| nucleotide sequence of the frua gene, encoding the fructose permease of the rhodobacter capsulatus phosphotransferase system, and analyses of the deduced protein sequence. | the nucleotide sequence of the frua gene, the terminal gene in the fructose operon of rhodobacter capsulatus, is reported. this gene codes for the fructose permease (molecular weight, 58,575; 578 aminoacyl residues), the fructose enzyme ii (iifru) of the phosphoenolpyruvate-dependent phosphotransferase system. the deduced aminoacyl sequence of the encoded gene product was found to be 55% identical throughout most of its length with the fructose enzyme ii of escherichia coli, with some regions st ... | 1990 | 2254279 |
| conserved enzymes mediate the early reactions of carotenoid biosynthesis in nonphotosynthetic and photosynthetic prokaryotes. | carotenoids comprise one of the most widespread classes of pigments found in nature. the first reactions of c40 carotenoid biosynthesis proceed through common intermediates in all organisms, suggesting the evolutionary conservation of early enzymes from this pathway. we report here the nucleotide sequence of three genes from the carotenoid biosynthesis gene cluster of erwinia herbicola, a nonphotosynthetic epiphytic bacterium, which encode homologs of the crtb, crte, and crti proteins of rhodoba ... | 1990 | 2263648 |
| a rapid burst preceding the steady-state rate of h(+)-transhydrogenase during illumination of chromatophores of rhodobacter capsulatus. implications for the mechanism of interaction between protonmotive force and enzyme. | at the onset of illumination of chromatophores there was a burst (t1/2 approx. 5 ms) in the rate of the h(+)-transhydrogenase reaction before establishment of the steady-state rate. the burst was suppressed at high ph with a pka of approx. 8.5. the burst and the steady-state rate were inhibited by either (i) a combination of myxothiazol and carbonylcyanide-p-trifluoromethoxyphenylhydrazone, or (ii) nad+, or (iii) dicyclohexylcarbodiimide. the results support a model in which substrate binding to ... | 1990 | 2269368 |
| effects on the formation of antenna complex b870 of rhodobacter capsulatus by exchange of charged amino acids in the n-terminal domain of the alpha and beta pigment-binding proteins. | the n-terminal domains of the alpha and beta polypeptides of the b870 antenna complex of rhodobacter capsulatus are oppositely charged. in both polypeptides two charged amino acids are located close to the n-terminus, and two of them are close to the hydrophobic central domain. to test the hypothesis that charged amino acids in the n-terminus have a function for insertion and assembly of pigment-binding polypeptides, charged amino acids were replaced by amino acids of opposite charge. the result ... | 1990 | 2271533 |
| role of tyrosine m210 in the initial charge separation of reaction centers of rhodobacter sphaeroides. | femtosecond spectroscopy was used in combination with site-directed mutagenesis to study the influence of tyrosine m210 (ym210) on the primary electron transfer in the reaction center of rhodobacter sphaeroides. the exchange of ym210 to phenylalanine caused the time constant of primary electron transfer to increase from 3.5 +/- 0.4 ps to 16 +/- 6 ps while the exchange to leucine increased the time constant even more to 22 +/- 8 ps. the results suggest that tyrosine m210 is important for the fast ... | 1990 | 2271535 |
| two distinct ferredoxins from rhodobacter capsulatus: complete amino acid sequences and molecular evolution. | two distinct ferredoxins were purified from rhodobacter capsulatus sb1003. their complete amino acid sequences were determined by a combination of protease digestion, brcn cleavage and edman degradation. ferredoxins i and ii were composed of 64 and 111 amino acids, respectively, with molecular weights of 6,728 and 12,549 excluding iron and sulfur atoms. both contained two cys clusters in their amino acid sequences. the first cluster of ferredoxin i and the second cluster of ferredoxin ii had a s ... | 1990 | 2277040 |
| osmoregulation in rhodobacter sphaeroides. | betaine (n,n,n-trimethylglycine) functioned most effectively as an osmoprotectant in osmotically stressed rhodobacter sphaeroides cells during aerobic growth in the dark and during anaerobic growth in the light. the presence of the amino acids l-glutamate, l-alanine, or l-proline in the growth medium did not result in a significant increase in the growth rate at increased osmotic strengths. the addition of choline to the medium stimulated growth at increased osmolarities but only under aerobic c ... | 1990 | 2294084 |
| a plant-ferredoxin-like gene is located upstream of ferredoxin i gene (fdxn) of rhodobacter capsulatus. | | 1990 | 2315024 |
| cloning and sequencing the genes encoding uptake-hydrogenase subunits of rhodocyclus gelatinosus. | rhodocyclus gelatinosus grew photosynthetically in the light and consumed h2 at a rate of about 665 nmol/min per mg protein. the uptake-hydrogenase (h2ase) was found to be membrane bound and insensitive to inhibition by co. the structural genes of r. gelatinosus uptake-h2ase were isolated from a 40 kb cosmid gene library of r. gelatinosus dna by hybridization with the structural genes of uptake-h2ase of bradyrhizobium japonicum and rhodobacter capsulatus. the r. gelatinosus genes were localized ... | 1990 | 2325631 |
| molybdopterin guanine dinucleotide: a modified form of molybdopterin identified in the molybdenum cofactor of dimethyl sulfoxide reductase from rhodobacter sphaeroides forma specialis denitrificans. | the nature of molybdenum cofactor in the bacterial enzyme dimethyl sulfoxide reductase has been investigated by application of alkylation conditions that convert the molybdenum cofactor in chicken liver sulfite oxidase and milk xanthine oxidase to the stable, well-characterized derivative [di(carboxamidomethyl)]molybdopterin. the alkylated pterin obtained from dimethyl sulfoxide reductase was shown to be a modified form of alkylated molybdopterin with increased absorption in the 250-nm region of ... | 1990 | 2326278 |
| energy-transfer dynamics in three light-harvesting mutants of rhodobacter sphaeroides: a picosecond spectroscopy study. | picosecond absorption spectroscopy has been used to investigate energy-transfer dynamics within the lh1 and lh2 light-harvesting complexes of three mutants of rhodobacter sphaeroides. we demonstrate that both complexes are inhomogeneous; each contains a specialized pigment pool which absorbs maximally at a longer wavelength. within lh2 (mutant nf57), bchl850 transfers energy to bchl870 in 39 +/- 9 ps; within lh1 (mutants m21 and m2192), energy is transferred from bchl875 to bchl896 in 22 +/- 4 a ... | 1990 | 2334690 |
| surface-enhanced resonance raman scattering spectroscopy of bacterial photosynthetic membranes: orientation of the carotenoids of rhodobacter sphaeroides 2.4.1. | surface-enhanced resonance raman scattering (serrs) spectra were obtained from carotenoids, in the all-trans configuration, located on the antenna complexes of rhodobacter sphaeroides 2.4.1 membranes. since resonance raman (rr) spectra are barely detectable at the concentration that serrs signals saturate, serrs represents a very sensitive means of detecting pigments in biological systems. prominent serrs spectra of sphaeroidenone were detected in chromatophores (cytoplasmic side out) but not in ... | 1990 | 2337590 |
