| exciton delocalization in the b808-866 antenna of the green bacterium chloroflexus aurantiacus as revealed by ultrafast pump-probe spectroscopy. | a model of pigment organization in the b808-866 bacteriochlorophyll a antenna of the green photosynthetic bacterium chloroflexus aurantiacus based on femtosecond pump-probe studies is proposed. the building block of the antenna was assumed to be structurally similar to that of the b800-850 light-harvesting 2 (lh2) antenna of purple bacteria and to have the form of two concentric rings of n strongly coupled bchl866 pigments and of n/2 weakly coupled bchl808 monomers, where n = 24 or 32. we have s ... | 1999 | 10388768 |
| oxygen uncouples light absorption by the chlorosome antenna and photosynthetic electron transfer in the green sulfur bacterium chlorobium tepidum | in photosynthetic green sulfur bacteria excitation energy is transferred from large bacteriochlorophyll (bchl) c chlorosome antennas via small bchl a antennas to the reaction centers which then transfer electrons from cytochrome c to low-potential iron-sulfur proteins. under oxidizing conditions a reversible mechanism is activated in the chlorosomes which quenches excited bchl c. we used flash-induced cytochrome c oxidation to investigate the effect of this quenching on photosynthetic electron t ... | 1999 | 10393254 |
| exciton levels structure of antenna bacteriochlorophyll c aggregates in the green bacterium chloroflexus aurantiacus as probed by 1.8-293 k fluorescence spectroscopy. | we have demonstrated temperature-dependence of the steady-state fluorescence lineshape of the bacteriochlorophyll (bchl) c band measured for intact cells of the green bacterium chloroflexus aurantiacus over the 1.8-293 k range. the measured temperature-dependence has been shown to be in good agreement with the theoretical one, calculated for our original model of pigment organization in the chlorosomal oligomeric antenna of green photosynthetic bacteria based on spectral hole-burning studies (fe ... | 1999 | 10456316 |
| exogenous quinones inhibit photosynthetic electron transfer in chloroflexus aurantiacus by specific quenching of the excited bacteriochlorophyll c antenna. | in the photosynthetic green filamentous bacterium chloroflexus aurantiacus, excitation energy is transferred from a large bacteriochlorophyll (bchl) c antenna via smaller bchl a antennas to the reaction center. the effects of substituted 1,4-naphthoquinones on bchl c and bchl a fluorescence and on flash-induced cytochrome c oxidation were studied in whole cells under aerobic conditions. bchl c fluorescence in a cell suspension with 5.4 microm bchl c was quenched to 50% by addition of 0.6 microm ... | 1999 | 10556623 |
| association of bacteriochlorophyll a with the csma protein in chlorosomes of the photosynthetic green filamentous bacterium chloroflexus aurantiacus. | the protein assumed to be associated with bacteriochlorophyll (bchl) a in chlorosomes from the photosynthetic green filamentous bacterium chloroflexus aurantiacus was investigated by alkaline treatment, proteolytic digestion and a new treatment using 1-hexanol, sodium cholate and triton x-100. upon alkaline treatment, only the 5.7 kda csma protein was removed from the chlorosomes among six proteins detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis (sds-page) analysis, concomi ... | 1999 | 10556629 |
| [on the mechanism of autotrophic fixation of carbone dioxide by chloroflexus aurantiacus]. | the activity of two carboxylating enzymes was studied in the green filamentous bacterium chloroflexus aurantiacus. the carboxylation reaction involving pyruvate synthase was optimized using 14co2 and cell extracts. pyruvate synthase was shown to be absent from cells of cfl. aurantiacus ok-70 and present (in a quantity sufficient to account for autotrophic growth) in cells of cfl. aurantiacus b-3. differences in the levels of acetyl coa carboxylase activity were revealed between cells of the stra ... | 2000 | 10776614 |
| phototrophs in high iron microbial mats: microstructure of mats in iron-depositing hot springs. | chocolate pots hot springs in yellowstone national park are high in ferrous iron, silica and bicarbonate. the springs are contributing to the active development of an iron formation. the microstructure of photosynthetic microbial mats in these springs was studied with conventional optical microscopy, confocal laser scanning microscopy and transmission electron microscopy. the dominant mats at the highest temperatures (48-54 degrees c) were composed of synechococcus and chloroflexus or pseudanaba ... | 2000 | 10858577 |
| influence of sulfide and temperature on species composition and community structure of hot spring microbial mats. | in solfataric fields in southwestern iceland, neutral and sulfide-rich hot springs are characterized by thick bacterial mats at 60 to 80 degrees c that are white or yellow from precipitated sulfur (sulfur mats). in low-sulfide hot springs in the same area, grey or pink streamers are formed at 80 to 90 degrees c, and a chloroflexus mat is formed at 65 to 70 degrees c. we have studied the microbial diversity of one sulfur mat (high-sulfide) hot spring and one chloroflexus mat (low-sulfide) hot spr ... | 2000 | 10877776 |
