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rhodobacter sphaeroides uses a reductive route via propionyl coenzyme a to assimilate 3-hydroxypropionate.3-hydroxypropionate is a product or intermediate of the carbon metabolism of organisms from all three domains of life. however, little is known about how carbon derived from 3-hydroxypropionate is assimilated by organisms that can utilize this c(3) compound as a carbon source. this work uses the model bacterium rhodobacter sphaeroides to begin to elucidate how 3-hydroxypropionate can be incorporated into cell constituents. to this end, a quantitative assay for 3-hydroxypropionate was developed b ...201222056933
comparison of chloroflexus aurantiacus strain j-10-fl proteomes of cells grown chemoheterotrophically and photoheterotrophically.chloroflexus aurantiacus j-10-fl is a thermophilic green bacterium, a filamentous anoxygenic phototroph, and the model organism of the phylum chloroflexi. we applied high-throughput, liquid chromatography-mass spectrometry in a global quantitative proteomics investigation of c. aurantiacus cells grown under oxic (chemoorganoheterotrophically) and anoxic (photoorganoheterotrophically) redox states. our global analysis identified 13,524 high-confidence peptides that matched to 1,286 annotated prot ...201222249883
investigation of the redox interaction between mn-bicarbonate complexes and reaction centers from rhodobacter sphaeroides r-26, chromatium minutissimum, and chloroflexus aurantiacus.the change in the dark reduction rate of photooxidized reaction centers (rc) of type ii from three anoxygenic bacteria (rhodobacter sphaeroides r-26, chromatium minutissimum, and chloroflexus aurantiacus) having different redox potentials of the p(+)/p pair and availability of rc for exogenous electron donors was investigated upon the addition of mn(2+) and hco(3)(-). it was found that the dark reduction of p(870)(+) from rb. sphaeroides r-26 is considerably accelerated upon the combined additio ...201122150281
production of 3-hydroxypropionate homopolymer and poly(3-hydroxypropionate-co-4-hydroxybutyrate) copolymer by recombinant escherichia coli.conversion of 3-hydroxypropionate (3hp) from 1,3-propanediol (pdo) was improved by expressing dehydratase gene (dhat) and aldehyde dehydrogenase gene (aldd) of pseudomonas putida kt2442 under the promoter of phacab operon from ralstonia eutropha h16. expression of these genes in aeromonas hydrophila 4ak4 produced up to 21 g/l 3hp in a fermentation process. to synthesize homopolymer poly(3-hydroxypropionate) (p3hp), and copolymer poly(3-hydroxypropionate-co-3-hydroxybutyrate) (p3hp4hb), dhat and ...201122024131
Dynamics of microbial community structure of and enhanced biological phosphorus removal by aerobic granules cultivated on propionate or acetate.Aerobic granules are dense microbial aggregates with the potential to replace floccular sludge for the treatment of wastewaters. In bubble-column sequencing batch reactors, distinct microbial populations dominated propionate- and acetate-cultivated aerobic granules after 50 days of reactor operation when only carbon removal was detected. Propionate granules were dominated by Zoogloea (40%), Acidovorax, and Thiothrix, whereas acetate granules were mainly dominated by Thiothrix (60%). Thereafter, ...201121926195
ftir spectroscopy of the reaction center of chloroflexus aurantiacus: photoreduction of the bacteriopheophytin electron acceptor.mid-infrared spectral changes associated with the photoreduction of the bacteriopheophytin electron acceptor h(a) in reaction centers (rcs) of the filamentous anoxygenic phototrophic bacterium chloroflexus (cfl.) aurantiacus are examined by light-induced fourier transform infrared (ftir) spectroscopy. the light-induced h(a)(-)/h(a) ftir (1800-1200cm(-1)) difference spectrum of cfl. aurantiacus rcs is compared to that of the previously well characterized purple bacterium rhodobacter (rba.) sphaer ...201121641333
excitation energy transfer and trapping dynamics in the core complex of the filamentous photosynthetic bacterium roseiflexus castenholzii.the light-harvesting core complex of the thermophilic filamentous anoxygenic phototrophic bacterium roseiflexus castenholzii is intrinsic to the cytoplasmic membrane and intimately bound to the reaction center (rc). using ultrafast transient absorption and time-resolved fluorescence spectroscopy with selective excitation, energy transfer, and trapping dynamics in the core complex have been investigated at room temperature in both open and closed rcs. results presented in this report revealed tha ...201121792612
co-assimilation of organic substrates via the autotrophic 3-hydroxypropionate bi-cycle in chloroflexus aurantiacus.chloroflexus aurantiacus is a facultative autotrophic green non-sulfur bacterium that grows phototrophically in thermal springs and forms microbial mats with cyanobacteria. cyanobacteria produce glycolate during the day (photorespiration) and excrete fermentation products at night. c. aurantiacus uses the 3-hydroxypropionate bi-cycle for autotrophic carbon fixation. this pathway was supposed to be also suited for the co-assimilation of various organic substrates like glycolate, acetate, propiona ...201121764971
phylogenetic and gene expression analysis of cyanobacteria and diatoms in the twilight waters of the temperate northeast pacific ocean.in this study, to explore the microbial community structure and its functionality in the deep-sea environments, we initially performed a 16s ribosomal rna (rrna)-based community structure analyses for microbial communities in the sea water collected from sites of 765-790-ám in depth in the pacific ocean. interestingly, in the clone library we detected the presence of both photoautotrophic bacteria such as cyanobacteria and photoheterotrophic bacteria, such as chloroflexus sp. to further explore ...201121698402
production of 3-hydroxypropionic acid via malonyl-coa pathway using recombinant escherichia coli strains.malonyl-coa is an intermediary compound that is produced during fatty acid metabolism. our study aimed to produce the commercially important platform chemical 3-hydroxypropionic acid (3-hp) from its immediate precursor malonyl-coa by recombinant escherichia coli strains heterologously expressing the mcr gene of chloroflexus aurantiacus dsm 635, encoding an nadph-dependent malonyl-coa reductase (mcr). the recombinant e. coli overexpressing mcr under the t5 promoter showed mcr activity of 0.015umg ...201121723339
comparing the temperature dependence of photosynthetic electron transfer in chloroflexus aurantiacus and rhodobactor sphaeroides reaction centers.the process of electron transfer from the special pair, p, to the primary electron donor, h(a), in quinone-depleted reaction centers (rcs) of chloroflexus (cf.) aurantiacu s has been investigated over the temperature range from 10 to 295 k using time-resolved pump-probe spectroscopic techniques. the kinetics of the electron transfer reaction, p* ôåæ p(+)h(a)(-), was found to be nonexponential, and the degree of nonexponentiality increased strongly as temperature decreased. the temperature-depend ...201121827152
complete genome sequence of the filamentous anoxygenic phototrophic bacterium chloroflexus aurantiacus.chloroflexus aurantiacus is a thermophilic filamentous anoxygenic phototrophic (fap) bacterium, and can grow phototrophically under anaerobic conditions or chemotrophically under aerobic and dark conditions. according to 16s rrna analysis, chloroflexi species are the earliest branching bacteria capable of photosynthesis, and cfl. aurantiacus has been long regarded as a key organism to resolve the obscurity of the origin and early evolution of photosynthesis. cfl. aurantiacus contains a chimeric ...201121714912
