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Hartmut Grammel - One of the best experts on this subject based on the ideXlab platform.
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quorum sensing influences growth and Photosynthetic Membrane production in high cell density cultivations of rhodospirillum rubrum
BMC Microbiology, 2013Co-Authors: Lisa Carius, Anke Berit Carius, Matthew Mcintosh, Hartmut GrammelAbstract:Background: The facultative anoxygenic Photosynthetic bacterium Rhodospirillum rubrum exhibits versatile metabolic activity allowing the adaptation to rapidly changing growth conditions in its natural habitat, the microaerobic and anoxic zones of stagnant waters. The microaerobic growth mode is of special interest as it allows the high-level expression of Photosynthetic Membranes when grown on succinate and fructose in the dark, which could significantly simplify the industrial production of compounds associated with PM formation. However, recently we showed that PM synthesis is no longer inducible when R. rubrum cultures are grown to high cell densities under aerobic conditions. In addition a reduction of the growth rate and the continued accumulation of precursor molecules for bacteriochlorophyll synthesis were observed under high cell densities conditions. Results: In the present work, we demonstrate that the cell density-dependent effects are reversible if the culture supernatant is replaced by fresh medium. We identified six N-acylhomoserine lactones and show that four of them are produced in varying amounts according to the growth phase and the applied growth conditions. Further, we demonstrate that N-acylhomoserine lactones and tetrapyrrole compounds released into the growth medium affect the growth rate and PM expression in high cell density cultures. Conclusions: In summary, we provide evidence that R. rubrum possesses a Lux-type quorum sensing system which influences the biosynthesis of PM and the growth rate and is thus likely to be involved in the phenotypes of high cell density cultures and the rapid adaptation to changing environmental conditions.
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quorum sensing influences growth and Photosynthetic Membrane production in high cell density cultivations of rhodospirillum rubrum
BMC Microbiology, 2013Co-Authors: Lisa Carius, Anke Berit Carius, Matthew Mcintosh, Hartmut GrammelAbstract:The facultative anoxygenic Photosynthetic bacterium Rhodospirillum rubrum exhibits versatile metabolic activity allowing the adaptation to rapidly changing growth conditions in its natural habitat, the microaerobic and anoxic zones of stagnant waters. The microaerobic growth mode is of special interest as it allows the high-level expression of Photosynthetic Membranes when grown on succinate and fructose in the dark, which could significantly simplify the industrial production of compounds associated with PM formation. However, recently we showed that PM synthesis is no longer inducible when R. rubrum cultures are grown to high cell densities under aerobic conditions. In addition a reduction of the growth rate and the continued accumulation of precursor molecules for bacteriochlorophyll synthesis were observed under high cell densities conditions. In the present work, we demonstrate that the cell density-dependent effects are reversible if the culture supernatant is replaced by fresh medium. We identified six N-acylhomoserine lactones and show that four of them are produced in varying amounts according to the growth phase and the applied growth conditions. Further, we demonstrate that N-acylhomoserine lactones and tetrapyrrole compounds released into the growth medium affect the growth rate and PM expression in high cell density cultures. In summary, we provide evidence that R. rubrum possesses a Lux-type quorum sensing system which influences the biosynthesis of PM and the growth rate and is thus likely to be involved in the phenotypes of high cell density cultures and the rapid adaptation to changing environmental conditions.