| phosphonate utilization by bacterial cultures and enrichments from environmental samples. | a selection of axenic microbial strains and a variety of environmental samples were investigated with respect to the utilization of a series of natural and xenobiotic phosphonates as the sole phosphorus source for growth. phosphonate degradation was observed only with bacteria and not with eucaryotic microorganisms. all representatives of the phosphonates examined supported bacterial growth, with the exception of methylphosphonate diethylester. yet, distinctly different phosphonate utilization p ... | 1990 | 2339877 |
| 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 |
| modified reaction centers from rhodobacter sphaeroides r26. 2: bacteriochlorophylls with modified c-3 substituents at sites ba and bb. | monomeric bacteriochlorophylls ba and bb in photosynthetic reaction centers from rhodobacter sphaeroides r26 were exchanged with (13(2)-hydroxy-)bacteriochlorophylls containing a 3-vinyl- or 3-(alpha-hydroxyethyl)-substituent instead of the 3-acetyl group. the corresponding binding sites must be tolerant to the introduction of the polar residue at c-13(2) and modifications of the 3-acetyl group. according to hplc analysis, the exchange with both pigments amounts to less than or equal to 50% of t ... | 1990 | 2384154 |
| 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 |
| femtosecond dynamics of energy transfer in b800-850 light-harvesting complexes of rhodobacter sphaeroides. | we report femtosecond transient absorption studies of energy transfer dynamics in the b800-850 light-harvesting complex (lhc) of rhodobacter sphaeroides 2.4.1. for complexes solubilized in lauryldimethylamine-n-oxide (ldao), the carotenoid to bacteriochlorophyll (bchl) b800 and carotenoid to bchl b850 energy transfer times are 0.34 and 0.20 ps, respectively. the b800 to b850 energy transfer time is 2.5 ps. for complexes treated with lithium dodecyl sulfate (lds), a carotenoid to b850 energy tran ... | 1990 | 2404276 |
| investigations on the influence of headgroup substitution and isoprene side-chain length in the function of primary and secondary quinones of bacterial reaction centers. | the contributions of headgroup and side-chain in the binding and function of the primary (qa) and secondary (qb) quinones of isolated reaction centers (rcs) from rhodobacter sphaeroides were investigated. various ubiquinones and structurally similar quinones were reconstituted into rcs depleted of one (1q-rcs) or both (0q-rcs) quinones. the influence of partition coefficients on the apparent binding affinities was minimized by expressing dissociation constants in terms of the mole fraction of qu ... | 1990 | 2404516 |
| complementation of a reaction center-deficient rhodobacter sphaeroides puflmx deletion strain in trans with pufbalm does not restore the photosynthesis-positive phenotype. | the puf operon in rhodobacter sphaeroides is composed of the genes for the photosynthetic reaction center l and m subunits, light-harvesting antenna complex i, and one other open reading frame termed pufx. complementation of a reaction center-deficient, photosynthetically incompetent puflmx deletion strain in trans with a fragment containing the entire puf operon, including pufx and an additional 1,100 base pairs of dna downstream of pufx, restored the reaction center and the photosynthesis-posi ... | 1990 | 2404961 |
| membrane ionic currents in rhodobacter capsulatus. evidence for electrophoretic transport of k+, rb+ and nh4+. | 1. the cytoplasmic membrane ionic current of cells of rhodobacter capsulatus, washed to lower the endogenous k+ concentration, had a non-linear dependence on the membrane potential measured during photosynthetic illumination. treatment of the cells with venturicidin, an inhibitor of the h(+)-atp synthase, increased the membrane potential and decreased the membrane ionic current at values of membrane potential below a threshold. 2. the addition of k+ or rb+, but not of na+, led to an increase in ... | 1990 | 2406135 |
| origin of the mrna stoichiometry of the puf operon in rhodobacter sphaeroides. | the lh-i structural genes are located 5' of the rc-l and -m structural genes on what has been designated as the puf operon of rhodobacter sphaeroides. analysis of puf operon expression in r. sphaeroides by northern hybridization with probes specific for individual structural gene has identified two transcripts encoded by this operon. the large (2.6 kilobase pairs (kb] transcript contains sequences for all four polypeptides of the puf operon, whereas the small (0.5 kb) transcript, which is more a ... | 1986 | 2426264 |
| characterization of the thioredoxin system in the facultative phototroph rhodobacter sphaeroides y. | this paper reports the purification and characterization of a thioredoxin system (thioredoxin, thioredoxin reductase, nadph) from the facultative phototroph rhodobacter sphaeroides y. rhodobacter sph. y thioredoxin was purified to homogeneity with an assay based on the reduction of 5,5'-dithiobis(2-nitrobenzoic acid) by nadph and escherichia coli thioredoxin reductase. rhodobacter sph. y thioredoxin reductase was purified with the same assay using nadph and e. coli thioredoxin. rhodobacter sph. ... | 1986 | 2430804 |
| oxygen-regulated mrnas for light-harvesting and reaction center complexes and for bacteriochlorophyll and carotenoid biosynthesis in rhodobacter capsulatus during the shift from anaerobic to aerobic growth. | the stability and regulation by oxygen of mrnas for the photosynthetic apparatus in rhodobacter capsulatus have been studied by using proflavin to inhibit transcription and by shifting cells from anaerobic to aerobic conditions. the results from the inhibition experiments show that the mrna for the light-harvesting lh-ii polypeptides (beta, alpha) is more stable than that for the light-harvesting lh-i polypeptides (beta, alpha) during anaerobic growth, whereas the mrnas for the reaction center p ... | 1986 | 2430948 |
| evolutionary relationship of denitrifying bacteria as deduced from 5s rrna sequences. | the nucleotide sequences of 5s rrna from seven denitrifying bacteria have been determined. based on these sequences and those reported in the literature (including two denitrifiers), a phylogenic tree of 104 eubacterial 5s rrna sequences has been constructed to establish the position of the denitrifying bacteria. these bacteria belong to either one of the three major subgroups of gram-negative bacteria. the grouping based on 5s rrna sequences is almost compatible with the type of the nitrite red ... | 1986 | 2434470 |