insights into chemotaxonomic composition and carbon cycling of phototrophic communities in an artesian sulfur-rich spring (zodletone, oklahoma, usa), a possible analog for ancient microbial mat systems.zodletone spring in oklahoma is a unique environment with high concentrations of dissolved-sulfide (10 mm) and short-chain gaseous alkanes, exhibiting characteristics that are reminiscent of conditions that are thought to have existed in earth's history, in particular the late archean and early-to-mid proterozoic. here, we present a process-oriented investigation of the microbial community in two distinct mat formations at the spring source, (1) the top of the sediment in the source pool and (2) ...201121244620
sulfur-metabolizing bacterial populations in microbial mats of the nakabusa hot spring, japan.at the nakabusa hot spring, japan, dense olive-green microbial mats develop in regions where the slightly alkaline, sulfidic effluent has cooled to 65°c. the microbial community of such mats was analyzed by focusing on the diversity, as well as the in situ distribution and function of bacteria involved in sulfur cycling. analyses of 16s rrna and functional genes (apra, pufm) suggested the importance of three thermophilic bacterial groups: aerobic chemolithotrophic sulfide-oxidizing species of th ...201121353426
temperature and ionic strength effects on the chlorosome light-harvesting antenna complex.chlorosomes, the peripheral light-harvesting antenna complex from green photosynthetic bacteria, are the largest and one of the most efficient light-harvesting antenna complexes found in nature. in contrast to other light-harvesting antennas, chlorosomes are constructed from more than 150,000 self-assembled bacteriochlorophylls (bchls) and contain relatively few proteins that play secondary roles. these unique properties have led to chlorosomes as an attractive candidate for developing biohybrid ...201121405043
electronic pathway in reaction centers from rhodobacter sphaeroides and chloroflexus aurantiacus.the reaction centers (rc) of chloroflexus aurantiacus and rhodobacter sphaeroidesh(m182)l mutant were investigated. prediction for electron transfer (et) at very low temperatures was also performed. to describe the kinetics of the c. aurantiacus rcs, the incoherent model of electron transfer was used. it was shown that the asymmetry in electronic coupling parameters must be included to explain the experiments. for the description of r. sphaeroidesh(m182)l mutant rcs, the coherent and incoherent ...201021629589
cultivation and genomic, nutritional, and lipid biomarker characterization of roseiflexus strains closely related to predominant in situ populations inhabiting yellowstone hot spring microbial mats.roseiflexus sp. strains were cultivated from a microbial mat of an alkaline siliceous hot spring in yellowstone national park. these strains are closely related to predominant filamentous anoxygenic phototrophs found in the mat, as judged by the similarity of small-subunit rrna, lipid distributions, and genomic and metagenomic sequences. like a japanese isolate, r. castenholzii, the yellowstone isolates contain bacteriochlorophyll a, but not bacteriochlorophyll c or chlorosomes, and grow photohe ...201020363941
molecular signatures for the main phyla of photosynthetic bacteria and their subgroups.the bacterial groups corresponding to different photosynthetic prokaryotes are presently identified mainly on the basis of their branching in phylogenetic trees. the availability of genome sequences is enabling identification of many molecular signatures that are specific for different groups of photosynthetic bacteria. our recent work has identified large numbers of signatures consisting of conserved inserts or deletions (indels) in widely distributed proteins, as well as whole proteins that ar ...201020414806
the small subunit arob of arsenite oxidase: lessons on the [2fe-2s] rieske protein superfamily.here, we describe the characterization of the [2fe-2s] clusters of arsenite oxidases from rhizobium sp. nt-26 and ralstonia sp. 22. both reduced rieske proteins feature epr signals similar to their homologs from rieske-cyt b complexes, with g values at 2.027, 1.88, and 1.77. redox titrations in a range of ph values showed that both [2fe-2s] centers have constant e(m) values up to ph 8 at approximately +210 mv. above this ph value, the e(m) values of both centers are ph-dependent, similar to what ...201020421651
kinetic and structural characterization of a heterohexamer 4-oxalocrotonate tautomerase from chloroflexus aurantiacus j-10-fl: implications for functional and structural diversity in the tautomerase superfamily .4-oxalocrotonate tautomerase (4-ot) isozymes play prominent roles in the bacterial utilization of aromatic hydrocarbons as sole carbon sources. these enzymes catalyze the conversion of 2-hydroxy-2,4-hexadienedioate (or 2-hydroxymuconate) to 2-oxo-3-hexenedioate, where pro-1 functions as a general base and shuttles a proton from the 2-hydroxyl group of the substrate to the c-5 position of the product. 4-ot, a homohexamer from pseudomonas putida mt-2, is the most extensively studied 4-ot isozyme a ...201020465238
structural analysis of alternative complex iii in the photosynthetic electron transfer chain of chloroflexus aurantiacus.the green photosynthetic bacterium chloroflexus aurantiacus, which belongs to the phylum of filamentous anoxygenic phototrophs, does not contain a cytochrome bc or bf type complex which is found in all other known groups of phototrophs. this suggests that a functional replacement exists to link the reaction center photochemistry to cyclic electron transfer as well as respiration. earlier work identified a potential substitute of the cytochrome bc complex, now named alternative complex iii (aciii ...201020614874
comparative analysis of bacterioplankton assemblages from karenia brevis bloom and nonbloom water on the west florida shelf (gulf of mexico, usa) using 16s rrna gene clone libraries.the brevetoxin-producing dinoflagellate, karenia brevis, forms nearly annual blooms off the florida west coast, severely impacting the region's ecology and economy. bacteria are often cited as either promoting or interfering with the development of algal blooms, and thus a detailed study of the bacterioplankton assemblages associated with k. brevis was undertaken. we developed sixteen 16s rrna gene clone libraries from k. brevis bloom and adjacent nonbloom water to determine the bacterial groups ...201020618855
gradual adaptive changes of a protein facing high salt concentrations.several experimental techniques were applied to unravel fine molecular details of protein adaptation to high salinity. we compared four homologous enzymes, which suggested a new halo-adaptive state in the process of molecular adaptation to high-salt conditions. together with comparative functional studies, the structure of malate dehydrogenase from the eubacterium salinibacter ruber shows that the enzyme shares characteristics of a halo-adapted archaea-bacterial enzyme and of non-halo-adapted en ...201020888835
sans investigation of the photosynthetic machinery of chloroflexus aurantiacus.green photosynthetic bacteria harvest light and perform photosynthesis in low-light environments, and contain specialized antenna complexes to adapt to this condition. we performed small-angle neutron scattering (sans) studies to obtain structural information about the photosynthetic apparatus, including the peripheral light-harvesting chlorosome complex, the integral membrane light-harvesting b808-866 complex, and the reaction center (rc) in the thermophilic green phototrophic bacterium chlorof ...201020959079