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stepwise reduction of the culture redox potential allows the analysis of microaerobic metabolism and Photosynthetic Membrane synthesis in rhodospirillum rubrum
Biotechnology and Bioengineering, 2013Co-Authors: Lisa Carius, Oliver Hadicke, Hartmut GrammelAbstract:Bacterial growth under oxygen-limited (microaerobic) conditions is often accompanied by phenomena of great interest for fundamental research and industrial application. The microaerobic lifestyle of anoxygenic Photosynthetic bacteria like Rhodospirillum rubrum harbors such a phenomenon, as it allows the formation of Photosynthetic Membranes and related interesting products without light. However, due to the technical difficulties in process control of microaerobic cultivations and the limited sensitivity of available oxygen sensors, the analysis of microaerobic growth and physiology is still underrepresented in current research. The main focus of the present study was to establish an experimental set-up for the systematic study of physiological processes, associated with the growth of R. rubrum under microaerobic conditions in the dark. For this purpose, we introduce a robust and reliable microaerobic process control strategy, which applies the culture redox potential (CRP) for assessing different degrees of oxygen limitation in bioreactor cultivations. To describe the microaerobic growth behavior of R. rubrum cultures for each of these defined CRP reduction steps, basic growth parameters were experimentally determined. Flux variability analysis provided an insight into the metabolic activity of the TCA cycle and implied its connection to the respiratory capacity of the cells. In this context, our results suggest that microaerobic growth of R. rubrum can be described as an oxygen-activated cooperative mechanism. The present study thus contributes to the investigation of metabolic and regulatory events responsible for the redox-sensitive formation of Photosynthetic Membranes in facultative Photosynthetic bacteria. Furthermore, the introduced microaerobic cultivation setup should be generally applicable for any microbial system of interest which can be cultivated in common stirred-tank bioreactors. Biotechnol. Bioeng. 2013; 110: 573–585. © 2012 Wiley Periodicals, Inc.
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a glutathione redox effect on Photosynthetic Membrane expression in rhodospirillum rubrum
Journal of Bacteriology, 2011Co-Authors: Anke Berit Carius, Marius Henkel, Hartmut GrammelAbstract:The formation of intracytoplasmic Photosynthetic Membranes by facultative anoxygenic Photosynthetic bacteria has become a prime example for exploring redox control of gene expression in response to oxygen and light. Although a number of redox-responsive sensor proteins and transcription factors have been characterized in several species during the last several years in some detail, the overall understanding of the metabolic events that determine the cellular redox environment and initiate redox signaling is still poor. In the present study we demonstrate that in Rhodospirillum rubrum, the amount of Photosynthetic Membranes can be drastically elevated by external supplementation of the growth medium with the low-molecular-weight thiol glutathione. Neither the widely used reductant dithiothreitol nor oxidized glutathione caused the same response, suggesting that the effect was specific for reduced glutathione. By determination of the extracellular and intracellular glutathione levels, we correlate the GSH/GSSG redox potential to the expression level of Photosynthetic Membranes. Possible regulatory interactions with periplasmic, Membrane, and cytosolic proteins are discussed. Furthermore, we found that R. rubrum cultures excrete substantial amounts of glutathione to the environment.
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redox state dynamics of ubiquinone 10 imply cooperative regulation of Photosynthetic Membrane expression in rhodospirillum rubrum
Journal of Bacteriology, 2008Co-Authors: Hartmut Grammel, Robin GhoshAbstract:It is now well established that, for Photosynthetic bacteria, the aerobic-to-microaerophilic transition activates the Membrane-bound sensor kinase RegB, which subsequently phosphorylates the transcriptional activator RegA, thereby inducing elevated levels of intracellular Photosynthetic Membranes. The mechanism of RegB activation—in particular, the role of ubiquinone-10—is controversial at present. One problem here is that very limited quantitative in vivo data for the response of the ubiquinone redox state to different cultivation conditions exist. Here, we utilize Rhodospirillum rubrum to study the correlation of the quinone redox state to the expression level of Photosynthetic Membranes and determine an effective response function directly. Our results show that changes in the Photosynthetic Membrane levels between 50 and 95% of that maximally attainable are associated with only a twofold change in the ubiquinol/ubiquinone ratio and are not necessarily proportional to the total levels of either quinone or [NAD+ + NADH]. There is no correlation between the redox potentials of the quinone and pyridine nucleotide pools. Hill function analysis of the Photosynthetic Membrane induction in response to the quinone redox state suggests that the induction process is highly cooperative. Our results are probably generally applicable to quinone redox regulation in bacteria.
Egbert J Boekema - One of the best experts on this subject based on the ideXlab platform.
