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  • 1
    Electronic Resource
    Electronic Resource
    Isolation of phosphorylation-deficient mutants of the Rhizobium Meliloti two-component regulatory protein, FixJ (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 6 (1992), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Rhizobium meliloti FixL and FixJ are members of a symbiotically essential two-component system that regulates nitrogen-fixation genes in response to environmental oxygen concentrations. FixL is a membrane protein that is thought to relay information about oxygen availability to FixJ via a phosphotransfer mechanism. FixJ increases expression of the nifA and fixK genes by activating transcription of the nifA and fixK promoters (p-nifA and p-fixK, respectively). In this study, we examined the relationship between the in vivo activity of FixJ as a transcriptional regulator and its ability to be phosphorylated in vitro by the sensor FixL. FixJ mutants were isolated that showed decreased activity on p-nifA in Escherichia coli. Most of the FixJ mutant proteins also showed decreased activity on the fixK promoter. These mutants were analysed in R. meliloti for activity on p-nifA during vegetative growth, where similarities and differences were observed when compared with their phenotypes in E. coli. Three mutants showing significantly less activity in R. meliloti were examined for symbiotic activity in planta and were found to be ineffective. When these three mutant FixJ proteins were examined in vitro for their ability to be phosphorylated by FixL, two mutants were found to have a significantly decreased ability to accept phosphate from FixL. These findings are discussed in relation to signal transduction in the FixLJ system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1992.tb01377.x
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of poly(3-hydroxybutyrate) (PHB) content on the starvation-survival of bacteria in natural waters (1995)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 16 (1995), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The effect of poly(3-hydroxybutyrate) (PHB) content on the survival of wild-type strains and PHB negative mutants of Bacillus megaterium and Alcaligenes eutrophus in natural waters was studied. The survival strategy of B. megaterium was dominated by the development of resistant forms, but the number of the wild-type vegetative cells was higher than that of PHB mutant strain. In some environmental conditions the mutant spores needed a heat shock for germination, a fact that suggests, for the first time, that PHB plays a role in this phenomenon. Survival of A. eutrophus wild-type strain in all experiments was higher compared to the PHB mutant, and differences were significant. In raw river water, survival of both species was lower than in sterile river water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.1995.tb00273.x
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  • 3
    Electronic Resource
    Electronic Resource
    Phosphorylation of the α and β polypeptides of the light-harvesting complex I (B870) of Rhodobacter capsulatus in an in vitro translation system (1994)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 124 (1994), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Synthesis and phosphorylation of the proteins α and β of the light-harvesting (LH) complex I (B870) were investigated in a cell-free translation system of Rhodobacter capsulatus. Both proteins were incorporated into the membrane fraction; LHIβ was inserted in the absence of LHIα was phosphorylated in the presence of [γ-32P]ATP only when membranes were present. Phosphorylated LHIβ was found only in the absence of membranes. The phosphate group bound to LHIβ was not transferred to LHIα during insertion. The results indicate that a membrane-bound and a soluble protein kinase are involved. Strong light reduced the amount of phosphorylated LHIα. The results are discussed with respect to the assembly and function of LHI.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1994.tb07266.x
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  • 4
    Electronic Resource
    Electronic Resource
    Fusion of proteoliposomes containing the B800-850 light-harvesting complex with membranes of the mutant strain NK3 of Rhodopseudomonas capsulata lacking B800-850 (1985)
    Springer
    Archives of microbiology 141 (1985), S. 239-243 
    Details
    ISSN: 1432-072X