| proposal of oscillochloridaceae fam. nov. on the basis of a phylogenetic analysis of the filamentous anoxygenic phototrophic bacteria, and emended description of oscillochloris and oscillochloris trichoides in comparison with further new isolates. | the nucleotide sequences of the genes of 16s rrnas were determined for the type strain oscillochloris trichoides dg-6t and three new strains of oscillochloris-like mesophilic filamentous green bacteria. two major clusters have been found within the family chloroflexaceae by phylogenetic-analysis: one cluster includes thermophilic species of chloroflexus and the second includes mesophilic strains of oscillochloris. the degree of relatedness of these clusters was below an intergeneric level, havin ... | 2000 | 10939660 |
| molecular evidence for the early evolution of photosynthesis. | the origin and evolution of photosynthesis have long remained enigmatic due to a lack of sequence information of photosynthesis genes across the entire photosynthetic domain. to probe early evolutionary history of photosynthesis, we obtained new sequence information of a number of photosynthesis genes from the green sulfur bacterium chlorobium tepidum and the green nonsulfur bacterium chloroflexus aurantiacus. a total of 31 open reading frames that encode enzymes involved in bacteriochlorophyll/ ... | 2000 | 10976061 |
| quenching of bacteriochlorophyll fluorescence in chlorosomes from chloroflexus aurantiacus by exogenous quinones. | the quenching of bacteriochlorophyll (bchl) c fluorescence in chlorosomes isolated from chloroflexus aurantiacus was examined by the addition of various benzoquinones, naphthoquinones (nq), and anthraquinones (aq). many quinones showed strong quenching in the micromolar or submicromolar range. the number of quinone molecules bound to the chlorosomes was estimated to be as small as one quinone molecule per 50 bchl c molecules. quinones which exhibit a high quenching effect have sufficient hydroph ... | 2000 | 10989605 |
| electronic energy transfer involving carotenoid pigments in chlorosomes of two green bacteria: chlorobium tepidum and cholroflexus aurantiacus. | electronic energy transfer processes in chlorosomes isolated from the green sulphur bacterium chlorobium tepidum and from the green filamentous bacterium chloroflexus aurantiacus have been investigated. steady-state fluorescence excitation spectra and time-resolved triplet-minus-singlet (tms) spectra, recorded at ambient temperature and under non-reducing or reducing conditions, are reported. the carotenoid (car) pigments in both species transfer their singlet excitation to bacteriochlorophyll c ... | 2000 | 10989892 |
| exciton dynamics in the chlorosomal antennae of the green bacteria chloroflexus aurantiacus and chlorobium tepidum. | the energy transfer processes in isolated chlorosomes from green bacteria chlorobium tepidum and chloroflexus aurantiacus have been studied at low temperatures (1.27 k) by two-pulse photon echo and one-color transient absorption techniques with approximately 100 fs resolution. the decay of the coherence in both types of chlorosomes is characterized by four different dephasing times stretching from approximately 100 fs up to 300 ps. the fastest component reflects dephasing that is due to interact ... | 2000 | 11023914 |
| biosynthetic controls on the 13c contents of organic components in the photoautotrophic bacterium chloroflexus aurantiacus. | to assess the effects related to known and proposed biosynthetic pathways on the (13)c content of lipids and storage products of the photoautotrophic bacterium chloroflexus aurantiacus, the isotopic compositions of bulk cell material, alkyl and isoprenoid lipids, and storage products such as glycogen and polyhydroxyalkanoic acids have been investigated. the bulk cell material was 13 per thousand depleted in (13)c relative to the dissolved inorganic carbon. evidently, inorganic carbon fixation by ... | 2001 | 11145961 |
| crystal structure of auracyanin, a "blue" copper protein from the green thermophilic photosynthetic bacterium chloroflexus aurantiacus. | auracyanin b, one of two similar blue copper proteins produced by the thermophilic green non-sulfur photosynthetic bacterium chloroflexus aurantiacus, crystallizes in space group p6(4)22 (a=b=115.7 a, c=54.6 a). the structure was solved using multiple wavelength anomalous dispersion data recorded about the cuk absorption edge, and was refined at 1.55 a resolution. the molecular model comprises 139 amino acid residues, one cu, 247 h(2)o molecules, one cl(-) and two so(4)(2-). the final residual a ... | 2001 | 11178893 |
| autotrophy of green non-sulphur bacteria in hot spring microbial mats: biological explanations for isotopically heavy organic carbon in the geological record. | inferences about the evidence of life recorded in organic compounds within the earth's ancient rocks have depended on 13c contents low enough to be characteristic of biological debris produced by the well-known co2 fixation pathway, the calvin cycle. 'atypically' high values have been attributed to isotopic alteration of sedimentary organic carbon by thermal metamorphism. we examined the possibility that organic carbon characterized by a relatively high 13c content could have arisen biologically ... | 2000 | 11234931 |
| autotrophic co(2) fixation by chloroflexus aurantiacus: study of glyoxylate formation and assimilation via the 3-hydroxypropionate cycle. | in the facultative autotrophic organism chloroflexus aurantiacus, a phototrophic green nonsulfur bacterium, the calvin cycle does not appear to be operative in autotrophic carbon assimilation. an alternative cyclic pathway, the 3-hydroxypropionate cycle, has been proposed. in this pathway, acetyl coenzyme a (acetyl-coa) is assumed to be converted to malate, and two co(2) molecules are thereby fixed. malyl-coa is supposed to be cleaved to acetyl-coa, the starting molecule, and glyoxylate, the car ... | 2001 | 11418572 |