kinetics and energetics of electron transfer in reaction centers of the photosynthetic bacterium roseiflexus castenholzii.the kinetics and thermodynamics of the photochemical reactions of the purified reaction center (rc)-cytochrome (cyt) complex from the chlorosome-lacking, filamentous anoxygenic phototroph, roseiflexus castenholzii are presented. the rc consists of l- and m-polypeptides containing three bacteriochlorophyll (bchl), three bacteriopheophytin (bph) and two quinones (q(a) and q(b)), and the cyt is a tetraheme subunit. two of the bchls form a dimer p that is the primary electron donor. at 285k, the lif ...201021126505
a spectrophotometric assay for measuring acetyl-coenzyme a carboxylase.acetyl-coenzyme a (coa) carboxylase catalyzes the first step in the biosynthesis of fatty acids in bacteria and eukaryota. this enzyme is the target of drug design for treatment of human metabolic diseases and of herbicides acting specifically on the eukaryotic form of the enzyme in grasses. acetyl-coa carboxylase activity screening in drug and herbicide design depends mostly on a time-consuming enzyme assay that is based on the incorporation of radiolabeled bicarbonate into the product malonyl- ...201021138728
the role of diglycosyl lipids in photosynthesis and membrane lipid homeostasis in arabidopsis.the galactolipid digalactosyldiacylglycerol (dgd) is an abundant thylakoid lipid in chloroplasts. the introduction of the bacterial lipid glucosylgalactosyldiacylglycerol (ggd) from chloroflexus aurantiacus into the dgd-deficient arabidopsis (arabidopsis thaliana) dgd1 mutant was previously shown to result in complementation of growth, but photosynthetic efficiency was only partially restored. here, we demonstrate that ggd accumulation in the double mutant dgd1dgd2, which is totally devoid of dg ...200919403724
optoelectronic energy transfer at novel biohybrid interfaces using light harvesting complexes from chloroflexus aurantiacus.in nature, nanoscale supramolecular light harvesting complexes initiate the photosynthetic energy collection process at high quantum efficiencies. in this study, the distinctive antenna structure from chloroflexus aurantiacusthe chlorosomeis assessed for potential exploitation in novel biohybrid optoelectronic devices. electrochemical characterization of bacterial fragments containing intact chlorosomes with the photosynthetic apparatus show an increase in the charge storage density near the wor ...200919405485
3-hydroxypropionyl-coenzyme a dehydratase and acryloyl-coenzyme a reductase, enzymes of the autotrophic 3-hydroxypropionate/4-hydroxybutyrate cycle in the sulfolobales.a 3-hydroxypropionate/4-hydroxybutyrate cycle operates in autotrophic co(2) fixation in various crenarchaea, as studied in some detail in metallosphaera sedula. this cycle and the autotrophic 3-hydroxypropionate cycle in chloroflexus aurantiacus have in common the conversion of acetyl-coenzyme a (coa) and two bicarbonates via 3-hydroxypropionate to succinyl-coa. both cycles require the reductive conversion of 3-hydroxypropionate to propionyl-coa. in m. sedula the reaction sequence is catalyzed b ...200919429610
[search for an optimal orientational ordering of qy transition dipoles of subantennae molecules in superantenna of photosynthetic green bacteria. model calculations].this work continues a series of our investigations on efficient strategies of functioning of natural light-harvesting antennae, initiated by our concept of rigorous optimization of photosynthetic apparatus structure by functional criterion. using computer modeling for the functioning of the natural antennae, we suggested some basic principles for designing optimal model systems. targeted searches for these principles in in vivo systems allowed us to recognize some of them in natural antennae. th ...200919548533
refolding, characterization and crystal structure of (s)-malate dehydrogenase from the hyperthermophilic archaeon aeropyrum pernix.tartrate oxidation activity was found in the crude extract of an aerobic hyperthermophilic archaeon aeropyrum pernix, and the enzyme was identified as (s)-malate dehydrogenase (mdh), which, when produced in escherichia coli, was mainly obtained as an inactive inclusion body. the inclusion body was dissolved in 6 m guanidine-hcl and gradually refolded to the active enzyme through dilution of the denaturant. the purified recombinant enzyme consisted of four identical subunits with a molecular mass ...200919555779
characterization of a blue-copper protein, auracyanin, of the filamentous anoxygenic phototrophic bacterium roseiflexus castenholzii.a blue-copper protein auracyanin of the filamentous anoxygenic phototroph roseiflexus castenholzii was purified and characterized. genomic sequence analysis showed that r. castenholzii has only one auracyanin, whereas chloroflexus aurantiacus is known to have two auracyanins, a and b. absorption spectrum of the roseiflexus auracyanin was similar to that of auracyanin b of c. aurantiacus. on the other hand, esr spectrum of the roseiflexus auracyanin resembles that of auracyanin a of c. aurantiacu ...200919683508
structure of chlorosomes from the green filamentous bacterium chloroflexus aurantiacus.the green filamentous bacterium chloroflexus aurantiacus employs chlorosomes as photosynthetic antennae. chlorosomes contain bacteriochlorophyll aggregates and are attached to the inner side of a plasma membrane via a protein baseplate. the structure of chlorosomes from c. aurantiacus was investigated by using a combination of cryo-electron microscopy and x-ray diffraction and compared with that of chlorobi species. cryo-electron tomography revealed thin chlorosomes for which a distinct crystall ...200919717605
purification, characterization and crystallization of menaquinol:fumarate oxidoreductase from the green filamentous photosynthetic bacterium chloroflexus aurantiacus.the integral membrane protein complex, menaquinol:fumarate oxidoreductase (mqfr) has been purified, identified and characterized from the thermophilic green filamentous anoxygenic photosynthetic bacterium chloroflexus aurantiacus. the complex is composed of three subunits: a 74 kda flavoprotein that contains a covalently bound flavin adenine dinucleotide, a 28 kda iron-sulfur cluster-containing polypeptide, and a 27 kda transmembrane polypeptide, which is also the binding site of two b-type heme ...200919103151
iron binding effects on the kinetic stability and unfolding energetics of a thermophilic phenylalanine hydroxylase from chloroflexus aurantiacus.the effects of non-heme iron binding on the function, structure, and stability of a monomeric phenylalanine hydroxylase from the thermophile chloroflexus aurantiacus (capah) were investigated. comparative studies on holo (iron-bound) and apo (iron-depleted) capah indicated that iron(ii) binding does not significantly affect the overall structure of the enzyme. thermal denaturation studies performed using differential scanning calorimetry showed that the unfolding reaction was kinetically control ...200919153779
spatial and temporal variability in a stratified hypersaline microbial mat community.hypersaline microbial mat communities have recently been shown to be more diverse than once thought. the variability in community composition of hypersaline mats, both in terms of spatial and temporal dimensions, is still poorly understood. because this information is essential to understanding the complex biotic and abiotic interactions within these communities, terminal restriction fragment analysis and 16s rrna gene sequencing were used to characterize the near-surface community of a hypersal ...200919175677
