Publications

[molecular organization in photosystem ii reaction center].		1989	2748911
new approaches to the prediction of the folding of membrane proteins with redox function.	a new method is elaborated for determining the hydropathy profile of membrane haemoproteins. the method is called membrane propensity for haemoproteins (mph) and is based on the statistical analysis of the amino acid composition of the predicted transmembrane regions of cytochrome b from the bc1 and the b6f complexes. the accuracy of the mph method in predicting the ends of the known transmembrane segments of the reaction center of rhodopseudomonas viridis is higher than that obtained by hydropa ...	1989	2759832
nucleotide sequence of wild-type and mutant nifr4 (ntra) genes of rhodobacter capsulatus: identification of an essential glycine residue.		1989	2762129
induction of anaerobic gene expression in rhodobacter capsulatus is not accompanied by a local change in chromosomal supercoiling as measured by a novel assay.	in the photosynthetic bacterium rhodobacter capsulatus, the enzyme dna gyrase has been implicated in the expression of genes for anaerobic metabolic processes such as nitrogen fixation and photosynthesis. to assess the involvement of supercoiling in anaerobic gene expression, we have developed an assay to detect in vivo changes in superhelicity of small regions of the bacterial chromosome. our method is based on the preferential intercalaction of psoralen into supercoiled versus relaxed dna, and ...	1989	2768190
membrane proteins. detergent ringing true as a model for membranes.		1989	2770865
composition and toxicity of lipids from rhodococcus rhodochrous grown on medium containing galactose, glucose or mannose.	rhodococcus rhodochrous, a producer of mycolic acid of approx. c40, exhibited a higher cellular mass yield when grown on glucose than when grown on galactose or mannose. the cellular content of the diethyl ether-soluble lipids in microorganisms cultivated on glucose or mannose varied with the incubation time, while that of microorganisms grown on galactose remained constant. the lipids extracts from cells cultivated on different hexoses and collected at the exponential phase of growth were more ...	1989	2775761
diphosphoryl lipid a from rhodopseudomonas sphaeroides atcc 17023 blocks induction of cachectin in macrophages by lipopolysaccharide.	purified diphosphoryl lipid a (dpla) obtained from the nontoxic lipopolysaccharide of rhodopseudomonas sphaeroides atcc 17023 was shown to block the induction of cachectin (tumor necrosis factor) in the raw 264.7 macrophage cell line by toxic deep-rough-chemotype lipopolysaccharide (relps) of escherichia coli in a concentration-dependent manner. the relps-to-dpla mass ratios of 1:10 and 1:100 (when 1.0 ng of relps per ml was used) gave 55 and 95% inhibitions, respectively, of the induction of ca ...	1989	2784418
the phototrophic bacterium rhodopseudomonas capsulata sp108 encodes an indigenous class a beta-lactamase.	the nucleotide sequence of a 2.37 kb dna fragment derived from cloning a total dna digest of rhodopseudomonas capsulata sp108 was determined. the dna codes for a beta-lactamase, a protein showing sequence similarity to the ampr protein of enterobacter cloacae and an unidentified open reading frame. hybridization experiments with a probe carrying dna from within the beta-lactamase gene suggests a chromosomal location for the coding sequences in strain sp108 and in sp109, a penicillin-sensitive re ...	1989	2788410
the photosynthetic reaction center from the purple bacterium rhodopseudomonas viridis.	the history and methods of membrane protein crystallization are described. the solution of the structure of the photosynthetic reaction center from the bacterium rhodopseudomonas viridis is described, and the structure of this membrane protein complex is correlated with its function as a light-driven electron pump across the photosynthetic membrane. conclusions about the structure of the photosystem ii reaction center from plants are drawn, and aspects of membrane protein structure are discussed ...	1989	17776797
characterization of naturally occurring atrazine-resistant isolates of the purple non-sulfur bacteria.	six isolates of the purple non-sulfur bacteria, which upon primary isolation were naturally resistant to the herbicide atrazine, were characterized with respect to their taxonomic identity and the mechanism of their resistance. on the basis of electron microscopy, photopigment analysis, and other criteria, they were identified as strains of rhodopseudomonas acidophila, rhodopseudomonas palustris, or rhodocyclus gelatinosus. these isolates exhibited degrees of atrazine resistance which ranged fro ...	1990	16348126
structure and transcription of the genes encoding the b1015 light-harvesting complex beta and alpha subunits and the photosynthetic reaction center l, m, and cytochrome c subunits from rhodopseudomonas viridis.	the genes encoding the beta and alpha subunits of the b1015 light-harvesting complex (lhc) and the l, m, and cytochrome c subunits of the photosynthetic reaction center from rhodopseudomonas viridis are organized in an operon, in analogy to other nonsulfur purple bacteria, named the puf operon. in photoheterotrophically grown cells, two abundant puf operon mrna species of 3,581 and 621 bases were present. the large transcript encoded the lhc beta, lhc alpha, and reaction center l, m, and cytochr ...	1990	1693143
sequence analysis and transcriptional organization of the rhodopseudomonas viridis cytochrome c2 gene.	the cytochrome c2 gene (cyca) of the purple nonsulfur bacterium rhodopseudomonas viridis was isolated from a genomic library by using two degenerate oligonucleotides containing all possible dna sequences predicted from the published amino acid sequence of this protein (ambler et al., proc. natl. acad. sci. usa 73:472-475, 1976). cloning and sequence analysis of the cytochrome c2 gene indicated the presence of a typical procaryotic 20-residue signal peptide, suggesting that this periplasmic prote ...	1990	1697576
oriented immobilization of bacterial photosynthetic membrane.	we have examined a method for oriented immobilization of photosynthetic membrane fragments on a solid surface by specific avidin-biotin interaction. photosynthetic membrane fragments from the purple non-sulphur photosynthetic bacterium rhodopseudomonas viridis, of which the h-subunit of the photosynthetic reaction centre was biotinylated, was immobilized on an avidin-adsorbed plate. orientation of the immobilized membrane on the plastic plate was checked by an antisera binding assay that could r ...	1990	1366521
molecular modelling studies on the binding of phenylurea inhibitors to the d 1 protein of photosystem ii.	a hypothetical molecular model of part of the d 1 protein of photosystem ii, based on the analogous portion of the l subunit of the rhodopseudomonas viridis reaction centre, has been used to study the binding of an extended hydrophobic phenylurea inhibitor (n,n-dimethyl-carbamoyl)4-amino-4'-chloro-trans-stilbene) (i) to the qb site. the inhibitor was fitted by eye into a cleft in the site, and a limited part of the inhibitor/d 1 complex was energy minimized. the gross orientation of the inhibito ...	1990	2116126