| photosynthetic and phylogenetic primers for detection of anoxygenic phototrophs in natural environments. | primer sets were designed to target specific 16s ribosomal dna (rdna) sequences of photosynthetic bacteria, including the green sulfur bacteria, the green nonsulfur bacteria, and the members of the heliobacteriaceae (a gram-positive phylum). due to the phylogenetic diversity of purple sulfur and purple nonsulfur phototrophs, the 16s rdna gene was not an appropriate target for phylogenetic rdna primers. thus, a primer set was designed that targets the pufm gene, encoding the m subunit of the phot ... | 2001 | 11425703 |
| biosynthetic controls on the 13c contents of organic components in the photoautotrophic bacterium chloroflexus aurantiacus. | to assess the effects related to known and proposed biosynthetic pathways on the (13)c content of lipids and storage products of the photoautotrophic bacterium chloroflexus aurantiacus, the isotopic compositions of bulk cell material, alkyl and isoprenoid lipids, and storage products such as glycogen and polyhydroxyalkanoic acids have been investigated. the bulk cell material was 13 per thousand depleted in (13)c relative to the dissolved inorganic carbon. evidently, inorganic carbon fixation by ... | 2001 | 11439929 |
| diversity and distribution in hypersaline microbial mats of bacteria related to chloroflexus spp. | filamentous bacteria containing bacteriochlorophylls c and a were enriched from hypersaline microbial mats. based on phylogenetic analyses of 16s rrna gene sequences, these organisms form a previously undescribed lineage distantly related to chloroflexus spp. we developed and tested a set of pcr primers for the specific amplification of 16s rrna genes from filamentous phototrophic bacteria within the kingdom of "green nonsulfur bacteria." pcr products recovered from microbial mats in a saltern i ... | 2001 | 11526049 |
| effects of oxidants and reductants on the efficiency of excitation transfer in green photosynthetic bacteria. | the efficiency of energy transfer in chlorosome antennas in the green sulfur bacteria chlorobium vibrioforme and chlorobium limicola was found to be highly sensitive to the redox potential of the suspension. energy transfer efficiencies were measured by comparing the absorption spectrum of the bacteriochlorophyll c or d pigments in the chlorosome to the excitation spectrum for fluorescence arising from the chlorosome baseplate and membrane-bound antenna complexes. the efficiency of energy tran ... | 1990 | 11536463 |
| distribution of cultivated and uncultivated cyanobacteria and chloroflexus-like bacteria in hot spring microbial mats. | oligodeoxynucleotide hybridization probes were developed to complement specific regions of the small subunit (ssu) rrna sequences of cultivated and uncultivated cyanobacteria and chloroflexus-like bacteria, which inhabit hot spring microbial mats. the probes were used to investigate the natural distribution of ssu rrnas from these species in mats of yellowstone hot springs of different temperatures and phs as well as changes in ssu rrna distribution resulting from 1-week in situ shifts in temper ... | 1994 | 11536630 |
| complex polar lipids of a hot spring cyanobacterial mat and its cultivated inhabitants. | the complex polar lipids of the hot spring cyanobacterial mat in the 50 to 55 degrees c region of octopus spring, yellowstone national park, and of thermophilic bacteria cultivated from this or similar habitats, were compared in an attempt to understand the microbial sources of the major lipid biomarkers in this community. intact complex lipids were analyzed directly by fast atom bombardment mass spectrometry (fab-ms), two-dimensional thin-layer chromatography (tlc), and combined tlc-fab-ms. fab ... | 1994 | 11536647 |
| photosynthesis and the origin of life. | the origin and evolution of photosynthesis is considered to be the key to the origin of life. this eliminates the need for a soup as the synthesis of the bioorganics are to come from the fixation of carbon dioxide and nitrogen. no soup then no rna world or protein world. cyanobacteria have been formed by the horizontal transfer of green sulfur bacterial photoreaction center genes by means of a plasmid into a purple photosynthetic bacterium. the fixation of carbon dioxide is considered to have ev ... | 1998 | 11536891 |
| ultrafast energy transfer in chlorosomes from the green photosynthetic bacterium chloroflexus aurantiacus. | energy transfers between the bacteriochlorophyll c and a antennae in light-harvesting chlorosomes from the green bacterium chloroflexes aurantiacus have been studied in two-color pump-probe experiments with improved sensitivity and wavelength versatility. the bchl c --> bchl a energy transfers are well simulated with biexponential kinetics, with lifetimes of 2-3 and 11 ps. they do not exhibit an appreciable subpicosecond component. in the context of a kinetic model for chlorosomes, these life ... | 1996 | 11539413 |
