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cyclic gmp controls rhodospirillum centenum cyst development.adenylyl cyclases are widely distributed across all kingdoms whereas guanylyl cyclases are generally thought to be restricted to eukaryotes. here we report that the α-proteobacterium rhodospirillum centenum secretes cgmp when developing cysts and that a guanylyl cyclase deletion strain fails to synthesize cgmp and is defective in cyst formation. the r. centenum cyclase was purified and shown to effectively synthesize cgmp from gtp in vitro, demonstrating that it is a functional guanylyl cyclase. ...201121214648
phaeovibrio sulfidiphilus gen. nov., sp. nov., phototrophic alphaproteobacteria isolated from brackish water.two strains (ja480(t) and ja481) of phototrophic alphaproteobacteria were isolated from sediment samples collected from brackish water near nagapattinam, india. they were gram-negative, vibrioid cells containing bacteriochlorophyll a and rhodopin as major photosynthetic pigments. most cells of both strains were non-flagellated; 1 % of cells showed two monopolar flagella. cells showed positive phototaxis. both strains showed chimeric intracellular photosynthetic membranes, where both lamellar sta ...201120495036
effects of ethanol, formaldehyde, and gentle heat fixation in confocal resonance raman microscopy of purple nonsulfur bacteria.resonance raman microscopy is well suited to examine living bacterial samples without further preparation. therefore, comparatively little thought has been given to its compatibility with common fixation methods. however, fixation of cell samples is a very important tool in the microbiological sciences, allowing the preservation of samples in a specific condition for further examination, future measurements, transport, or later reference. we examined the effects of three common fixatives-ethanol ...201120544803
Novel substrate (algal protein) for cultivation of Rhodospirillum rubrum.Rhodospirillum rubrum was grown under light anaerobic conditions with phycocyanin (C-pc) extracted from Spirulina platensis as the sole source of carbon and nitrogen. When grown under these conditions cellular components like lipids, carbohydrates, protein, carotenoids, bacteriochlorophyll were similar to the one grown with malic acid and ammonium chloride. Growth of R. rubrum increased with increase in concentration of C-pc (200 to 1000 mg/l). R. rubrum also utilized C-pc under dark anaerobic c ...201122013744
bacterial genome chimaerism and the origin of mitochondria.many studies have sought to determine the origin and evolution of mitochondria. although the alphaproteobacteria are thought to be the closest relatives of the mitochondrial progenitor, there is dispute as to what its particular sister group is. some have argued that mitochondria originated from ancestors of the order rickettsiales, or more specifically of the rickettsiaceae family, while others believe that ancestors of the family rhodospirillaceae are also equally likely the progenitors. to re ...201121217797
a ctra homolog affects swarming motility and encystment in rhodospirillum centenum.the a-proteobacterium, rhodospirillum centenum, has a complex life cycle that allows adaptation to different environments. transitions between vegetative swim cell and swarmer cell types depend on whether the organism is growing in liquid surroundings or on a solid substrate. moreover, starvation can induce vegetative cells to differentiate into quiescent cysts. this paper describes the results of our investigation into the role of a putative dna-binding response regulator that is homologous to ...201121243338
camp, c-di-gmp, c-di-amp and now cgmp: bacteria use them all! 201121255104
biochemical characterization of a new type of intracellular phb depolymerase from rhodospirillum rubrum with high hydrolytic activity on native phb granules.a rhodospirillum rubrum gene that is predicted to code for an extracellular poly(3-hydroxybutyrate) (phb) depolymerase by the recently published polyhydroxyalkanoates (pha) depolymerase engineering database was cloned. the gene product (phaz3( rru )) was expressed in recombinant e. coli, purified and biochemically characterized. phaz3( rru ) turned out, however, to share characteristics of intracellular phb depolymerases and revealed a combination of properties that have not yet been described f ...201121274528
thermostability of rhodopseudomonas viridis and rhodospirillum rubrum chromatophores reflecting physiological conditions.relationships between growth conditions and thermostability were examined for photosynthetic inner membranes (chromatophores) from rhodopseudomonas viridis and rhodospirillum rubrum of which morphology, lipid composition, and protein/lipid rate are rather mutually different. signals observed by differential scanning calorimetry of the chromatophores were correlated with thermal state transitions of the membrane components by reference to temperature dependencies of circular dichroism and absorpt ...201121354412
dark excited states of carotenoid regulated by bacteriochlorophyll in photosynthetic light harvesting.in photosynthesis, carotenoids play important roles in light harvesting (lh) and photoprotective functions, which have been described mainly in terms of two singlet excited states of carotenoids: s(1) and s(2). in addition to the "dark" s(1) state, another dark state, s*, was recently identified and its involvement in photosynthetic functions was determined. however, there is no consistent picture concerning its nature or the mechanism of its formation. one particularly anomalous behavior obtain ...201121388114
identification of chromatophore membrane protein complexes formed under different nitrogen availability conditions in rhodospirillum rubrum.the chromatophore membrane of the photosynthetic diazotroph rhodospirillum rubrum is of vital importance for a number of central processes, including nitrogen fixation. using a novel amphiphile, we have identified protein complexes present under different nitrogen availability conditions by the use of two-dimensional blue native/sds-page and nsi-lc-ltq-orbitrap mass spectrometry. we have identified several membrane protein complexes, including components of the atp synthase, reaction center, lig ...201121443180
a glutathione redox effect on photosynthetic membrane expression in rhodospirillum rubrum.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 ...201121317329
the poor growth of rhodospirillum rubrum mutants lacking rubisco is due to the accumulation of ribulose-1, 5-bisphosphate.ribulose-1, 5-bisphosphate carboxylase/oxygenase (rubisco) catalyzes the first step of co(2) fixation in the calvin-benson-bassham (cbb) cycle. besides its function in fixing co(2) to support photoautotrophic growth, the cbb cycle is also important under photoheterotrophic growth conditions in purple nonsulfur photosynthetic bacteria. it has been assumed that the poor photoheterotrophic growth of rubisco-deficient strains was due to the accumulation of excess intracellular reductant, which impli ...201121531802
shedding light on selenium biomineralization: proteins associated with bionanominerals.selenium reducing microorganisms produce elemental selenium nanoparticles with particular physico-chemical properties being due to an associated organic fraction. this study identified high affinity proteins being associated with such bionanominerals and with non-biogenic elemental selenium. proteins with an anticipated functional role in selenium reduction, such as a metalloid reductase, were found associated with nanoparticles formed by one selenium respirer, sulfurospirillum barnesii.201121602371