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supramolecular organization of photosystem ii in green plants
Biochimica et Biophysica Acta, 2012Co-Authors: Roman Kouřil, Jan P Dekker, Egbert J BoekemaAbstract:Green plant photosystem II (PSII) is involved in the light reactions of photosynthesis, which take place in the thylakoid Membrane of the chloroplast. PSII is organized into large supercomplexes with variable amounts of Membrane-bound peripheral antenna complexes. These supercomplexes are dimeric and contain usually 2-4 copies of trimeric LHCII complexes and have a further tendency to associate into megacomplexes or into crystalline domains, of which several types have been characterized. This review focuses on the overall composition and structure of the PSII supercomplex of green plants and its organization and interactions within the Photosynthetic Membrane. Further, we present the current knowledge how the thylakoid Membrane is three-dimensionally organized within the chloroplast. We also discuss how the supramolecular organization in the thylakoid Membrane and the PSII flexibility may play roles in various short-term regulatory mechanisms of green plant photosynthesis. This article is part of a Special Issue entitled: Photosystem II.
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single particle analysis of thylakoid proteins from thermosynechococcus elongatus and synechocystis 6803 localization of the cupa subunit of ndh 1
FEBS Letters, 2008Co-Authors: Mihaela I Folea, Pengpeng Zhang, Marc M Nowaczyk, Teruo Ogawa, Egbert J BoekemaAbstract:The larger protein complexes of the cyanobacterial Photosynthetic Membrane of Thermosynechoccus elongatus and Synechocystis 6803 were studied by single particle electron microscopy after detergent solubilization, without any purification steps. Besides the “standard” L-shaped NDH-1L complex, related to complex I, large numbers of a U-shaped NDH-1MS complex were found in both cyanobacteria. In Membranes from Synechocystis ΔcupA and ΔcupA/cupB mutants the U-shaped complexes were absent, indicating that CupA is responsible for the U-shape by binding at the tip of the Membrane-bound arm of NDH-1MS. Comparison of Membranes grown under air levels of CO2 or 3% CO2 indicates that the number of NDH-1MS particles is 30-fold higher under low-CO2.
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structural characterization of a complex of photosystem i and light harvesting complex ii of arabidopsis thaliana
Biochemistry, 2005Co-Authors: Roman Kouril, Jan P Dekker, Poul Erik Jensen, Agnieszka Zygadlo, Ana A Arteni, C D De Wit, Henrik Vibe Scheller, Egbert J BoekemaAbstract:Chloroplasts are central to the provision of energy for green plants. Their Photosynthetic Membrane consists of two major complexes converting sunlight: photosystem I (PSI) and photosystem II (PSII). The energy flow toward both photosystems is regulated by light-harvesting complex II (LHCII), which after phosphorylation can move from PSII to PSI in the so-called state 1 to state 2 transition and can move back to PSII after dephosphorylation. To investigate the changes of PSI and PSII during state transitions, we studied the structures and frequencies of all major Membrane complexes from Arabidopsis thaliana chloroplasts at conditions favoring either state 1 or state 2. We solubilized thylakoid Membranes with digitonin and analyzed the complete set of complexes immediately after solubilization by electron microscopy and image analysis. Classification indicated the presence of a PSI-LHCII supercomplex consisting of one PSI-LHCI complex and one LHCII trimer, which was more abundant in state 2 conditions. The presence of LHCII was confirmed by excitation spectra of the PSI emission of Membranes in state 1 or state 2. The PSI-LHCII complex could be averaged with a resolution of 16 A, showing that LHCII has a specific binding site at the PSI-A, -H, -L, and -K subunits.
Lu-ning Liu - One of the best experts on this subject based on the ideXlab platform.