| the microbial community at laguna figueroa, baja california mexico: from miles to microns. | laguna figueroa is a lagoonal complex on the pacific coast of the baja california penisula 200 km south of the mexican-united states border. the hypersaline lagoon is 16 km long and 2-3 km wide with a salt marsh and evaporite flat and is separated from the ocean by a barrier dune and beach. at the salt marsh-evaporite flat interface a stratified microbial community dominated by microcoleus chthonoplastes is depositing laminated sediments. similar stratiform deposits with associated microbial ... | 1985 | 11539612 |
| analysis of lipophilic pigments from a phototrophic microbial mat community by high performance liquid chromatography. | as assay for lipophilic pigments in phototrophic microbial mat communities using reverse phase-high performance liquid chromatography was developed which allows the separation of 15 carotenoids and chloropigments in a single 30 min program. lipophilic pigments in a laminated mat from a commercial salina near laguna guerrero negro, baja california sur, mexico reflected their source organisms. myxoxanthophyll, echinenone, canthaxanthin, and zeaxanthin were derived from cyanobacteria; chlorophyll ... | 1988 | 11539747 |
| the evolution of glutathione metabolism in phototrophic microorganisms. | of the many roles ascribed to glutathione (gsh) the one most clearly established is its role in the protection of higher eucaryotes against oxygen toxicity through destruction of thiol-reactive oxygen byproducts. if this is the primary function of gsh then gsh metabolism should have evolved during or after the evolution of oxygenic photosynthesis. that many bacteria do not produce gsh is consistent with this view. in the present study we have examined the low-molecular-weight thiol compositio ... | 1987 | 11542078 |
| were the original eubacteria thermophiles? | thermotoga maritima is one of the more unusual eubacteria: it is highly thermophilic, growing at temperatures higher than any other eubacterium; its cell wall appears to have a unique structure and its lipids a unique composition; and the organism is surrounded by a loose-fitting sheath of unknown function. its phenotypic uniqueness is matched by its phylogenetic position; thermotoga maritima represents the deepest known branching in the eubacterial line of descent, as measured by ribosomal rn ... | 1987 | 11542087 |
| the green non-sulfur bacteria: a deep branching in the eubacterial line of descent. | ribosomal rna sequence comparisons define a phylogenetic grouping, the green non-sulfur bacteria and relatives (gns), known to contain the genera chloroflexus, herpetosiphon and thermomicrobium--organisms that have little phenotypic similarity. the unit is phylogenetically deep, but entirely distinct from any other eubacterial division (phylum). it is also relatively ancient--branching from the common eubacterial stem earlier than any other group of eubacteria reported thus far. the group phe ... | 1987 | 11542088 |
| all-cis hentriaconta-9,15,22-triene in microbial mats formed by the phototrophic prokaryote chloroflexus. | all-cis hentriaconta-9,15,22-triene (i) has been isolated from chloroflexus mats, yellowstone national park (usa), and identified by gc-(hr)ms analysis of i and its hydrogenated and dmds-derivatized products and by 1h and 13c nmr spectroscopy. | 1999 | 11543197 |
| propionyl-coenzyme a synthase from chloroflexus aurantiacus, a key enzyme of the 3-hydroxypropionate cycle for autotrophic co2 fixation. | the 3-hydroxypropionate cycle has been proposed as a new autotrophic co(2) fixation pathway for the phototrophic green non-sulfur eubacterium chloroflexus aurantiacus and for some chemotrophic archaebacteria. the cycle requires the reductive conversion of the characteristic intermediate 3-hydroxypropionate to propionyl-coa. the specific activity of the 3-hydroxypropionate-, coa-, k(+)-, and mgatp-dependent oxidation of nadph in autotrophically grown cells was 0.09 micromol min(-1) mg(-1) protein ... | 2002 | 11821399 |
| roseiflexus castenholzii gen. nov., sp. nov., a thermophilic, filamentous, photosynthetic bacterium that lacks chlorosomes. | a novel thermophilic, photosynthetic bacterium, designated strain hlo8t, was isolated from a bacterial mat in a japanese hot spring. morphologically, the isolate was an unbranched multicellular filament with a cell diameter of 0.8-1.0 microm. the bacterium was red to reddish-brown in colour and formed a distinct red bacterial mat in the natural environment. it was able to grow photoheterotrophically under anaerobic light conditions and also chemoheterotrophically under aerobic dark conditions. o ... | 2002 | 11837302 |
| fractionation of cytochromes of phototrophically grown chloroflexus aurantiacus. is there a cytochrome bc complex among them? | the cytochrome-containing membrane complexes of the phototrophically grown green non-sulfur bacterium chloroflexus aurantiacus were fractionated by anion exchange chromatography. three cytochrome b and four cytochrome c peaks were observed. none of the separated complexes met the features of the cytochrome bc complex. two main cytochrome b-containing complexes were further purified: a dimer of identical subunits with unknown function and a succinate:quinone oxidoreductase containing three subuni ... | 2002 | 11852065 |