towards the understanding of the function of rb sphaeroides y wild type reaction center: gene cloning, protein and detergent structures in the three-dimensional crystals.	we report various experiments aimed at the resolution of the 3-dimensional structure of the photosynthetic reaction center from wild type y rhodobacter sphaeroides. the genes encoding the l and m polypeptides have been cloned and sequenced. they bear 2 mutations each when compared to those already sequenced in another rb sphaeroides strain (2.4.1). in the l gene, these codon changes are silent. in the m gene, one is silent and the other one leads to a leu-met substitution at position 140. at the ...	1990	2126457
anaerobic phototrophic metabolism of 3-chlorobenzoate by rhodopseudomonas palustris ws17.	a mixed phototrophic culture was found to reductively metabolize 3-chlorobenzoate in the presence of benzoate following adaptation for a period of 7 weeks. the dominant bacterial isolate from this mixed culture, identified as rhodopseudomonas palustris ws17, metabolized 3-chlorobenzoate completely in the presence of benzoate and light and in the absence of oxygen. [14c]3-chlorobenzoate was converted to 14co2 and cell 3-chlorobenzoate metabolism is a common phenomenon in this species.	1990	2128012
inactivation of suppressor t cell activity by the nontoxic lipopolysaccharide of rhodopseudomonas sphaeroides.	antibody responses of mice immunized with type iii pneumococcal polysaccharide were examined with and without treatment with nontoxic lipopolysaccharide from rhodopseudomonas sphaeroides (rs-lps). the results obtained were similar to those described previously for mice treated with monophosphoryl lipid a (mpl) except that lower amounts of rs-lps were needed. both were without effect when given at the time of immunization with type iii pneumococcal polysaccharide but elicited significant enhancem ...	1990	2143752
carotenoid desaturases from rhodobacter capsulatus and neurospora crassa are structurally and functionally conserved and contain domains homologous to flavoprotein disulfide oxidoreductases.	the characteristic red color of some photosynthetic bacteria and the orange color of neurospora conidia is due to the presence of carotenoids, photoprotective pigments synthesized by plants, algae, bacteria, and fungi. generally, carotenoids are tetraterpenes in which absorption of visible light and photoprotection are mediated by a chain of conjugated double bonds, the chromophore, which is formed by successive desaturations of phytoene, a colorless precursor. the genes al-1 and crti mediate th ...	1990	2144293
hypocholesterolemic effect of phototrophic bacterial cells in rats.	the effect of diets containing the cells of a phototrophic bacteria (ptb). rhodopseudomonas capsulata, on lipid metabolism was examined in the serum and liver of rats. three groups of rats, 5 animals per group, were fed either a diet containing 0.2 or 2.0% ptb cells or a casein-based control diet. each diet contained 1% cholesterol (chol). while serum glucose levels were not significantly different between the control and the ptb groups, total chol and triacylglycerol (tg) in the serum were sign ...	1990	2151451
isolation of a rhodobacter capsulatus mutant that lacks c-type cytochromes and excretes porphyrins.	a rhodobacter capsulatus mutant lacking cytochrome oxidase activity was isolated by tn5 mutagenesis. difference spectroscopy of crude extracts and extracted c-type cytochromes demonstrated that this mutant completely lacked all c-type cytochromes. the strain did, however, synthesize normal amounts of b-type cytochromes and nonheme iron. this mutant also excreted large amounts of coproporphyrin and protoporphyrin and synthesized reduced amounts of bacteriochlorophyll, suggesting a link between th ...	1990	2155198
isolation of a rhodobacter capsulatus biob mutant and cloning of the biob gene.	we isolated a tn5 insertion mutant of rhodobacter capsulatus which requires biotin for growth. crossfeeding studies with escherichia coli bio mutants indicated that the insertion is in the biob gene. a cosmid that complements the biob insertion was isolated, and the biob gene was localized to a 2.85-kilobase ecori-psti fragment.	1990	2156812
kinetics of photosynthetic electron transfer in artificial vesicles reconstituted with purified complexes from rhodobacter capsulatus. i. the interaction of cytochrome c2 with the reaction center.	1. the kinetics of the interaction of cytochrome c2 and photosynthetic reaction centers purified from rhodobacter capsulatus were studied in proteoliposomes reconstituted with a mixture of phospholipids simulating the native membrane (i.e. containing 25% l-alpha-phosphatidylglycerol). 2. at low ionic strength, the kinetics of cytochrome-c2 oxidation induced by a single turnover flash was very different, depending on the concentration of cytochrome c2: at concentrations lower than 1 microm, the p ...	1990	2158888
kinetics of photosynthetic electron transfer in artificial vesicles reconstituted with purified complexes from rhodobacter capsulatus. ii. direct electron transfer between the reaction center and the bc1 complex and role of cytochrome c2.	1. the cyclic photosynthetic chain of rhodobacter capsulatus has been reconstituted incorporating into phospholipid liposomes containing ubiquinone-10 two multiprotein complexes: the reaction center and the ubiquinol-cytochrome-c2 reductase (or bc1 complex). 2. in the presence of cytochrome c2 added externally, at concentrations in the range 10-10(4) nm, a flash-induced cyclic electron transfer can be observed. in the presence of antimycin, an inhibitor of the quinone-reducing site of the bc1 co ...	1990	2158893
genetic and biochemical characterization of carotenoid biosynthesis mutants of rhodobacter capsulatus.	we have used genetic and biochemical techniques to study carotenoid biosynthesis (crt) mutants of rhodobacter capsulatus, a purple non-sulfur photosynthetic bacterium. all nine identified crt genes are located within the 46-kilobase pair photosynthesis gene cluster, and eight of the crt genes form a subcluster. we have studied the operon structure of the crt gene cluster using transposon tn5.7 mutants. the tn5.7 insertion sites in 10 mutants have been mapped to high resolution (25-267 base pairs ...	1990	2159477
assignment of the 1h and 15n nmr spectra of rhodobacter capsulatus ferrocytochrome c2.	the peptide resonances of the 1h and 15n nuclear magnetic resonance spectra of ferrocytochrome c2 from rhodobacter capsulatus are sequentially assigned by a combination of 2d 1h-1h and 1h-15n spectroscopy, the latter performed on 15n-enriched protein. short-range nuclear overhauser effect (noe) data show alpha-helices from residues 3-17, 55-65, 69-88, and 103-115. within the latter two alpha-helices, there are three single 3(10) turns, 70-72, 76-78, and 107-109. in addition alpha h-nhi+1 and alp ...	1990	2159796
soluble cytochromes and ferredoxins from the marine purple phototrophic bacterium, rhodopseudomonas marina.	four soluble c-type cytochromes, the high redox potential 4-fe-s ferredoxin known as hipip, a large molecular weight 2-fe-s ferredoxin and a 4-fe-s 'bacterial' ferredoxin, were isolated from extracts of two strains of rps. marina. cytochrome c-550, cytochrome c' and cytochrome c-549 were previously described, and we have extended their characterization. cytochrome c-558, which has not previously been observed in rps. marina, appears to be a low-spin isozyme of the more commonly observed high-spi ...	1990	2161686