forces guiding assembly of light-harvesting complex 2 in native membranes.interaction forces of membrane protein subunits are of importance in their structure, assembly, membrane insertion, and function. in biological membranes, and in the photosynthetic apparatus as a paradigm, membrane proteins fulfill their function by ensemble actions integrating a tight assembly of several proteins. in the bacterial photosynthetic apparatus light-harvesting complexes 2 (lh2) transfer light energy to neighboring tightly associated core complexes, constituted of light-harvesting co ...201121606335
in silico predictions of lh2 ring sizes from the crystal structure of a single subunit using molecular dynamics simulations.most of the currently known light-harvesting complexes 2 (lh2) rings are formed by 8 or 9 subunits. as of now, questions like "what factors govern the lh2 ring size?" and "are there other ring sizes possible?" remain largely unanswered. here, we investigate by means of molecular dynamics (md) simulations and stochastic modeling the possibility of predicting the size of an lh2 ring from the sole knowledge of the high resolution crystal structure of a single subunit. starting with single subunits ...201121604304
identification of a new gene required for the biosynthesis of rhodoquinone in rhodospirillum rubrum.rhodoquinone (rq) is a required cofactor for anaerobic respiration in rhodospirillum rubrum, and it is also found in several helminth parasites that utilize a fumarate reductase pathway. rq is an aminoquinone that is structurally similar to ubiquinone (q), a polyprenylated benzoquinone used in the aerobic respiratory chain. rq is not found in humans or other mammals, and therefore inhibition of its biosynthesis may provide a novel anti-parasitic drug target. to identify a gene specifically requi ...201122194448
site-specific genome integration in alphaproteobacteria mediated by tg1 integrase.the serine-type phage integrase is an enzyme that catalyzes site-specific recombination between two attachment sites of phage and host bacterial genomes (attp and attb, respectively) having relatively short but distinct sequences without host auxiliary factor(s). previously, we have established in vivo and in vitro site-specific recombination systems based on the serine-type integrase produced by actinophage tg1 and determined the minimal sizes of attp ( tg1 ) and attb ( tg1 ) sites required for ...201121887508
effect of pyruvate on the metabolic regulation of nitrogenase activity in rhodospirillum rubrum in darkness.rhodospirillum rubrum, a photosynthetic diazotroph, is able to regulate nitrogenase activity in response to environmental factors such as ammonium ions or darkness, the so-called switch-off effect. this is due to reversible modification of the fe-protein, one of the two components of nitrogenase. the signal transduction pathway(s) in this regulatory mechanism is not fully understood, especially not in response to darkness. we have previously shown that the switch-off response and metabolic state ...201121393366
complete genome sequence of rhodospirillum rubrum type strain (s1).rhodospirillum rubrum (esmarch 1887) molisch 1907 is the type species of the genus rhodospirillum, which is the type genus of the family rhodospirillaceae in the class alphaproteobacteria. the species is of special interest because it is an anoxygenic phototroph that produces extracellular elemental sulfur (instead of oxygen) while harvesting light. it contains one of the most simple photosynthetic systems currently known, lacking light harvesting complex 2. strain s1(t) can grow on carbon monox ...201121886856
evolution of vacuolar proton pyrophosphatase domains and volutin granules: clues into the early evolutionary origin of the acidocalcisome.volutin granules appear to be universally distributed and are morphologically and chemically identical to acidocalcisomes, which are electron-dense granular organelles rich in calcium and phosphate, whose functions include storage of phosphorus and various metal ions, metabolism of polyphosphate, maintenance of intracellular ph, osmoregulation and calcium homeostasis. prokaryotes are thought to differ from eukaryotes in that they lack membrane-bounded organelles. however, it has been demonstrate ...201121974828
the specificity of proton-translocating transhydrogenase for nicotinamide nucleotides.in its forward direction, transhydrogenase couples the reduction of nadp(+) by nadh to the outward translocation of protons across the membrane of bacteria and animal mitochondria. the enzyme has three components: di and diii protrude from the membrane and dii spans the membrane. hydride transfer takes place between nucleotides bound to di and diii. studies on the kinetics of a lag phase at the onset of a "cyclic reaction" catalysed by complexes of the di and diii components of transhydrogenase ...201120732298
Metabolic network modeling of redox balancing and biohydrogen production in purple nonsulfur bacteria.Purple nonsulfur bacteria (PNSB) are facultative photosynthetic bacteria and exhibit an extremely versatile metabolism. A central focus of research on PNSB dealt with the elucidation of mechanisms by which they manage to balance cellular redox under diverse conditions, in particular under photoheterotrophic growth.201121943387
ab inito study on triplet excitation energy transfer in photosynthetic light-harvesting complexes.we have studied the triplet energy transfer (tet) for photosynthetic light-harvesting complexes, the bacterial light-harvesting complex ii (lh2) of rhodospirillum molischianum and rhodopseudomonas acidophila, and the peridinin-chlorophyll a protein (pcp) from amphidinium carterae. the electronic coupling factor was calculated with the recently developed fragment spin difference scheme (you and hsu, j. chem. phys. 2010, 133, 074105), which is a general computational scheme that yields the overall ...201121410281
two putative histidine kinases are required for cyst formation in rhodospirillum centenum.the photosynthetic bacterium, rhodospirillum centenum, has a flexible life cycle that permits it to survive starvation as dormant cyst cells. previous studies have identified some of the key regulators for encystment and demonstrated that the control of development is intricate. this complexity may arise from the need to integrate several environmental signals to mediate a switch from one mode of energy metabolism to another and to ensure that a transition to dormancy is initiated only when nece ...201021184217
coupling of collective motions of the protein matrix to vibrations of the non-heme iron in bacterial photosynthetic reaction centers.non-heme iron is a conservative component of type ii photosynthetic reaction centers of unknown function. we found that in the reaction center from rba. sphaeroides it exists in two forms, high and low spin ferrous states, whereas in rsp. rubrum mostly in a low spin state, in line with our earlier finding of its low spin state in the algal photosystem ii reaction center (burda et al., 2003). the temperature dependence of the non-heme iron displacement studied by mössbauer spectroscopy shows that ...201020603098
