Photoreaction center of Ectothiorhodospira sp. Pigment, heme, quinone, and polypeptide composition

Lefebvre, Suzie; Picorel, Rafael; Cloutier, Yves; Gingras, G

doi:10.1021/bi00317a028

Cited by 31 publications

(19 citation statements)

References 32 publications

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“…When we measured flashinduced absorption changes on RC samples prepared according to ref. 20, we observed a dominant fast back-reaction resembling the terbutryn-inhibited case, demonstrating that these samples are strongly depleted in Q B . The results reported in ref.…”

Section: Resultsmentioning

confidence: 57%

“…The results reported in ref. 20 thus identify Q A as MK, but do not inform on the identity of Q B . We therefore decided to use a milder purification protocol yielding RC-light harvesting (RC-LH) complexes (see Materials and Methods).…”

Section: Resultsmentioning

confidence: 98%

“…As discussed above, only UQ had been found thus far in purple bacterial quinone pools and hence also in Q B . In 1984, Lefebvre et al (20) reported that only MK could be observed after chemical extraction of purified RC. However, because purified RCs frequently are depleted in Q B , the actual presence of Q B has to be demonstrated before extraction of lipophilic components from RC samples.…”

Section: Resultsmentioning

confidence: 99%

“…We therefore extracted RC-LH complexes using LDAO as described in ref. 20 but submitted the crude LDAO extract directly to ultracentrifugation without dilution of LDAO. The supernatant was then loaded on a 30 -10% sucrose gradient equilibrated in 0.01% dodecyl maltoside (DM) in buffer A.…”

Section: Preparation Of Photosynthetic Rcs and Rc-lh Complexesmentioning

confidence: 99%

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Menaquinone as pool quinone in a purple bacterium

Schoepp‐Cothenet

Lieutaud

Baymann

et al. 2009

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

110

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Purple bacteria have thus far been considered to operate lightdriven cyclic electron transfer chains containing ubiquinone (UQ) as liposoluble electron and proton carrier. We show that in the purple ␥-proteobacterium Halorhodospira halophila, menaquinone-8 (MK-8) is the dominant quinone component and that it operates in the QB-site of the photosynthetic reaction center (RC). The redox potentials of the photooxidized pigment in the RC and of the Rieske center of the bc1 complex are significantly lower (Em ‫؍‬ ؉270 mV and ؉110 mV, respectively) than those determined in other purple bacteria but resemble those determined for species containing MK as pool quinone. These results demonstrate that the photosynthetic cycle in H. halophila is based on MK and not on UQ. This finding together with the unusual organization of genes coding for the bc1 complex in H. halophila suggests a specific scenario for the evolutionary transition of bioenergetic chains from the low-potential menaquinones to higher-potential UQ in the proteobacterial phylum, most probably induced by rising levels of dioxygen 2.5 billion years ago. This transition appears to necessarily proceed through bioenergetic ambivalence of the respective organisms, that is, to work both on MK-and on UQ-pools. The establishment of the corresponding low-and high-potential chains was accompanied by duplication and redox optimization of the bc1 complex or at least of its crucial subunit oxidizing quinols from the pool, the Rieske protein. Evolutionary driving forces rationalizing the empirically observed redox tuning of the chain to the quinone pool are discussed.electron transport ͉ evolution ͉ photosynthesis C hemiosmotic energy-converting mechanisms in all life on this planet are variations on a strikingly conserved theme. Electrons derived from reduced substrates enter a chain of membrane-integral and/or associated enzymes and are channeled on toward terminal electron-accepting substrates. Some of the free energy available during individual electron-transfer steps is stored in a transmembrane proton motive gradient. Mitchell (1) proposed a general mechanism for coupling electron transfer to proton translocation, which accounts for the majority of these systems. In this mechanism, electrons travel through 2 types of carrier ''arms'' back and forth across the energetic membrane. In an ''electrogenic arm,'' electrons move alone across the membrane from the positively to the negatively charged side, building up an electric field. Via a ''neutral arm,'' electrons travel in the opposite direction, along with protons. Placing electrogenic and neutral arms in series leads to net proton translocation across the membrane.Without exception, the chemiosmotic neutral arms involve diffusion of small, lipophilic molecules across the energetic membrane. In all bioenergetic systems except methanogenesis, these molecules are quinones that diffuse in the lipid bilayer. The bulk of these diffusing quinones electrochemically connecting redox enzymes is called the quinone pool, to disti...

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Section: Resultsmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Preparation Of Photosynthetic Rcs and Rc-lh Complexesmentioning

confidence: 99%

See 2 more Smart Citations

Menaquinone as pool quinone in a purple bacterium

Schoepp‐Cothenet

Lieutaud

Baymann

et al. 2009

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

110

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“…We have shown that the cytochrome c-553 is a component of the B885-RC complex. Interestingly, however, RC or RC-LHI complexes from other Bchl a containing members of the Rhodospirillaceae do not appear to contain cytochrome (Feher & Okamura, 1978 ;Gingras, 1978 ;Firsow & Drews, 1977;Hayashi et al, 1982b) but such preparations from the Bchl b containing R. viridis (Pucheu et al, 1976;Jay et al, 1984), Thiocapsa pfennigii (Seftor & Thornber, 1984) and several other Bchl a containing members of the Chromatiaceae (Lin & Thornber, 1975;Bartsch, 1978;Lefebvre et al, 1984) do contain multi-haem cytochrome c-552-558 bound to a polypeptide of M, 35-45 000. However, only in R. viridis have cross-linking studies been done to investigate the spatial relationships between the RC and this c-type cytochrome (Peters et al, 1984) and these have indicated binding to the 27000 Mr (M) RC subunit.…”

Section: Discussionmentioning

confidence: 99%

Isolation, Characterization and Topographical Relationships of Pigment-protein Complexes from Membranes of Rhodomicrobium vannielii

Kelly

Dow

1985

Microbiology

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Pigment-protein complexes from Rhodomicrobium vannielii were prepared by detergent solubilization of intra-cytoplasmic membranes followed by gel electrophoresis or sucrose gradient centrifugation. These procedures gave rise to two native pigmented complexes. The major one (designated B800-865) was associated with two polypeptides of M , 1 1 000 and 13000 and was identified with the 'accessory' light-harvesting complex I1 found in other members of the Rhodospirillaceae. The minor complex (designated B885-RC) contained both reaction centre and light-harvesting bacteriochlorophyll. Detergent fractionation and reversible chemical cross-linking, followed by two-dimensional polyacrylamide gel electrophoresis, indicated a specific relationship between a membrane-bound cytochrome c-553 and the M , 3 1 000 subunit of the reaction centre.

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Cytochromes, Iron-Sulfur, and Copper Proteins Mediating Electron Transfer from the Cyt bc1 Complex to Photosynthetic Reaction Center Complexes

Meyer

Donohue

Advances in Photosynthesis and Respiration

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Photoreaction center of Ectothiorhodospira sp. Pigment, heme, quinone, and polypeptide composition

Cited by 31 publications

References 32 publications

Menaquinone as pool quinone in a purple bacterium

Menaquinone as pool quinone in a purple bacterium

Isolation, Characterization and Topographical Relationships of Pigment-protein Complexes from Membranes of Rhodomicrobium vannielii

Cytochromes, Iron-Sulfur, and Copper Proteins Mediating Electron Transfer from the Cyt bc1 Complex to Photosynthetic Reaction Center Complexes

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