally comprises four subunits: the P840 reaction center protein PscA, the BChla antenna protein FMO, the FeS protein PscB with centers A and B, and a positively charged 17-kDa protein denoted PscD. The preparation from Chlorobium tepidum additionally contained PscC, a cytochrome c-551. The BChla absorption peak of the purified complexes was at 810 nm, with a shoulder at 835 nm. The ratio of the shoulder to the peak was 0.25, which corresponds to 1 reaction center per 70 BChla molecules if a uniform extinction coefficient of BChla is assumed. However, bleaching at 610 nm in continuous light corresponded up to 1 photoactive reaction center per 50 BChla molecules. Therefore, either the extinction coefficient of BChla in the reaction center is overestimated or the one for photobleaching is underestimated. In any case, the major portion of the reaction center was photoactive in the preparations. A P840 reaction center subcomplex, lacking PscD and deficient in FMO and PscB, but retaining the cytochrome c subunit, was obtained as a side product. It was photoinactive and had an absorption peak at 814 nm and a 835/814 absorbance ratio of 0.42. FMO and PscB show the tendency to form a complementary subcomplex. FMO and PscD are apparently required to stabilize the photoactive reaction center, while the cytochrome c subunit is not.
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A transcription unit for the Rieske FeS-protein and cytochrome b in Chlorobium limicola.
Photosynthesis research, 1994Co-Authors: Michael Schütz, Dian-lin Xie, Nathan Nelson, S. Zirngibl, J. Le Coutre, Michael Büttner, R. Deutzmann, Günter HauskaAbstract:A transcription unit petCB from Chlorobium limicola is described. The leading gene petC codes for a Rieske FeS-protein of 19.04 kDa with 181 amino acid residues. The following gene petB codes for a cytochrome b of 47.48 kDa with 428 amino acid residues. The transcription unit lacks a third gene pet-A for cytochrome c1 or-f, which is found in the fbc-operons of gram-negative bacteria. In the derived amino acid sequence for the Rieske FeS-protein the four cysteines and the 2 histidines are conserved in the peptides binding the 2Fe2S-cluster, although the redox potential of the cluster is about 150 mV more negative in Chlorobium. The gene for cytochrome b includes the coding region for an N-terminal, positively charged extension which is typical for Chlorobium. The gene is not split into two parts for cytochrome b6 and subunit IV. However, a fourteenth amino acid between the two histidines in the fourth, putative transmembrane helix, and the lack of an eighth transmembrane helix at the C-terminus, among other features, clearly resemble the cytochrome b6f-complexes. Therefore, the separation into b6f- and bc1-type complexes during evolution must have occurred before the split of the gene.
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photosynthetic reaction center genes in green sulfur bacteria and in photosystem 1 are related
Proceedings of the National Academy of Sciences of the United States of America, 1992Co-Authors: Michael Büttner, Günter Hauska, Dian-lin Xie, Hannah Nelson, Wilfried Pinther, Nathan NelsonAbstract:Oxygenic photosynthesis of chloroplasts and cyanobacteria involves two photosystems, which originate from different prokaryotic ancestors. The reaction center of photo-system 2 (PS2) is related to the well-characterized reaction center of purple bacteria, while the reaction center of photosystem 1 (PS1) is related to the green sulfur bacteria, as is convincingly documented here. An operon encoding the P840 reaction center of Chlorobium limicola f.sp. thiosulfatophilum has been cloned and sequenced. It contains two structural genes, coding for proteins of 730 and 232 amino acids. The first protein resembles the large subunits of the PS1 reaction center. Putative binding elements for the primary donor, P840 in Chlorobium and P700 in PS1, and for the acceptors A0, A1, and FeS center X are conserved. The second protein is related to the PS1 subunit carrying the FeS centers A and B. An adjacent third gene, not belonging to the reaction center, encodes a protein related to dolichyl-phosphate-D-mannose synthase from yeast. The different origins of PS1 and PS2 are discussed.
Daniel Barker - One of the best experts on this subject based on the ideXlab platform.
