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  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    Bioenergetic factors controlling in vitro phosphorylation of LHIα (B870) polypeptides in membranes isolated from Rhodobacter capsulatus (1996)
    Springer
    Archives of microbiology 165 (1996), S. 119-125 
    Details
    ISSN: 1432-072X
    Keywords: Key words Protein phosphorylation ; ATP-Pi exchange ; Light-harvesting complexes ; Reaction center ; Photosynthesis ; Photomorphogenesis ; Membrane ; growth ; Polypeptide insertion ; Phospho-amino esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Membranes of Rhodobacter capsulatus strain U43 (pTX35) showed qualitatively very similar phosphorylation patterns under in vitro and in vivo conditions. In vitro, it was irrelevant whether the phosphate source was orthophosphate or ATP. Inhibitors of electron transport did not inhibit light-harvesting complex I (LHIα) (B870) polypeptide phosphorylation, except for o-phenanthroline, which was strongly inhibitory. Redox conditions regulated the amount of protein phosphorylated; external redox potentials between +200 and +300 mV promoted the reaction. Phosphorylation was inhibited by uncouplers such as carbonyl cyanide m-chlorophenyl hydrazone and nigericin plus valinomycin plus potassium ions. Inhibitors of the H+-ATPase were also inhibitory when the phosphate source was [32P]Pi or [γ-32P]ATP. From these results, it was concluded that an operative reaction center, a coupled membrane, and external redox potentials higher than +200 mV are required for optimum LHIα phosphorylation. We also demonstrated that phosphorylation of LHIα polypeptide occurs before insertion into the membrane and that phosphate is preferentially incorporated into specific domains within the cytoplasmic membrane. Intracytoplasmic membranes, identified here as light membranes, were found to contain a dephosphorylated LHIα polypeptide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050306
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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    The reconstitution of photophosphorylation and the effect of inorganic phosphate at different pH's on the phenazine methosulfate photoinhibition of Rhodospirillum rubrum chromatophores (1979)
    Springer
    Archives of microbiology 120 (1979), S. 283-287 
    Details
    ISSN: 1432-072X
    Keywords: PMS photoinhibition ; Photophosphorylation ; Chromatophores ; Bacteriochlorophyll ; Coupling factor ; Structural changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Preillumination of R. rubrum membranes in the presence of 50μM phenazine methosulfate produces an inhibition of their photophosphorylating capacity. At low pH's phosphate protects against this photo-inhibition, whereas increasing the pH eliminates this protective effect. The inhibition can be produced not only by preillumination at high pH in the presence of phenazine methosulfate, but also by preillumination at low pH (5.0) and then shifting the pH to 8.0 in the dark. We have also measured the effect of preillumination in the presence of an uncoupler such as carbonylcyanide p-trifluoromethoxyphenylhydrazone, and found that at normal pH's while photophosphorylation was protected, the uncoupler activated ATPase was inhibited pointing to a clear difference for both reactions and perhaps different structural requirements for their activities. The purified coupling factor protein isolated from either normal or photoinactivated membrane will reconstitute normal photophosphorylation in previously uncoupled membranes but not in uncoupled membranes which were inactivated by preillumination with phenazine methosulfate prior to uncoupling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00423077
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  • 7
    Electronic Resource
    Electronic Resource
    Temperature dependency of the Mg-ATPase and photophosphorylation activities in Rhodospirillum rubrum chromatophores (1985)
    Springer
    Archives of microbiology 140 (1985), S. 365-368 
    Details
    ISSN: 1432-072X
    Keywords: Photophosphorylation ; ATP hydrolysis ; Arrhenius plots ; Rhodospirillum rubrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Arrhenius plots for ATP synthesis, coupled to endogenous and Phenazine methosulfate or N,N,N′,N′,-Tetramenthyl-1,4-Phenylene diamine-mediated photosynthetic election transport and for ATP hydrolysis were studied in Rhodospirillum rubrum chromatophores. Coupled or uncoupler induced Mg-ATPase show no discontinuity in the range tested (30°C-5°C) and they also have the same activation energy. Phenazine methosulfatecatalyzed photophosphorylation has also a single activation energy where as the endogenous reaction shows complex and ageing dependent behaviour, alternating temperature ranges having high (45.2 to 144,4 kJ·mol-1) and very low (ca 0.0 to 3.3 kJ·mol-1) activation energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446979
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  • 8
    Electronic Resource
    Electronic Resource
    Association of LHIα(B870) Polypeptide with Phospholipids During Insertion in the Photosynthetic Membrane of an LHII− Mutant of Rhodobacter capsulatus (1997)
    Springer
    Current microbiology 34 (1997), S. 155 -161 
    Details