degradation of puflmx mrna in rhodobacter capsulatus is initiated by nonrandom endonucleolytic cleavage.	differential expression of genes within the puf photosynthesis operon of rhodobacter capsulatus is achieved primarily through marked segmental differences in stability within the polycistronic puf operon transcripts. the comparatively stable pufba segment of these transcripts outlives the labile puflmx segment and accumulates as an abundant puf mrna degradation intermediate. here we present further evidence that degradation of pufbalmx mrna is initiated by endonucleolytic cleavage within the sho ...	1990	2165480
the role of c-type cytochromes in the photosynthetic electron transport pathway of rhodobacter capsulatus.	(1) short flash excitation of membrane vesicles of a cytochrome-c2-deficient mutant of rhodobacter capsulatus (strain mt-g4/s4) led to rapid oxidation of a c-type cytochrome. in redox titrations, the photooxidation of c-type cytochrome was attenuated with a midpoint of approx. +360 mv. vesicles from a control strain, mt1131, gave similar results. these findings are consistent with those of prince et al. (prince, r.c., davidson, e., haith, l.e. and daldal, f. (1986) biochemistry 25, 5208-5214). ( ...	1990	2168749
proton nmr study of the comparative electronic/magnetic properties and dynamics of the acid in equilibrium with alkaline transition in a series of ferricytochromes c'.	the proton nmr spectra of ferricytochrome c' from rhodopseudomonas palustris, rhodospirillum molischianum, rhodospirillum rubrum, and chromatium vinosum have been investigated for the purpose of further elucidating the common spectral and/or structural properties for this subclass of cytochromes in the acidic and alkaline forms, and to characterize in detail the dynamics and structural basis for this acid in equilibrium with alkaline transition. the identification of strongly upfield-shifted mes ...	1990	2168882
porin of rhodobacter capsulatus: biochemical and functional characterization.	the major outer membrane protein of rhodobacter capsulatus 37b4 (capsule-free) was isolated. strong porin-activity was observed after reconstitution into artificial lipid bilayer membranes with a single channel conductance of 3.15 ns in 1 m kcl. the porin migrated as a broad, single band (mr above 90,000) on sodium dodecyl sulfate polyacrylamide gel electrophoresis and dissociated into a single species of polypeptides (mr 36,000) on treatment with edta (10 mm at 30 degrees c, 20 min) or by heati ...	1990	2169246
evaluation of the buffer capacity and permeability constant for protons in chromatophores from rhodobacter capsulatus.	1. the kinetics of decay in the dark of the transmembrane ph difference (delta ph) induced by light in nonphosphorylating chromatophores of rhodobacter capsulatus were studied using the fluorescent probe 9-aminoacridine, in the presence of 50 mm kcl and 2 microm valinomycin. the transient fluorescence changes induced by acid to base transitions of chromatophore suspensions were used as an empirical calibration [casadio, r. & melandri, b. a. (1985) arch. biophys. biochem. 238, 219-228]. the kinet ...	1990	2169415
the prediction of transmembrane protein sequences and their conformation: an evaluation.	the prediction of transmembrane protein sequences can be performed with reasonable accuracy. however, the prediction of their conformation leaves room for significant improvement.	1990	2183408
p+qa- and p+qb- charge recombinations in rhodopseudomonas viridis chromatophores and in reaction centers reconstituted in phosphatidylcholine liposomes. existence of two conformational states of the reaction centers and effects of ph and o-phenanthroline.	the p+qa- and p+qb- charge recombination decay kinetics were studied in reaction centers from rhodopseudomonas viridis reconstituted in phosphatidylcholine bilayer vesicles (proteoliposomes) and in chromatophores. p represents the primary electron donor, a dimer of bacteriochlorophyll; qa and qb are the primary and secondary stable quinone electron acceptors, respectively. in agreement with recent findings for reaction centers isolated in detergent [sebban, p., & wraight, c.a. (1989) biochim. bi ...	1990	2186805
stark effect in wild-type and heterodimer-containing reaction centers from rhodobacter capsulatus.	the effect of an external electric field on the optical absorption spectra of wild-type rhodobacter capsulatus and two rb. capsulatus reaction centers that have been genetically modified through site-directed mutagenesis (hism200----leum200 and hism200----phem200) was measured at 77 k. the two genetically modified reaction centers replace histidine m200, the axial ligand to the m-side bacteriochlorophyll of the special pair, with either leucine or phenylalanine. these substitutions result in the ...	1990	2187533
statistical distribution of hydrophobic residues along the length of protein chains. implications for protein folding and evolution.	we consider in this paper the statistical distribution of hydrophobic residues along the length of protein chains. for this purpose we used a binary hydrophobicity scale which assigns hydrophobic residues a value of one and non-hydrophobes a value of zero. the resulting binary sequences are tested for randomness using the standard run test. for the majority of the 5,247 proteins examined, the distribution of hydrophobic residues along a sequence cannot be distinguished from that expected for a r ...	1990	2188687
observations concerning topology and locations of helix ends of membrane proteins of known structure.	hydropathy plots of amino acid sequences reveal the approximate locations of the transbilayer helices of membrane proteins of known structure and are thus used to predict the helices of proteins of unknown structure. because the three-dimensional structures of membrane proteins are difficult to obtain, it is important to be able to extract as much information as possible from hydropathy plots. we describe an "augmented" hydropathy plot analysis of the three membrane proteins of known structure, ...	1990	2192066
partial symmetrization of the photosynthetic reaction center.	the bacterial photosynthetic reaction center (rc) is a pigmented intrinsic membrane protein that performs the primary charge separation event of photosynthesis, thereby converting light to chemical energy. the rc pigments are bound primarily by two homologous peptides, the l and m subunits, each containing five transmembrane helices. these alpha helices and pigments are arranged in an approximate c2 symmetry and form two possible electron transfer pathways. only one of these pathways is actually ...	1990	2192455
structure and evolution of a multidomain multiphosphoryl transfer protein. nucleotide sequence of the frub(hi) gene in rhodobacter capsulatus and comparisons with homologous genes from other organisms.	the gene order of the fructose (fru) operon and nucleotide sequence of the first gene (frub(hi) of rhodobacter capsulatus are reported, analyzed and compared with homologous genes from other bacteria, and the gene products are identified. included within the region reported is a gene encoding a multiphosphoryl transfer protein (mtp) of the phosphoenolpyruvate:sugar phosphotransferase system (pts). mtp consists of three moieties: a fructose-specific enzyme iii (iiifru)-like n-terminal moiety (res ...	1990	2193161
