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Frauke Baymann - One of the best experts on this subject based on the ideXlab platform.
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The "green" phylogenetic clade of Rieske/cytb complexes.
Photosynthesis Research, 2010Co-Authors: Wolfgang Nitschke, R. Van Lis, Barbara Schoepp-cothenet, Frauke BaymannAbstract:More than a decade ago, Heliobacteria were recognised to contain a Rieske/cytb complex in which the cytochrome b subunit is split into two separate proteins, a peculiar feature characteristic of the cyanobacterial and plastidic b6f complex. The common presence of RCI-type reaction centres further emphasise possible evolutionary links between Heliobacteria, Chlorobiaceae and Cyanobacteria. In this contribution, we further explore the evolutionary relationships among these three phototrophic lineages by both molecular phylogeny and consideration of phylogenetic marker traits of the superfamily of Rieske/cytb complexes. The combination of these two methods suggests the existence of a “green” clade involving many non-phototrophs in addition to the mentioned RCI-type photosynthetic organisms. Structural and functional idiosyncrasies are (re-)interpreted in the framework of evolutionary biology and more specifically evolutionary bioenergetics.
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the rieske cytochrome b complex of Heliobacteria
Biochimica et Biophysica Acta, 2008Co-Authors: Anne-lise Ducluzeau, Emilie Chenu, Line Capowiez, Frauke BaymannAbstract:Heliobacteria have a Rieske/cytochrome b complex composed of a Rieske protein, a cytochrome b(6,) a subunit IV and a di-heme cytochrome c. The overall structure of the complex seems close to the b(6)f complex from cyanobacteria and chloroplasts to the exception of the di-heme cytochrome. We show here by biochemical and biophysical studies that a heme c(i) is covalently attached to the Rieske/cytochrome b complex from Heliobacteria. We studied the EPR signature of this heme in two different species, Heliobacterium modesticaldum and Heliobacillus mobilis. In contrast to the case of b(6)f complex, a strong axial ligand to the heme is present, most probably a protonatable amino acid residue.
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The Rieske/cytochrome b complex of Heliobacteria
Biochimica et Biophysica Acta, 2008Co-Authors: Anne-lise Ducluzeau, Emilie Chenu, Line Capowiez, Frauke BaymannAbstract:ARTICLE I NFO Heliobacteria have a Rieske/cytochrome b complex composed of a Rieske protein, a cytochrome b6, a subunit IV and a di-heme cytochrome c. The overall structure of the complex seems close to the b6f complex from cyanobacteria and chloroplasts to the exception of the di-heme cytochrome. We show here by biochemical and biophysical studies that a heme ci is covalently attached to the Rieske/cytochrome b complex from Heliobacteria. We studied the EPR signature of this heme in two different species, Heliobacterium modesticaldum and Heliobacillus mobilis. In contrast to the case of b6f complex, a strong axial ligand to the heme is present, most probably a protonatable amino acid residue.
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The Rieske/cytochrome b complex of Heliobacteria
Biochimica et biophysica acta, 2008Co-Authors: Anne-lise Ducluzeau, Emilie Chenu, Line Capowiez, Frauke BaymannAbstract:Heliobacteria have a Rieske/cytochrome b complex composed of a Rieske protein, a cytochrome b(6,) a subunit IV and a di-heme cytochrome c. The overall structure of the complex seems close to the b(6)f complex from cyanobacteria and chloroplasts to the exception of the di-heme cytochrome. We show here by biochemical and biophysical studies that a heme c(i) is covalently attached to the Rieske/cytochrome b complex from Heliobacteria. We studied the EPR signature of this heme in two different species, Heliobacterium modesticaldum and Heliobacillus mobilis. In contrast to the case of b(6)f complex, a strong axial ligand to the heme is present, most probably a protonatable amino acid residue.
Michael T Madigan - One of the best experts on this subject based on the ideXlab platform.