    Keywords: Absorption spectra ; Fluorescence emission spectra ; Carotenoid band shift ; Excition transfer ; Light-harvesting complexes ; Rhodopseudomonas capsulata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Intracytoplasmic membranes of the mutant strain NK3 of Rhodopseudomonas capsulata lacking the lightharvesting complex B800-850 were fused with proteoliposomes containing the B800-850 complex. Fluorescence emission spectroscopy at 77K showed that after fusion the fluorescence of the B850 bacteriochlorophyll disappeared nearly completely and the B870 fluorescence became prominent. This result and control experiments with proteoliposome-chromatophore mixture and with chromatophore and solubilized B800-850 complexes, respectively, indicate that in fused membranes a reorientation of membrane particles took place and excitons migrated from B850 to B870 bacteriochlorophyll. In fused proteoliposome-chromatophore vesicles a light-induced carotenoid band shift was observed, reflecting the building of an electrical membrane potential due to chargeseparation. Carotenoid band shift was not observed in separated proteoliposomes and NK3 chromatophores. It is concluded that by membrane fusion and lateral diffusion of membrane particles reaction center-light-harvesting B870 complexes came in functional contact with B800-850 antenna complexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408065
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  • 5
    Electronic Resource
    Electronic Resource
    Occurrence of oscillations in ATP synthesis and hydrolysis in chromatophores of Rhodospirillum rubrum (1985)
    Springer
    Archives of microbiology 143 (1985), S. 192-195 
    Details
    ISSN: 1432-072X
    Keywords: Oscillations ; Photophosphorylation ; ATPase ; Cooperative behaviour ; Chromatophores ; Rhodospirillum rubrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The conditions under which an oscillatory behaviour is observed during net hydrolysis or synthesis of ATP in chromatophores of Rhodospirillum rubrum FR1 are described. In the case of ATPase the oscillations are observed at low temperature (ca. 11°C) in the dark after an initial transient behaviour. These oscillations are attenuated or disappear by the addition of an uncoupler. Oscillations are also observed during ATP synthesis. At 3°C the oscillations appear spontaneously if photophosphorylation is measured during a sufficiently long time. At 30°C the mere intercalation of a dark period also at 30°C is sufficient to trigger the oscillations in the following light period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00411046
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  • 6
    Electronic Resource
    Electronic Resource
    Isolation and purification of reaction center from Rhodopseudomonas viridis NHTC 133 by means of LDAO (1976)
    Springer
    Archives of microbiology 109 (1976), S. 301-305 
    Details
    ISSN: 1432-072X
    Keywords: Photosynthetic membrane ; Reaction center ; Quinones ; Cytochromes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two different procedures are described to isolate and purify the reaction center complex from Rhodopseudomonas viridis NHTC 133 by means of the non-ionic detergent dodecyldimethylamine oxide. Both reaction center particles thus obtained were active, as shown by a photobleaching centered at 975 nm. The reaction center also contained, in addition to bacteriochlorophyll, bacteriopheophytin. Other components were also found in this particle: cytochromes C553 and C558 and a menaquinone-like substance. The SDS gel electrophoresis of reaction centers is shown. The molecular weights of the subunits forming the reaction center in 0.5% sodium dodecyl sulfate and 1% mercaptoethanol were calculated as being: 45±1.5 and 37±1.5 kdalton, 29±1.5 and 23±1.5 kdalton. The molecular weight of the complex determined by means of gel filtration (Sepharose 6-B and Bio-Gel P-300) gives a value of approximately 240 kdalton. The minimum molecular weight of the complex calculated by disc gel electrophoresis was 231 kdalton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446642
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  • 7
    Electronic Resource
    Electronic Resource
    Characterization of three membrane fractions isolated from cells of Rhodopseudomonas capsulata adapting from chemotrophic to phototrophic conditions (1980)
    Springer
    Archives of microbiology 127 (1980), S. 157-161 
    Details
    ISSN: 1432-072X
    Keywords: Rhodopseudomonas capsulata ; Membrane differentiation ; Photophosphorylation ; Succinate dehydrogenase ; NADH dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By means of sucrose density centrifugation three membrane fractions, named “light, medium and heavy” have been isolated from cells of Rhodopseudomonas capsulata strain 37b4, adapting from chemotrophic to phototrophic growth conditions. Succinate dehydrogenase activity of aerobically grown cells was mainly confined to the heavy (chromatophore) fraction. Upon changing to phototrophic conditions the activity of the succinate dehydrogenase increased in the medium and light fraction. All fractions contain bacteriochlorophyll. NADH dehydrogenase of chemotrophically grown cells was enriched in the light and medium fraction but is increased in the heavy fraction under phototrophic growth conditions. The capacity of photophosphorylation is high in the light and heavy fraction. The results indicate a differentially incorporation of functional subunits into specific parts of the membrane system during membrane differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428019