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Membranes from in vivo labeled cells of Rhodobacter capsulatus U43[pTX35] grown photosynthetically carried 60% of the [32P]-Pi in the “heavy” fraction (HM) after sucrose gradient sedimentation. Metal-chelating chromatography of either “heavy” or “light” (LM) membrane fractions rendered similar Bchl-protein complex profiles after octyl-glucoside treatment, including most of the radioactivity in the same corresponding elution fraction (F II). Similar labeling distribution of pigment-protein complexes was obtained for membranes of dark-grown cells induced by lowering oxygen tension. Fractions derived from HM showed highly labeled LHIα, whereas the same complex from LM was essentially [32P]-Pi-free, as revealed by SDS-PAGE followed by autoradiography. Phospholipid analysis showed a similar pattern for membranes isolated from cells photosynthetically or semiaerobically grown, being the most abundant: phosphatidylglycerol, phosphatidylethanolamine, cardiolipin, and phosphatidylcholine. Part of the phospholipids from HM comigrated with LHIα during SDS-PAGE and dissociated from the complexes only after solvent extraction and hydrophobic chromatography. However, a small amount remained always attached to LHIα, indicating an unusual strong interaction. These results suggest the existence of two operationally defined membrane regions carrying LHIα complexes differing in phosphorylation status and protein-phospholipid interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002849900161
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  • 9
    Electronic Resource
    Electronic Resource
    The LHIα and LHIIα Complexes in Association with Phospholipids Are Able to Be Inserted in Heavy Membranes of Rhodobacter capsulatus B10 (1999)
    Springer
    Current microbiology 39 (1999), S. 37-42 
    Details
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. We show in this paper that a complex constituted by phospholipids and LHI and LHII α polypeptides was inserted in a heavy membrane fraction in a nonextractable form, indicating a transmembrane localization. The best accepting membranes originated from aerobically grown cells. Addition of ATP during the insertion inhibited this reaction 25 to 30% in heavy membranes isolated from aerobically grown cells (HMaer) and a higher inhibition (60 to 65%) was detected when using heavy membranes isolated from photosynthetically grown cells (HMpho). Purification by gel filtration of a crude Na2CO3 extract yielded three phosphate-labeled fractions. Two of them contained protein and phospholipids in a stable association. However, only fractions containing phosphatidylethanolamine were shown to be reconstituted. The third radioactive fraction contained labeled ATP and protein, but no phospholipids and could not be reassociated to the heavy membranes of any origin. A model for the insertion of the LH polypeptides is presented in which the recently synthesized polypeptides are phosphorylated and become associated to anionic phospholipids. The interaction of this complex to the membrane spontaneously leads to stable insertion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006824
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  • 10
    Electronic Resource
    Electronic Resource
    Regulation of the Expression of the Photosynthetic Apparatus of Rhodobacter capsulatus Grown in Nitrogen-Limited Chemostat Cultures (1996)
    Springer
    Current microbiology 33 (1996), S. 176-180 
    Details
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Rhodobacter capsulatus was grown in chemostat cultures under different dilution rates and with ammonium ions as the limiting nutrient. The maximal growth rate (μmax) and the Monod cell growth saturation coefficient (Ks), were calculated from batch cultures grown at different concentrations of NH4 +. The experiments in chemostat were carried out at 0.25 mM (NH4)2SO4, and the dilution rates were varied between 38% and 75% of μmax. The results indicated that under continuous culture conditions the cell yield coefficient (Y) (mg dry weight × μmol consumed ammonium sulfate−1) decreased with increasing dilution rate (D). On the contrary, the cell yield was constant when expressed as mg cellular protein ×μmol consumed ammonium sulfate−1. This occurred as a consequence of both an increase in the consumed ammonium sulfate and a simultaneous decrease in the cell biomass production at increasing growth rates. The cells produced at higher growth rates had a higher protein content per cell. The specific content of bacteriochlorophyll (Bchl) decreased (between 3 and 4 times) with increasing growth rates measured in either cells or chromatophores. However, the absorption spectra of the cells indicated that the ratio LHI (light-harvesting complex I) to LHII (light-harvesting complex II) Bchl complexes did not change. The reaction center (RC) complex content varied in parallel with the total Bchl content, yielding a constant photosynthetic unit of 65 mol Bchl × mol RC−1 at different Ds. On the other hand, the uncoupled ATPase-specific activity measured in chromatophores was usually between 30% and 40% higher at the highest growth rates reached in these experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002849900096
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