| posttranscriptional regulation by light of the steady-state levels of mature b800-850 light-harvesting complexes in rhodobacter capsulatus. | photosynthetic organisms exhibit a variety of responses to changes in light intensity, including differential biosynthesis of chlorophyll-protein complexes. cultures of rhodobacter capsulatus grown anaerobically with a low intensity of light (2 w/m2) contained about four times as much b800-850 light-harvesting complex as cells grown under high light intensity (140 w/m2). the mrna transcripts encoding b800-850 beta and alpha peptides were analyzed by northern blot (rna blot), s1 nuclease protecti ... | 1988 | 2448296 |
| complete nucleotide sequence of a 23s ribosomal rna gene from rhodobacter capsulatus. | | 1988 | 2451812 |
| in vivo analysis of puf operon expression in rhodobacter sphaeroides after deletion of a putative intercistronic transcription terminator. | the intercistronic region of the mrna derived from the puf operon of rhodobacter sphaeroides is capable of forming two stable stem-loop structures, the first of which resembles a factor-independent transcription terminator. a puf operon construction lacking the putative transcription terminator was made in vitro and crossed into the chromosome of r. sphaeroides pufb1 to yield a single chromosomal copy in the terminator-deleted strain. the mutant strain, designated puf delta 348-420 which was oth ... | 1988 | 2459108 |
| posttranscriptional control of puc operon expression of b800-850 light-harvesting complex formation in rhodobacter sphaeroides. | the puc operon of rhodobacter sphaeroides comprises the pucba structural genes which encode b800-850 light-harvesting beta and alpha polypeptides, respectively. northern (rna) blot hybridization analysis of puc operon expression has identified two pucba-specific transcripts. the small (0.5-kilobase [kb]) transcript encodes the beta and alpha polypeptides and, under photoheterotrophic growth conditions, was approximately 200-fold more abundant than the large (2.3-kb) transcript. the 5' end of the ... | 1989 | 2470727 |
| structural and functional analysis of transcriptional control of the rhodobacter capsulatus puf operon. | we report data indicating that the rhodobacter capsulatus puf operon promoter and the site for its oxygen regulation are located more than 700 base pairs upstream from the previously identified puf genes and have identified the nucleotide sequences that constitute these control signals. a model is proposed in which a polycistronic transcript at least 3.4 kilobases in length is initiated near the o2-regulated promoter and is processed posttranscriptionally by endonucleolytic cleavage at multiple ... | 1989 | 2492501 |
| evolutionary conservation of protein regions in the protonmotive cytochrome b and their possible roles in redox catalysis. | the amino acid sequences of the protonmotive cytochrome b from seven representative and phylogenetically diverse species have been compared to identify protein regions or segments that are conserved during evolution. the sequences analyzed included both prokaryotic and eukaryotic examples as well as mitochondrial cytochrome b and chloroplast b6 proteins. the principal conclusion from these analyses is that there are five protein regions--each comprising about 20 amino acid residues--that are con ... | 1989 | 2509716 |
| nucleotide transport in rhodobacter capsulatus. | cytoplasmic membrane vesicles isolated from the gram-negative photosynthetic bacterium rhodobacter capsulatus catalyzed the transport of nucleotides. no transport occurred in the intact bacteria unless they were pretreated with edta. the transport rate was measured by incorporation of radioactive phosphate into externally added adp or by incorporation of nonradioactive phosphate into added labeled adp. the catalytic activities which utilized the added adp were photosynthetic atp synthesis, pi-ad ... | 1989 | 2512281 |
| isolation of plasmid dna sequences that complement rhodobacter sphaeroides mutants deficient in the capacity for co2-dependent growth. | mutants deficient in the proper regulation and derepression of ribulose-1.5-bisphosphate carboxylase oxygenase (rubpc/o) in rhodobacter sphaeroides were isolated by ethyl methanesulphonate (ems) and tn5 mutagenesis of a reca parental strain. mutants were identified by their ability to grow under conditions where the organism requires basal levels of rubpc c/o for growth yet fail to grow under conditions which require derepression of the enzyme (aut-). the newly isolated aut- mutants exhibited ph ... | 1989 | 2515249 |
| predictions of thermodynamic efficiency in a pumped biochemical reaction. | we propose and analyze a possible experimental system for the investigation of the thermodynamic efficiency of generating biochemical gradients. we investigate the efficiency of a model pump that uses 6-phosphofructokinase (ec 2.7.1.11, an enzyme that exhibits highly nonlinear kinetics), chromatophores from rhodobacter sphaeroides, and light to generate a biochemical gradient. we analyze the experimental system and an equivalent alternative configuration and show that the establishment and maint ... | 1989 | 2531897 |
| crystallization and preliminary x-ray analysis of porin from rhodobacter capsulatus. | porin monomers of the phototrophic bacterium rhodobacter capsulatus were purified. crystals were obtained from a solution of porin solubilized with the detergent octyltetraoxyethylene within 5 days using the vapor phase equilibration technique. the crystals were rhombohedral with an edge length of 0.4 mm. the space group was trigonal r3 with unit cell constants of a = b = 95 a, c = 147 a. reflexions were observed to 3.2 a. | 1989 | 2536626 |
| expression of the rhodobacter sphaeroides cytochrome c2 structural gene. | a rhodobacter sphaeroides mutant (cyca1) lacking cytochrome c2 (cyt c2) was previously constructed (t. j. donohue, a. g. mcewan, s. van doren, a. r. crofts, and s. kaplan, biochemistry, 27: 1918-1924, 1988) by a combination of in vivo and in vitro molecular genetic techniques. cyca1 was incapable of photosynthetic growth (ps-); in this presentation, we show that chemoheterotrophically grown cyca1 contained significant quantities of a high potential soluble c-type cytochrome(s) with an alpha band ... | 1989 | 2536660 |
| isolation of mutants and genes involved in cytochromes c biosynthesis in rhodobacter capsulatus. | mutants of the photosynthetic bacterium rhodobacter capsulatus that have combined deficiencies in the cytochrome b/c1 complex and other c-type cytochromes have been isolated. these mutants were unable to grow anaerobically in the light or dark but could grow aerobically. cosmids with r. capsulatus wild-type dna that complement the mutants have been used to construct genetic and physical maps of the affected genes. complementation profiles with tn5 and mini-mu insertions in these cosmids and subc ... | 1989 | 2536664 |
| identification and isolation of genes essential for h2 oxidation in rhodobacter capsulatus. | mutants of rhodobacter capsulatus unable to grow photoautotrophically with h2 and co2 were isolated. those lacking uptake hydrogenase activity as measured by h2-dependent methylene blue reduction were analyzed genetically and used in complementation studies for the isolation of the wild-type genes. results of further subcloning and transposon tn5 mutagenesis suggest the involvement of a minimum of five genes. hybridization to the 2.2-kilobase-pair ssti fragment that lies within the coding region ... | 1989 | 2536678 |