the crystal structure of auracyanin a at 1.85 a resolution: the structures and functions of auracyanins a and b, two almost identical "blue" copper proteins, in the photosynthetic bacterium chloroflexus aurantiacus.auracyanins a and b are two closely similar "blue" copper proteins produced by the filamentous anoxygenic phototrophic bacterium chloroflexus aurantiacus. both proteins have a water-soluble 140-residue globular domain, which is preceded in the sequence by an n-terminal tail. the globular domains of auracyanins a and b have sequences that are 38% identical. the sequences of the n-terminal tails, on the other hand, are distinctly different, suggesting that auracyanins a and b occupy different memb ...200919190939
microbial synthesis of poly((r)-3-hydroxybutyrate-co-3-hydroxypropionate) from unrelated carbon sources by engineered cupriavidus necator.cupriavidus necator was engineered aiming to synthesize poly[(r)-3-hydroxybutyrate-co-3-hydroxypropionate] copolyester, p(3hb-co-3hp), from structurally unrelated carbon sources without addition of any precursor compounds. we modified a metabolic pathway in c. necator for generation of 3-hydroxypropionyl-coa (3hp-coa) by introducing malonyl-coa reductase and the 3hp-coa synthetase domain of trifunctional propionyl-coa synthase; both members of the 3-hydroxypropionate cycle, a novel co(2)-fixatio ...200919267466
role of the acsf protein in chloroflexus aurantiacus.the green phototrophic bacteria contain a unique complement of chlorophyll pigments, which self-assemble efficiently into antenna structures known as chlorosomes with little involvement of protein. the few proteins found in chlorosomes have previously been thought to have a primarily structural function. the biosynthetic pathway of the chlorosome pigments, bacteriochlorophylls c, d, and e, is not well understood. in this report, we used spectroscopic, proteomic, and gene expression approaches to ...200919346304
enzymatic activity of the alternative complex iii as a menaquinol:auracyanin oxidoreductase in the electron transfer chain of chloroflexus aurantiacus.the surprising lack of the cytochrome bc1 complex in the filamentous anoxygenic phototrophic bacterium chloroflexus aurantiacus suggests that a functional replacement exists to link the cyclic electron transfer chain. earlier work identified the alternative complex iii (aciii) as a substitute of cytochrome bc1 complex. herein, the enzymatic activity of aciii is studied. the results strongly support the view that the aciii functions as menaquinol:auracyanin oxidoreductase in the c. aurantiacus el ...200919755122
femtosecond phase of charge separation in reaction centers of chloroflexus aurantiacus.difference absorption spectroscopy with temporal resolution of approximately 20 fsec was used to study the primary phase of charge separation in isolated reaction centers (rcs) of chloroflexus aurantiacus at 90 k. an ensemble of difference (light-minus-dark) absorption spectra in the 730-795 nm region measured at -0.1 to 4 psec delays relative to the excitation pulse was analyzed. comparison with analogous data for rcs of hm182l mutant of rhodobacter sphaeroides having the same pigment compositi ...200919817684
identifying the missing steps of the autotrophic 3-hydroxypropionate co2 fixation cycle in chloroflexus aurantiacus.the phototrophic bacterium chloroflexus aurantiacus uses a yet unsolved 3-hydroxypropionate cycle for autotrophic co(2) fixation. it starts from acetyl-coa, with acetyl-coa and propionyl-coa carboxylases acting as carboxylating enzymes. in a first cycle, (s)-malyl-coa is formed from acetyl-coa and 2 molecules of bicarbonate. (s)-malyl-coa cleavage releases the co(2) fixation product glyoxylate and regenerates the starting molecule acetyl-coa. here we complete the missing steps devoted to glyoxyl ...200919955419
the hydroxypropionate pathway of co2 fixation: fait accompli. 200919996176
in silico approaches to study mass and energy flows in microbial consortia: a syntrophic case study.three methods were developed for the application of stoichiometry-based network analysis approaches including elementary mode analysis to the study of mass and energy flows in microbial communities. each has distinct advantages and disadvantages suitable for analyzing systems with different degrees of complexity and a priori knowledge. these approaches were tested and compared using data from the thermophilic, phototrophic mat communities from octopus and mushroom springs in yellowstone national ...200920003240
wave packet motions coupled to electron transfer in reaction centers of chloroflexus aurantiacus.transient absorption difference spectroscopy with approximately 20 femtosecond (fs) resolution was applied to study the time and spectral evolution of low-temperature (90 k) absorbance changes in isolated reaction centers (rcs) of chloroflexus (c.) aurantiacus. in rcs, the composition of the b-branch chromophores is different with respect to that of purple bacterial rcs by occupying the b(b) binding site of accessory bacteriochlorophyll by bacteriopheophytin molecule (phi(b)). it was found that ...200818763734
pressure-induced red shift and broadening of the qy absorption of main light-harvesting antennae chlorosomes from green photosynthetic bacteria and their dependency upon alkyl substituents of the composite bacteriochlorophylls.when pressure was applied to the main light-harvesting apparatus (chlorosomes) isolated from several green photosynthetic bacteria (up to 128 mpa), the qy-absorption band in an aqueous solution was shifted to longer wavelengths. the shift, deltav, was completely reversible for (de)compression and also showed a linear relation as a function of the applied pressure. the pressure-sensitivity in the deltav was dependent upon the bacterial species. the pressure coefficient, deltav/deltap, was -565 to ...200819367895
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
immobilization of functional light antenna structures derived from the filamentous green bacterium chloroflexus aurantiacus.the integration of highly efficient, natural photosynthetic light antenna structures into engineered systems while their biophotonic capabilities are maintained has been an elusive goal in the design of biohybrid photonic devices. in this study, we report a novel technique to covalently immobilize nanoscaled bacterial light antenna structures known as chlorosomes from chloroflexus aurantiacus on both conductive and nonconductive glass while their energy transducing functionality was maintained. ...200818590285
two-dimensional mapping of photopigment distribution and activity of chloroflexus-like bacteria in a hypersaline microbial mat.pigment analysis in an intact hypersaline microbial mat by hyperspectral imaging revealed very patchy and spatially uncorrelated distributions of photopigments chl a and bchl a/c, which are characteristic photopigments for oxygenic (diatoms and cyanobacteria) and anoxygenic phototrophs (chloroflexaceae). this finding is in contrast to the expectation that these biomarker pigments should be spatially correlated, as oxygenic phototrophs are thought to supply the chloroflexaceae members with organi ...200818616583
characterization of thermotolerant purple nonsulfur bacteria isolated from hot-spring chloroflexus mats and the reclassification of "rhodopseudomonas cryptolactis" stadtwald-demchick et al.1990 as rhodoplanes cryptolactis nom. rev., comb. nov. 200718187892
