Photoreaction center of photosynthetic bacteria. 1. Further chemical characterization of the photoreaction center from Rhodospirillum rubrum

Vadeboncoeur, Christian; Noël, Henri; Poirier, Louis; Cloutier, Yves; Gingras, G

doi:10.1021/bi00587a007

Cited by 58 publications

(30 citation statements)

References 26 publications

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“…Antibody, detected by labeling with radioiodinated protein A, bound to bands (Fig. lb) identified (5,33,38,49,51) as the H subunit of the photochemical reaction center (RC) and the light-harvesting antenna (LH).…”

Section: Resultsmentioning

confidence: 99%

Immunocytochemical ultrastructural analysis of chromatophore membrane formation in Rhodospirillum rubrum

Crook¹,

Treml²,

Collins³

1986

J Bacteriol

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An immunocytochemical ultrastructural study of Rhodospirilum rubrum cultured under semiaerobic conditions was conducted to correlate the localization of functional components with membrane formation. R. rubrum is a facultatively phototrophic organism. Under reduced oxygen, this bacterium forms an intracytoplasmic chromatophore membrane that is the site of the photosynthetic apparatus. Immunogold techniques were used to localize intracellular protein antigens associated with the photosynthetic apparatus. Antibody, demonstrated by immunoblotting to be specific for the reaction center and light-harvesting photochemical components, was conjugated to colloidal gold particles and used for direct immunolabeling of fixed, sectioned specimens. Membrane invaginations appeared by 4 h after transition to induction conditions, and mature chromatophore membrane was abundant by 22 h. The occurrence of chromatophore membrane was correlated with bacteriochlorophyll a content and the density of the immunolabel. In uninduced (aerobic) cells and those obtained from cultures 0.5 h posttransition, the immunogold preferentially labeled the peripheral area of the cell. In contrast, in cells obtained after 22 h of induction, the central region of the cell was preferentially immunolabeled. These findings provided immunocytochemical evidence supporting the hypothesis that the chromatophore membrane is formed by invagination of the cytoplasmic membrane.Rhodospirillum rubrum is a facultatively photosynthetic bacterium that has been used as a model in studies of membrane structure and formation (22,36). Under aerobic conditions nonpigmented cells undergo chemotrophic metabolism. Under anaerobic conditions in the light, R. rubrum grows phototrophically. Bacteriochlorophyll a (BCHL) and carotenoids and associated proteins are localized in the intracytoplasmic chromatophore membrane. Ultrastructural and physical evidence has suggested that this chromatophore membrane is continuous with the cytoplasmic membrane (for a review, see reference 39). Moreover, studies revealing the opposite asymmetry of the chromatophore and cytoplasmic membranes in R. rubrum (34, 42) and other photosynthetic bacteria (8,11,25) imply the existence of a membrane continuum because the cytoplasmic face of the chromatophore membrane forms the outer surface of isolated chromatophores.The apparent continuity between the chromatophore and cytoplasmic membrane has led to the hypothesis that the chromatophore membrane is formed by invagination of the cytoplasmic membrane (35). Evidence to support this hypothesis is provided by the freeze-etching studies of Golecki and Oelze (13 Electron microscopy. Cells were harvested, washed, and suspended in a minimal amount of 10 mM potassium phosphate buffer (pH 7.0) and held at 0°C until cell blocks were prepared with 2% agarose (Seakem HGT; FMC Corp., Marine Colloids Div., Rockland, Maine). Double-distilled water used in all reagents was boiled for 10 min and filter sterilized. For cell block preparation, cell suspensions were broug...

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Section: Resultsmentioning

confidence: 99%

Immunocytochemical ultrastructural analysis of chromatophore membrane formation in Rhodospirillum rubrum

Crook¹,

Treml²,

Collins³

1986

J Bacteriol

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“…Resolution, according to their size, of complexes with absorption peaks at wavelengths from 775 to 873 nm is in favor of that hypothesis (15,16). For our part, we have attributed the line narrowing in the EPR spectra of oxidized B880 Bchl, either in the chromatophores or in isolated complexes, to hexameric structures containing 12 Bchl molecules (17, were extracted by alumina grinding followed by centrifugation (20), dispersed in 50 mM sodium phosphate (pH 7.0), and kept in the dark at 40C for a maximum of 2 days before use.…”

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confidence: 87%

Supramolecular arrangement of Rhodospirillum rubrum B880 holochrome as studied by radiation inactivation and electron paramagnetic resonance.

Gingras

Picorel

1990

Proc. Natl. Acad. Sci. U.S.A.