| a ubiquinone derivative that inhibits mitochondrial cytochrome b-c1 complex but not chloroplast cytochrome b6-f complex activity. | a ubiquinone derivative, 3-chloro-5-hydroxyl-2-methyl-6-decyl- 1,4-benzoquinone (3-chmdb), which shows different effects on the mitochondrial cytochrome b-c1 complex and chloroplast cytochrome b6-f complex, has been synthesized and characterized. when the cytochrome b-c1 complex is treated with varying concentrations of 3-chmdb and assayed at constant substrate (q2h2) concentration, a 50% inhibition is observed when 2 mol of 3-chmdb per mol of enzyme are used. the degree of inhibition is depende ... | 1989 | 2538447 |
| location and magnetic relaxation properties of the stable tyrosine radical in photosystem ii. | dipolar interactions with neighboring metal ions can cause enhanced spin-lattice relaxation of free radicals. we have applied the theory of dipolar relaxation enhancement and shown that the dependence of the enhanced relaxation on the protein structure surrounding the free radical can be used to obtain distances from the free radical to the protein surface. to test the theoretical predictions, we have examined the effect of added dy3+ complexes on the microwave power saturation of free radicals ... | 1989 | 2540815 |
| effect of aerobic growth conditions on the soluble cytochrome content of the purple phototrophic bacterium rhodobacter sphaeroides: induction of cytochrome c554. | when grown anaerobically in the light, rhodobacter sphaeroides contains appreciable quantities of cytochromes c2 and c', but smaller amounts of other soluble cytochromes such as cytochrome c551.5, cytochrome c554, and an oxygen-binding heme protein. when r. sphaeroides is mass cultured aerobically in the dark to stationary phase, the content of cytochrome c2 does not change appreciably, whereas cytochrome c554 is approximately 8-fold more abundant, cytochrome c' is at least 10-fold less abundant ... | 1989 | 2543295 |
| expression of a cytochrome c2 isozyme restores photosynthetic growth of rhodobacter sphaeroides mutants lacking the wild-type cytochrome c2 gene. | deletion of the cytochrome c2 gene in the purple bacterium rhodobacter sphaeroides renders it incapable of phototrophic growth (strain cyca65). however, suppressor mutants which restore the ability to grow phototrophically are obtained at relatively high frequency (1-10 in 10(7)). we examined two such suppressors (strains cyca65r5 and cyca65r7) and found the expected complement of electron transfer proteins minus cytochrome c2: shp, c', c551.5, and c554. instead of cytochrome c2 which elutes fro ... | 1989 | 2543298 |
| role of specific lysine residues in the reaction of rhodobacter sphaeroides cytochrome c2 with the cytochrome bc1 complex. | the reaction of rhodobacter sphaeroides cytochrome c2 with the rb. sphaeroides cytochrome bc1 complex was studied by using singly labeled cytochrome c2 derivatives. cytochrome c2 was treated with chlorodinitrobenzoic acid to modify lysine amino groups to negatively charged carboxydinitrophenyllysines and separated into eight different fractions by ion-exchange chromatography on a whatman se 53 (sulfoxyethyl)cellulose column. peptide mapping studies indicated that six of these fractions were modi ... | 1989 | 2543445 |
| circular dichroic spectroscopy of membrane haemoproteins. the molecular determinants of the dichroic properties of the b cytochromes in various ubiquinol:cytochrome c reductases. | the circular dichroism (cd) of dihaem cytochrome b from mitochondrial and bacterial ubiquinol:cytochrome-c reductase (bc1 complex) has been characterized. the dichroic properties of the yeast purified cyt b are very similar to those of the native cyt b within the mitochondrial bc1 complex. the cd spectra in the soret region of the native cytochrome b present in all species studied show an intense bisignate cotton effect having a zero-crossing wavelength close to the absorbance maximum. in prepar ... | 1989 | 2543573 |
| correlation of paramagnetic states and molecular structure in bacterial photosynthetic reaction centers: the symmetry of the primary electron donor in rhodopseudomonas viridis and rhodobacter sphaeroides r-26. | the orientation of the principal axes of the primary electron donor triplet state measured in single crystals of photosynthetic reaction centers is compared to the x-ray structures of the bacteria rhodobacter (rb.) sphaeroides r-26 and rhodopseudomonas (rps.) viridis. the primary donor of rps. viridis is significantly different from that of rb. sphaeroides. the measured directions of the axes indicate that triplet excitation is almost completely localized on the l-subunit half of the dimer in rp ... | 1989 | 2543969 |
| the coupling between protonmotive force and the nad(p)+ transhydrogenase in chromatophores from photosynthetic bacteria. | 1. the activity of nad(p)+ transhydrogenase in chromatophores of rhodobacter capsulatus relaxed from a high rate during illumination to a lower rate after darkening with a half-time of approximately 100 ms. 2. the dissipative ionic current flowing across the chromatophore membrane was increased in the presence of transhydrogenase substrates. this is attributed to proton current through the transhydrogenase enzyme. subject to the assumption that transhydrogenase does not conduct in the absence of ... | 1989 | 2546762 |
| construction of tnphoa gene fusions in rhodobacter sphaeroides: isolation and characterization of a respiratory mutant unable to utilize dimethyl sulfoxide as a terminal electron acceptor during anaerobic growth in the dark on glucose. | we have constructed a suicide vector, pu1800, containing the transposable element tnphoa (tn5 is50l::phoa), for the purpose of producing protein fusions in vivo between the escherichia coli alkaline phosphatase (apase) and proteins of the facultative photoheterotroph, rhodobacter sphaeroides. we introduced tnphoa into the genome of r. sphaeroides at a coupled conjugation-transposition frequency of approximately 1 x 10(-6). fusions giving rise to apase expression, as judged by blue-colony pigment ... | 1989 | 2546920 |
| carotenoid biosynthesis in photosynthetic bacteria. genetic characterization of the rhodobacter capsulatus crti protein. | carotenoids are photoprotective pigments present in many photosynthetic and nonphotosynthetic organisms. the desaturation of phytoene into phytofluene is an early step in the biosynthetic pathway that in the photosynthetic bacterium rhodobacter capsulatus is mediated by the product of the crti gene. here we report the sequence of this gene and the identification of crti as a membrane protein of approximate mr 60,000. mutant strains with 5-fold lower or 10-fold higher levels of crti with respect ... | 1989 | 2546948 |
| synthesis of rhodobacter sphaeroides cytochrome c2 in escherichia coli. | the cytochrome c2 structural gene, cyca, from rhodobacter sphaeroides was expressed in escherichia coli. cyca-specific mrna was detected in e. coli both under aerobic and anaerobic conditions with trimethylamine-n-oxide as electron acceptor. however mature holocytochrome c2 was only detected in anaerobically-grown cells. the mature form of cytochrome c2 (mr = 12,500) was secreted into the periplasm of e. coli suggesting that the signal polypeptide was processed. the cytochrome c2 synthesized in ... | 1989 | 2547689 |