excitation transfer connectivity in different purple bacteria: a theoretical and experimental study.photosynthetic membranes accommodate densely packed light-harvesting complexes which absorb light and convey excitation to the reaction center (rc). the relationship between the fluorescence yield (phi) and the fraction (x) of closed rcs is informative about the probability for an excitation reaching a closed rc to be redirected to another rc. in this work, we have examined in this respect membranes from various bacteria and searched for a correlation with the arrangement of the light-harvesting ...201020655292
time-dependent atomistic view on the electronic relaxation in light-harvesting system ii.aiming at a better understanding of the molecular details in light absorption during photosynthesis, spatial and temporal correlation functions as well as spectral densities have been determined. at the focus of the present study are the light-harvesting ii complexes of the purple bacterium rhodospirillum molischianum. the calculations are based on a time-dependent combination of molecular dynamics simulations and quantum chemistry methods. using a 12 ps long trajectory, different quantum chemic ...201020809619
[recent studies on gas sensors, cooa, fixl, and dos].heme-containing proteins, the heme proteins, are known to have physiologic functions in humans, mammalians, fish, plants, and bacteria. for example, hemoglobin and myoglobin, which belong to the globin family, have been studied in terms of their structures and functions with spectroscopic and mutagenic methods. recently, a new class of heme proteins has been discovered, referred to as gas sensors. these are heme-based sensor proteins that play important roles in transcriptional activation, histi ...201020823675
aniline-induced tryptophan production and identification of indole derivatives from three purple bacteria.growth on aniline by three purple non-sulfur bacteria (rhodospirillum rubrum atcc 11170, rhodobacter sphaeroides dsm 158, and rubrivivax benzoatiliticus ja2) as nitrogen, or carbon source could not be demonstrated. however in its presence, production of indole derivatives was observed with all the strains tested. at least 14 chromatographically (hplc) distinct peaks were observed at the absorption maxima of 275-280 nm from aniline induced cultures. five major indoles were identified based on hpl ...201020852980
the photosensor protein ppr of rhodocista centenaria is linked to the chemotaxis signalling pathway.rhodocista centenaria is a phototrophic α-proteobacterium exhibiting a phototactic behaviour visible as colony movement on agar plates directed to red light. as many phototrophic purple bacteria r. centenaria possesses a soluble photoactive yellow protein (pyp). it exists as a long fusion protein, designated ppr, consisting of three domains, the pyp domain, a putative bilin binding domain (bbd) and a histidine kinase domain (pph). the ppr protein is involved in the regulation of polyketide synth ...201021062468
diazotrophic growth of rhodospirillum rubrum with 2-oxoglutarate as sole carbon source affects regulation of nitrogen metabolism as well as the soluble proteome.2-oxoglutarate plays a central role as a signal in the regulation of nitrogen metabolism in the phototrophic diazotroph rhodospirillum rubrum. in order to further study the role of this metabolite, we have constructed an r. rubrum strain that has the capacity to grow on 2-oxoglutarate as sole carbon source, in contrast to wild-type r. rubrum. this strain has the same growth characteristics as wild-type with malate as carbon source, but showed clear metabolic differences when 2-oxoglutarate was u ...201020600859
chaperonin-catalyzed rescue of kinetically trapped states in protein folding.groel and groes form a chaperonin nano-cage for single protein molecules to fold in isolation. the folding properties that render a protein chaperonin dependent are not yet understood. here, we address this question using a double mutant of the maltose-binding protein dm-mbp as a substrate. upon spontaneous refolding, dm-mbp populates a kinetically trapped intermediate that is collapsed but structurally disordered. introducing two long-range disulfide bonds into dm-mbp reduces the entropic foldi ...201020603018
membrane invagination in rhodobacter sphaeroides is initiated at curved regions of the cytoplasmic membrane, then forms both budded and fully detached spherical vesicles.the purple phototrophic bacteria synthesize an extensive system of intracytoplasmic membranes (icm) in order to increase the surface area for absorbing and utilizing solar energy. rhodobacter sphaeroides cells contain curved membrane invaginations. in order to study the biogenesis of icm in this bacterium mature (icm) and precursor (upper pigmented band - upb) membranes were purified and compared at the single membrane level using electron, atomic force and fluorescence microscopy, revealing fun ...201020444085
evidence that ubiquinone is a required intermediate for rhodoquinone biosynthesis in rhodospirillum rubrum.rhodoquinone (rq) is an important cofactor used in the anaerobic energy metabolism of rhodospirillum rubrum. rq is structurally similar to ubiquinone (coenzyme q or q), a polyprenylated benzoquinone used in the aerobic respiratory chain. rq is also found in several eukaryotic species that utilize a fumarate reductase pathway for anaerobic respiration, an important example being the parasitic helminths. rq is not found in humans or other mammals, and therefore inhibition of its biosynthesis may p ...201019933361
eukaryotic behaviour of a prokaryotic energy-transducing membrane: fully detached vesicular organelles arise by budding from the rhodobacter sphaeroides intracytoplasmic photosynthetic membrane.a major feature that distinguishes prokaryotic organisms from eukaryotes is their less complex internal structure, in which all membrane-associated functions are thought to be present within a continuous lipid-protein bilayer, rather than with distinct organelles. contrary to this notion, as described by tucker and co-workers in this issue of molecular microbiology, the application of cryo-electron tomography to the purple bacterium rhodobacter sphaeroides has demonstrated a heretofore unrecogni ...201020412442
model-based high cell density cultivation of rhodospirillum rubrum under respiratory dark conditions.the potential of facultative photosynthetic bacteria as producers of photosynthetic pigments, vitamins, coenzymes and other valuable products has been recognized for decades. however, mass cultivation under photosynthetic conditions is generally inefficient due to the inevitable limitation of light supply when cell densities become very high. the previous development of a new cultivation process for maximal expression of photosynthetic genes under semi-aerobic dark conditions in common bioreacto ...201019882736
ultrafast energy-transfer pathway in a purple-bacterial photosynthetic core antenna, as revealed by femtosecond time-resolved spectroscopy. 201021268203
a new system for heterologous expression of membrane proteins: rhodospirillum rubrum.heterologous expression of membrane proteins has met with only limited success. this work presents a new host/vector system for the production of heterologous membrane proteins based on a mutant of the facultatively phototrophic bacterium rhodospirillum rubrum. under certain growth conditions, r. rubrum forms an intracytoplasmic membrane (icm) that houses the photosynthetic apparatus, the structural proteins of which are encoded by puha and pufbalm. the mutant r. rubrum h2, which was constructed ...201019887111