properties of r-citramalyl-coenzyme a lyase and its role in the autotrophic 3-hydroxypropionate cycle of chloroflexus aurantiacus.the autotrophic co(2) fixation pathway (3-hydroxypropionate cycle) in chloroflexus aurantiacus results in the fixation of two molecules of bicarbonate into one molecule of glyoxylate. glyoxylate conversion to the co(2) acceptor molecule acetyl-coenzyme a (coa) requires condensation with propionyl-coa (derived from one molecule of acetyl-coa and one molecule of co(2)) to beta-methylmalyl-coa, which is converted to citramalyl-coa. extracts of autotrophically grown cells contained both s- and r-cit ...200717259315
self-assembled single- and double-stack pi-aggregates of chlorophyll derivatives on highly ordered pyrolytic graphite.the highly efficient, light-harvesting antennae systems present in chlorosomes of green phototrophic bacteria, such as chloroflexus aurantiacus, serve as a model for the design of bioinspired nanostructured materials. a semisynthetic zinc chlorin, derived from natural chlorophyll a, is used as a building block that self-assembles into excitonically coupled chromophore stacks. temperature-dependent uv/vis and circular dichroism spectroscopic measurements show the reversible formation of soluble c ...200717366649
initial characterization of the photosynthetic apparatus of "candidatus chlorothrix halophila," a filamentous, anoxygenic photoautotroph."candidatus chlorothrix halophila" is a recently described halophilic, filamentous, anoxygenic photoautotroph (j. a. klappenbach and b. k. pierson, arch. microbiol. 181:17-25, 2004) that was enriched from the hypersaline microbial mats at guerrero negro, mexico. analysis of the photosynthetic apparatus by negative staining, spectroscopy, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the photosynthetic apparatus in this organism has similarities to the photosyntheti ...200717369303
diversity and function of chloroflexus-like bacteria in a hypersaline microbial mat: phylogenetic characterization and impact on aerobic respiration.we studied the diversity of chloroflexus-like bacteria (clb) in a hypersaline phototrophic microbial mat and assayed their near-infrared (nir) light-dependent oxygen respiration rates. pcr with primers that were reported to specifically target the 16s rrna gene from members of the phylum chloroflexi resulted in the recovery of 49 sequences and 16 phylotypes (sequences of the same phylotype share more than 96% similarity), and 10 of the sequences (four phylotypes) appeared to be related to filame ...200717449697
polarized fluorescence of aggregated bacteriochlorophyll c and baseplate bacteriochlorophyll a in single chlorosomes isolated from chloroflexus aurantiacus.the polarization anisotropy of fluorescence from single chlorosomes isolated from a green filamentous bacterium, chloroflexus aurantiacus, was measured using a confocal laser microscope at 13 k. each single chlorosome that is floating in a frozen solvent exhibited strong polarization anisotropy of fluorescence. we calculated the degrees of fluorescence polarization for 51 floating single chlorosomes. the value ranged from 0.1 to 0.76 for the bchl-c aggregate in the core chlorosomes and from 0 to ...200717503774
effect of salinity changes on the bacterial diversity, photosynthesis and oxygen consumption of cyanobacterial mats from an intertidal flat of the arabian gulf.the effects of salinity fluctuation on bacterial diversity, rates of gross photosynthesis (gp) and oxygen consumption in the light (ocl) and in the dark (ocd) were investigated in three submerged cyanobacterial mats from a transect on an intertidal flat. the transect ran 1 km inland from the low water mark along an increasingly extreme habitat with respect to salinity. the response of gp, ocl and ocd in each sample to various salinities (65 per thousand, 100 per thousand, 150 per thousand and 20 ...200717504476
contribution of chloroflexus respiration to oxygen cycling in a hypersaline microbial mat from lake chiprana, spain.in dense stratified systems such as microbial mats, photosynthesis and respiration are coupled due to a tight spatial overlap between oxygen-producing and -consuming microorganisms. we combined microsensors and a membrane inlet mass spectrometer with two independent light sources emitting in the visible (vis) and near infrared (nir) regions to study this coupling in more detail. using this novel approach, we separately quantified the activity of the major players in the oxygen cycle in a hypersa ...200717635546
comparative genomics provides evidence for the 3-hydroxypropionate autotrophic pathway in filamentous anoxygenic phototrophic bacteria and in hot spring microbial mats.stable carbon isotope signatures of diagnostic lipid biomarkers have suggested that roseiflexus spp., the dominant filamentous anoxygenic phototrophic bacteria inhabiting microbial mats of alkaline siliceous hot springs, may be capable of fixing bicarbonate via the 3-hydroxypropionate pathway, which has been characterized in their distant relative, chloroflexus aurantiacus. the genomes of three filamentous anoxygenic phototrophic chloroflexi isolates (roseiflexus sp. rs-1, roseiflexus castenholz ...200717635550
femtosecond spectroscopy of the primary charge separation in reaction centers of chloroflexus aurantiacus with selective excitation in the qy and soret bands.the primary charge separation and electron-transfer processes of photosynthesis occur in the reaction center (rc). isolated rcs of the green filamentous anoxygenic phototrophic bacterium chloroflexus aurantiacus were studied at room temperature by using femtosecond transient absorption spectroscopy with selective excitation. upon excitation in the q(y) absorbance band of the bacteriochlorophyll (bchl) dimer (p) at 865 nm, a 7.0 +/- 0.5 ps kinetic component was observed in the 538 nm region (q(x) ...200717715904
direct counting of submicrometer-sized photosynthetic apparatus dispersed in medium at cryogenic temperature by confocal laser fluorescence microscopy: estimation of the number of bacteriochlorophyll c in single light-harvesting antenna complexes chlorosomes of green photosynthetic bacteria.the number of pigments in single light-harvesting complexes (chlorosomes) were calculated by imaging single chlorosomes in a frozen buffer at cryogenic temperature with a confocal laser fluorescence microscope and pigment extraction. chlorosomes were isolated from two types of green photosynthetic bacteria chlorobium (chl.) tepidum and chloroflexus (cfl.) aurantiacus and were individually imaged in the frozen medium. each fluorescence spot observed mainly came from a single chlorosome and was as ...200717918876
screening and characterization of an enzyme with beta-glucosidase activity from environmental dna.a novel beta-glucosidase gene, bgla, was isolated from uncultured soil bacteria and characterized. using genomic libraries constructed from soil dna, a gene encoding a protein that hydrolyzes a fluorogenic analog of cellulose, 4-methylumbelliferyl beta-d-cellobioside (muc), was isolated using a microtiter plate assay. the gene, bgla, was sequenced using a shotgun approach, and expressed in e. coli. the deduced 55-kda amino acid sequence for bgla showed a 56% identity with the family 1 glycosyl h ...200718050907
optimal coupling of subantennas as a strategy for efficient functioning of the light-harvesting antennas in photosynthesizing organisms: model computations. 200718064833
quantum chemical simulation of excited states of chlorophylls, bacteriochlorophylls and their complexes.the present review describes the use of quantum chemical methods in estimation of structures and electronic transition energies of photosynthetic pigments in vacuum, in solution and imbedded in proteins. monomeric mg-porphyrins, chlorophylls and bacteriochlorophylls and their solvent 1:1 and 1:2 complexes were studied. calculations were performed for mg-porphyrin, mg-chlorin, mg-bacteriochlorin, mesochlorophyll a, chlorophylls a, b, c(1), c(2), c(3), d and bacteriochlorophylls a, b, c, d, e, f, ...200616482307