| genes downstream from pucb and puca are essential for formation of the b800-850 complex of rhodobacter capsulatus. | the formation of the light-harvesting complex b800-850 (lh-ii) of rhodobacter capsulatus requires, in addition to the synthesis of the polypeptides alpha and beta (the gene products of puca and pucb), the synthesis of bacteriochlorophyll and carotenoids and the expression of at least one gene localized downstream from the pucba operon. this was concluded from the observation that a tn5 insertion downstream from pucba inhibited the formation of the lh-ii complex and the formation of the pucba mrn ... | 1989 | 2549005 |
| characterization and localization of phosphatidylglycerophosphate and phosphatidylserine synthases in rhodobacter sphaeroides. | catalytic properties and membrane associations of the phosphatidylglycerophosphate (pgp) and phosphatidylserine (ps) synthases of rhodobacter sphaeroides were examined to further characterize sites of phospholipid biosynthesis. in preparations of cytoplasmic membrane (cm) enriched in these activities, apparent km values of pgp synthase were 90 microm for sn-glycerol-3-phosphate and 60 microm for cdp-diacylglycerol; the apparent km of ps synthase for l-serine was near 165 microm. both enzymes req ... | 1989 | 2549900 |
| genetic evidence for superoperonal organization of genes for photosynthetic pigments and pigment-binding proteins in rhodobacter capsulatus. | three adjacent operons, each concerned with photosynthesis in rhodobacter capsulatus, have been shown by genetic means to be cotranscribable. in the course of describing the characteristics of the bchca operon, which encodes two enzymes essential for bacteriochlorophyll synthesis, we found that the expression of the bchca genes is influenced by readthrough from the upstream crte and crtf genes. the crte and crtf genes encode enzymes required for carotenoid biosynthesis and function as an operon. ... | 1989 | 2550757 |
| monomeric bacteriochlorophyll is required for the triplet energy transfer between the primary donor and the carotenoid in photosynthetic bacterial reaction centers. | reaction centers from the carotenoidless mutant rb. sphaeroides r26 were treated with sodium borohydride which is known to remove one of the accessory monomeric bacteriochlorophylls (bb). subsequently, the carotenoid, spheroidene, was incorporated into the modified reaction centers. it is demonstrated by optical absorption and circular dichroism experiments that spheroidene, reconstituted into the sodium borohydride-treated rb. sphaeroides r26 reaction centers, is bound in a single site, in the ... | 1989 | 2551387 |
| synthesis of different nucleoside 5'-diphospho-sulfoquinovoses and their use for studies on sulfolipid biosynthesis in chloroplasts. | 6-sulfo-alpha-d-quinovopyranosyl phosphate was reacted with different nucleoside monophosphate morpholidates to form adp-, cdp-, gdp- and udp-sulfoquinovose. analytical and preparative hplc of these nucleotides was performed on reversed-phase columns using volatile buffer systems as eluant. the isolated compounds were characterized by nmr spectroscopy (except the cdp derivative) and used for an investigation of sulfolipid biosynthesis by chloroplasts. for this purpose intact spinach chloroplasts ... | 1989 | 2551689 |
| construction, expression, and localization of a cyca::phoa fusion protein in rhodobacter sphaeroides and escherichia coli. | we demonstrated the utility of escherichia coli alkaline phosphatase, encoded by phoa, as a reporter molecule for genetic fusions in rhodobacter sphaeroides. a portion of the r. sphaeroides cyca gene was fused to phoa, yielding a fusion protein comprising the putative signal sequence and first 10 amino acids of the cytochrome c2 apoprotein joined to the sixth amino acid of alkaline phosphatase. the fusion protein was efficiently transported to the periplasm of r. sphaeroides as determined by enz ... | 1989 | 2553661 |
| physical and genetic mapping of the rhodobacter sphaeroides 2.4.1 genome: genome size, fragment identification, and gene localization. | four restriction endonucleases, asei (5'-attaat), spei (5'-actagt), drai (5'-tttaaa), and snabi (5'-tacgta), generated dna fragments of suitable size distributions for mapping the genome of rhodobacter sphaeroides by transverse alternating field electrophoresis. asei produced 17 fragments, ranging in size from 3 to 1,105 kilobases (kb), spei yielded 16 fragments (12 to 1,645 kb), drai yielded at least 25 fragments (6 to 800 kb), and snabi generated 10 fragments (12 to 1,225 kb). a total genome s ... | 1989 | 2553662 |
| the cytochrome bc1 complex of rhodobacter sphaeroides can restore cytochrome c2-independent photosynthetic growth to a rhodobacter capsulatus mutant lacking cytochrome bc1. | plasmids encoding the structural genes for the rhodobacter capsulatus and rhodobacter sphaeroides cytochrome (cyt) bc1 complexes were introduced into strains of r. capsulatus lacking the cyt bc1 complex, with and without cyt c2. the r. capsulatus merodiploids contained higher than wild-type levels of cyt bc1 complex, as evidenced by immunological and spectroscopic analyses. on the other hand, the r. sphaeroides-r. capsulatus hybrid merodiploids produced only barely detectable amounts of r. sphae ... | 1989 | 2553670 |
| role of specific lysine residues in binding cytochrome c2 to the rhodobacter sphaeroides reaction center in optimal orientation for rapid electron transfer. | the role of specific lysine residues in facilitating electron transfer from rhodobacter sphaeroides cytochrome c2 to the rb. sphaeroides reaction center was studied by using six cytochrome c2 derivatives each labeled at a single lysine residue with a carboxydinitrophenyl group. the reaction of native cytochrome c2 at low ionic strength has a fast phase with a half-time of 0.6 microseconds that has been assigned to the reaction of bound cytochrome c2 [overfield, r.e., wraight, c.a., & devault, d. ... | 1989 | 2554961 |
| promoter mapping and nucleotide sequence of the bchc bacteriochlorophyll biosynthesis gene from rhodobacter capsulatus. | because there are not yet direct assays for most of the proteins required for differentiation of rhodobacter capsulatus cytoplasmic membrane into photosynthetically competent intracytoplasmic membrane, a molecular inquiry into the mechanism and regulation of this process is difficult. we have, therefore, chosen to isolate r. capsulatus photosynthesis genes by creating in-frame fusions to lac'z vectors, and selecting for those that direct appropriately regulated levels of beta-galactosidase in r. ... | 1989 | 2555268 |