nitrogenase switch-off and regulation of ammonium assimilation in response to light deprivation in rhodospirillum rubrum are influenced by the nitrogen source used during growth.nitrogen fixation and ammonium assimilation in rhodospirillum rubrum are regulated in response to changes in light availability, and we show that the response in terms of glutamine synthetase activity and p(ii) modification is dependent on the nitrogen source used for growth, n(2) or glutamate, although both lead to nitrogenase derepression.201020023013
roles of rubisco and the rubisco-like protein in 5-methylthioadenosine metabolism in the nonsulfur purple bacterium rhodospirillum rubrum.ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) catalyzes the assimilation of atmospheric co(2) into organic matter and is thus central to the existence of life on earth. the beginning of the 2000s was marked by the discovery of a new family of proteins, the rubisco-like proteins (rlps), which are structural homologs of rubisco. rlps are unable to catalyze co(2) fixation. the rlps from chlorobaculum tepidum, bacillus subtilis, geobacillus kaustophilus, and microcystis aeruginosa have b ...201020038587
[cloning and molecular organization of the polyhydroxyalkanoic acid synthase gene (phac) of ralstonia eutropha strain b5786].class i polyhydroxyalkanoic acid (pha) synthase gene (phac) of ralstonia eutropha strain b5786 was cloned and characterized. r. eutropha b5786 features the ability to synthesize multicomponent phas with short- and medium-chain-length monomers from simple carbohydrate substrate. a correlation was made between the molecular structure of pha synthase and substrate specificity and the ability of strain-producers to accumulate phas of this or that structure. a strong similarity of pha synthase of r. ...201020391757
sustaining n2-dependent growth in the presence of co.low levels of carbon monoxide inhibit the n(2)-dependent growth of rhodospirillum rubrum unless the ∼100-residue cown protein is expressed. expression requires the co-responsive regulator rcom and is maximal in cells grown in the presence of co and a poor nitrogen source, consistent with the role of cown in n(2) fixation.201021115659
metabolic flexibility revealed in the genome of the cyst-forming alpha-1 proteobacterium rhodospirillum centenum.rhodospirillum centenum is a photosynthetic non-sulfur purple bacterium that favors growth in an anoxygenic, photosynthetic n2-fixing environment. it is emerging as a genetically amenable model organism for molecular genetic analysis of cyst formation, photosynthesis, phototaxis, and cellular development. here, we present an analysis of the genome of this bacterium.201020500872
toxicogenomic response of rhodospirillum rubrum s1h to the micropollutant triclosan.in the framework of the micro-ecological life support system alternative (melissa) project, a pilot study was performed to identify the effects of triclosan on the melissa carbon-mineralizing microorganism rhodospirillum rubrum s1h. triclosan is a biocide that is commonly found in human excrement and is considered an emerging pollutant in wastewater and the environment. chronic exposure to melissa-relevant concentrations (> or =25 microg liter(-1)) of triclosan resulted in a significant extensio ...201020363786
revealing linear aggregates of light harvesting antenna proteins in photosynthetic membranes.how light energy is harvested in a natural photosynthetic membrane through energy transfer is closely related to the stoichiometry and arrangement of light harvesting antenna proteins in the membrane. the specific photosynthetic architecture facilitates a rapid and efficient energy transfer among the light harvesting proteins (lh2 and lh1) and to the reaction center. here we report the identification of linear aggregates of light harvesting proteins, lh2, in the photosynthetic membranes under am ...201019572507
tobacco biomass hydrolysate enhances coenzyme q10 production using photosynthetic rhodospirillum rubrum.coenzyme q10 (coq10), a potent antioxidative dietary supplement, was produced using a photosynthetic bacteria rhodospirillum rubrum atcc 25852 by submerged fermentation supplemented with tobacco biomass hydrolysate (tbh) in comparison with media supplemented with hydrolysates prepared with alfalfa (abh) or spinach (sbh). growth medium supplemented with 20% (v/v) tbh was found favorable with regard to cell density and coq10 concentration. the stimulation effects on cell growth (shortened lag phas ...201020554198
an evolutionally conserved lys122 is essential for function in rhodospirillum rubrum bona fide rubisco and bacillus subtilis rubisco-like protein.ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) and rubisco-like protein (rlp) catalyze similar enolase-type reactions. both enzymes have a conserved non-catalytic lys122 or arg122 on the beta-strand e lying in the interface between the n- and c-terminal domains. we used site-directed mutagenesis to analyze the function of lys122 in the form ii rhodospirillum rubrum rubisco (rrrubisco) and bacillus subtilis rlp (bsrlp). the k122r mutant of rrrubisco had a 40% decrease in k(cat) for car ...201020060808
excitation energy pathways in the photosynthetic units of reaction center lm- and h-subunit deletion mutants of rhodospirillum rubrum.light-induced reaction dynamics of isolated photosynthetic membranes obtained from wild-type (wt) and reaction center (rc)-subunit deletion strains spuhk1 (an h-subunit deletion mutant) and sk delta lm (an (l+m) deletion mutant) of the purple non-sulphur bacterium rhodospirillum rubrum have been investigated by femtosecond transient absorption spectroscopy. upon excitation of the spirilloxanthin (spx) s(2) state at 546 nm, of the bacteriochlorophyll soret band at 388 nm and probing spectral regi ...201020099080
exploring electron spin-spin interactions of paramagnetic iron and radical cations of bacteriochlorophyll from oxidized lh1 in the presence of electron transfer in the frozen state.cation free radicals of bacteriochlorophyll (bchl(+)) are formed in the light harvesting complex 1 (lh1) of photosynthetic bacteria upon oxidation by potassium ferricyanide. unusually narrow epr line widths are observed for bchl(+) in the frozen state. these narrow line widths are consistent with a molecular-wire behavior where rapid electron/hole transfer occurs between the bchl constituents of the pigment array responsible for light harvesting in bacterial photosynthesis. however, in addition ...201020151665
dimerisation of the rhodobacter sphaeroides rc-lh1 photosynthetic complex is not facilitated by a gxxxg motif in the pufx polypeptide.in purple photosynthetic bacteria the initial steps of light energy transduction take place in an rc-lh1 complex formed by the photochemical reaction centre (rc) and the lh1 light harvesting pigment-protein. in rhodobacter sphaeroides, the rc-lh1 complex assembles in a dimeric form in which two rcs are surrounded by an s-shaped lh1 antenna. there is currently debate over the detailed architecture of this dimeric rc-lh1 complex, with particular emphasis on the location and precise function of a m ...201020646993