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supramolecular architecture of Photosynthetic Membrane in red algae in response to nitrogen starvation
Biochimica et Biophysica Acta, 2016Co-Authors: Longsheng Zhao, Lu-ning Liu, Baicheng Zhou, Binbin Xie, Xiying Zhang, Xiulan Chen, Feng Huang, Yuzhong ZhangAbstract:The availability of nitrogen is one of the most important determinants that can limit the growth of Photosynthetic organisms including plants and algae; however, direct observations on the supramolecular architecture of Photosynthetic Membranes in response to nitrogen stress are still lacking. Red algae are an important evolutionary group of algae which contain phycobilisomes (PBSs) on their thylakoid Membranes, as do cyanobacteria. PBSs function not only as light-harvesting antennae but also as nitrogen storage. In this report, alterations of the supramolecular architecture of thylakoid Membranes from red alga Porphyridium cruentum during nitrogen starvation were characterized. The morphology of the intact thylakoid Membrane was observed to be round vesicles. Thylakoid Membranes were reduced in content and PBSs were degraded during nitrogen starvation. The size and density of PBSs were both found to be reduced. PBS size decreased by less than one-half after 20days of nitrogen starvation, but their hemispherical morphology was retained. The density of PBSs on thylakoid Membranes was more seriously affected as time proceeded. Upon re-addition of nitrogen led to increasing of PBSs on thylakoid Membranes. This work reports the first direct observation on alterations in the supramolecular architecture of thylakoid Membranes from a Photosynthetic organism in response to nitrogen stress.
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investigation of Photosynthetic Membrane structure using atomic force microscopy
Trends in Plant Science, 2013Co-Authors: Lu-ning Liu, Simon ScheuringAbstract:Photosynthetic processes, including light capture, electron transfer, and energy conversion, are not only ensured by the activities of individual Photosynthetic complexes but also substantially determined and regulated by the composition and assembly of the overall Photosynthetic apparatus at the supramolecular level. In recent years, atomic force microscopy (AFM) has matured as a unique and powerful tool for directly assessing the supramolecular assembly of integral Membrane protein complexes in their native Membrane environment at submolecular resolution. This review highlights the major contributions and advances of AFM studies to our understanding of the structure of the bacterial Photosynthetic machinery and its regulatory arrangement during chromatic adaptation. AFM topographs of other biological Membrane systems and potential future applications of AFM are also discussed.
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Native architecture of the Photosynthetic Membrane from Rhodobacter veldkampii.
J. Struct. Biol., 2011Co-Authors: Lu-ning Liu, James Sturgis, Simon ScheuringAbstract:The Photosynthetic Membrane in purple bacteria contains several pigment-protein complexes that assure light capture and establishment of the chemiosmotic gradient. The bioenergetic tasks of the Photosynthetic Membrane require the strong interaction between these various complexes. In the present work, we acquired the first images of the native outer Membrane architecture and the supramolecular organization of the Photosynthetic apparatus in vesicular chromatophores of Rhodobacter (Rb.) veldkampii. Mixed with LH2 (light-harvesting complex 2) rings, the PufX-containing LH1-RC (light-harvesting complex 1―reaction center) core complexes appear as C-shaped monomers, with random orientations in the Photosynthetic Membrane. Within the LH1 fence surrounding the RC, a remarkable gap that is probably occupied (or partially occupied) by PufX is visualized. Sequence alignment revealed that one specific region in PufX may be essential for PufX-induced core dimerization. In this region of ten amino acids in length all Rhodobacter species had five conserved amino acids, with the exception of Rb. veldkampii. Our findings provide direct evidence that the presence of PufX in Rb. veldkampii does not directly govern the dimerization of LH1-RC core complexes in the native Membrane. It is indicated, furthermore, that the high Membrane curvature of Rb. veldkampii chromatophores (Rb. veldkampii features equally small vesicular chromatophores alike Rb. sphaeroides) is not due to Membrane bending induced by dimeric RC-LH1-PufX cores, as it has been proposed in Rb. sphaeroides.