| mutations conferring resistance to quinol oxidation (qz) inhibitors of the cyt bc1 complex of rhodobacter capsulatus. | several spontaneous mutants of the photosynthetic bacterium rhodobacter capsulatus resistant to myxothiazol, stigmatellin and mucidin--inhibitors of the ubiquinol: cytochrome c oxidoreductase (cyt bc1 complex)--were isolated. they were grouped into eight different classes based on their genetic location, growth properties and inhibitor cross-resistance. the petabc (fbcfbc) cluster that encodes the structural genes for the rieske fes protein, cyt b and cyt c1 subunits of the cyt bc1 complex was c ... | 1989 | 2556259 |
| electron transport pathways to nitrous oxide in rhodobacter species. | 1. electron transport components involved in nitrous oxide reduction in several strains of rhodobacter capsulatus and in the denitrifying strain of rhodobacter sphaeroides (f. sp. denitrificans) have been investigated. detailed titrations with antimycin a and myxothiazol, inhibitors of the cytochrome bc1 complex, show that part of the electron flow to nitrous oxide passes through this complex. the sensitivity to myxothiazol varies between strains and growth conditions of r. capsulatus; the highe ... | 1989 | 2556273 |
| role of glutamine as a direct co-repressor of glutamine synthetase in rhodobacter capsulatus e1f1. | high performance liquid chromatography (hplc) has been used to determine the internal levels of amino acids in rhodobacter capsulatus e1f1 cells, subjected to different treatments and nutritional conditions. glutamine synthetase activity and enzyme concentration correlated negatively with the level of glutamine, suggesting that glutamine per se acts as a co-repressor in the enzyme synthesis. moreover, addition of the specific inhibitor l-methionine-d,l-sulfoximine, that produced an increase in e ... | 1989 | 2566555 |
| pathway of proton transfer in bacterial reaction centers: replacement of glutamic acid 212 in the l subunit by glutamine inhibits quinone (secondary acceptor) turnover. | the mechanism of proton transfer in the reaction centers (rcs) from rhodobacter sphaeroides was investigated by site-directed mutagenesis. replacement of glu-212 of the l subunit, a protonatable residue located near the secondary acceptor (qb) binding site, by glutamine reduced the in vitro electron turnover from cytochrome c to 2,3-dimethoxy-5-methylbenzoquinone (uq0) by a factor of 25. the electron transfer rate to qb remained essentially unimpaired. consequently, it is postulated that the red ... | 1989 | 2570421 |
| allosteric regulation of the state of adenylylation of glutamine synthetase in permeabilized cell preparations of rhodopseudomonas sphaeroides. | following a freeze-thaw cycle, and the treatment of rhodopseudomonas sphaeroides with the nonionic detergent lubrol px, the permeabilized cell suspensions can be assayed directly both for the intracellular levels of glutamine synthetase and the state of adenylylation (i.e. the average number n of adenylylated subunits/dodecameric molecules). it seems that all components of the bicycle system are retained if cells grown with low concentrations of ammonia as the sole nitrogen source are used. the ... | 1989 | 2575389 |
| effects of light, oxygen, and substrates on steady-state levels of mrna coding for ribulose-1,5-bisphosphate carboxylase and light-harvesting and reaction center polypeptides in rhodopseudomonas sphaeroides. | the mrna levels specific for ribulose-1,5-bisphosphate carboxylase, light-harvesting i polypeptides alpha and beta, and reaction center polypeptides l and m were assayed by use of a series of dna probes specific for each cognate mrna. both the steady-state amounts and sizes of the specific mrnas were measured as a function of the light intensity incident to the culture, the presence or absence of oxygen, and the type of substrate present in the growth medium. northern hybridization revealed at l ... | 1985 | 2581935 |
| nucleotide sequence of the gene encoding the rsri methyltransferase. | | 1989 | 2602165 |
| transient optical spectroscopy of single crystals of the reaction center from rhodobacter sphaeroides wild-type 2.4.1. | the photoactivity of the crystallized reaction centers from rhodobacter sphaeroides wild-type strain 2.4.1 has been examined by light-induced absorption spectral changes associated with charge separation and triplet state formation in the reaction center. upon excitation of a crystal at ambient redox potential, the primary donor 865 nm band bleaches reversibly. the kinetics of its recovery were found to be biphasic with rate constants 11.5 +/- 1.3 s-1 and 0.9 +/- 0.4 s-1 which correspond to life ... | 1989 | 2643991 |
| control of photosynthetic membrane assembly in rhodobacter sphaeroides mediated by puha and flanking sequences. | a reaction center h- strain (rch-) of rhodobacter sphaeroides, puha1, was made by in vitro deletion of an xhoi restriction endonuclease fragment from the puha gene coupled with insertion of a kanamycin resistance gene cartridge. the resulting construct was delivered to r. sphaeroides wild-type 2.4.1, with the defective puha gene replacing the wild-type copy by recombination, followed by selection for kanamycin resistance. when grown under conditions known to induce intracytoplasmic membrane deve ... | 1989 | 2644200 |
| absence of a bicarbonate-depletion effect in electron transfer between quinones in chromatophores and reaction centers of rhodobacter sphaeroides. | higher plants, algae, and cyanobacteria are known to require bicarbonate ions for electron flow from the first stable electron acceptor quinone qa to the second electron acceptor quinone qb, and to the intersystem quinone pool. it has been suggested that in photosystem ii of oxygenic photosynthesis, bicarbonate ion functions to maintain the reaction center in a proper conformation and, perhaps, to provide the protons needed to stabilize the semiquinone (qb-). in this paper, we show that bicarbon ... | 1989 | 2647143 |
| in photosynthetic reaction centers, the free energy difference for electron transfer between quinones bound at the primary and secondary quinone-binding sites governs the observed secondary site specificity. | the secondary quinone-binding site (qb site) of bacterial reaction centers from rhodobacter sphaeroides is generally regarded to be highly specific for its native ubiquinone-10 molecule. we demonstrate here that this is a misconception rooted in the kinetic methods used to assay for occupancy of a quinone in the qb site. we show that observance of occupancy of the qb site, revealed by kinetic assay, is sensitive to the free-energy difference for electron transfer between the quinone at the prima ... | 1989 | 2649889 |
| the primary structure of the chloroflexus aurantiacus reaction-center polypeptides. | the complete nucleotide sequence of two chloroflexus aurantiacus reaction-center genes has been obtained. the amino acid sequence deduced from the first gene showed 40% similarity to the l subunit of the rhodobacter sphaeroides reaction center. this l subunit was 310 amino acids long and had an approximate molecular mass of 35 kda. the second gene began 17 bases downstream from the first gene. the amino acid sequence deduced from it (307 amino acids; 34950 da) was 42% similar to the m subunit of ... | 1989 | 2651125 |
| organization and expression of genes for photosynthetic pigments-protein complexes in photosynthetic bacteria. | | 1989 | 2653478 |