elimination of rubisco alters the regulation of nitrogenase activity and increases hydrogen production in rhodospirillum rubrum.nitrogenase not only reduces atmospheric nitrogen to ammonia, but also reduces protons to hydrogen (h(2)). the nitrogenase system is the primary means of h(2) production under photosynthetic and nitrogen-limiting conditions in many photosynthetic bacteria, including rhodospirillum rubrum. the efficiency of this biological h(2) production largely depends on the nitrogenase enzyme and the availability of atp and electrons in the cell. previous studies showed that blockage of the co(2) fixation pat ...201020652089
udp xylose synthase 1 is required for morphogenesis and histogenesis of the craniofacial skeleton.udp-xylose synthase (uxs1) is strongly conserved from bacteria to humans, but because no mutation has been studied in any animal, we do not understand its roles in development. furthermore, no crystal structure has been published. uxs1 synthesizes udp-xylose, which initiates glycosaminoglycan attachment to a protein core during proteoglycan formation. crystal structure and biochemical analyses revealed that an r233h substitution mutation in zebrafish uxs1 alters an arginine buried in the dimer i ...201020226781
characterization of triclosan-resistant mutants reveals multiple antimicrobial resistance mechanisms in rhodospirillum rubrum s1h.antimicrobial resistance mechanisms were identified in 11 spontaneous high- and low-level triclosan resistance (tcs(r)) mutants of rhodospirillum rubrum s1h by genotyping complemented with transcriptional analyses, antibiotic resistance screening, and membrane permeability analyses. high-end tcs(r) (mic = 8 mg/liter) was the result of a fabi1(g98v) mutation. this point mutation led to an even higher level of tcs(r) (mic > or = 16 mg/liter) in combination with constitutive upregulation of mexb an ...201020305019
a techno-economic analysis of polyhydroxyalkanoate and hydrogen production from syngas fermentation of gasified biomass.a techno-economic analysis was conducted to investigate the feasibility of a gasification-based hybrid biorefinery producing both hydrogen gas and polyhydroxyalkanoates (pha), biodegradable polymer materials that can be an attractive substitute for conventional petrochemical plastics. the biorefinery considered used switchgrass as a feedstock and converted that raw material through thermochemical methods into syngas, a gaseous mixture composed mainly of hydrogen and carbon monoxide. the syngas w ...201019247588
regulation of the ppr histidine kinase by light-induced interactions between its photoactive yellow protein and bacteriophytochrome domains.ppr is a unique bacteriophytochrome that bleaches rather than forming a far-red-shifted pfr state upon red light activation. ppr is also unusual in that it has a blue light photoreceptor domain, pyp, which is n-terminally fused to the bacteriophytochrome domain (bph). when both photoreceptors are activated by light, the fast phase of bph recovery (1 min lifetime) corresponds to the formation of an intramolecular long-lived complex between the activated pyp domain and the bph domain (lifetime of ...201020095642
role of the pufb and pufa c-terminal extensions in the assembly of rhodospirillum rubrum light-harvesting antenna.the light-harvesting antenna (lh) proteins of rhodospirillum rubrum are encoded by pufa and pufb with c-terminal extensions not present in the mature proteins. point mutations were introduced into pufb, pufa, and both pufb and pufa so that proteins equivalent to the mature proteins were encoded. the mutants with these truncated proteins produced 3-30% of the wild-type level of lh. these findings suggest that the c-terminal extensions are required for wild-type levels of lh.201019924477
mutagenesis and functional characterization of the four domains of glnd, a bifunctional nitrogen sensor protein.glnd is a bifunctional uridylyltransferase/uridylyl-removing enzyme (utase/ur) and is believed to be the primary sensor of nitrogen status in the cell by sensing the level of glutamine in enteric bacteria. it plays an important role in nitrogen assimilation and metabolism by reversibly regulating the modification of p(ii) protein; p(ii) in turn regulates a variety of other proteins. glnd appears to have four distinct domains: an n-terminal nucleotidyltransferase (nt) domain; a central hd domain, ...201020363937
chemical synthesis and biological screening of 2-aminoimidazole-based bacterial and fungal antibiofilm agents.a collection of 2-aminoimidazole/triazole amides has been synthesized and screened for antibiofilm activity. this class of small molecules was found to modulate the biofilm activity of pseudomonas aeruginosa, a multidrug-resistant strain of acinetobacter baumannii (mdrab), a methicillin-resistant staphylococcus aureus strain (mrsa), escherichia coli, rhodospirillum salexigens, staphylococcus epidermidis, vibrio vulnificus, and vancomycin-resistant enterococcus faecium as well as the yeast candid ...201020049758
light-harvesting mechanism of bacteria exploits a critical interplay between the dynamics of transport and trapping.light-harvesting bacteria rhodospirillum photometricum were recently found to adopt strikingly different architectures depending on illumination conditions. we present analytic and numerical calculations which explain this observation by quantifying a dynamical interplay between excitation transfer kinetics and reaction center cycling. high light-intensity membranes exploit dissipation as a photoprotective mechanism, thereby safeguarding a steady supply of chemical energy, while low light-intens ...201020482023
atomic force microscopy studies of native photosynthetic membranes.in addition to providing the earliest surface images of a native photosynthetic membrane at submolecular resolution, examination of the intracytoplasmic membrane (icm) of purple bacteria by atomic force microscopy (afm) has revealed a wide diversity of species-dependent arrangements of closely packed light-harvesting (lh) antennae, capable of fulfilling the basic requirements for efficient collection, transmission, and trapping of radiant energy. a highly organized architecture was observed with ...200919265434
[enzymes of the citramalate cycle in rhodospirillum rubrum].rhodospirillum rubrum is among the bacteria that can assimilate acetate in the absence of isocitrate lyase, the key enzyme of glyoxylate shunt. previously we have suggested the functioning of a new anaplerotic cycle of acetate assimilation in this bacterium: citramalate cycle, where acetyl-coa is oxidized to glyoxylate. this work has demonstrated the presence of all the key enzymes of this cycle in r. rubrum extracts: citramalate synthase catalyzing condensation of acetyl-coa and pyruvate with t ...200919334594
ungual and trans-ungual iontophoretic delivery of terbinafine for the treatment of onychomycosis.the application of iontophoresis was demonstrated in the nail drug delivery of terbinafine (th) recently. this study explored a systematic assessment of this approach to enhance the drug delivery using a novel topical formulation, and the subsequent release of th from the drug loaded nails. for the first time, a nail on-agar plate model was used to study the release of drug from the iontophoresis (0.5 ma/cm(2)) loaded nails. in addition, the activity of the drug released from the drug loaded nai ...200919340887