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The Chlorobiaceae, Chloroflexaceae , and Heliobacteriaceae
Modern Topics in the Phototrophic Prokaryotes, 2017Co-Authors: Michael T Madigan, Nicole A. Vander Schaaf, W. Matthew SattleyAbstract:Here we examine the basic biology of three major groups of “green” anoxygenic phototrophic bacteria: the green sulfur bacteria (Chlorobiaceae), the green nonsulfur bacteria (also called the filamentous anoxygenic phototrophs) (Chloroflexaceae), and the Heliobacteria (Heliobacteriaceae). Only organisms that have been grown in laboratory culture are considered. Interestingly, the model organisms for each family are thermophiles: the green sulfur bacterium Chlorobaculum tepidum, the filamentous green nonsulfur bacterium Chloroflexus aurantiacus, and the hot spring heliobacterium species, Heliobacterium modesticaldum. All model green bacteria have had their genomes sequenced, and in the green sulfur bacteria, genome sequences of all recognized species have been completed and compared. Although species in each family are distinct from species in each of the other families in many ways, there are key properties that unite two families to the exclusion of the third. These include the presence of chlorosomes in the green sulfur and green nonsulfur bacteria and the structure of the reaction centers in the green sulfur bacteria and Heliobacteria. However, the three families of green-colored bacteria are phylogenetically distinct and thus any similarities are likely the result of horizontal gene transfers.
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Amino acid-assimilating phototrophic Heliobacteria from soda lake environments: Heliorestis acidaminivorans sp. nov. and ‘Candidatus Heliomonas lunata’
Extremophiles, 2012Co-Authors: Marie Asao, Shinichi Takaichi, Michael T MadiganAbstract:Two novel taxa of Heliobacteria, Heliorestis acidaminivorans sp. nov. strain HR10B^T and ‘ Candidatus Heliomonas lunata’ strain SLH, were cultured from shoreline sediments/soil of Lake El Hamra (Egypt) and lake water/benthic sediments of Soap Lake (USA), respectively; both are highly alkaline soda lakes. Cells of strain HR10B were straight rods, while cells of strain SLH were curved rods. Both organisms were obligate anaerobes, produced bacteriochlorophyll g , and lacked intracytoplasmic photosynthetic membrane systems. Although the absorption spectrum of strain HR10B was typical of other Heliobacteria, that of strain SLH showed unusually strong absorbance of the OH-chlorophyll a component. Major carotenoids of both organisms were OH-diaponeurosporene glucosyl esters, as in other alkaliphilic Heliobacteria, and both displayed an alkaliphilic and mesophilic phenotype. Strain HR10B was remarkable among Heliobacteria in its capacity to photoassimilate a number of carbon sources, including several amino acids. Nitrogenase activity was observed in strain HR10B, but not in strain SLH. The 16S ribosomal RNA gene tree placed strain HR10B within the genus Heliorestis , but distinct from other described species. By contrast, strain SLH was phylogenetically more closely related to neutrophilic Heliobacteria and is the first alkaliphilic heliobacterium known outside of the genus Heliorestis .
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Taxonomy, phylogeny, and ecology of the Heliobacteria
Photosynthesis Research, 2010Co-Authors: Marie Asao, Michael T MadiganAbstract:Heliobacteria are a recently discovered group of anoxygenic phototrophic bacteria, first described in 1983. Heliobacteria contain bacteriochlorophyll g , a pigment unique to species of this group, and synthesize the simplest photosynthetic complexes of all known phototrophs. Also, unlike all other phototrophs, Heliobacteria lack a mechanism for autotrophy and produce endospores. Four genera of Heliobacteria containing a total of 10 species are known. Species of the genera Heliobacterium , Heliobacillus , and Heliophilum grow best at neutral pH, whereas species of Heliorestis are alkaliphilic. Heliobacterium , Heliobacillus , and Heliophilum species form one phylogenetic clade of Heliobacteria, while Heliorestis species form a second within the phylum Firmicutes of the domain Bacteria . Heliobacteria have a unique ecology, being primarily terrestrial rather than aquatic phototrophs, and may have evolved a mutualistic relationship with plants, in particular, rice plants. The genome sequence of the thermophile Heliobacterium modesticaldum supports the hypothesis that Heliobacteria are “minimalist phototrophs” and that they may have played a key role in the evolution of phototrophic bacteria.