| gene transfer system for rhodopseudomonas viridis. | a gene transfer system for rhodopseudomonas viridis was established which uses conjugation with escherichia coli s17-i as the donor and mobilizable plasmids as vectors. initially, plasmids of the incompatibility group p1 (prk290 and prk404) were used. the more effective shuttle vectors between e. coli and r. viridis, pkv1 and pkvs1, were derived from plasmid pbr322 and showed the highest conjugation frequency (10(-2] thus far demonstrated in purple bacteria. it was also demonstrated that rhizobi ... | 1989 | 2666398 |
| hydrophobic organization of membrane proteins. | membrane-exposed residues are more hydrophobic than buried interior residues in the transmembrane regions of the photosynthetic reaction center from rhodobacter sphaeroides. this hydrophobic organization is opposite to that of water-soluble proteins. the relative polarities of interior and surface residues of membrane and water soluble proteins are not simply reversed, however. the hydrophobicities of interior residues of both membrane and water-soluble proteins are comparable, whereas the bilay ... | 1989 | 2667138 |
| formation of functional inter-species hybrid photosynthetic complexes in rhodobacter capsulatus. | a rhodobacter capsulatus mutant strain deficient in all pigment-binding peptides and hence incapable of photosynthetic growth was genetically complemented with a plasmid-borne copy of the rhodobacter sphaeroides puf operon. hybrid reaction centers composed of r. sphaeroides l and m and r. capsulatus h subunits assembled in vivo, and host cells were photosynthetically competent. light-harvesting complex b875, also encoded by the r. sphaeroides puf operon, was present along with the hybrid reactio ... | 1989 | 2668034 |
| immunological detection of phytoene desaturase in algae and higher plants using an antiserum raised against a bacterial fusion-gene construct. | immunological characterization of phytoene desaturase, a key enzyme of carotenoid biosynthesis, is reported. for this purpose, a phytoene-desaturase fusion protein has been employed. for its construction 921 base pairs of the crti gene were fused to the n-terminal region of the escherichia coli lacz gene. plasmid pgabx2 resulted from insertion of a bgli - xhoi fragment from the rhodobacter capsulatus carotenoid biosynthesis gene cluster, carrying the crti, crta and crtb genes, into pbr322. a 968 ... | 1989 | 2676534 |
| isolation of a high frequency donor of rhodobacter capsulatus by integration of the plasmid pmt1000 into the chromosome. | the temperature-independent clone of rhodobacter capsulatus ua7041, carrying the temperature-sensitive plasmid pmt1000, has been obtained by selection for plasmid markers at the non-permissive temperature. the transfer to escherichia coli of all drug resistance encoded by pmt1000 was of about 10(-7) when the donor was the ua7041 strain, and of 5 x 10(-4) when the donor was the temperature-sensitive strain of r. capsulatus. electrophoretic analyses showed no plasmid band typical of the autonomous ... | 1989 | 2679770 |
| molecular cloning and sequence analysis of the structural gene of ferredoxin i from the photosynthetic bacterium rhodobacter capsulatus. | the structural gene (fdxn) encoding ferredoxin i (fdi) in the photosynthetic bacterium rhodobacter capsulatus was isolated from a cosmid library by using an oligonucleotide probe corresponding to the n-terminal amino acid sequence of fdi. the nucleotide sequences of the gene and of the 3'- and 5'-flanking regions were determined. the gene fdxn codes for a polypeptide of 64 mino acids having a calculated molecular weight of 6,728. amino acid sequencing of the n- and c-terminal ends of fdi allowed ... | 1989 | 2681157 |
| orientation of reaction center complexes from rhodobacter sphaeroides in proteoliposomes and the effect of o-phenanthroline on electrogenesis during primary photochemical reaction. | the orientation of rhodobacter sphaeroides reaction center complexes (rc complexes) in proteoliposomal membranes was investigated by a direct electrometric method. conditions were found that allow monitoring of only that rc complex fraction that is oriented with its donor side to the inner part of the proteoliposome. it is shown that o-phenanthroline, an inhibitor of electron transfer between primary (qa) and secondary (qb) quinone acceptors, can also inhibit the photoinduced qa reduction. the e ... | 1989 | 2681179 |
| linear optimization of predictors for secondary structure. application to transbilayer segments of membrane proteins. | sliding-window averaging of amino acid properties is a standard method for predicting protein secondary structure. for example, transmembrane segments are predicted to occur near the peaks in a hydropathy plot of a membrane protein. such a scheme (linear convolutional recognizer, lcr) assigns a number (weight) to each type of monomer, and then convolutes some window function with the sequence of weights. the window has commonly been rectangular, and the weights derived from singlet amino acid fr ... | 1989 | 2685329 |
| structure of spheroidene in the photosynthetic reaction center from y rhodobacter sphaeroides. | the structure of the reaction center of y rhodobacter sphaeroides has been solved at 3 a resolution, using the atomic coordinates of the reaction center from the carotenoidless mutant r26 rhodobacter sphaeroides. the structure has been refined by a stimulated annealing with the computer program x-plor, leading to a crystallographic r factor of 0.22 using reflections between 8 and 3 a. the spheroidene molecule which is bound to the y reaction center has been fitted in the electron density map as ... | 1989 | 2687022 |
| purification, cloning and sequence analysis of rsri dna methyltransferase: lack of homology between two enzymes, rsri and ecori, that methylate the same nucleotide in identical recognition sequences. | rsri dna methyltransferase (m-rsri) from rhodobacter sphaeroides has been purified to homogeneity, and its gene cloned and sequenced. this enzyme catalyzes methylation of the same central adenine residue in the duplex recognition sequence d(gaattc) as does m-ecori. the reduced and denatured molecular weight of the rsri methyltransferase (mtase) is 33,600 da. a fragment of r. sphaeroides chromosomal dna exhibited m.rsri activity in e. coli and was used to sequence the rsrim gene. the deduced amin ... | 1989 | 2690017 |
| characterization and complementation of a mutant of rhodobacter sphaeroides with a chromosomal deletion in the light-harvesting (lh2) genes. | an lh2- strain of rhodobacter sphaeroides, dbc1, has been constructed by deleting the puc operon, which encodes the lh2 alpha and beta polypeptides, from the chromosome and replacing it with a kanamycin resistance gene. southern blot analysis indicates that the 950 bp bamhi restriction fragment which contains the puc operon has been lost and has been replaced by the 1.25 kb km(r) cassette derived from tn903. strain dbc1 lacked the lh2 complex, as shown by loss of the characteristic absorbance ba ... | 1989 | 2693605 |