properties of succinyl-coenzyme a:l-malate coenzyme a transferase and its role in the autotrophic 3-hydroxypropionate cycle of chloroflexus aurantiacus.the 3-hydroxypropionate cycle has been proposed to operate as the autotrophic co2 fixation pathway in the phototrophic bacterium chloroflexus aurantiacus. in this pathway, acetyl coenzyme a (acetyl-coa) and two bicarbonate molecules are converted to malate. acetyl-coa is regenerated from malyl-coa by l-malyl-coa lyase. the enzyme forming malyl-coa, succinyl-coa:l-malate coenzyme a transferase, was purified. based on the n-terminal amino acid sequence of its two subunits, the corresponding genes ...200616547052
functional differences between galactolipids and glucolipids revealed in photosynthesis of higher plants.galactolipids represent the most abundant lipid class in thylakoid membranes, where oxygenic photosynthesis is performed. the identification of galactolipids at specific sites within photosynthetic complexes by x-ray crystallography implies specific roles for galactolipids during photosynthetic electron transport. the preference for galactose and not for the more abundant sugar glucose in thylakoid lipids and their specific roles in photosynthesis are not understood. introduction of a bacterial ...200616648262
[factors controlling the biosynthesis of chlorosome antenna bacteriochlorophylls in green filamentous anoxygenic phototrophic bacteria of the family oscillochloridaceae].we determined the concentrations of bacteriochlorophylls (bchl) in the light-harvesting antennae of oscillochloris trichoides (of the family oscillochloridaceae belonging to green filamentous mesophilic bacteria) cultivated either with gabaculine, an inhibitor of the c-5 pathway of bchl biosynthesis in a number of bacteria, or at various illumination intensities. we determined the bchl c: bchl a molar ratios in intact cells, in chlorosome-membrane complexes, and in isolated chlorosomes. we revea ...200616758863
the cyanobacterial genome core and the origin of photosynthesis.comparative analysis of 15 complete cyanobacterial genome sequences, including "near minimal" genomes of five strains of prochlorococcus spp., revealed 1,054 protein families [core cyanobacterial clusters of orthologous groups of proteins (core cyogs)] encoded in at least 14 of them. the majority of the core cyogs are involved in central cellular functions that are shared with other bacteria; 50 core cyogs are specific for cyanobacteria, whereas 84 are exclusively shared by cyanobacteria and pla ...200616924101
low-temperature fluorescence from single chlorosomes, photosynthetic antenna complexes of green filamentous and sulfur bacteria.fluorescence spectra of single chlorosomes isolated from a green filamentous bacterium (chloroflexus (cfl.) aurantiacus) and a green sulfur bacterium (chlorobium (cb.) tepidum) were measured by using a confocal laser microscope at 13 k. chlorosomes were frozen either in a liquid solution (floating chlorosome) or on a quartz plate after being adsorbed (adsorbed chlorosome). fluorescence peak wavelengths were shorter for the adsorbed single chlorosomes than for the floating ones. single floating c ...200616950839
properties of succinyl-coenzyme a:d-citramalate coenzyme a transferase and its role in the autotrophic 3-hydroxypropionate cycle of chloroflexus aurantiacus.the phototrophic bacterium chloroflexus aurantiacus uses the 3-hydroxypropionate cycle for autotrophic co(2) fixation. this cycle starts with acetyl-coenzyme a (coa) and produces glyoxylate. glyoxylate is an unconventional cell carbon precursor that needs special enzymes for assimilation. glyoxylate is combined with propionyl-coa to beta-methylmalyl-coa, which is converted to citramalate. cell extracts catalyzed the succinyl-coa-dependent conversion of citramalate to acetyl-coa and pyruvate, the ...200616952935
transmission electron microscopic study on supramolecular nanostructures of bacteriochlorophyll self-aggregates in chlorosomes of green photosynthetic bacteria.supramolecular nanostructures of bacteriochlorophyll (bchl) self-aggregates in major light-harvesting complexes (chlorosomes) of green photosynthetic bacteria were successfully observed by freeze-fracture transmission electron microscope. rod-shaped nanostructures with approximately 10 nm in diameter could be visualized in three types of green sulfur bacteria (chlorobium). diameter of the rod-shaped nanostructures in chlorobium chlorosomes was independent of the molecular structures of their lig ...200617027873
malonyl-coenzyme a reductase in the modified 3-hydroxypropionate cycle for autotrophic carbon fixation in archaeal metallosphaera and sulfolobus spp.autotrophic members of the sulfolobales (crenarchaeota) contain acetyl-coenzyme a (coa)/propionyl-coa carboxylase as the co2 fixation enzyme and use a modified 3-hydroxypropionate cycle to assimilate co2 into cell material. in this central metabolic pathway malonyl-coa, the product of acetyl-coa carboxylation, is further reduced to 3-hydroxypropionate. extracts of metallosphaera sedula contained nadph-specific malonyl-coa reductase activity that was 10-fold up-regulated under autotrophic growth ...200617041055
microbial diversity in natural environments: focusing on fundamental questions.interactions with gijs kuenen and other dutch scientists have led my lab to fundamental insights into the composition, structure and function of a hot spring cyanobacterial mat community that should influence our thinking about all microbial communities. by focusing on the distribution of molecular sequence variants of predominant mat phototrophs, we have discovered that small-scale sequence variation can be ecologically meaningful. by applying novel cultivation approaches, we have been able to ...200617063383
[biogeochemical processes in the algal-bacterial mats of the urinskii alkaline hot spring].the structure and production characteristics of microbial communities from the urinskii alkaline hot spring (buryat republic, russia) have been investigated. a distinctive characteristic of this hot spring is the lack of sulfide in the issuing water. the water temperature near the spring vents ranged from 69 to 38.5 degrees c and ph values ranged from 8.8 to 9.2. the total mineralization of water was less than 0.1 g/liter. temperature has a profound effect on the species composition and biogeoch ...200617091594
occurrence of hydrogenases in cyanobacteria and anoxygenic photosynthetic bacteria: implications for the phylogenetic origin of cyanobacterial and algal hydrogenases.hydrogenases are important enzymes in the energy metabolism of microorganisms. therefore, they are widespread in prokaryotes. we analyzed the occurrence of hydrogenases in cyanobacteria and deduced a fefe-hydrogenase in three different heliobacterial strains. this allowed the first phylogenetic analysis of the hydrogenases of all five major groups of photosynthetic bacteria (heliobacteria, green nonsulfur bacteria, green sulfur bacteria, photosynthetic proteobacteria, and cyanobacteria). in the ...200617103058
self-aggregation of synthetic zinc oxo-bacteriochlorins bearing substituents characteristic of chlorosomal chlorophylls.we prepared novel zinc 8-ethyl-8-methyl-7-oxo- and 7-ethyl-7-methyl-8-oxo-bacteriochlorins 1 and 2 possessing substituents characteristic of chlorosomal chlorophylls, exclusively observed in extramembraneous light-harvesting antennas of photosynthetic green bacteria. the electronic absorption spectra of monomeric 1 and 2 in thf were obviously different: the q(y) maximum of the former was 724 and that of the latter was 683 nm. this observed spectral difference was clearly explained by theoretical ...200515675838