lipid transport in microorganisms.	microorganisms are useful model systems for the study of intracellular transport of lipids. eukaryotic microorganisms, such as the yeast saccharomyces cerevisiae, are similar to higher eukaryotes with respect to organelle structure and membrane assembly. experiments in vivo showed that transport of phosphatidylcholine between yeast microsomes and mitochondria is energy independent; transfer of phosphatidylinositol to the plasma membrane and the flux of secretory vesicles take place by different ...	1990	2193822
development of a cell-free system to study the membrane assembly of photosynthetic proteins of rhodobacter capsulatus.	a cell-free translation system from the facultatively photoheterotrophic bacterium rhodobacter capsulatus is described. synthesis of two proteins of the bacterium's photosynthetic apparatus (light-harvesting complex b870 alpha and beta) was performed by sp6 polymerase transcription of the subcloned genes, isolation of the mrna and translation in vitro using a cell-free extract of r. capsulatus cells. the integration of these proteins in vitro into added intracytoplasmic membrane vesicles (icm) i ...	1990	2195040
isolation and characterization of a subunit form of the b875 light-harvesting complex from rhodobacter capsulatus.	a structural subunit (called b816) has been isolated from the b875 light-harvesting complex of rhodobacter capsulatus using a detergent-mediated dissociation of chromatophores. rb. capsulatus mw442 (b800-850- b875+ car+) chromatophores were extracted with benzene and titrated with octyl glucoside (og) to shift the near-infrared absorption maximum from 873 to 816 nm. gel filtration chromatography was then used to separate b816 from reaction centers. b816 could be quantitatively shifted back to a ...	1990	2195560
electrostatic control of charge separation in bacterial photosynthesis.	electrostatic interaction energies of the electron carriers with their surroundings in a photosynthetic bacterial reaction center are calculated. the calculations are based on the detailed crystal structure of reaction centers from rhodopseu-domonas viridis, and use an iterative, self-consistent procedure to evaluate the effects of induced dipoles in the protein and the surrounding membrane. to obtain the free energies of radical-pair states, the calculated electrostatic interaction energies are ...	1990	2196939
first glance on the three-dimensional structure of the photosynthetic reaction center from a herbicide-resistant rhodopseudomonas viridis mutant.	a first model of the three-dimensional structure of the photosynthetic reaction center of the mutant t1 (serl223----ala, argl217----his) from rhodopseudomonas viridis, resistant toward the triazine herbicide terbutryn (2-methylthio-4-ethylamino-6-t-butylamino-s-triazine), has been developed from x-ray data measured to a resolution of 2.5 a. the secondary quinone, qb, which in t1 binds better than in the wild type, is present in the crystals. both substituted residues are clearly visible in the d ...	1990	2198873
sequence analysis of four atrazine-resistant mutants from rhodopseudomonas viridis.	four atrazine-resistant mutants from the purple bacterium rhodopseudomonas viridis were isolated. sequence analysis revealed three different mutant strains carrying mutations in the herbicide-binding pocket: i) mav 2: l212-glu----lys, ii) mav 3: l216-phe----ser and iii) mav 4 = mav 5: l217-arg----his, l220-val----leu. except mav 3 all rps. viridis mutants are different from those selected by their resistance towards the closely related triazine terbutryn.	1990	2198874
rhodobacter capsulatus genes involved in early steps of the bacteriochlorophyll biosynthetic pathway.	three open reading frames in the rhodobacter capsulatus photosynthesis gene cluster, designated f0, f108, and f1025, were disrupted by site-directed mutagenesis. mutants bearing insertions in these reading frames were defective in converting protoporphyrin ix to magnesium-protoporphyrin monomethyl ester, protochlorophyllide to chlorophyllide a, and magnesium-protoporphyrin monomethyl ester to protochlorophyllide, respectively. these results demonstrate that the genes examined most likely encode ...	1990	2203738
a plant-ferredoxin-like gene is located upstream of ferredoxin i gene (fdxn) of rhodobacter capsulatus.		1990	2315024
immobilized uroporphyrinogen i synthetase from rhodopseudomonas palustris.	rhodopseudomonas palustris uroporphyrinogen i synthetase (uro-s) has been chemically attached to sepharose 4b and some of its properties have been studied. when 7-8 mg protein/ml activated sepharose was used, immobilized uro-s retained 45% of the activity of the original soluble preparation, with a coupling yield of 66% after a period of 15 h. optimal incubation conditions for the activity of gel-enzyme were determined. unlike the soluble enzyme, the sepharose-bound uro-s showed a biphasic subst ...	1990	2360991
a protein conformational change associated with the photoreduction of the primary and secondary quinones in the bacterial reaction center.	a comparison is made between the pqa----p+qa- and pqaqb----p+qaqb-transitions in rps. viridis and rb. sphaeroides reaction centers (rcs) by the use of light-induced fourier transform infrared (ftir) difference spectroscopy. in rb. sphaeroides rcs, we identify a signal at 1650 cm-1 which is present in the p+qa-minus-pqa spectrum and not in the p+qaqb(-)-minus-pqaqb spectrum. in contrast, this signal is present in both p+qa(-)-minus-pqa- and p+qaqb(-)-minus-pqaqb spectra of rps. viridis rcs. these ...	1990	2365070
isolation and characterization of rhodobacter capsulatus mutants defective in oxygen regulation of the puf operon.	cis-acting mutations that affect regulation of the rhodobacter capsulatus puf operon by oxygen were isolated by placing the mutagenized puf regulatory region 5' to a promoterless tn5 neo gene, which encodes resistance to kanamycin (kmr). r. capsulatus mutants that failed to show wild-type repression of kmr by oxygen were selected and analyzed. four independent clones contained point mutations, three of which were identical, in a region of dyad symmetry located between puf operon nucleotide posit ...	1990	2376568
cloning and sequencing of the hema gene of rhodobacter capsulatus and isolation of a delta-aminolevulinic acid-dependent mutant strain.	the rhodobacter capsulatus hema gene, coding for the enzyme delta-aminolevulinic acid synthase (alas), was isolated from a genome bank by hybridization with a hemt probe from rhodobacter sphaeroides. subcloning of the initial 3.9 kb hindiii fragment allowed the isolation of a 2.5 kb hindiii-bglii fragment which was able to complement the delta-aminolevulinic acid-requiring (ala-requiring) escherichia coli mutant shsp19. dna sequencing revealed an open reading frame coding for a protein with 401 ...	1990	2381418
nucleotide sequence of fdxa encoding a 7fe ferredoxin of rhodobacter capsulatus.		1990	2388848