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DOI 10.1186/s13104-015-1535-8
2016Co-Authors: Short Report, Kristin M. Wreggelsworth, Daniel BarkerAbstract:A comparison of the protein-coding genomes of two green sulphur bacteria, Chlorobium tepidum TLS and Pelodictyon phaeoclathratiforme BU-
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a comparison of the protein coding genomes of two green sulphur bacteria chlorobium tepidum tls and pelodictyon phaeoclathratiforme bu 1
BMC Research Notes, 2015Co-Authors: Kristin Wreggelsworth, Daniel BarkerAbstract:Chlorobium tepidum and Pelodictyon phaeoclathratiforme are organisms within the green sulphur bacteria family, Chlorobiaceae, occupying very different habitats. It has recently been proposed that the genera Chlorobium and Pelodictyon are synonymous. To investigate generic boundaries for the two species, protein families were predicted computationally based on sequence similarity across the genome-wide protein sets of Chlorobium tepidum TLS and Pelodictyon phaeoclathratiforme BU-1. The distribution of the resulting protein families across the two species was summarized. The largest number of families exhibited 1:1 putative orthology between the two species (1468 families). Of families unique to one of the species, the largest number was unique to P. phaeoclathratiforme (113 families), of which the largest family contained pentapeptide repeat proteins (16 proteins). Families unique to P. phaeoclathratiforme also included a family of gas vesicle synthesis proteins (four proteins). Although only seven families were identified as containing paralogous proteins in both species (with two or more proteins in each species), this group included families of major biochemical importance. One such family, with three members in each species, contained magnesium chelatase, an enzyme involved in the chlorophyll biosynthetic pathway. The unique protein family groups in both C. tepidum and P. phaeoclathratiforme mirror the occupancy of different environments, while key shared family groups provide evidence for a common origin for the species, as previously suggested in the literature. The current study only uses sequence similarity-based protein families for the two species. This, alone, does not permit a firm conclusion to be drawn on the taxonomic question, of whether the two species belong in one genus or two.
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MOESM2 of A comparison of the protein-coding genomes of two green sulphur bacteria, Chlorobium tepidum TLS and Pelodictyon phaeoclathratiforme BU-1
2015Co-Authors: Kristin Wreggelsworth, Daniel BarkerAbstract:Additional file 2. C_tepidum.fa. The genome-wide protein set of Chlorobium tepidum TLS in Fasta format, downloaded from UniProt
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MOESM4 of A comparison of the protein-coding genomes of two green sulphur bacteria, Chlorobium tepidum TLS and Pelodictyon phaeoclathratiforme BU-1
2015Co-Authors: Kristin Wreggelsworth, Daniel BarkerAbstract:Additional file 4. ensembl_cct.fa. The Fasta file containing the genome-wide protein set of Chlorobium tepidum TLS from Ensembl Genomes
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MOESM19 of A comparison of the protein-coding genomes of two green sulphur bacteria, Chlorobium tepidum TLS and Pelodictyon phaeoclathratiforme BU-1
2015Co-Authors: Kristin Wreggelsworth, Daniel BarkerAbstract:Additional file 19. Table_S1.docx. Table S1: The main protein counts of sequence similarity-based protein families (based on UniProt protein sets) between Chlorobium tepidum TLS and Pelodictyon phaeoclathratiforme BU-1 that do not contain any proteins with functional annotation
Shigeru Itoh - One of the best experts on this subject based on the ideXlab platform.
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intensity borrowing via excitonic couplings among soret and qy transitions of bacteriochlorophylls in the pigment aggregates of chlorosomes the light harvesting antennae of green sulfur bacteria
Biochemistry, 2010Co-Authors: Yutaka Shibata, Shigeru Itoh, Shingo Tateishi, Shosuke Nakabayashi, Hitoshi TamiakiAbstract:Model calculations of linear dichroism (LD) and circular dichroism (CD) spectra were conducted for the chlorosomes of green sulfur bacteria, Chlorobium phaeobacteroides and Chlorobium tepidum, on t...
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parallel electron donation pathways to cytochrome cz in the type i homodimeric photosynthetic reaction center complex of chlorobium tepidum
Biochimica et Biophysica Acta, 2008Co-Authors: Yusuke Tsukatani, Shigeru Itoh, Toru Kondo, Chihiro Azai, Hirozo OhokaAbstract:Abstract We studied the regulation mechanism of electron donations from menaquinol:cytochrome c oxidoreductase and cytochrome c -554 to the type I homodimeric photosynthetic reaction center complex of the green sulfur bacterium Chlorobium tepidum . We measured flash-induced absorption changes of multiple cytochromes in the membranes prepared from a mutant devoid of cytochrome c -554 or in the reconstituted membranes by exogenously adding cytochrome c -555 purified from Chlorobium limicola . The results indicated that the photo-oxidized cytochrome c z bound to the reaction center was rereduced rapidly by cytochrome c -555 as well as by the menaquinol:cytochrome c oxidoreductase and that cytochrome c -555 did not function as a shuttle-like electron carrier between the menaquinol:cytochrome c oxidoreductase and cytochrome c z . It was also shown that the rereduction rate of cytochrome c z by cytochrome c -555 was as high as that by the menaquinol:cytochrome c oxidoreductase. The two electron-transfer pathways linked to sulfur metabolisms seem to function independently to donate electrons to the reaction center.