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Oxidation of the B880 antenna holochrome gives rise to a 3.8-G linewidth electron paramagnetic resonance (EPR) signal that is considerably narrower than the 13-G signal of monomeric bacteriochlorophyll (Bchl) cation. Radiation inactivation was used to verify a model according to which this linewidth narrowing is due to delocalization over several Bchl molecules. Chromatophores of the photoreaction centerless mutant F24 of Rhodospirillum rubrum were subjected to different doses of vrradiation. This induced not only a decay of the

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“…While Q is a ubiquitous lipid component involved in aerobic respiratory electron transport (9, 36, 60), RQ functions in anaerobic respiration in R. rubrum (19) and in several other phototrophic purple bacteria (21,22,41) and is also present in a few aerobic chemotrophic bacteria, including Brachymonas denitrificans and Zoogloea ramigera (23). In these varied species of bacteria, RQ has been proposed to function in fumarate reduction to maintain NAD ϩ /NADH redox balance, either during photosynthetic anaerobic metabolism (12,(15)(16)(17)(18)64) or in chemotrophic metabolism when the availability of oxygen as a terminal oxidant is limiting (23). Another recent finding is that RQH 2 is capable of inducing Q-cycle bypass reactions in the cytochrome bc 1 complex in Saccharomyces cerevisiae, resulting in superoxide formation (7).…”

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Evidence that Ubiquinone Is a Required Intermediate for Rhodoquinone Biosynthesis in Rhodospirillum rubrum

et al. 2010

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Rhodoquinone (RQ) is an important cofactor used in the anaerobic energy metabolism of Rhodospirillum rubrum. RQ is structurally similar to ubiquinone (coenzyme Q or Q), a polyprenylated benzoquinone used in the aerobic respiratory chain. RQ is also found in several eukaryotic species that utilize a fumarate reductase pathway for anaerobic respiration, an important example being the parasitic helminths. RQ is not found in humans or other mammals, and therefore inhibition of its biosynthesis may provide a parasite-specific drug target. In this report, we describe several in vivo feeding experiments with R. rubrum used for the identification of RQ biosynthetic intermediates. Cultures of R. rubrum were grown in the presence of synthetic analogs of ubiquinone and the known Q biosynthetic precursors demethylubiquinone, demethoxyubiquinone, and demethyldemethoxyubiquinone, and assays were monitored for the formation of RQ 3 . Data from time course experiments and S-adenosyl-L-methionine-dependent O-methyltransferase inhibition studies are discussed. Based on the results presented, we have demonstrated that Q is a required intermediate for the biosynthesis of RQ in R. rubrum.Rhodospirillum rubrum is a well-characterized and metabolically diverse member of the family of purple nonsulfur bacteria (29, 61). R. rubrum is typically found in aquatic environments and can adapt to a variety of growth conditions by using photosynthesis, respiration, or fermentation pathways (28, 70). In the light, R. rubrum exhibits photoheterotrophic growth using organic substrates or photoautotrophic growth using CO 2 and H 2 (15, 70). In the dark, R. rubrum can utilize either aerobic respiration (70,73) or anaerobic respiration with a fumarate reduction pathway or with nonfermentable substrates in the presence of oxidants such as dimethyl sulfoxide (DMSO) or trimethylamine oxide (15,58,73). R. rubrum can also grow anaerobically in the dark by fermentation of sugars in the presence of bicarbonate (58). The focus of this work was the biosynthesis of quinones used by R. rubrum for aerobic and anaerobic respiration.Rhodoquinone (RQ; compound 1 in Fig. 1) is an aminoquinone structurally similar to ubiquinone (coenzyme Q or Q [compound 2]) (44); however, the two differ considerably in redox potential (that of RQ is Ϫ63 mV, and that of Q is ϩ100 mV) (2). Both RQ and Q have a fully substituted benzoquinone ring and a polyisoprenoid side chain that varies in length (depending on the species; see Fig. 1 for examples). The only difference between the structures is that RQ has an amino substituent (NH 2 ) instead of a methoxy substituent (OCH 3 ) on the quinone ring. While Q is a ubiquitous lipid component involved in aerobic respiratory electron transport (9, 36, 60), RQ functions in anaerobic respiration in R. rubrum (19) and in several other phototrophic purple bacteria (21,22,41) and is also present in a few aerobic chemotrophic bacteria, including Brachymonas denitrificans and Zoogloea ramigera (23). In these varied species of bacteria, RQ has been ...

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Photoreaction center of photosynthetic bacteria. 1. Further chemical characterization of the photoreaction center from Rhodospirillum rubrum

Cited by 58 publications

References 26 publications

Immunocytochemical ultrastructural analysis of chromatophore membrane formation in Rhodospirillum rubrum

Immunocytochemical ultrastructural analysis of chromatophore membrane formation in Rhodospirillum rubrum

Supramolecular arrangement of Rhodospirillum rubrum B880 holochrome as studied by radiation inactivation and electron paramagnetic resonance.

Evidence that Ubiquinone Is a Required Intermediate for Rhodoquinone Biosynthesis in Rhodospirillum rubrum

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