combined actions of multiple hairpin loop structures and sites of rate-limiting endonucleolytic cleavage determine differential degradation rates of individual segments within polycistronic puf operon mrna.	differential expression of the genes within the puf operon of rhodobacter capsulatus is accomplished in part by differences in the rate of degradation of different segments of the puf transcript. we report here that decay of puf mrna sequences specifying the light-harvesting i (lhi) and reaction center (rc) photosynthetic membrane peptides is initiated endoribonucleolytically within a discrete 1.4-kilobase segment of the rc-coding region. deletion of this segment increased the half-life of the r ...	1990	2394682
the nucleotide sequence of a flavodoxin-like gene which precedes two ferredoxin genes in rhodobacter capsulatus.		1990	2402451
purification and characterization of a new nad(+)-dependent enzyme, l-tartrate decarboxylase, from pseudomonas sp. group ve-2.	a new enzyme, l-tartrate decarboxylase, was found in cells of pseudomonas sp. group ve-2. the enzyme was purified to homogeneity and characterized. the enzyme requires k+, mg2+, and nad+ for l-tartrate decarboxylation. the dependence of the enzymatic decarboxylation on nad+ suggests that the decarboxylation involves redox reactions of the substrate. the enzyme catalyzes nad(+)-linked oxidative decarboxylation of d-malate as well. the enzyme is composed of four subunits with identical molecular w ...	1991	1778975
organization of the genes coding for the reaction-centre l and m subunits and b870 antenna polypeptides alpha and beta from the aerobic photosynthetic bacterium erythrobacter species och114.	in the aerobic photosynthetic bacterium erythrobacter species och114 the structural genes coding for the light-harvesting (lh) complex b870 and the reaction-centre (rc) polypeptides (the gene products of the pufb, pufa, pufl and pufm genes) are mapped on a 2.728 kbp ecori fragment. sequencing of this fragment revealed that the deduced amino acid sequences contain 50 (b870 beta), 52 (b850 alpha), 283 (rcl) and 331 (rcm) residues with the corresponding molecular weights of 5592, 5814, 31364, and 3 ...	1991	1787796
structures of bacterial photosynthetic reaction centers.		1991	1809346
thiazolylidene-ketonitriles are efficient inhibitors of electron transport in reaction centers from photosynthetic bacteria.	thiazolylidene-ketonitriles are efficient inhibitors of photosynthetic electron flow in reaction centers from either rhodobacter sphaeroides or rhodobacter capsulatus. some compounds of this class exhibit a higher inhibitor potency in the bacterial system as compared to photosystem ii. up to now, photosystem ii inhibitors were generally less active in photosynthetic bacteria. an azido-thiazolylidene-ketonitrile upon illumination almost exclusively tags the l-subunit in the bacterial reaction cen ...	1991	1817514
reaction of cytochrome c2 with photosynthetic reaction centers from rhodopseudomonas viridis.	the reactions of rhodopseudomonas viridis cytochrome c2 and horse cytochrome c with rps. viridis photosynthetic reaction centers were studied by using both single- and double-flash excitation. single-flash excitation of the reaction centers resulted in rapid photooxidation of cytochrome c-556 in the cytochrome subunit of the reaction center. the photooxidized cytochrome c-556 was subsequently reduced by electron transfer from ferrocytochrome c2 present in the solution. the rate constant for this ...	1991	1846750
expression in escherichia coli of c-type cytochrome genes from rhodopseudomonas viridis.	the genes coding for the photosynthetic reaction center cytochrome c subunit (pufc) and the soluble cytochrome c2 (cyca) from the purple non-sulfur bacterium rhodopseudomonas viridis were expressed in escherichia coli. biosynthesis of the reaction center cytochrome without a signal peptide resulted in the formation of inclusion bodies in the cytoplasm amounting to 14% of the total cellular protein. a series of plasmids coding for the cytochrome subunit with varying n-terminal signal peptides was ...	1991	1848106
langmuir-blodgett monolayer films of bacterial photosynthetic membranes and isolated reaction centers: preparation, spectrophotometric and electrochemical characterization.	the langmuir-blodgett (lb) film technique has been successfully applied to the construction of stable and photo-active films of chromatophore membranes and isolated reaction centers from two species of photosynthetic bacteria, rhodobacter sphaeroides and rhodopseudomonas viridis. lb films of these preparations were characterized at the air/water interface through compression isotherms and film stabilities. films deposited on glass slides were analyzed by spectrophotometric and redox potentiometr ...	1991	1849739
langmuir-blodgett monolayer films of the rhodopseudomonas viridis reaction center: determination of the order of the hemes in the cytochrome c subunit.	the langmuir-blodgett (lb) film technique has been applied to produce oriented and photo-active films of isolated reaction center cytochrome c complexes (rc-cyt c) and chromatophore membranes from the photosynthetic bacterium rhodopseudomonas viridis. linear dichroism (ld) and redox potentiometry have been used to identify the four cytochrome c hemes of the rc-cyt c complex. resolved angular orientations of the four hemes in lb films of both isolated rc-cyt-c complexes and of chromatophore membr ...	1991	1849740
lipopolysaccharidelike immunological properties of cell wall glycoproteins isolated from cytophaga johnsonae.	glycoproteins (gp) previously shown to be involved in the gliding motility of cytophaga johnsonae were examined for biological activities characteristic of lipopolysaccharide (lps). these integral membrane proteins activated 70z/3 pre-b cells to synthesize immunoglobulin m, induced b cells to synthesize non-antigen-specific polyclonal immunoglobulin, induced macrophages to produce tumor necrosis factor, and modulated the antibody response to type iii pneumococcal polysaccharide in the absence of ...	1991	1855983
immunogenicity of streptococcus pneumoniae type 14 capsular polysaccharide: influence of carriers and adjuvants on isotype distribution.	this project investigated the effects of novel carriers and adjuvants on the isotype of murine immunoglobulin g (igg) antibody to pneumococcal capsular polysaccharide type 14 (s14ps). s14ps conjugated to bovine serum albumin induced a weak antibody response which was 100% igg1 following injection without adjuvant. the same polysaccharide conjugated to flagella of salmonella typhi induced an antibody response which was 88% igg3. s14ps-bovine serum albumin was injected with block copolymer l121 or ...	1991	1855991
high-resolution structures of photosynthetic reaction centers.		1991	1867718
dynamics of the excited state of the primary electron donor in reaction centers of rhodopseudomonas viridis as revealed by hole burning at 1.7k. different conformational states.	the spectra of absorbance changes (delta a) due to the formation of p+q- (p, primary electron donor, q, primary quinone acceptor) at 1.7k in rhodopseudomonas viridis reaction centers (rcs) excited at 1014 nm has been shown to include, besides a progression of broad (170-190 cm-1) gaussian vibronic bands separated by 150 cm-1, a 'narrow' structure near 1014 nm which can be simulated by a lorentian zero-phonon hole (zph) and lorentian one-mode (26.8 cm-1) phonon wings. the widths of zph of approxi ...	1991	1879522