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The Genome of Heliobacterium modesticaldum, a Phototrophic Representative of the Firmicutes Containing the Simplest Photosynthetic Apparatus
Journal of bacteriology, 2008Co-Authors: W. Matthew Sattley, Michael T Madigan, Deborah O. Jung, Wesley D. Swingley, Patricia C. Cheung, Kate M. Clocksin, Amber L. Conrad, Liza C. Dejesa, Barbara M. Honchak, Lauren E. KarbachAbstract:Despite the fact that Heliobacteria are the only phototrophic representatives of the bacterial phylum Firmicutes, genomic analyses of these organisms have yet to be reported. Here we describe the complete sequence and analysis of the genome of Heliobacterium modesticaldum, a thermophilic species belonging to this unique group of phototrophs. The genome is a single 3.1-Mb circular chromosome containing 3,138 open reading frames. As suspected from physiological studies of Heliobacteria that have failed to show photoautotrophic growth, genes encoding enzymes for known autotrophic pathways in other phototrophic organisms, including ribulose bisphosphate carboxylase (Calvin cycle), citrate lyase (reverse citric acid cycle), and malyl coenzyme A lyase (3-hydroxypropionate pathway), are not present in the H. modesticaldum genome. Thus, Heliobacteria appear to be the only known anaerobic anoxygenic phototrophs that are not capable of autotrophy. Although for some cellular activities, such as nitrogen fixation, there is a full complement of genes in H. modesticaldum, other processes, including carbon metabolism and endosporulation, are more genetically streamlined than they are in most other low-G+C gram-positive bacteria. Moreover, several genes encoding photosynthetic functions in phototrophic purple bacteria are not present in the Heliobacteria. In contrast to the nutritional flexibility of many anoxygenic phototrophs, the complete genome sequence of H. modesticaldum reveals an organism with a notable degree of metabolic specialization and genomic reduction.
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Heliorestis convoluta sp. nov., a coiled, alkaliphilic heliobacterium from the Wadi El Natroun, Egypt
Extremophiles, 2006Co-Authors: Marie Asao, Laurie A. Achenbach, Deborah O. Jung, Michael T MadiganAbstract:A morphologically distinct heliobacterium, strain HH, was isolated from Lake El Hamra, a soda lake in the Wadi El Natroun region of northwest Egypt. Strain HH consisted of ring-shaped cells that remained attached after cell division to yield coils of various lengths. Strain HH showed several of the physiological properties of known Heliobacteria and grouped in the Heliorestis clade by virtue of its phylogeny and alkaliphily. The closest relative of strain HH was the filamentous alkaliphilic heliobacterium Heliorestis daurensis . However, genomic DNA:DNA hybridization results clearly indicated that strain HH was a distinct species of Heliorestis . Based on its unique phenotypic and genetic properties we describe strain HH here as a new species of the genus Heliorestis , H. convoluta sp. nov.
Robert E. Blankenship - One of the best experts on this subject based on the ideXlab platform.
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unique central carbon metabolic pathways and novel enzymes in phototrophic bacteria revealed by integrative genomics 13c based metabolomics and fluxomics
2013Co-Authors: Kuohsiang Tang, Xueyang Feng, Himadri B Pakrasi, Yinjie J Tang, Anindita Bandyopadhyay, Robert E. BlankenshipAbstract:Photosynthesis is the process to convert solar energy to biomass and biofuels, which are the only major solar energy storage means on Earth. To satisfy the increased demand for sustainable energy sources, it is essential to understand the process of solar energy storage, that is, the carbon metabolism in photosynthetic organisms. It has been well-recognized that one bottleneck of photosynthesis is carbon assimilation. In this report, we summarize our recent studies on the carbon metabolism pathways of several types of photosynthetic bacteria, including aerobic anoxygenic phototrophic proteobacteria, green sulfur bacteria, Heliobacteria and cyanobacteria, using physiological studies, transcriptomics, enzyme assays, 13C-based metabolomics and fluxomics. Our studies have revealed several unique and/or significant central carbon metabolic pathways and novel enzymes that operate in these phototrophs, quantified CO2 assimilation pathways operative during mixotrophic cultivation conditions, and also suggested evolutionary links between photosynthetic and non-photosynthetic organisms.