| comparison of the nucleotide and amino acid sequences of the rsri and ecori restriction endonucleases. | the rsri endonuclease, a type-ii restriction endonuclease (enase) found in rhodobacter sphaeroides, is an isoschizomer of the ecori enase. a clone containing an 11-kb bamhi fragment was isolated from an r. sphaeroides genomic dna library by hybridization with synthetic oligodeoxyribonucleotide probes based on the n-terminal amino acid (aa) sequence of rsri. extracts of e. coli containing a subclone of the 11-kb fragment display rsri activity. nucleotide sequence analysis reveals an 831-bp open r ... | 1989 | 2695392 |
| open reading frame 5 (orf5), encoding a ferredoxinlike protein, and nifq are cotranscribed with nife, nifn, nifx, and orf4 in rhodobacter capsulatus. | dna sequence analysis of a 1,600-base-pair fragment located downstream of nifenx in nif region a of rhodobacter capsulatus revealed two additional open reading frames (orfs): orf5, encoding a ferredoxinlike protein, and nifq. the ferredoxinlike gene product contained two cysteine motifs, typical of ferredoxins coordinating two 4fe-4s clusters, but the distance between these two motifs was unusual for low-molecular-weight ferredoxins. the r. capsulatus nifq gene product shared a high degree of ho ... | 1989 | 2708314 |
| the dna sequence of the rhodobacter capsulatus ntra, ntrb and ntrc gene analogues required for nitrogen fixation. | we have determined the dna sequence for the genes nifr1, nifr2 and nifr4 in the photosynthetic bacterium rhodobacter capsulatus. these genes regulate transcription of the nifhdk operon and so limit the expression of nitrogen fixation activity to periods of low environmental concentrations of both oxygen and fixed nitrogen. the sequences of these three genes are similar to components of the ntr regulation system in escherichia coli and klebsiella pneumoniae. the two-component regulatory system of ... | 1989 | 2710108 |
| structural analysis of the nontoxic lipid a of rhodobacter capsulatus 37b4. | lipid a from rhodobacter capsulatus 37b4 consists of a d-glucosaminyl-(beta 1-6)-d-glucosamine disaccharide backbone, carrying diphosphorylethanolamine at c-1 of the reducing glucosamine and phosphorylethanolamine at c-4' of the nonreducing glucosamine. 1,4'-bisphosphorylated lipid a, lacking the polar head groups, was also encountered and contributed to the observed microheterogeneity in the phosphate substitution. the amino functions of both glucosamines are substituted almost entirely by the ... | 1989 | 2714269 |
| purification and properties of l-alanine dehydrogenase of the phototrophic bacterium rhodobacter capsulatus e1f1. | in the phototrophic nonsulfur bacterium rhodobacter capsulatus e1f1, l-alanine dehydrogenase aminating activity functions as an alternative route for ammonia assimilation when glutamine synthetase is inactivated. l-alanine dehydrogenase deaminating activity participates in the supply of organic carbon to cells growing on l-alanine as the sole carbon source. l-alanine dehydrogenase is induced in cells growing on pyruvate plus nitrate, pyruvate plus ammonia, or l-alanine under both light-anaerobic ... | 1989 | 2722749 |
| purification and properties of the membrane-associated coenzyme f420-reducing hydrogenase from methanobacterium formicicum. | the membrane-associated coenzyme f420-reducing hydrogenase of methanobacterium formicicum was purified 87-fold to electrophoretic homogeneity. the enzyme contained alpha, beta, and gamma subunits (molecular weights of 43,000, 36,700, and 28,800, respectively) and formed aggregates (molecular weight, 1,020,000) of a coenzyme f420-active alpha 1 beta 1 gamma 1 trimer (molecular weight, 109,000). the hydrogenase contained 1 mol of flavin adenine dinucleotide (fad), 1 mol of nickel, 12 to 14 mol of ... | 1989 | 2738024 |
| nucleotide sequence, organization, and nature of the protein products of the carotenoid biosynthesis gene cluster of rhodobacter capsulatus. | carotenoid pigments are essential for the protection of both photosynthetic and non-photosynthetic tissues from photooxidative damage. although carotenoid biosynthesis has been studied in many organisms from bacteria to higher plants, little is known about carotenoid biosynthetic enzymes, or the nature and regulation of the genes encoding them. we report here the first dna sequence of carotenoid genes from any organism. we have determined the complete nucleotide sequence (11,039 bp) of a gene cl ... | 1989 | 2747617 |
| dna sequence and genetic analysis of the rhodobacter capsulatus nifenx gene region: homology between nifx and nifb suggests involvement of nifx in processing of the iron-molybdenum cofactor. | rhodobacter capsulatus genes homologous to klebsiella pneumoniae nife, nifn and nifx were identified by dna sequence analysis of a 4282 bp fragment of nif region a. four open reading frames coding for a 51,188 (nife), a 49,459 (nifn), a 17,459 (nifx) and a 17,472 (orf4) dalton protein were detected. a typical nifa activated consensus promoter and two imperfect putative nifa binding sites were located in the 377 bp sequence in front of the nife coding region. comparison of the deduced amino acid ... | 1989 | 2747620 |
| 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 |
| susceptibility of rhodobacter sphaeroides to beta-lactam antibiotics: isolation and characterization of a periplasmic beta-lactamase (cephalosporinase). | thirteen strains of the gram-negative, facultative phototrophic bacterium rhodobacter sphaeroides were examined fro susceptibility to beta-lactam antibiotics. all strains were sensitive to the semisynthetic penicillins ampicillin, carbenicillin, oxacillin, cloxacillin, and methicillin, but 10 of the 13 strains were resistant to penicillin g, as well as a number of cephalosporins, such as cephalothin, cephapirin, and cephalosporin c. a beta-lactamase (ec 3.5.2.6) with strong cephalosporinase acti ... | 1989 | 2783689 |
| 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 |
| role of metabolism in the chemotactic response of rhodobacter sphaeroides to ammonia. | rhodobacter sphaeroides only showed chemotaxis towards ammonia if grown under nitrogen-limited conditions. this chemotactic response was completely inhibited by the addition of methionine sulfoximine. there was no effect of methionine sulfoximine treatment on motility or taxis towards propionate, demonstrating that the effect is specific to ammonia taxis. it is known that methionine sulfoximine inhibits glutamine synthetase and hence blocks ammonia assimilation. methionine sulfoximine does not i ... | 1989 | 2785106 |
| purification, characterization, and transcriptional analyses of rna polymerases from rhodobacter sphaeroides cells grown chemoheterotrophically and photoheterotrophically. | rna polymerase was purified from rhodobacter sphaeroides cells grown both chemoheterotrophically and photoheterotrophically. both preparations of polymerase were comprised of five major subunits designated: beta' (160,000 da), beta (150,000 da), sigma (93,000 da), alpha (41,000 da), and a 35,000-da protein, designated epsilon. all five subunits of the polymerase isolated from photoheterotrophically grown cells were found to be serologically related to the major subunits (beta', beta, sigma, and ... | 1989 | 2788164 |