| light control over the size of an antenna unit building block as an efficient strategy for light harvesting in photosynthesis. | it was shown that an increase in the bacteriochlorophyll (bchl) c antenna size observed upon lowering growth light intensities led to enhancement of the hyperchromism of the bchl c q(y) absorption band of the green photosynthetic bacterium chloroflexus aurantiacus. with femtosecond difference absorption spectroscopy, it was shown that the amplitude of bleaching of the oligomeric bchl c q(y) band (as compared to that for monomeric bchl a) increased with increasing bchl c content in chlorosomes. t ... | 2002 | 11852066 |
| subcellular localization of chlorosome proteins in chlorobium tepidum and characterization of three new chlorosome proteins: csmf, csmh, and csmx. | chlorosomes are unique light-harvesting structures found in two families of photosynthetic bacteria. in this study, three chlorosome proteins (csmf, csmh, and csmx) of the green sulfur bacterium chlorobium tepidum were characterized by cloning and sequencing the genes which encode them, by overproducing the respective proteins in escherichia coli, and by raising polyclonal antisera to the purified proteins. three other proteins (atpf, ct1970, and ct2144) which were identified in chlorosome fract ... | 2002 | 11914082 |
| a bicyclic autotrophic co2 fixation pathway in chloroflexus aurantiacus. | phototrophic co(2) assimilation by the primitive, green eubacterium chloroflexus aurantiacus has been shown earlier to proceed in a cyclic mode via 3-hydroxypropionate, propionyl-coa, succinyl-coa, and malyl-coa. the metabolic cycle could be closed by cleavage of malyl-coa affording glyoxylate (the primary co(2) fixation product) with regeneration of acetyl-coa serving as the starter unit of the cycle. the pathway of glyoxylate assimilation to form gluconeogenic precursors has not been elucidate ... | 2002 | 11929869 |
| malonyl-coenzyme a reductase from chloroflexus aurantiacus, a key enzyme of the 3-hydroxypropionate cycle for autotrophic co(2) fixation. | the 3-hydroxypropionate cycle is a new autotrophic co(2) fixation pathway in chloroflexus aurantiacus and some archaebacteria. the initial step is acetyl-coenzyme a (coa) carboxylation to malonyl-coa by acetyl-coa carboxylase, followed by nadph-dependent reduction of malonyl-coa to 3-hydroxypropionate. this reduction step was studied in chloroflexus aurantiacus. a new enzyme was purified, malonyl-coa reductase, which catalyzed the two-step reduction malonyl-coa + nadph + h(+) --> malonate semial ... | 2002 | 11948153 |
| active and energy-dependent rapid formation of cell aggregates in the thermophilic photosynthetic bacterium chloroflexus aggregans. | the thermophilic filamentous phototroph chloroflexus aggregans was able to form a bacterial mat-like dense cell aggregate rapidly. the aggregate formation, which was observed in growing cells in a liquid medium in a bottle, occurred every time within 20-30 min after the cells were dispersed by shaking. the aggregation depended on the energy supplied by photosynthesis or respiration. cells aggregated most rapidly under temperature and ph conditions that support maximum growth. the aggregation was ... | 2002 | 11959449 |
| spectral heterogeneity in single light-harvesting chlorosomes from green sulfur photosynthetic bacterium chlorobium tepidum. | the fluorescence emission properties of single chlorosomes from the green sulfur photosynthetic bacterium chlorobium (chl.) tepidum are studied for the first time, using a total internal reflection fluorescence microscope. the fluorescence peak positions of bacteriochlorophyll (bchl)-c self-aggregates in a single chlorosome of chl. tepidum were widely distributed in the wavelength region between 750 and 768 nm, and the standard deviation (s.d. = 4.1 nm, n = 51) was larger than that of single chl ... | 2002 | 12003135 |
| structural basis for thermophilic protein stability: structures of thermophilic and mesophilic malate dehydrogenases. | the three-dimensional structure of four malate dehydrogenases (mdh) from thermophilic and mesophilic phototropic bacteria have been determined by x-ray crystallography and the corresponding structures compared. in contrast to the dimeric quaternary structure of most mdhs, these mdhs are tetramers and are structurally related to tetrameric malate dehydrogenases from archaea and to lactate dehydrogenases. the tetramers are dimers of dimers, where the structures of each subunit and the dimers are s ... | 2002 | 12054817 |
| microscopic examination of distribution and phenotypic properties of phylogenetically diverse chloroflexaceae-related bacteria in hot spring microbial mats. | we investigated the diversity, distribution, and phenotypes of uncultivated chloroflexaceae-related bacteria in photosynthetic microbial mats of an alkaline hot spring (mushroom spring, yellowstone national park). by applying a directed pcr approach, molecular cloning, and sequence analysis of 16s rrna genes, an unexpectedly large phylogenetic diversity among these bacteria was detected. oligonucleotide probes were designed to target 16s rrnas from organisms affiliated with the genus chloroflexu ... | 2002 | 12200318 |
| characterization of type 1851 organism isolated from activated sludge samples. | five orange pigmented filamentous strains of eikelboom's type 1851 were isolated from bulking activated sludge, and were examined for their phylogenetic lineage, morphology, and physiology. the analysis of 16s rdna sequence revealed that the isolates belong to chloroflexus subdivision in green non sulfur bacteria. they shared most common features with type 1851, but the result of gram stain was negative. furthermore, they showed polymorphic nature and gliding motility, which could not be seen in ... | 2002 | 12216610 |