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  • 8
    Electronic Resource
    Electronic Resource
    Differentiation of the membrane system in cells of Rhodopseudomonas capsulata after transition from chemotrophic to phototrophic growth conditions (1982)
    Springer
    Archives of microbiology 131 (1982), S. 313-322 
    Details
    ISSN: 1432-072X
    Keywords: Membrane differentiation ; Buoyant density ; Photosynthetic units ; Bacteriochlorophyll, emission, absorption ; Phospholipids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aerobically in the dark grown cultures of Rhodopseudomonas capsulata were shifted to low oxygen partial pressure for 30 min and afterwards to phototrophic conditions (anaerobic, light). During 210 min of adaptation to a phototrophic mode of life the bacteriochlorophyll (BChl) concentration increased 53-fold (doubling time 40 min) and the carotenoid content six fold. Growth was delayed. The light membrane fraction from chemotrophic and induced phototrophic cells contained low concentrations of small photosynthetic units (reaction center+light harvesting BChl B870), and low respiratory activities, especially of succinatecytochrome c oxidase. The heavy membrane fraction, i.e. the intracytoplasmic chromatophore fraction, increased during adaptation approximately 9-fold in surface area per cell, 42-fold in BChl content, 7-fold in reaction center content and 6-fold in the size of the photosynthetic unit. Phospholipid and fatty acid content and patterns changed slightly during adaptation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00411178
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  • 9
    Electronic Resource
    Electronic Resource
    Comparative studies on membranes isolated from Rhodopseudomonas viridis grown in the presence and in the absence of yeast extract (1974)
    Springer
    Archives of microbiology 101 (1974), S. 259-272 
    Details
    ISSN: 1432-072X
    Keywords: Photosynthetic Membrane ; Lipid and Protein Composition ; Reaction Center
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rhodopseudomonas viridis was grown in the presence and in the absence of yeast extract. The cells grown under this latter condition present a ten fold diminished bacteriochlorophyll (bchl) content. This decrease was paralleled by a similar increase in the ratio lipid phosphorous/bchl, whereas the ornithine lipid/bchl ratio remains constant. Some quantitative differences in the fatty acid composition are also reported. The protein composition of both membranes was also studied, only indicating quantitative differences. An active reaction center preparation was obtained from both types of cells. When isolated from cells grown in the presence of yeast extract, this reaction center preparation shows the presence of proteins a, b, c and d. Further treatment of this active reaction center results, in cells grown under either condition, in the isolation of green (oxidized behl) and brown (inactive reaction center) bchl containing fractions. The protein composition and absorption spectrum of the inactive reaction centers obtained from both types of cells were identical (proteins a, c and d). On the other hand the green complexes differ in their protein composition as well as in their absorption spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00455943
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  • 10
    Electronic Resource
    Electronic Resource
    Heterogeneity of the coupling factor isolated from Rhodospirillum rubrum chromatophores by means of lithium chloride (1980)
    Springer
    Archives of microbiology 125 (1980), S. 149-152 
    Details
    ISSN: 1432-072X
    Keywords: ATPase ; Coupling factor ; Photophosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By means of 2.0 M lithium chloride we have been able to extract a coupling factor protein complex from membranes of Rhodospirillum rubrum strain W. The subunit composition analyzed by SDS-gel electrophoresis showed the presence of both the α and β subunits. The coupling factor protein analyzed by nondissociating gel electrophoresis indicated the presence of two protein bands (Protein I and II), of which only one showed Ca-ATPase activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403212
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