isolation of two new natural pteridines from photosynthetic bacteria, rhodopseudomonas sphaeroides.	two new natural pteridines have been isolated from the cultured medium of rhodopseudomonas sphaeroides gm-1. the compounds are tentatively identified as 2-amino-4-hydroxy-6-hydroxy-6-(1,2, 3,4-tetrahydroxybutyl)pteridine and 2-amino-4-hydroxy-6-(3-hydroxy-4-phosphonoxy-1-butenyl)pteridine by degradative experiments and by electrophoretic and paper chromatographic comparison with authentic materials.	1991	1888755
study of qb- stabilization in herbicide-resistant mutants from the purple bacterium rhodopseudomonas viridis.	the ph dependences of the rate constants of p+qb- (kbp) and p+qa- (kap) charge recombination decays have been studied by flash-induced absorbance change technique, in chromatophores of three herbicide-resistant mutants from rhodopseudomonas (rps.) viridis, and compared to the wild type. p, qa, and qb are the primary electron donor and the primary and the secondary quinone acceptors, respectively. the triazine resistant mutants t1 (arg l217----his and ser l223----ala), t3 (phe l216----ser and val ...	1991	1892821
structure of the detergent phase and protein-detergent interactions in crystals of the wild-type (strain y) rhodobacter sphaeroides photochemical reaction center.	rhodobacter sphaeroides (strain y) reaction center (rc) crystals were grown in the presence of n-octyl beta-glucoside (beta-og). in order to determine the structure of the detergent phase in these crystals, low-resolution neutron diffraction experiments were performed at different contrasts obtained by varying the h2o/d2o ratio in the solvent. from the contrast variation data and from the rc atomic coordinates determined by x-ray diffraction [arnoux, b., ducruix, a., reiss-husson, f., lutz, m., ...	1991	1892841
diphosphoryl lipid a derived from lipopolysaccharide (lps) of rhodopseudomonas sphaeroides inhibits activation of 70z/3 cells by lps.	diphosphoryl lipid a derived from nontoxic lipopolysaccharide (lps) of rhodopseudomonas sphaeroides atcc 17023 did not stimulate the murine pre-b cell line 70z/3 to synthesize surface immunoglobulin or kappa mrna. however, it effectively blocked escherichia coli lps-induced activation of 70z/3 cells in a concentration-dependent manner. this inhibition was specific only to cells activated by lps, since it did not inhibit activation of 70z/3 cells by gamma interferon. maximal inhibitory effect occ ...	1991	1898897
the puh structural gene coding for the h subunit of the rhodospirillum rubrum photoreaction center.	the rhodospirillum rubrum structural gene puh, coding for the photoreaction center h polypeptide, and three other putative genes that surround puh were cloned and sequenced. the deduced 257 amino acid h polypeptide has a molecular weight of 27,909, in close agreement with polyacrylamide gel electrophoresis determination. hydropathy plots predict a single hydrophobic alpha helix. the h polypeptide of rhodospirillum rubrum shares only 23% of its residues with all three of the h polypeptides from r ...	1991	1903263
h218o isotope exchange studies on the mechanism of reduction of nitric oxide and nitrite to nitrous oxide by denitrifying bacteria. evidence for an electrophilic nitrosyl during reduction of nitric oxide.	reduction of no and no2-by whole cells of eight strains of denitrifying bacteria known to contain either heme cd1 or copper-containing nitrite reductases (nirs) has been examined in the presence of h218o. all organisms containing heme cd1 nirs exhibited relatively large extents of exchange between no2- and h218o (39-100%), as monitored by the 18o content of product n2o. organisms containing copper nirs gave highly variable results, with achromobacter cycloclastes and pseudomonas aureofaciens exh ...	1991	1906460
kinetic properties of the acceptor quinone complex in rhodopseudomonas viridis.	the kinetics of electron transfer from the primary (qa) to the secondary (qb) quinone acceptor in whole cells and chromatophores of rhodopseudomonas viridis was studied as a function of the redox state of qb and of ph by using a photovoltage technique. under conditions where qb was oxidized, the reoxidation of qa- was found to be essentially monophasic and independent of ph with a half-time of about 20 microseconds. when qb was reduced to the semiquinone form by a preflash, the reoxidation of qa ...	1991	1911749
electrostatic control of midpoint potentials in the cytochrome subunit of the rhodopseudomonas viridis reaction center.	the photosynthetic reaction center of rhodopseudomonas viridis has four hemes in a linear arrangement with alternating high- and low-potential sites. their midpoints are -60, 20, 310, and 380 mv [dracheva, s. m., drachev, l. a., konstantinov, a. a., semenov, a. y., skulachev, v. p., arutjunjan, a. m., shuvalov, v. a. & zaberezhnaya, s. m. (1988) eur. j. biochem. 171, 253-264]. electrostatic calculations reproduce the 440-mv midpoint spread and assignments of high- and low-potential hemes. when c ...	1991	1924378
cytotoxicity of bacteriohopane-32-ol against mouse leukemia l1210 and p388 cells in vitro.	to investigate the biological activities of the hopane group of pentacyclic triterpenoids, we isolated one hopanoid, bacteriohopane-32-ol from rhodopseudomonas palustris and tested its cytotoxicity against mouse leukemia cells in vitro. the ic50 of the hopanoid for l1210 and p388 was 22 and 19 microm respectively. this activity was slightly reduced by co-incubation with cholesterol. as the mechanism of cytotoxic action, disturbances of membrane function and metabolism are discussed.	1991	1957326
diphosphoryl lipid a obtained from the nontoxic lipopolysaccharide of rhodopseudomonas sphaeroides is an endotoxin antagonist in mice.	diphosphoryl lipid a (dpla) obtained from the nontoxic lipopolysaccharide (lps) of rhodopseudomonas sphaeroides atcc 17023 did not induce interleukin-1 release by murine peritoneal macrophages. however, it blocked this induction by toxic deep-rough chemotype lps (relps) from escherichia coli d31m4. previously, we obtained similar results on the induction of tumor necrosis factor (tnf) by macrophages. these results showed that dpla is able to block in vitro the induction of two important mediator ...	1991	1987057
involvement of the protein-protein interactions in the thermodynamics of the electron-transfer process in the reaction centers from rhodopseudomonas viridis.	reaction centers from rhodopseudomonas viridis were reconstituted into dimyristoylphosphatidylcholine (dmpc) and dielaidoylphosphatidylcholine (depc) liposomes. freeze-fracture electron micrographs were performed on the samples frozen from temperatures above and below the phase transition temperatures of those lipids (tc = 23 and 9.5 degrees c, in dmpc and depc, respectively). above tc, in the fluid conformation of the lipids, the reaction centers are randomly distributed in the vesicle membrane ...	1991	1991111
phosphatidyl-tris rather than n-acylphosphatidylserine is synthesized by rhodopseudomonas sphaeroides grown in tris-containing media.	we have synthesized 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho(n-oleoyl)serine (n-acyl-ps) and 1,2-dioleoyl-sn-glycero-3-phospho-tris (phosphatidyl-tris) and have characterized both phospholipids by their chemical and chromatographic properties, as well as by their ir, 13c nmr, and 1h nmr spectra. comparison of these data with those reported for a phospholipid isolated from rhodopseudomonas sphaeroides grown in tris-supplemented media [donohue et al. (1982) biochemistry 21, 2765-2773] indicates t ...	1991	1993190