| l-malyl-coenzyme a lyase/beta-methylmalyl-coenzyme a lyase from chloroflexus aurantiacus, a bifunctional enzyme involved in autotrophic co(2) fixation. | the 3-hydroxypropionate cycle is a bicyclic autotrophic co(2) fixation pathway in the phototrophic chloroflexus aurantiacus (bacteria), and a similar pathway is operating in autotrophic members of the sulfolobaceae (archaea). the proposed pathway involves in a first cycle the conversion of acetyl-coenzyme a (acetyl-coa) and two bicarbonates to l-malyl-coa via 3-hydroxypropionate and propionyl-coa; l-malyl-coa is cleaved by l-malyl-coa lyase into acetyl-coa and glyoxylate. in a second cycle, glyo ... | 2002 | 12374834 |
| 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 ... | 2003 | 12560989 |
| 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 ... | 2003 | 12589566 |
| 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 ... | 2003 | 12603323 |
| 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 ... | 2003 | 12679550 |
| 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 ... | 2003 | 12681478 |
| [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 ... | 2003 | 12751248 |
| auracyanin b structure in space group p6(5). | the structure of auracyanin b, a 'blue' copper protein produced by chloroflexus aurantiacus, has previously been solved and refined in the hexagonal space group p6(4)22 with a single molecule in the asymmetric unit. the protein has now been crystallized in space group p6(5), with unit-cell parameters a = b = 115.9, c = 108.2 a. in the new crystal form, the asymmetric unit contains four protein molecules. the structure has been solved by molecular replacement and refined at 1.9 a resolution. the ... | 2003 | 12925783 |
| isolation and characterization of the b798 light-harvesting baseplate from the chlorosomes of chloroflexus aurantiacus. | the b798 light-harvesting baseplate of the chlorosome antenna complex of the thermophilic, filamentous anoxygenic phototrophic bacterium chloroflexus aurantiacus has been isolated and characterized. isolation was performed by using a hexanol-detergent treatment of freeze-thawed chlorosomes. the isolated baseplate consists of bchl a, beta-carotene, and the 5.7 kda csma protein with a ratio of 1.0 csma protein/1.6 bchl a/4.2 beta-carotenes. the baseplate has characteristic absorbance at 798 nm as ... | 2003 | 12939153 |
| compound-specific isotopic fractionation patterns suggest different carbon metabolisms among chloroflexus-like bacteria in hot-spring microbial mats. | stable carbon isotope fractionations between dissolved inorganic carbon and lipid biomarkers suggest photoautotrophy by chloroflexus-like organisms in sulfidic and nonsulfidic yellowstone hot springs. where co-occurring, cyanobacteria appear to cross-feed chloroflexus-like organisms supporting photoheterotrophy as well, although the relatively small 13c fractionation associated with cyanobacterial sugar biosynthesis may sometimes obscure this process. | 2003 | 14532055 |
| electrostatic interactions across the dimer-dimer interface contribute to the ph-dependent stability of a tetrameric malate dehydrogenase. | malate dehydrogenase (mdh) from the moderately thermophilic bacterium chloroflexus aurantiacus (camdh) is a tetrameric enzyme, while mdhs from mesophilic bacteria usually are dimers. using site-directed mutagenesis, we show here that a network of electrostatic interactions across the extra dimer-dimer interface in camdh is important for thermal stability and oligomeric integrity. stability effects of single point mutations (e25q, e25k, d56n, d56k) varied from -1.2 degrees c to -26.8 degrees c, a ... | 2003 | 14572663 |
| exciton theory for supramolecular chlorosomal aggregates: 1. aggregate size dependence of the linear spectra. | the interior of chlorosomes of green bacteria forms an unusual antenna system organized without proteins. the steady-spectra (absorption, circular dichroism, and linear dichroism) have been modeled using the frenkel hamiltonian for the large tubular aggregates of bacteriochlorophylls with geometries corresponding to those proposed for chloroflexus aurantiacus and chlorobium tepidum chlorosomes. for the cf. aurantiacus aggregates we apply a structure used previously (v. i. prokhorenko., d. b. ste ... | 2003 | 14581217 |
| characterization of the chlorosome antenna of the filamentous anoxygenic phototrophic bacterium chloronema sp. strain udg9001. | the absorption and fluorescence properties of chlorosomes of the filamentous anoxygenic phototrophic bacterium chloronema sp. strain udg9001 were analyzed. the chlorosome antenna of chloronema consists of bacteriochlorophyll (bchl) d and bchl c together with gamma-carotene as the main carotenoid. hplc analysis combined with apci lc-ms/ms showed that the chlorosomal bchls comprise a highly diverse array of homologues that differ in both the degree of alkylation of the macrocycle at c-8 and/or c-1 ... | 2003 | 14610639 |
| stabilization of a tetrameric malate dehydrogenase by introduction of a disulfide bridge at the dimer-dimer interface. | malate dehydrogenase (mdh) from the moderately thermophilic bacterium chloroflexus aurantiacus (camdh) is a tetrameric enzyme, while mdhs from mesophilic organisms usually are dimers. to investigate the potential contribution of the extra dimer-dimer interface in camdh with respect to thermal stability, we have engineered an intersubunit disulfide bridge designed to strengthen dimer-dimer interactions. the resulting mutant (t187c, containing two 187-187 disulfide bridges in the tetramer) showed ... | 2003 | 14636605 |