structural and spectroscopic properties of a reaction center complex from the chlorosome-lacking filamentous anoxygenic phototrophic bacterium roseiflexus castenholzii.the photochemical reaction center (rc) complex of roseiflexus castenholzii, which belongs to the filamentous anoxygenic phototrophic bacteria (green filamentous bacteria) but lacks chlorosomes, was isolated and characterized. the genes coding for the subunits of the rc and the light-harvesting proteins were also cloned and sequenced. the rc complex was composed of l, m, and cytochrome subunits. the cytochrome subunit showed a molecular mass of approximately 35 kda, contained hemes c, and functio ...200515716441
reversible self-organization of semisynthetic zinc chlorins into well-defined rod antennae. 200515844109
pentaplot: a software tool for the illustration of genome mosaicism.dekapentagonal maps depict the phylogenetic relationships of five genomes in a visually appealing diagram and can be viewed as an alternative to a single evolutionary consensus tree. in particular, the generated maps focus attention on those gene families that significantly deviate from the consensus or plurality phylogeny. pentaplot is a software tool that computes such dekapentagonal maps given an appropriate probability support matrix.200515938752
diel variations in carbon metabolism by green nonsulfur-like bacteria in alkaline siliceous hot spring microbial mats from yellowstone national park.green nonsulfur-like bacteria (gnslb) in hot spring microbial mats are thought to be mainly photoheterotrophic, using cyanobacterial metabolites as carbon sources. however, the stable carbon isotopic composition of typical chloroflexus and roseiflexus lipids suggests photoautotrophic metabolism of gnslb. one possible explanation for this apparent discrepancy might be that gnslb fix inorganic carbon only during certain times of the day. in order to study temporal variability in carbon metabolism ...200516000812
new class of bacterial membrane oxidoreductases.a new class of bacterial multisubunit membrane-bound electron-transfer complexes has been identified based on biochemical and bioinformatic data. it contains subunits homologous to the three-subunit molybdopterin oxidoreductases and four additional subunits, two of which are c-type cytochromes. the complex was purified from the filamentous anoxygenic phototrophic bacterium chloroflexus aurantiacus, and putative operons for similar complexes were identified in a wide range of bacteria. in most ca ...200516042380
purification and characterization of the b808-866 light-harvesting complex from green filamentous bacterium chloroflexus aurantiacus.the integral membrane light-harvesting complex b808-866 from the thermophilic green filamentous bacterium chloroflexus aurantiacus has been isolated and characterized. reversed-phase hplc analysis demonstrated that the number of bacteriochlorophyll (bchl) in the b808-866 antenna complex is 36 +/- 2 per reaction center. the main carotenoid type is gamma-carotene, and the molar ratio of bchl to carotenoid is 3:2. the steady-state absorption and fluorescence spectroscopy of the b808-866 complex are ...200516172935
bacterial diversity in the rhizosphere of proteaceae species.the cape floral kingdom is an area of unique plant biodiversity in south africa with exceptional concentrations of rare and endemic species and experiencing drastic habitat loss. here we present the first molecular study of the microbial diversity associated with the rhizosphere soil of endemic plants of the proteaceae family (leucospermum truncatulum and leucadendron xanthoconus). genomic dna was extracted from l. truncatulum rhizosphere soil, l. xanthoconus rhizosphere and non-rhizosphere soil ...200516232290
assaying for the 3-hydroxypropionate cycle of carbon fixation.the 3-hydroxypropionate cycle is a novel pathway for autotrophic co2 fixation, which has been demonstrated in the thermophilic phototrophic bacterium chloroflexus aurantiacus; a yet to be defined variant of this pathway occurs in autotrophic members of the sulfolobales (crenarchaeota). the 3-hydroxypropionate cycle consists of the conversion of acetyl-coa to succinyl-coa, via malonyl-coa, 3-hydroxypropionate, propionyl-coa, and methylmalonyl-coa. carboxylation of acetyl-coa and propionyl-coa by ...200516260293
phylogenetic and physiological characterization of a filamentous anoxygenic photoautotrophic bacterium ' candidatus chlorothrix halophila' gen. nov., sp. nov., recovered from hypersaline microbial mats.we report the phylogenetic and physiological characterization of a mesophilic and halophilic member of the filamentous anoxygenic phototrophic (fap) bacteria, provisionally named ' candidatus chorothrix halophila' gen. nov. sp. nov., that has been maintained in a highly enriched culture in our laboratory for over a decade. phylogenetic analysis of small-subunit rna-encoding sequences places ' candidatus chlorothrix halophila' in a clade that includes cultivated members of the genera chloroflexus ...200414655000
horizontal gene transfer from eukarya to bacteria and domain shuffling: the alpha-amylase model.alpha-amylases are present in all kingdoms of the living world. despite strong conservation of the tertiary structure, only a few amino acids are conserved in interkingdom comparisons. animal alpha-amylases are characterized by several typical motifs and biochemical properties. a few cases of such alpha-amylases have been previously reported in some eubacterial species. we screened the bacterial genomes available in the sequence databases for new occurrences of animal-like alpha-amylases. three ...200414704857
molybdenum-containing arsenite oxidase of the chemolithoautotrophic arsenite oxidizer nt-26.the chemolithoautotroph nt-26 oxidizes arsenite to arsenate by using a periplasmic arsenite oxidase. purification and preliminary characterization of the enzyme revealed that it (i) contains two heterologous subunits, aroa (98 kda) and arob (14 kda); (ii) has a native molecular mass of 219 kda, suggesting an alpha2beta2 configuration; and (iii) contains two molybdenum and 9 or 10 iron atoms per alpha2beta2 unit. the genes that encode the enzyme have been cloned and sequenced. sequence analyses r ...200414996791
the bchu gene of chlorobium tepidum encodes the c-20 methyltransferase in bacteriochlorophyll c biosynthesis.bacteriochlorophylls (bchls) c and d, two of the major light-harvesting pigments in photosynthetic green sulfur bacteria, differ only by the presence of a methyl group at the c-20 methine bridge position in bchl c. a gene potentially encoding the c-20 methyltransferase, bchu, was identified by comparative analysis of the chlorobium tepidum and chloroflexus aurantiacus genome sequences. homologs of this gene were amplified and sequenced from chlorobium phaeobacteroides strain 1549, chlorobium vib ...200415090495
[model of aggregation of pigments in the chlorosomal antenna of the green bacteria chloroflexus aurantiacus].independent experimental and theoretical evaluation was performed for the adequacy of our previously proposed general molecular model of structural organization of light-harvesting pigments in chlorosomal bacteriochlorophyll (bchl) c/d/e-containing superantenna of different green bacteria. simultaneous measurement of hole burning in the optical spectra of chlorosomal bchl c and temperature dependence of steady-state fluorescence spectra of bchl c was accomplished in intact cells of photosyntheti ...200415125238