gut-associated denitrification and in vivo emission of nitrous oxide by the earthworm families megascolecidae and lumbricidae in new zealand.previous studies have documented the capacity of european earthworms belonging to the family lumbricidae to emit the greenhouse gas nitrous oxide (n(2)o), an activity attributed primarily to the activation of ingested soil denitrifiers. to extend the information base to earthworms in the southern hemisphere, four species of earthworms in new zealand were examined for gut-associated denitrification. lumbricus rubellus and aporrectodea rosea (introduced species of lumbricidae) emitted n(2)o, where ...200919346358
self-assembly of f0f1-atpase motors and ghost.f0f1-atpase motors have unique mechanical properties, making them attractive building blocks in the field of nanotechnology. however, their organization into well-defined structures with practical functions remains a critical challenge. here, we describe a self-assembling complex formed by f0f1-atpase and a ghost which is ordered. formation of the complex includes two steps: the molecular motors first self-assemble into filaments and then attach to the ghost. the ghost and attached filaments the ...200919374455
experimental design and environmental parameters affect rhodospirillum rubrum s1h response to space flight.in view of long-haul space exploration missions, the european space agency initiated the micro-ecological life support system alternative (melissa) project targeting the total recycling of organic waste produced by the astronauts into oxygen, water and food using a loop of bacterial and higher plant bioreactors. in that purpose, the alpha-proteobacterium, rhodospirillum rubrum s1h, was sent twice to the international space station and was analyzed post-flight using a newly developed r. rubrum wh ...200919571896
comparison of rhizobacterial community composition in soil suppressive or conducive to tobacco black root rot disease.work on soils suppressive to thielaviopsis basicola-mediated tobacco black root rot has focused on antagonistic pseudomonads to date. the role of non-pseudomonas rhizosphere populations has been neglected, and whether they differ in black root rot-suppressive versus -conducive soils is unknown. to assess this possibility, tobacco was grown in a suppressive and a conducive soil of similar physicochemical properties, and rhizobacterial community composition was compared using a 16s rrna taxonomic ...200919554036
guanidine hydrochloride-induced unfolding of the three heme coordination states of the co-sensing transcription factor, cooa.cooa is a heme-dependent co-sensing transcription factor that has three observable heme coordination states. there is some evidence that each cooa heme state has a distinct protein conformation; the goal of this study was to characterize these conformations by measuring their structural stabilities through guanidine hydrochloride (guhcl) denaturation. by studying the denaturation processes of the fe(iii) state of wt cooa and several variants, we were able to characterize independent unfolding pr ...200919594171
putative functional role for the invariant aspartate 263 residue of rhodospirillum rubrum rubisco.although aspartate residue d263 of rhodospirillum rubrum rubisco is close to the active site and invariant in all reported rubiscos, its possible functional and structural roles in rubisco activity have not been investigated. we have mutagenised d263 to several selected amino acids (asparagine, alanine, serine, glutamate, and glutamine) to probe possible roles in facilitating proton movements within the active site and maintaining structural positioning of key active-site groups. the mutants hav ...200919231887
cooc1 from carboxydothermus hydrogenoformans is a nickel-binding atpase.the maturation of nickel-dependent enzymes requires the participation of several accessory proteins. typically the hydrolysis of nucleotides is necessary for the final metal transfer steps. the atpase cooc has been implicated in the insertion of nickel into the ni,fe cluster (c cluster) of the carbon monoxide dehydrogenase from rhodospirillum rubrum. analysis of the amino acid sequence of cooc suggests the presence of motifs typical for the mind family of simibi class ntpases, which contain a de ...200919883128
shotgun proteome analysis of rhodospirillum rubrum s1h: integrating data from gel-free and gel-based peptides fractionation methods.beside bioreactor modeling studies, the molecular characterization of life-support organisms appeared to be essential to complete their global behavior picture, in particular, culture conditions. using a combination of lc-ms/ms approaches with gel-free and gel-based peptides fractionation steps, we identified 932 proteins from the alpha-proteobacterium rhodospirillum rubrum s1h. in addition, abundance data were retrieved using the recently developed empai approach which takes into account the nu ...200919243122
pigment organization and energy level structure in light-harvesting complex 4: insights from two-dimensional electronic spectroscopy.photosynthetic light-harvesting antennae direct energy collected from sunlight to reaction centers with remarkable efficiency and rapidity. despite their common function, the pigment-protein complexes that make up antenna systems in different types of photosynthetic organisms exhibit a wide variety of structural forms. some individual organisms express different types of complexes depending on growth conditions. for example, purple photosynthetic bacteria rp. palustris preferentially synthesize ...200919402730
quinone pathways in entire photosynthetic chromatophores of rhodospirillum photometricum.in photosynthetic organisms, membrane pigment-protein complexes [light-harvesting complex 1 (lh1) and light-harvesting complex 2 (lh2)] harvest solar energy and convert sunlight into an electrical and redox potential gradient (reaction center) with high efficiency. recent atomic force microscopy studies have described their organization in native membranes. however, the cytochrome (cyt) bc(1) complex remains unseen, and the important question of how reduction energy can efficiently pass from cor ...200919631224
effect of perturbation of atp level on the activity and regulation of nitrogenase in rhodospirillum rubrum.nitrogenase activity in rhodospirillum rubrum and in some other photosynthetic bacteria is regulated in part by the availability of light. this regulation is through a posttranslational modification system that is itself regulated by p(ii) homologs in the cell. p(ii) is one of the most broadly distributed regulatory proteins in nature and directly or indirectly senses nitrogen and carbon signals in the cell. however, its possible role in responding to light availability remains unclear. because ...200919542280
mechanism of adp-ribosylation removal revealed by the structure and ligand complexes of the dimanganese mono-adp-ribosylhydrolase drag.adp-ribosylation is a ubiquitous regulatory posttranslational modification involved in numerous key processes such as dna repair, transcription, cell differentiation, apoptosis, and the pathogenic mechanism of certain bacterial toxins. despite the importance of this reversible process, very little is known about the structure and mechanism of the hydrolases that catalyze removal of the adp-ribose moiety. in the phototrophic bacterium rhodospirillum rubrum, dinitrogenase reductase-activating glyc ...200919706507