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watching the native supramolecular architecture of Photosynthetic Membrane in red algae topography of phycobilisomes and their crowding diverse distribution patterns
Journal of Biological Chemistry, 2008Co-Authors: Lu-ning Liu, Thijs J Aartsma, Jeanclaude Thomas, Gerda E M Lamers, Baicheng Zhou, Yuzhong ZhangAbstract:The architecture of the entire Photosynthetic Membrane network determines, at the supramolecular level, the physiological roles of the Photosynthetic protein complexes involved. So far, a precise picture of the native configuration of red algal thylakoids is still lacking. In this work, we investigated the supramolecular architectures of phycobilisomes (PBsomes) and native thylakoid Membranes from the unicellular red alga Porphyridium cruentum using atomic force microscopy (AFM) and transmission electron microscopy. The topography of single PBsomes was characterized by AFM imaging on both isolated and Membrane-combined PBsomes complexes. The native organization of thylakoid Membranes presented variable arrangements of PBsomes on the Membrane surface. It indicates that different light illuminations during growth allow diverse distribution of PBsomes upon the isolated Photosynthetic Membranes from P. cruentum, random arrangement or rather ordered arrays, to be observed. Furthermore, the distributions of PBsomes on the Membrane surfaces are mostly crowded. This is the first investigation using AFM to visualize the native architecture of PBsomes and their crowding distribution on the thylakoid Membrane from P. cruentum. Various distribution patterns of PBsomes under different light conditions indicate the photoadaptation of thylakoid Membranes, probably promoting the energy-harvesting efficiency. These results provide important clues on the supramolecular architecture of red algal PBsomes and the diverse organizations of thylakoid Membranes in vivo.
Christoph Benning - One of the best experts on this subject based on the ideXlab platform.
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lipid trafficking in plant cells
Traffic, 2014Co-Authors: Anna K Hurlock, Rebecca L Roston, Kun Wang, Christoph BenningAbstract:Plant cells contain unique organelles such as chloroplasts with an extensive Photosynthetic Membrane. In addition, specialized epidermal cells produce an extracellular cuticle composed primarily of lipids, and storage cells accumulate large amounts of storage lipids. As lipid assembly is associated only with discrete Membranes or organelles, there is a need for extensive lipid trafficking within plant cells, more so in specialized cells and sometimes also in response to changing environmental conditions such as phosphate deprivation. Because of the complexity of plant lipid metabolism and the inherent recalcitrance of Membrane lipid transporters, the mechanisms of lipid transport within plant cells are not yet fully understood. Recently, several new proteins have been implicated in different aspects of plant lipid trafficking. While these proteins provide only first insights into limited aspects of lipid transport phenomena in plant cells, they represent exciting opportunities for further studies.
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chloroplast lipid synthesis and lipid trafficking through er plastid Membrane contact sites
Biochemical Society Transactions, 2012Co-Authors: Zhen Wang, Christoph BenningAbstract:Plant chloroplasts contain an intricate Photosynthetic Membrane system, the thylakoids, and are surrounded by two envelope Membranes at which thylakoid lipids are assembled. The glycoglycerolipids mono- and digalactosyldiacylglycerol, and sulfoquinovosyldiacylglycerol as well as phosphatidylglycerol, are present in thylakoid Membranes, giving them a unique composition. Fatty acids are synthesized in the chloroplast and are either directly assembled into thylakoid lipids at the envelope Membranes or exported to the ER (endoplasmic reticulum) for extraplastidic lipid assembly. A fraction of lipid precursors is reimported into the chloroplast for the synthesis of thylakoid lipids. Thus polar lipid assembly in plants requires tight co-ordination between the chloroplast and the ER and necessitates inter-organelle lipid trafficking. In the present paper, we discuss the current knowledge of the export of fatty acids from the chloroplast and the import of chloroplast lipid precursors assembled at the ER. Direct Membrane contact sites between the ER and the chloroplast outer envelopes are discussed as possible conduits for lipid transfer.
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a permease like protein involved in er to thylakoid lipid transfer in arabidopsis
The EMBO Journal, 2003Co-Authors: Jilian Fan, Wayne R Riekhof, John E Froehlich, Christoph BenningAbstract:In eukaryotes, enzymes of different subcellular compartments participate in the assembly of Membrane lipids. As a consequence, interorganelle lipid transfer is extensive in growing cells. A prominent example is the transfer of Membrane lipid precursors between the endoplasmic reticulum (ER) and the Photosynthetic thylakoid Membranes in plants. Mono- and digalactolipids are typical Photosynthetic Membrane lipids. In Arabidopsis, they are derived from one of two pathways, either synthesized de novo in the plastid, or precursors are imported from the ER, giving rise to distinct molecular species. Employing a high-throughput robotic screening procedure generating arrays of spot chromatograms, mutants of Arabidopsis were isolated, which accumulated unusual trigalactolipids. In one allelic mutant subclass, trigalactosyldiacylglycerol1, the primary defect caused a disruption in the biosynthesis of ER-derived thylakoid lipids. Secondarily, a processive galactosyltransferase was activated, leading to the accumulation of oligogalactolipids. Mutations in a permease-like protein of the outer chloroplastic envelope are responsible for the primary biochemical defect. It is proposed that this protein is part of a lipid transfer complex.