[mechanism of charge separation and their stabilization in bacterial reaction centers].the nuclear wavepacket formed by 20-fs excitation on the p* potential energy surface in native and mutant (ym210w and ym210l) reaction centers of rhodobacter (rb.) sphaeroides and chloroflexus (c.) aurantiacus rcs was found to be reversibly transferred to the p+ba- surface at 120, 380, and 640-fs delays (monitored by measurements of ba- absorption at 1020-1028 nm). the reaction centers of ym210w(l) mutant show the most simple pattern of fs oscillations with a period of 230 fs in stimulated emiss ...200415129622
a cambialistic superoxide dismutase in the thermophilic photosynthetic bacterium chloroflexus aurantiacus.superoxide dismutase from the thermophilic anoxygenic photosynthetic bacterium chloroflexus aurantiacus was cloned, purified, and characterized. this protein is in the manganese- and iron-containing family of superoxide dismutases and is able to use both manganese and iron catalytically. this appears to be the only soluble superoxide dismutase in c. aurantiacus. iron and manganese cofactors were identified by using electron paramagnetic resonance spectroscopy and were quantified by atomic absorp ...200415150226
large improvement in the thermal stability of a tetrameric malate dehydrogenase by single point mutations at the dimer-dimer interface.the stability of tetrameric malate dehydrogenase from the green phototrophic bacterium chloroflexus aurantiacus (camdh) is at least in part determined by electrostatic interactions at the dimer-dimer interface. since previous studies had indicated that the thermal stability of camdh becomes lower with increasing ph, attempts were made to increase the stability by removal of (excess) negative charge at the dimer-dimer interface. mutation of glu165 to gln or lys yielded a dramatic increase in ther ...200415321717
conservation of functional domain structure in bicarbonate-regulated "soluble" adenylyl cyclases in bacteria and eukaryotes.soluble adenylyl cyclase (sac) is an evolutionarily conserved bicarbonate sensor. in mammals, it is responsible for bicarbonate-induced, camp-dependent processes in sperm required for fertilization and postulated to be involved in other bicarbonate- and carbon dioxide-dependent functions throughout the body. among eukaryotes, sac-like cyclases have been detected in mammals and in the fungi dictyostelium; these enzymes display extensive similarity extending through two cyclase catalytic domains a ...200415322879
seeing green bacteria in a new light: genomics-enabled studies of the photosynthetic apparatus in green sulfur bacteria and filamentous anoxygenic phototrophic bacteria.based upon their photosynthetic nature and the presence of a unique light-harvesting antenna structure, the chlorosome, the photosynthetic green bacteria are defined as a distinctive group in the bacteria. however, members of the two taxa that comprise this group, the green sulfur bacteria (chlorobi) and the filamentous anoxygenic phototrophic bacteria ("chloroflexales"), are otherwise quite different, both physiologically and phylogenetically. this review summarizes how genome sequence informat ...200415340781
biotransformation and dissolution of petroleum hydrocarbons in natural flowing seawater at low temperature.the objective of this study was to establish methods for controlled studies of hydrocarbon depletion from thin oil films in cold natural seawater, and to determine biotransformation in relation to other essential depletion processes. mineral oil was immobilized on the surface of hydrophobic fluortex fabrics and used for studies of microbial biodegradation in an experimental seawater flow-through system at low temperatures (5.9-7.4 degrees c) during a test period of 42 days. the seawater was coll ...200415523916
a comparative study of bchg from green photosynthetic bacteria.the gene bchg, coding for bacteriochlorophyll a synthase from a variety of green sulfur bacteria and the filamentous anoxygenic phototrophic bacteria, chloroflexus aurantiacus, chloronema sp., and roseiflexus castenholzii hl08, was partially sequenced and compared. the deduced amino acid consensus sequences for green sulfur bacteria and green filamentous anoxygenic phototrophic bacteria were found to belong to the ubia enzyme family of polyprenyltransferases with the most similar sequences being ...200312560989
a thin-film electrochemical study of the "blue" copper proteins, auracyanin a and auracyanin b, from the photosynthetic bacterium chloroflexus aurantiacus: the reduction potential as a function of ph.the reversible formal potentials of auracyanin a and auracyanin b, two closely related "blue" copper proteins from the photosynthetic bacterium chloroflexus aurantiacus, have been determined by protein film voltammetry in the range 4<or=ph<or=9. at ph 7 in 0.1 m nacl, the values of for auracyanin a and auracyanin b are 205+/-7 mv and 215+/-7 mv, respectively, versus the standard hydrogen electrode. in both cases there is a smooth but non-sigmoidal change in from approximately 190 mv at ph 9 to a ...200312589566
acryloyl-coa reductase from clostridium propionicum. an enzyme complex of propionyl-coa dehydrogenase and electron-transferring flavoprotein.acryloyl-coa reductase from clostridium propionicum catalyses the irreversible nadh-dependent formation of propionyl-coa from acryloyl-coa. purification yielded a heterohexadecameric yellow-greenish enzyme complex [(alpha2betagamma)4; molecular mass 600 +/- 50 kda] composed of a propionyl-coa dehydrogenase (alpha2, 2 x 40 kda) and an electron-transferring flavoprotein (etf; beta, 38 kda; gamma, 29 kda). a flavin content (90% fad and 10% fmn) of 2.4 mol per alpha2betagamma subcomplex (149 kda) wa ...200312603323
arsenite oxidase, an ancient bioenergetic enzyme.operons coding for the enzyme arsenite oxidase have been detected in the genomes from archaea and bacteria by blast searches using the amino acid sequences of the respective enzyme characterized in two different beta-proteobacteria as templates. sequence analyses show that in all these species, arsenite oxidase is transported over the cytoplasmic membrane via the tat system and most probably remains membrane attached by an n-terminal transmembrane helix of the rieske subunit. the biochemical and ...200312679550
coupling of nuclear wavepacket motion and charge separation in bacterial reaction centers.the mechanism of the charge separation and stabilization of separated charges was studied using the femtosecond absorption spectroscopy. it was found that nuclear wavepacket motions on potential energy surface of the excited state of the primary electron donor p* leads to a coherent formation of the charge separated states p(+)b(a)(-), p(+)h(a)(-) and p(+)h(b)(-) (where b(a), h(b) and h(a) are the primary and secondary electron acceptors, respectively) in native, pheophytin-modified and mutant r ...200312681478
[the structure and biogeochemical activity of the phototrophic communities from the bol'sherechenskii alkaline hot spring].microbial communities growing in the bed of the alkaline, sulfide hot spring bol'sherechenskii (the baikal rift area) were studied over many years (1986-2001). the effluent water temperature ranged from 72 to 74 degrees c, ph was from 9.25 to 9.8, and sulfide content was from 12 to 13.4 mg/ml. simultaneous effects of several extreme factors restrict the spread of phototrophic microorganisms. visible microbial fouling appears with a decrease in the temperature to 62 degrees c and in the sulfide c ...200312751248
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