reduced activity of glutamine synthetase in rhodospirillum rubrum mutants lacking the adenylyltransferase glne.in the nitrogen-fixing bacterium rhodospirillum rubrum, the glne adenylyltransferase (encoded by glne) catalyzes reversible adenylylation of glutamine synthetase, thereby regulating nitrogen assimilation. we have generated glne mutant strains that are unable to adenylylate glutamine synthetase (gs). surprisingly, the activity of gs was lower in the mutants than in the wild type, even when grown in nitrogen-fixing conditions. our results support the proposal that r. rubrum can only cope with the ...200919761831
protein-induced membrane curvature investigated through molecular dynamics flexible fitting.in the photosynthetic purple bacterium rhodobacter (rba.) sphaeroides, light is absorbed by membrane-bound light-harvesting (lh) proteins lh1 and lh2. lh1 directly surrounds the reaction center (rc) and, together with pufx, forms a dimeric (rc-lh1-pufx)2 protein complex. in lh2-deficient rba. sphaeroides mutants, rc-lh1-pufx dimers aggregate into tubular vesicles with a radius of approximately 250-550 a, making rc-lh1-pufx one of the few integral membrane proteins known to actively induce membra ...200919580770
spectral diffusion and electron-phonon coupling of the b800 bchl a molecules in lh2 complexes from three different species of purple bacteria.we have investigated the spectral diffusion and the electron-phonon coupling of b800 bacteriochlorophyll a molecules in the peripheral light-harvesting complex lh2 for three different species of purple bacteria, rhodobacter sphaeroides, rhodospirillum molischianum, and rhodopseudomonas acidophila. we come to the conclusion that b800 binding pockets for rhodobacter sphaeroides and rhodopseudomonas acidophila are rather similar with respect to the polarity of the protein environment but that the p ...200919883604
energy transfer in light-adapted photosynthetic membranes: from active to saturated photosynthesis.in bacterial photosynthesis light-harvesting complexes, lh2 and lh1 absorb sunlight energy and deliver it to reaction centers (rcs) with extraordinarily high efficiency. submolecular resolution images have revealed that both the lh2:lh1 ratio, and the architecture of the photosynthetic membrane itself, adapt to light intensity. we investigate the functional implications of structural adaptations in the energy transfer performance in natural in vivo low- and high-light-adapted membrane architectu ...200919883589
structural and functional similarities between a ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco)-like protein from bacillus subtilis and photosynthetic rubisco.the sequences classified as genes for various ribulose-1,5-bisphosphate (rubp) carboxylase/oxygenase (rubisco)-like proteins (rlps) are widely distributed among bacteria, archaea, and eukaryota. in the phylogenic tree constructed with these sequences, rubiscos and rlps are grouped into four separate clades, forms i-iv. in rubisco enzymes encoded by form i, ii, and iii sequences, 19 conserved amino acid residues are essential for co(2) fixation; however, 1-11 of these 19 residues are substituted ...200919279009
thermodynamics of the beta(2) association in light-harvesting complex i of rhodospirillum rubrum. implication of peptide identity in dimer stability.the core light-harvesting lh1 protein from rhodospirillum rubrum can dissociate reversibly in the presence of n-octyl-beta-d-glucopyranoside into smaller subunit forms, exhibiting a dramatic blue-shift in absorption. during this process, two main species are observed: a dimer that absorbs at 820 nm (b820) and a monomer absorbing at 777 nm (b777). in the presence of n-octyl-beta-d-glucopyranoside, we have previously shown that the b820 form is not only constituted by the alphabeta heterodimer alo ...200818266761
electrostatic effect of surfactant molecules on bacteriochlorophyll a and carotenoid binding sites in the lh1 complex isolated from rhodospirillum rubrum s1 probed by stark spectroscopy.the lh1 complexes were isolated from the purple photosynthetic bacterium rhodospirillum rubrum strain s1. they were initially solubilized using ldao and then purified in the presence of triton x-100. the purified complexes were then either used directly or following an exchange into ldao. stark spectroscopy was applied to probe the electrostatic field around the bacteriochlorophyll a (bchl a) and carotenoid binding sites in the lh1 complexes surrounded by these two different surfactant molecules ...200817922213
biosilicification of dual-fusion enzyme immobilized on magnetic nanoparticle.rapid recovery, immobilization, and silica encapsulation of a dual-fusion enzyme was achieved by using iminodiacetic acid (ida) modified magnetic nanoparticle as a carrier. d-amino acid oxidase (daao) of rhodosporidium toruloides was used as a model enzyme in which a silica-precipitating peptide r5 and a metal ion complexing peptide (his)(6) were fused to its n- and c-terminal, respectively. after charging the magnetic particle with cu(2+), the dual-fusion daao of 0.43 g could be directly recove ...200818078291
regulation of aerobic photosystem synthesis in the purple bacterium rhodospirillum centenum by crtj and aerr.genes coding for putative crtj and aerr homologs were identified and characterized in the purple photosynthetic bacterium rhodospirillum centenum (also known as rhodocista centenaria), an organism that synthesizes photopigments even under highly aerated conditions. mutational analysis indicated that in rsp. centenum, gene crtj codes for a repressor for photosynthesis gene expression as in rhodobacter capsulatus, which exhibits a high level of oxygen repression of photosystem synthesis. in contra ...200818846293
probing binding site of bacteriochlorophyll a and carotenoid in the reconstituted lh1 complex from rhodospirillum rubrum s1 by stark spectroscopy.stark spectroscopy is a powerful technique to investigate the electrostatic interactions between pigments as well as between the pigments and the proteins in photosynthetic pigment-protein complexes. in this study, stark spectroscopy has been used to determine two nonlinear optical parameters (polarizability change tr(deltaalpha) and static dipole-moment change |deltamu| upon photoexcitation) of isolated and of reconstituted lh1 complexes from the purple photosynthetic bacterium, rhodospirillum ...200817912603
identification and functional characterization of nifa variants that are independent of glnb activation in the photosynthetic bacterium rhodospirillum rubrum.the activity of nifa, the transcriptional activator of the nitrogen fixation (nif) gene, is tightly regulated in response to ammonium and oxygen. however, the mechanisms for the regulation of nifa activity are quite different among various nitrogen-fixing bacteria. unlike the well-studied nifl-nifa regulatory systems in klebsiella pneumoniae and azotobacter vinelandii, in rhodospirillum rubrum nifa is activated by a direct protein-protein interaction with the uridylylated form of glnb, which in ...200818757802
mesaconyl-coenzyme a hydratase, a new enzyme of two central carbon metabolic pathways in bacteria.the coenzyme a (coa)-activated c5-dicarboxylic acids mesaconyl-coa and beta-methylmalyl-coa play roles in two as yet not completely resolved central carbon metabolic pathways in bacteria. first, these compounds are intermediates in the 3-hydroxypropionate cycle for autotrophic co2 fixation in chloroflexus aurantiacus, a phototrophic green nonsulfur bacterium. second, mesaconyl-coa and beta-methylmalyl-coa are intermediates in the ethylmalonyl-coa pathway for acetate assimilation in various bacte ...200818065535