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Carbon Flow of Heliobacteria Is Related More to Clostridia than to the Green Sulfur Bacteria *□S
2012Co-Authors: Kuohsiang Tang, Xueyang Feng, Robert E. Blankenship, Wei-qin Zhuang, Lisa Alvarez-cohen, Yinjie J TangAbstract:The recently discovered Heliobacteria are the only Gram-positive photosynthetic bacteria that have been cultured. One of the unique features of Heliobacteria is that they have properties of both the photosynthetic green sulfur bacteria (containing the type I reaction center) and Clostridia (forming heat-resistant endospores). Most of the previous studies of Heliobacteria, which are strict anaerobes and have the simplest known photosynthetic apparatus, have focused on energy and electron transfer processes. It has been assumed that like green sulfur bacteria, the major carbon flow in Heliobacteria is through the (incomplete) reductive (reverse) tricarboxylic acid cycle, whereas the lack of CO 2-enhanced growth has not been understood. Here, we report studies to fill the knowledge gap of Heliobacterial carbon metabolism. We confirm that the CO 2-anaplerotic pathway is active during phototrophic growth and that isoleucine i
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Carbon Flow of Heliobacteria Is Related More to Clostridia than to the Green Sulfur Bacteria
The Journal of biological chemistry, 2010Co-Authors: Kuohsiang Tang, Xueyang Feng, Robert E. Blankenship, Wei-qin Zhuang, Lisa Alvarez-cohen, Yinjie J TangAbstract:The recently discovered Heliobacteria are the only Gram-positive photosynthetic bacteria that have been cultured. One of the unique features of Heliobacteria is that they have properties of both the photosynthetic green sulfur bacteria (containing the type I reaction center) and Clostridia (forming heat-resistant endospores). Most of the previous studies of Heliobacteria, which are strict anaerobes and have the simplest known photosynthetic apparatus, have focused on energy and electron transfer processes. It has been assumed that like green sulfur bacteria, the major carbon flow in Heliobacteria is through the (incomplete) reductive (reverse) tricarboxylic acid cycle, whereas the lack of CO2-enhanced growth has not been understood. Here, we report studies to fill the knowledge gap of Heliobacterial carbon metabolism. We confirm that the CO2-anaplerotic pathway is active during phototrophic growth and that isoleucine is mainly synthesized from the citramalate pathway. Furthermore, to our surprise, our results suggest that the oxidative (forward) TCA cycle is operative and more active than the previously reported reductive (reverse) tricarboxylic acid cycle. Both isotopomer analysis and activity assays suggest that citrate is produced by a putative (Re)-citrate synthase and then enters the oxidative (forward) TCA cycle. Moreover, in contrast to (Si)-citrate synthase, (Re)-citrate synthase produces a different isomer of 2-fluorocitrate that is not expected to inhibit the activity of aconitase.
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Insights into Heliobacterial photosynthesis and physiology from the genome of Heliobacterium modesticaldum
Photosynthesis Research, 2010Co-Authors: W. Matthew Sattley, Robert E. BlankenshipAbstract:The complete annotated genome sequence of Heliobacterium modesticaldum strain Ice1 provides our first glimpse into the genetic potential of the Heliobacteriaceae, a unique family of anoxygenic phototrophic bacteria. H. modesticaldum str. Ice1 is the first completely sequenced phototrophic representative of the Firmicutes , and Heliobacteria are the only phototrophic members of this large bacterial phylum. The H. modesticaldum genome consists of a single 3.1-Mb circular chromosome with no plasmids. Of special interest are genomic features that lend insight to the physiology and ecology of Heliobacteria, including the genetic inventory of the photosynthesis gene cluster. Genes involved in transport, photosynthesis, and central intermediary metabolism are described and catalogued. The obligately heterotrophic metabolism of Heliobacteria is a key feature of the physiology and evolution of these phototrophs. The conspicuous absence of recognizable genes encoding the enzyme ATP-citrate lyase prevents autotrophic growth via the reverse citric acid cycle in Heliobacteria, thus being a distinguishing differential characteristic between Heliobacteria and green sulfur bacteria. The identities of electron carriers that enable energy conservation by cyclic light-driven electron transfer remain in question.
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Modulation of fluorescence in Heliobacterium modesticaldum cells.