Samuel Kaplan - One of the best experts on this subject based on the ideXlab platform.
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proteomic characterization of the rhodobacter sphaeroides 2 4 1 Photosynthetic Membrane identification of new proteins
Journal of Bacteriology, 2007Co-Authors: Xiaohua Zeng, Jung Hyeob Roh, Stephen J Callister, Christine L Tavano, Timothy J Donohue, Mary S Lipton, Samuel KaplanAbstract:The Rhodobacter sphaeroides intracytoplasmic Membrane (ICM) is an inducible Membrane that is dedicated to the major events of bacterial photosynthesis, including harvesting light energy, separating primary charges, and transporting electrons. In this study, multichromatographic methods coupled with Fourier transform ion cyclotron resonance mass spectrometry, combined with subcellular fractionation, was used to test the hypothesis that the Photosynthetic Membrane of R. sphaeroides 2.4.1 contains a significant number of heretofore unidentified proteins in addition to the integral Membrane pigment-protein complexes, including light-harvesting complexes 1 and 2, the photochemical reaction center, and the cytochrome bc1 complex described previously. Purified ICM vesicles are shown to be enriched in several abundant, newly identified Membrane proteins, including a protein of unknown function (AffyChip designation RSP1760) and a possible alkane hydroxylase (RSP1467). When the genes encoding these proteins are mutated, specific Photosynthetic phenotypes are noted, illustrating the potential new insights into solar energy utilization to be gained by this proteomic blueprint of the ICM. In addition, proteins necessary for other cellular functions, such as ATP synthesis, respiration, solute transport, protein translocation, and other physiological processes, were also identified to be in association with the ICM. This study is the first to provide a more global view of the protein composition of a Photosynthetic Membrane from any source. This protein blueprint also provides insights into potential mechanisms for the assembly of the pigment-protein complexes of the Photosynthetic apparatus, the formation of the lipid bilayer that houses these integral Membrane proteins, and the possible functional interactions of ICM proteins with activities that reside in domains outside this specialized bioenergetic Membrane.
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a sensory transducer homologous to the mammalian peripheral type benzodiazepine receptor regulates Photosynthetic Membrane complex formation in rhodobacter sphaeroides 2 4 1
Journal of Biological Chemistry, 1995Co-Authors: Alexei A Yeliseev, Samuel KaplanAbstract:The Rhodobacter sphaeroides 2.4.1 tryptophan-rich sensory protein gene, tspO (formerly crtK, ORF160) encodes a 17-kDa protein which has an unusually high content of aromatic amino acids in general and of L-tryptophan in particular. The TspO protein was localized to the outer Membrane of aerobically grown R. sphaeroides 2.4.1 by use of a polyclonal antibody against the purified protein. This protein is present in severalfold higher levels in Photosynthetic as opposed to aerobic grown cells. Although tspO lies within the crt gene cluster, null mutations have an intact carotenoid biosynthetic pathway. In the TSPO1 mutant there was an increased production of carotenoids and bacteriochlorophyll relative to the wild type, particularly when cells were grown aerobically or semiaerobically. When present in trans the tspO gene restored "normal" pigment production to TSPO1. The effect of the tspO gene on pigment production was shown to take place at the level of gene expression. Because the tspO gene product of R. sphaeroides 2.4.1 shows significant sequence homology and similarity to the peripheral-type benzodoazepine receptor from mammalian sources, TspO-specific antibodies when probed against liver and kidney mitochondrial protein showed strong cross-reactivity. The role of TspO in R. sphaeroides 2.4.1 and its relation to photosynthesis gene expression are discussed.