rhodospirillum rubrum: utilization of condensed corn solubles for poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) production.this study sought to develop a less expensive medium for growth of the polyhydroxyalkanoate-producing bacterium rhodospirillum rubrum from the ethanol production coproduct, condensed corn solubles (ccs).200818179537
comparative proteomic studies in rhodospirillum rubrum grown under different nitrogen conditions.forty-four differentially expressed proteins have been identified in the photosynthetic diazotroph rhodospirillum rubrum grown anaerobic and photoheterotrophically, with different nitrogen sources, using 2d-page and maldi-tof, from gels containing an average of 679 +/- 52 (in n(+)) and 619 +/- 37 (in n(-)) protein spots for each gel. a higher level of expression was found under nitrogen-rich growth, for proteins involved in carbon metabolism (reductive tricarboxylic acid cycle, co(2) fixation, a ...200818570453
biohydrogen production in a continuous stirred tank bioreactor from synthesis gas by anaerobic photosynthetic bacterium: rhodopirillum rubrum.hydrogen may be considered a potential fuel for the future since it is carbon-free and oxidized to water as a combustion product. bioconversion of synthesis gas (syngas) to hydrogen was demonstrated in continuous stirred tank bioreactor (cstbr) utilizing acetate as a carbon source. an anaerobic photosynthetic bacterium, rhodospirillum rubrum catalyzed water-gas shift reaction which was applied for the bioconversion of syngas to hydrogen. the continuous fermentation of syngas in the bioreactor wa ...200817582763
[a new methodical approach to the determination of the quantum yield of the photoelectric conversion of electronic excitations in reaction centers of purple bacteria].a new methodical approach has been developed, which enables one to determine with a high precision (approximately 1.5%) the quantum yield of energy conversion in reaction centers isolated from purple bacterium. this parameter for reaction centers from rhodospirillum rubrum was estimated to be 93.5 +/- 1,5%. our methodical approach makes it possible to calculate quantum yield values for complete photosystems of purple bacteria.200818634316
interaction of the signal transduction protein glnj with the cellular targets amtb1, glne and glnd in rhodospirillum rubrum: dependence on manganese, 2-oxoglutarate and the adp/atp ratio.the pii family of signal transduction proteins is widespread amongst the three domains of life, and its members have fundamental roles in the general control of nitrogen metabolism. these proteins exert their regulatory role by direct protein-protein interaction with a multitude of cellular targets. the interactions are dependent on the binding of metabolites such as atp, adp and 2-oxoglutarate (2-og), and on whether or not the pii protein is modified. in the photosynthetic nitrogen-fixing bacte ...200818667566
burst analysis spectroscopy: a versatile single-particle approach for studying distributions of protein aggregates and fluorescent assemblies.many essential cellular functions depend on the assembly and disassembly of macromolecular complexes. the size, form, and distribution of these assemblies can be heterogeneous and complex, rendering their detailed characterization difficult. here we describe a simple non-correlation-based method capable of directly measuring population distributions at very low sample concentrations. specifically, we exploit the highest signal-to-noise light bursts from single fluorescent particles transiting a ...200818780782
intermolecular vibrational coherence in the bacteriochlorophyll proteins b777 and b820 from rhodospirillum rubrum.the low-frequency vibrational coherence in the bacteriochlorophyll (bchl)-containing subunit proteins b777 and b820 from the lh1 light-harvesting complex isolated from rhodospirillum rubrum g9 exhibits rapidly damped modulation components arising from intermolecular, formally nonbonding interactions between the bchl macrocycle and polar groups in the surrounding detergent or protein. the vibrational coherence observed in the monomeric b777 system resembles that observed previously with bchl in a ...200818181604
bacteriophytochromes in anoxygenic photosynthetic bacteria.since the first discovery of a bacteriophytochrome in rhodospirillum centenum, numerous bacteriophytochromes have been identified and characterized in other anoxygenic photosynthetic bacteria. this review is focused on the biochemical and biophysical properties of bacteriophytochromes with a special emphasis on their roles in the synthesis of the photosynthetic apparatus.200818612842
probing the effect of the binding site on the electrostatic behavior of a series of carotenoids reconstituted into the light-harvesting 1 complex from purple photosynthetic bacterium rhodospirillum rubrum detected by stark spectroscopy.reconstitutions of the lh1 complexes from the purple photosynthetic bacterium rhodospirillum rubrum s1 were performed with a range of carotenoid molecules having different numbers of c=c conjugated double bonds. since, as we showed previously, some of the added carotenoids tended to aggregate and then to remain with the reconstituted lh1 complexes (nakagawa, k.; suzuki, s.; fujii, r.; gardiner, a.t.; cogdell, r.j.; nango, m.; hashimoto, h. photosynth. res. 2008, 95, 339-344), a further purificat ...200818613723
dynamic aspects and controllability of the melissa project: a bioregenerative system to provide life support in space.manmade ecosystems differ from their prototype biosphere by the principle of control. the earth biosphere is sustainable by stochastic control and very large time constants. by contrast, in a closed ecosystem such as the micro-ecological life support system alternative (melissa system) developed by the european space agency for space exploration, a deterministic control is a prerequisite of sustainable existence. melissa is an integrated sum of interconnected biological subsystems. on one hand, ...200818592407
mutations in transhydrogenase change the fluorescence emission state of trp72 from 1la to 1lb.the di component of rhodospirillum rubrum transhydrogenase has a single trp residue (trp(72)), which has distinctive optical properties, including short-wavelength fluorescence emission with clear vibrational fine structure, and long-lived, well-resolved phosphorescence emission. we have made a set of mutant di proteins in which residues contacting trp(72) are conservatively substituted. the room-temperature fluorescence-emission spectra of our three met(97) mutants are blue shifted by approxima ...200818599622
formation of a cross-linking complex of dinitrogenase reductase-activating glycohydrolase (drag) with membrane proteins from rhodospirillum rubrum chromatophores.association of dinitrogenase reductase-activating glycohydrolase (drag) with membrane proteins of chromatophores has been investigated. the formation of a multicomponent complex between drag and membrane proteins was demonstrated in the presence of glutaraldehyde and edc/nhs (n-(3-dimethylaminopropyl)-n -ethylcarbodiimide hydrochloride/hydroxy-2,5-dioxopyrrolidine-3-sulfonic acid sodium salt). complex formation was observed both in native chromatophore membrane and in chromatophores treated with ...200818298373
redox-state dynamics of ubiquinone-10 imply cooperative regulation of photosynthetic membrane expression in rhodospirillum rubrum.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 ubiquino ...200818487324
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