inactivation of t5 phage by cis-vaccenic acid, an antivirus substance from rhodopseudomonas capsulata, and by unsaturated fatty acids and related alcohols.	the antiviral extract from rhodopseudomonas capsulata was purified and the predominant active component was defined as cis-vaccenic acid (cl-8:1 delta 11) by gas-liquid chromatography and gas chromatography-mass spectrometry analyses. antiviral activities of unsaturated fatty acids and related alcohols against t5 phage were also tested. among them, linoelaidic acid, oleic acid, and petroselenyl alcohol inactivated 98%, 53%, 67% of t5 phage at the concentration of 50 micrograms/ml, respectively.	1991	2004693
phylogeny of the phototrophic rhizobium strain btai1 by polymerase chain reaction-based sequencing of a 16s rrna gene segment.	a 260-bp segment of the dna that encodes 16s rrna, corresponding to positions 44 to 337 in the escherichia coli sequence, was amplified by the polymerase chain reaction and sequenced from each of 13 bacteria (rhizobia and purple phototrophs) in the alpha subdivision of the class proteobacteria. the phylogenetic tree calculated from differences in the sequenced segment conforms well to our expectations based on other previously published data. the sequence from btai1 (a recently described phototr ...	1991	2007551
chemical reduction of 3-oxo and unsaturated groups in fatty acids of diphosphoryl lipid a from the lipopolysaccharide of rhodopseudomonas sphaeroides. comparison of biological properties before and after reduction.	unlike the diphosphoryl lipid a (dpla) derived from toxic lipopolysaccharide of escherichia coli and salmonella strains, the dpla from nontoxic lipopolysaccharide of rhodopseudomonas sphaeroides atcc 17023 is biologically inactive. this could be due to the presence of 3-oxotetradecanoic and delta 7-tetradecenoic acids. these two fatty acids in r. sphaeroides dpla were catalytically reduced in platinum oxide/h2 to the 3-hydroxy and saturated fatty acids, respectively. the biologically active e. c ...	1991	2007601
structure of the membrane-bound protein photosynthetic reaction center from rhodobacter sphaeroides.	the structure of the photosynthetic reaction center (rc) from rhodobacter sphaeroides was determined at 3.1-a resolution by the molecular replacement method, using the rhodopseudomonas viridis rc as the search structure. atomic coordinates were refined with the difference fourier method and restrained least-squares refinement techniques to a current r factor of 22%. the tertiary structure of the rc complex is stabilized by hydrophobic interactions between the l and m chains, by interactions of t ...	1991	2036404
comparison of reaction centers from rhodobacter sphaeroides and rhodopseudomonas viridis: overall architecture and protein-pigment interactions.	photosynthetic reaction centers (rcs) from the photosynthetic bacteria rhodobacter sphaeroides and rhodopseudomonas viridis are protein complexes closely related in both structure and function. the structure of the rps. viridis rc was used to determine the structure of the rc from rb. sphaeroides. small but meaningful differences between the positions of the helices and the cofactors in the two complexes were identified. the distances between helices al and am, between bl and bm, and between bac ...	1991	2036405
nucleotide sequence of the replication region of the marine rhodobacter plasmid prd31.	the minimum region required for replication of the marine rhodobacter endogenous plasmid prd31 has been sequenced. this region is located on a 1367-bp hincii-psti restriction fragment and is 62% rich in g-c base pairs. a region homologous to the bacteriophage p1 repa promoter, which overlaps two inverted repeats, has been identified. plasmids with mutations in this 1367-bp region could not replicate in marine rhodobacter hosts. this is the first identified replication origin of a photosynthetic ...	1991	2044764
adjuvant activity of non-ionic block copolymers. v. modulation of antibody isotype by lipopolysaccharides, lipid a and precursors.	non-ionic block copolymers and lipopolysaccharides are both effective immunological adjuvants which are thought to act via distinct mechanisms. we hypothesized that they might produce synergistic effects when used together. we prepared a series of lipopolysaccharide (lps) preparations ranging from the smallest precursor, lipid x through complete lps with o-polysaccharide chains. three preparations with reduced toxicity, monophosphoryl lipid a, partially hydrolysed ra-lps and lps of rhodopseudomo ...	1991	2058268
sub-picosecond dynamics of excited state of primary electron donor in reaction centers of rhodopseudomonas viridis as revealed by hole burning at 1.7k broad and narrow holes.	within the qf band of the primary electron donor (p), the spectra of absorbance changes due to the formation of a state of p+qa- (qa is the primary quinone) at 1.7k in rhodopseudomonas viridis reaction centers excited at 1014 nm have been shown to involve two spectral features characterized by: (i) a progression of broad (170-190 cm-1) gaussian vibronic bands (s-factor = 1.4) separated by 150 cm-1 and (ii) a 'narrow' structure near 1014 nm, characterized by 0-0 transition at 1014 nm with a width ...	1991	2060638
16s rrna sequences of bartonella bacilliformis and cat scratch disease bacillus reveal phylogenetic relationships with the alpha-2 subgroup of the class proteobacteria.	the primary structures of 16s rrnas of bartonella bacilliformis, an isolate of the cat scratch disease (csd) bacillus, and a strain phenotypically similar to the csd bacillus were determined by reverse transcriptase sequencing. these microorganisms were found to be members of the alpha-2 subgroup of the class proteobacteria. the sequence from b. bacilliformis was most closely related to the rrna of rochalimaea quintana (91.7% homology), the etiologic agent of trench fever. the sequence from the ...	1991	1719021
the cytochrome c peroxidase of paracoccus denitrificans.	the size, visible absorption spectra, nature of haem and haem content suggest that the cytochrome c peroxidase of paracoccus denitrificans is related to that of pseudomonas aeruginosa. however, the paracoccus enzyme shows a preference for cytochrome c donors with a positively charged 'front surface' and in this respect resembles the cytochrome c peroxidase from saccharomyces cerevisiae. paracoccus cytochrome c-550 is the best electron donor tested and, in spite of an acidic isoelectric point, ha ...	1991	1646012
sequence variability in bacterial cytochromes c.	cytochromes c are proteins that can be defined both phenotypically and by their possession of a characteristic sequence motif. many sequences from bacterial sources are known, and new ones are being reported every year. an analysis can be made as to what fraction of new sequences are members of already known classes or subclasses, and how many map into previously uninhabited regions of sequence space.	1991	1646017