| 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 ... | 2004 | 14655000 |
| 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 ... | 2004 | 14704857 |
| 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 ... | 2004 | 14996791 |
| 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 ... | 2004 | 15090495 |
| [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 ... | 2004 | 15125238 |
| [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 ... | 2004 | 15129622 |
| 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 ... | 2004 | 15150226 |
| 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 ... | 2004 | 15321717 |
| 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 ... | 2004 | 15322879 |
| 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 ... | 2004 | 15340781 |
| 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 ... | 2004 | 15523916 |
| 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 ... | 2005 | 15675838 |
| 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 ... | 2005 | 15716441 |
| reversible self-organization of semisynthetic zinc chlorins into well-defined rod antennae. | | 2005 | 15844109 |
| 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. | 2005 | 15938752 |
| 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 ... | 2005 | 16000812 |
| 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 ... | 2005 | 16042380 |
| 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 ... | 2005 | 16172935 |
| exciton dynamics in the chlorosomal antenna of the green bacterium chloroflexus aurantiacus: experimental and theoretical studies of femtosecond pump-probe spectra. | femtosecond absorption difference spectra were measured for chlorosomes isolated from the green bacterium chloroflexus aurantiacus at room temperature. using the relative difference absorption of the oligomeric bchl c and monomeric bchl a bands, the size of a unit bchl c aggregate as well as the exciton coherence size were estimated for the chlorosomal bchl c antenna under study. a quantitative fit of the data was obtained within the framework of the exciton model proposed before [fetisova et al ... | 2002 | 16228498 |
| structural investigation of oxidized chlorosomes from green bacteria using multifrequency electron paramagnetic resonance up to 330 ghz. | chemical oxidation of the chlorosomes from chloroflexus aurantiacus and chlorobium tepidum green bacteria produces bacteriochlorophyll radicals, which are characterized by an anomalously narrow epr signal compared to in vitro monomeric bchl c (.+) [van noort pi, zhu y, lobrutto r and blankenship re (1997) biophys j 72: 316-325]. we have performed oxidant concentration and temperature-dependent x-band epr measurements in order to elucidate the line narrowing mechanism. the linewidth decreases as ... | 2002 | 16228499 |
| optically detected magnetic resonance of intact membranes from chloroflexus aurantiacus. evidence for exciton interaction between the rc and the b808-866 complex. | optically detected magnetic resonance of chlorosome-containing membranes from the green filamentous bacterium chloroflexus aurantiacus has been performed both by fluorescence and absorption detection. triplet states localized in the chlorosomes and in the b808-866 complex have been characterized. after chemical reduction with ascorbate followed by illumination at 200 k, recombination triplet state localized in the primary donor becomes largely populated under illumination at low temperature whil ... | 2002 | 16228500 |
| determination of the topography and biometry of chlorosomes by atomic force microscopy. | isolated chlorosomes of several species of filamentous anoxygenic phototrophic bacteria (fapb) and green sulfur bacteria (gsb) were examined by atomic force microscopy (afm) to characterize their topography and biometry. chlorosomes of chloroflexus aurantiacus, chloronema sp., and chlorobium (chl.) tepidum exhibited a smooth surface, whereas those of chl. phaeobacteroides and chl. vibrioforme showed a rough one. the potential artifactual nature of the two types of surfaces, which may have arisen ... | 2002 | 16228503 |
| ;every dogma has its day': a personal look at carbon metabolism in photosynthetic bacteria. | dogmas are unscientific. what is perhaps the greatest biological dogma of all time, the 'unity of biochemistry' is, in the main, still having its day. according to present knowledge, the exceptions to this dogma are mere details when seen in relation to the biosystem as a whole. nevertheless the exceptions are scientifically interesting and the understanding of them has led to a better comprehension of photosynthesis and ecology. until the discovery of (14)c, photosynthetic co(2) fixation was li ... | 2003 | 16228573 |
| evolutionary relationships among photosynthetic bacteria. | to understand the evolution of photosynthetic bacteria it is necessary to understand how the main groups within bacteria have evolved from a common ancestor, a critical issue that has not been resolved in the past. recent analysis of shared conserved inserts or deletions (indels) in protein sequences has provided a powerful means to resolve this long-standing problem in microbiology. based on a set of 25 indels in highly conserved and widely distributed proteins, all main groups within bacteria ... | 2003 | 16228576 |