Photosynthesis Research, 2010Co-Authors: Aaron M. Collins, Kevin Redding, Robert E. BlankenshipAbstract:In what appears to be a common theme for all phototrophs, Heliobacteria exhibit complex modulations of fluorescence yield when illuminated with actinic light and probed on a time scale of μs to minutes. The fluorescence yield from cells of Heliobacterium modesticaldum remained nearly constant for the first 10–100 ms of illumination and then rose to a maximum level with one or two inflections over the course of many seconds. Fluorescence then declined to a steady-state value within about one minute. In this analysis, the origins of the fluorescence induction in whole cells of Heliobacteria are investigated by treating cells with a combination of electron accepters, donors, and inhibitors of the photosynthetic electron transport, as well as varying the temperature. We conclude that fluorescence modulation in H. modesticaldum results from acceptor-side limitation in the reaction center (RC), possibly due to charge recombination between P800+ and A0−.
Jan Amesz - One of the best experts on this subject based on the ideXlab platform.
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The antenna reaction center complex of Heliobacteria: composition, energy conversion and electron transfer.
Biochimica et Biophysica Acta, 2001Co-Authors: Sieglinde Neerken, Jan AmeszAbstract:Abstract A survey is given of various aspects of the photosynthetic processes in Heliobacteria. The review mainly refers to results obtained since 1995, which had not been covered earlier. It first discusses the antenna organization and pigmentation. The pigments of Heliobacteria include some unusual species: bacteriochlorophyll (BChl) g , the main pigment, 8 1 hydroxy chlorophyll a , which acts as primary electron acceptor, and 4,4′-diaponeurosporene, a carotenoid with 30 carbon atoms. Energy conversion within the antenna is very fast: at room temperature thermal equilibrium among the approx. 35 BChls g of the antenna is largely completed within a few ps. This is then followed by primary charge separation, involving a dimer of BChl g (P798) as donor, but recent evidence indicates that excitation of the acceptor pigment 8 1 hydroxy chlorophyll a gives rise to an alternative primary reaction not involving excited P798. The final section of the review concerns secondary electron transfer, an area that is relatively poorly known in Heliobacteria.
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The antenna reaction center complex of Heliobacteria: composition, energy conversion and electron transfer1Dedicated with fond memories and thanks to my mentor and friend, Jan Amesz, who died on 29 January 2001 shortly after the completion of this re
Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2001Co-Authors: Sieglinde Neerken, Jan AmeszAbstract:AbstractA survey is given of various aspects of the photosynthetic processes in Heliobacteria. The review mainly refers to results obtained since 1995, which had not been covered earlier. It first discusses the antenna organization and pigmentation. The pigments of Heliobacteria include some unusual species: bacteriochlorophyll (BChl) g, the main pigment, 81 hydroxy chlorophyll a, which acts as primary electron acceptor, and 4,4′-diaponeurosporene, a carotenoid with 30 carbon atoms. Energy conversion within the antenna is very fast: at room temperature thermal equilibrium among the approx. 35 BChls g of the antenna is largely completed within a few ps. This is then followed by primary charge separation, involving a dimer of BChl g (P798) as donor, but recent evidence indicates that excitation of the acceptor pigment 81 hydroxy chlorophyll a gives rise to an alternative primary reaction not involving excited P798. The final section of the review concerns secondary electron transfer, an area that is relatively poorly known in Heliobacteria
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Electron Transfer in Reaction Centers from Green Sulfur Bacteria
Photosynthesis: Mechanisms and Effects, 1998Co-Authors: Kristiane A. Schmidt, Sieglinde Neerken, Christof Francke, Hjalmar P. Permentier, R. De Wijn, Eric M. Franken, C. Hager-braun, Thijs J. Aartsma, Jan AmeszAbstract:The antenna system of green sulfur bacteria consists of three components: the chlorosome, the Fenna Matthews Olson (FMO) protein, and the reaction center core (RCC) complex. The RCC complex resembles the reaction centers of photosystem I and of Heliobacteria. The primary donor, P840, is a bacteriochlorophyll (BChl) a dimer and the primary acceptor, A0, is a Chi a-like pigment absorbing near 670 nm. The role of a menaquinone as secondary electron acceptor, A1, is still a matter of debate. As in photosystem I, the further electron transfer involves three iron-sulfur (Fe-S) centers, Fx, FA and FB (1).