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membrane bound cytochrome cz couples quinol oxidoreductase to the p840 reaction center complex in isolated membranes of the green sulfur bacterium chlorobium tepidum
Biochemistry, 1998Co-Authors: Hirozo Ohoka, Masayo Iwaki, Shigeru ItohAbstract:The reaction of quinol oxidoreductase and membrane-bound c-type cytochromes was studied in chlorosome-depleted membranes isolated from Chlorobium tepidum. Rapid oxidations of c-type cytochromes were detected after flash excitation. Their re-reductions occurred in parallel with the reduction of cytochrome b, especially in the presence of antimycin A, whereas reductions of both cytochromes c and b were suppressed by added stigmatellin. These results indicate the tight coupling between the photosynthetic reaction center and quinol oxidoreductase. Turnovers of two types of cytochromes c were detected. One was assigned to the monoheme-type cytochrome c (designated cytochrome cz), which is known to be tightly bound to the reaction center complex. The other was a new c-type cytochrome, cytochrome c-556, which functions the same as cytochrome c1. The steps of electron-transfer scheme, menaquinol --> Rieske FeS center --> cytochrom c-556 --> cytochrome cz --> P840, are estimated to have reaction times of 20 ms and 560, 150, and 40 microseconds, respectively. We conclude that quinol oxidoreductase and the reaction center complex in Chlorobium tepidum are linked by two distinct membrane-bound cytochromes, cz and c-556, with no involvement of water-soluble cytochromes.
Hitoshi Tamiaki - One of the best experts on this subject based on the ideXlab platform.
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characterization of glycolipids in light harvesting chlorosomes from the green photosynthetic bacterium chlorobium tepidum
Bulletin of the Chemical Society of Japan, 2011Co-Authors: Taichi Yoshitomi, Tadashi Mizoguchi, Michio Kunieda, Hitoshi TamiakiAbstract:Glycolipids were isolated from extramembraneous light-harvesting complexes, called “chlorosomes,” in a thermophilic green photosynthetic bacterium Chlorobium tepidum. The lipids were first characte...
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intensity borrowing via excitonic couplings among soret and qy transitions of bacteriochlorophylls in the pigment aggregates of chlorosomes the light harvesting antennae of green sulfur bacteria
Biochemistry, 2010Co-Authors: Yutaka Shibata, Shigeru Itoh, Shingo Tateishi, Shosuke Nakabayashi, Hitoshi TamiakiAbstract:Model calculations of linear dichroism (LD) and circular dichroism (CD) spectra were conducted for the chlorosomes of green sulfur bacteria, Chlorobium phaeobacteroides and Chlorobium tepidum, on t...
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transmission electron microscopic study on supramolecular nanostructures of bacteriochlorophyll self aggregates in chlorosomes of green photosynthetic bacteria
Journal of Bioscience and Bioengineering, 2006Co-Authors: Yoshitaka Saga, Hitoshi TamiakiAbstract:Supramolecular nanostructures of bacteriochlorophyll (BChl) self-aggregates in major light-harvesting complexes (chlorosomes) of green photosynthetic bacteria were successfully observed by freeze-fracture transmission electron microscope. Rod-shaped nanostructures with approximately 10 nm in diameter could be visualized in three types of green sulfur bacteria (Chlorobium). Diameter of the rod-shaped nanostructures in Chlorobium chlorosomes was independent of the molecular structures of their light-harvesting pigments, namely BChl-c or d. In contrast, chlorosomes of the green filamentous bacterium Chloroflexus aurantiacus had rod-shaped nanostructures with approximately 5 nm in diameter. The present results support that BChl self-aggregates in chlorosomes form rod-shaped nanostructures called rod-elements with approximately 10- and 5-nm diameters for Chlorobium and Chloroflexus, respectively.