| 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 ... | 2005 | 16232290 |
| 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 ... | 2005 | 16260293 |
| structure, growth, and decomposition of laminated algal-bacterial mats in alkaline hot springs. | laminated mats of unique character in siliceous alkaline hot springs of yellowstone park are formed predominantly by two organisms, a unicellular blue-green alga, synechococcus lividus, and a filamentous, gliding, photosynthetic bacterium, chloroflexus aurantiacus. the mats can be divided approximately into two major zones: an upper, aerobic zone in which sufficient light penetrates for net photosynthesis, and a lower, anaerobic zone, where photosynthesis does not occur and decomposition is the ... | 1977 | 16345254 |
| microelectrode studies of interstitial water chemistry and photosynthetic activity in a hot spring microbial mat. | microelectrodes were used to measure oxygen, ph, and oxygenic photosynthetic activity in a hot spring microbial mat (octopus spring, yellowstone national park), where the cyanobacterium synechococcus lividus and the filamentous bacterium chloroflexus aurantiacus are the only known phototrophs. the data showed very high biological activities in the topmost layers of the microbial mat, resulting in extreme values for oxygen and ph. at a 1-mm depth at a 55 degrees c site, oxygen and ph reached 900 ... | 1984 | 16346607 |
| use of chloroflexus-specific antiserum to evaluate filamentous bacteria of a hot spring microbial mat. | polyclonal antiserum prepared against chloroflexus aurantiacus reacted with all chloroflexus strains examined but not with other morphologically or physiologically similar bacteria. only one of three filament types in a natural hot spring cyanobacterial mat reacted with this antiserum. reacting filaments remained antigenically positive deep within the mat in material estimated to be several years old. | 1987 | 16347422 |
| formation and fate of fermentation products in hot spring cyanobacterial mats. | the fate of representative fermentation products (acetate, propionate, butyrate, lactate, and ethanol) in hot spring cyanobacterial mats was investigated. the major fate during incubations in the light was photoassimilation by filamentous bacteria resembling chloroflexus aurantiacus. some metabolism of all compounds occurred under dark aerobic conditions. under dark anaerobic conditions, only lactate was oxidized extensively to carbon dioxide. extended preincubation under dark anaerobic conditio ... | 1987 | 16347455 |
| purification and properties of a maltotetraose- and maltotriose-producing amylase from chloroflexus aurantiacus. | a maltotetraose- and maltotriose-producing amylase which is stable at alkaline phs and high temperatures was detected in the culture filtrate of a strain of chloroflexus aurantiacus j-10-f1, a thermophilic, green, photosynthetic bacterium. the enzyme was purified to homogeneity, as demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, by means of ultrafiltration, ammonium sulfate fractionation, and deae-cellulose, hydroxyapatite, and high-performance liquid chromatographies. ... | 1992 | 16348751 |
| 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, ... | 2006 | 16482307 |
| 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 ... | 2006 | 16547052 |
| primary photochemistry in the facultatively aerobic green photosynthetic bacterium chloroflexus aurantiacus. | photochemical activity was examined in membrane fragments and a purified membrane preparation from chloroflexus. flash-induced absorption difference spectroscopy strongly suggests a primary donor (p(865)) that is more similar to the p(870) bacteriochlorophyll a dimer found in the purple photosynthetic bacteria than it is to p(840) found in the anaerobic green bacteria. redox measurements on p(865) and an early acceptor also indicate a photochemical system characteristic of the purple bacteria. t ... | 1982 | 16593246 |
| isolation and spectral characterization of photochemical reaction centers from the thermophilic green bacterium chloroflexus aurantiacus strain j-10-f1. | a rapid procedure has been devised to extract photochemically active reaction centers from the green bacterium chloroflexus aurantiacus strain j-10-f1 and a mutant lacking colored carotenoids (73-3). the isolated material was completely free of antenna bacteriochlorophyll and cytochromes and nearly free of carotenoids and had near ir absorption maxima at 865, 815, and 756 nm. on oxidation, the peak at 865 nm was bleached and the remaining two peaks were shifted to 806 and 757 nm. although these ... | 1983 | 16593269 |
| 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 ... | 2006 | 16648262 |
| [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 ... | 2006 | 16758863 |
| 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 ... | 2006 | 16924101 |
| 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 ... | 2006 | 16950839 |
| 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 ... | 2006 | 16952935 |
| 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 ... | 2006 | 17027873 |
| 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 ... | 2006 | 17041055 |
| 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 ... | 2006 | 17063383 |