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The Heliobacteria, a new group of photosynthetic bacteria
Journal of Photochemistry and Photobiology B: Biology, 1995Co-Authors: Jan AmeszAbstract:Abstract A review is given of the photosynthetic properties of the Heliobacteria, a new group of photosynthetic bacteria, discovered only 14 years ago. These bacteria contain a “new” pigment, bacteriochlorophyll g, and they have a relatively simple pigment system, consisting of a core-reaction center complex only. Like the green sulfur bacteria, they have a Photosystem I-type reaction center, with a chlorophyll a derivative as primary electron acceptor. Because of the absence of an extensive peripheral antenna system, the reaction center processes in these bacteria are much easier to study than those in the green sulfur bacteria.
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Spurious circular dichroism signals with intact cells of Heliobacteria
Biochimica et Biophysica Acta (BBA) - Bioenergetics, 1994Co-Authors: Christof Francke, Stephan C.m. Otte, Jos C. Van Der Heiden, Jan AmeszAbstract:Abstract Strong anomalous circular dichroism (CD) signals were observed with suspensions of intact cells of the Heliobacteria Heliobacillus mobilis and Heliobacterium chlorum. They were an order of magnitude larger than with isolated membranes at 6 K and changed dramatically with temperature. From the fact that suspensions of intact cells of Heliobacteria showed linear dichroism (LD), it was concluded that the cells were oriented. The signals were proven to be artifacts, caused by coupling between LD and strain linear birefringence together with a smaller direct contribution of LD. The same effects were observed with oriented membrane fragments. The orientation of the cells was caused by gravity and could be eliminated by suspending the cells in an isopycnic solution. This way the real CD of intact cells could be measured. As expected, this spectrum was very similar to that of membrane fragments.
Anne-lise Ducluzeau - One of the best experts on this subject based on the ideXlab platform.
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the rieske cytochrome b complex of Heliobacteria
Biochimica et Biophysica Acta, 2008Co-Authors: Anne-lise Ducluzeau, Emilie Chenu, Line Capowiez, Frauke BaymannAbstract:Heliobacteria have a Rieske/cytochrome b complex composed of a Rieske protein, a cytochrome b(6,) a subunit IV and a di-heme cytochrome c. The overall structure of the complex seems close to the b(6)f complex from cyanobacteria and chloroplasts to the exception of the di-heme cytochrome. We show here by biochemical and biophysical studies that a heme c(i) is covalently attached to the Rieske/cytochrome b complex from Heliobacteria. We studied the EPR signature of this heme in two different species, Heliobacterium modesticaldum and Heliobacillus mobilis. In contrast to the case of b(6)f complex, a strong axial ligand to the heme is present, most probably a protonatable amino acid residue.
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The Rieske/cytochrome b complex of Heliobacteria
Biochimica et Biophysica Acta, 2008Co-Authors: Anne-lise Ducluzeau, Emilie Chenu, Line Capowiez, Frauke BaymannAbstract:ARTICLE I NFO Heliobacteria have a Rieske/cytochrome b complex composed of a Rieske protein, a cytochrome b6, a subunit IV and a di-heme cytochrome c. The overall structure of the complex seems close to the b6f complex from cyanobacteria and chloroplasts to the exception of the di-heme cytochrome. We show here by biochemical and biophysical studies that a heme ci is covalently attached to the Rieske/cytochrome b complex from Heliobacteria. We studied the EPR signature of this heme in two different species, Heliobacterium modesticaldum and Heliobacillus mobilis. In contrast to the case of b6f complex, a strong axial ligand to the heme is present, most probably a protonatable amino acid residue.
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The Rieske/cytochrome b complex of Heliobacteria
Biochimica et biophysica acta, 2008Co-Authors: Anne-lise Ducluzeau, Emilie Chenu, Line Capowiez, Frauke BaymannAbstract:Heliobacteria have a Rieske/cytochrome b complex composed of a Rieske protein, a cytochrome b(6,) a subunit IV and a di-heme cytochrome c. The overall structure of the complex seems close to the b(6)f complex from cyanobacteria and chloroplasts to the exception of the di-heme cytochrome. We show here by biochemical and biophysical studies that a heme c(i) is covalently attached to the Rieske/cytochrome b complex from Heliobacteria. We studied the EPR signature of this heme in two different species, Heliobacterium modesticaldum and Heliobacillus mobilis. In contrast to the case of b(6)f complex, a strong axial ligand to the heme is present, most probably a protonatable amino acid residue.