electron transfer proteins of the purple phototrophic bacterium, rhodopseudomonas rutila.	the soluble electron transfer protein content of rhodopseudomonas rutila was found to consist of two basic cytochromes and a (4fe-4s) ferredoxin. cytochrome c' was easily identified by its characteristic high spin absorption spectra. the native molecular weight is 29,000 and the subunit is 14,000. cytochrome c-550 has low spin absorption spectra and a high redox potential (376 mv) typical of cytochromes c2. the molecular weight is about 14,000. the ferredoxin is apparently a dimer (43,000) of ap ...	1991	1654788
photooxidation of high-potential (c559, c556) and low-potential (c552) hemes in the cytochrome subunit of rhodopseudomonas viridis reaction center. characterization by ftir spectroscopy.	the photooxidation of c559, c556 and c552 hemes in rhodopseudomonas viridis cytochrome has been characterized by light-induced ftir difference spectroscopy. apart from the common features at 1659 cm-1 and 1561/1551 cm-1 which could arise from one (or possibly two) peptide bond(s), no evidence for major structural rearrangement of the polypeptide backbone was observed. a significant difference with respect to redox-induced ftir spectra of cytochrome c is the absence of the tyr marker at 1514/1518 ...	1991	1660005
the primary structure of cytochrome c-554 from the green photosynthetic bacterium chloroflexus aurantiacus.	the complete nucleotide sequence of the cytochrome c-554 gene from the green photosynthetic bacterium chloroflexus aurantiacus has been determined. the derived amino acid sequence showed that the cytochrome precursor protein consists of 414 residues and contains 4-cys-x-x-cys-his- heme binding motifs. the only regions of the cytochrome c-554 sequence that were found to be significantly similar to the sequences of cytochromes from other organisms were the heme binding sites. the highest similarit ...	1991	1660302
characterization of cytochromes c550 and c555 from bradyrhizobium japonicum: cloning, mutagenesis, and sequencing of the c555 gene (cycc).	the major soluble c-type cytochromes in cultured cells of bradyrhizobium japonicum usda 110 comprised a co-reactive c555 (mr, approximately 15,500) and a non-co-reactive c550 (mr, approximately 12,500). levels of cytochrome per gram of soluble protein in aerobic, anaerobic, and symbiotic cells were 32, 21, and 30 nmol, respectively, for c555 and 31, 44, and 65 nmol, respectively, for c550. the midpoint redox potentials (em,7) of the purified cytochromes were +236 mv for c555 and +277 mv for c550 ...	1991	1660457
an electrochemical assay for the characterization of redox proteins from biological electron transfer chains.	a sensitive and quick assay for redox proteins based on electrochemical titrations in a thin-layer electrochemical cell is described. using a combination of modified-electrode and "mediator-enhanced" electrochemistry, equilibration of the cell volume (4 microliters) with the applied potential allows series of spectra as a function of the potential to be recorded rapidly. a complete redox titration between +500 and -600 mv (vs ag/agcl/3 m kcl) in 30-mv intervals takes approximately 2 h. the detec ...	1991	1667456
use of ultrafiltration to isolate viruses from seawater which are pathogens of marine phytoplankton.	viruses may be major structuring elements of phytoplankton communities and hence important regulators of nutrient and energy fluxes in aquatic environments. in order to ascertain whether viruses are potentially important in dictating phytoplankton community structure, it is essential to determine the extent to which representative phytoplankton taxa are susceptible to viral infection. we used a spiral ultrafiltration cartridge (30,000-molecular-weight cutoff) to concentrate viruses from seawater ...	1991	16348439
a novel directly coupled gradostat.	the original bidirectional compound chemostat (gradostat) described by lovitt and wimpenny has been simplified by making a more compact apparatus in which chemical gradients are established by diffusion between adjacent culture chambers. the experimental model (diffusion coupled (dc) gradostat) consisted of five chambers whose contents could be agitated by turbines rotating in the horizontal plane on a common shaft. two biological experiments were designed to reveal the value of the dc gradost ...	1992	11540058
distribution of an l-isoaspartyl protein methyltransferase in eubacteria.	a protein carboxyl methyltransferase (ec 2.1.1.77) that recognizes age-damaged proteins for potential repair or degradation reactions has been found in all vertebrate tissues and cells examined to date. this enzyme catalyzes the transfer of methyl groups from s-adenosylmethionine to the carboxyl groups of d-aspartyl or l-isoaspartyl residues that are formed spontaneously from normal l-aspartyl and l-asparaginyl residues. a similar methyltransferase has been found in two bacterial species, escher ...	1992	1729230
chromophore-protein interactions and the function of the photosynthetic reaction center: a molecular dynamics study.	the coupling between electron transfer and protein structure and dynamics in the photosynthetic reaction center of rhodopseudomonas viridis is investigated. for this purpose molecular dynamics simulations of the essential portions (a segment of 5797 atoms) of this protein complex have been carried out. electron transfer in the primary event is modeled by altering the charge distributions of the chromophores according to quantum chemical calculations. the simulations show (i) that fluctuations of ...	1992	1729721
light-induced charge separation in rhodopseudomonas viridis reaction centers monitored by fourier-transform infrared difference spectroscopy: the quinone vibrations.	static ftir light-induced difference spectra have been recorded for reaction centers from rhodopseudomonas viridis in the following charge-separated states: p+qa(-)-pqa, p+qb(-)-pqb, i(-)-i, i-qa(-)-iqa, and i-qa(2-)-iqa. a comparison of the i(-)-i difference spectra with the i-qa(-)-iqa difference spectra reveals new bands which can be assigned to qa- vibrations; these vibrations are also observed in the p+qa(-)-pqa and p+qb(-)-pqb difference spectra. through an analysis of all of the static di ...	1992	1736990
the fluorescence yield of rhodopseudomonas viridis in relation to the redox state of the primary electron donor.	the fluorescence yield of bacteriochlorophyll (bchl) b in membranes of rhodopseudomonas viridis was measured immediately and at a variable time-interval after a saturating laser flash to bring about charge separation. at 4 k a decrease of the yield by 28% was observed immediately after the flash. this yield recovered mono-exponentially with a time constant of 6.3 +/- 0.4 ms to approximately the original level. the same time constant was observed for the re-reduction of the primary electron donor ...	1992	1739729
anoxygenic degradation of aromatic substances by rhodopseudomonas palustris.	three strains of the phototrophic purple nonsulfur bacterium rhodopseudomonas palustris were isolated from different environments and were evaluated for their aromatic degradative potential under phototrophic conditions. all three strains (pfr1, pnr4, and mrl1) utilized benzoate, 4-hydroxybenzoate, 4-aminobenzoate, 4-aminophenol, cinnamate, ferulate, phloroglucinol, and 4-dimethylaminobenzaldehyde in the absence of exogenous co2. 4-aminobenzoate and 4-aminophenol served as a carbon and nitrogen ...	1992	1369192