Functional Coupling Between Reaction Centers and Cytochrome bc 1 Complexes

Lavergne, Jérôme; Vermeglio, André; Joliot, Pierre

doi:10.1007/978-1-4020-8815-5_26

Cited by 28 publications

(50 citation statements)

References 173 publications

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“…Cytochrome c 2 has been extensively studied in several purple bacterial species (28,30,31), and the protein found in TIE-1 appears to be typical of this family. Its reduction potential (ϩ350 mV) is typical of cytochromes c 2 , and our experiments with purified protein and membrane fragments show that the electron transfer rate from cytochrome c 2 to the reaction center is within the range found in other purple bacteria (8,32).…”

Section: Discussionmentioning

confidence: 99%

“…Using qRT-PCR, we tested the response of Rpal_4085 under anoxic conditions to the cations Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Ca(II), and hydrogen peroxide (H 2 O 2 ). With the exception of Zn(II) and Ca(II), these divalent metals are known to be redox active at physiological pH (19,(26)(27)(28)(29). We used H 2 O 2 as an oxidative stress-inducing control and Zn(II) and Ca(II) as nonredox active divalent metal controls.…”

Section: Mutant Analysismentioning

confidence: 99%

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Nonredundant Roles for Cytochrome c ₂ and Two High-Potential Iron-Sulfur Proteins in the Photoferrotroph Rhodopseudomonas palustris TIE-1

et al. 2014

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eThe purple bacterium Rhodopseudomonas palustris TIE-1 expresses multiple small high-potential redox proteins during photoautotrophic growth, including two high-potential iron-sulfur proteins (HiPIPs) (PioC and Rpal_4085) and a cytochrome c 2 . We evaluated the role of these proteins in TIE-1 through genetic, physiological, and biochemical analyses. Deleting the gene encoding cytochrome c 2 resulted in a loss of photosynthetic ability by TIE-1, indicating that this protein cannot be replaced by either HiPIP in cyclic electron flow. PioC was previously implicated in photoferrotrophy, an unusual form of photosynthesis in which reducing power is provided through ferrous iron oxidation. Using cyclic voltammetry (CV), electron paramagnetic resonance (EPR) spectroscopy, and flash-induced spectrometry, we show that PioC has a midpoint potential of 450 mV, contains all the typical features of a HiPIP, and can reduce the reaction centers of membrane suspensions in a light-dependent manner at a much lower rate than cytochrome c 2 . These data support the hypothesis that PioC linearly transfers electrons from iron, while cytochrome c 2 is required for cyclic electron flow. Rpal_4085, despite having spectroscopic characteristics and a reduction potential similar to those of PioC, is unable to reduce the reaction center. Rpal_4085 is upregulated by the divalent metals Fe(II), Ni(II), and Co(II), suggesting that it might play a role in sensing or oxidizing metals in the periplasm. Taken together, our results suggest that these three small electron transfer proteins perform different functions in the cell.

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Section: Discussionmentioning

confidence: 99%

Section: Mutant Analysismentioning

confidence: 99%

Nonredundant Roles for Cytochrome c ₂ and Two High-Potential Iron-Sulfur Proteins in the Photoferrotroph Rhodopseudomonas palustris TIE-1

et al. 2014

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“…However, this would seem difficult to reconcile with the long-range transfer necessitated by the localization of cytochrome bc 1 complexes in regions remote from RCs, apparently arising from bilayer congestion as a result of extensive LH2 arrays in membranes capable of functioning at low light intensity [Woronowicz et al, 2010a]. The possibility has been considered that in such membranes with a scarcity of bc 1 complexes, the longrange lateral diffusion of quinones might be augmented by exchange during collision with complexes that retain quinone aggregates [Lavergne et al, 2009].…”

Section: Fluorescence/induction Relaxation Measurements Provide Functmentioning

confidence: 99%

“…Radiant energy harvested by LH2 is transferred to LH1, which funnels these excitations to the RC-bacteriochlorophyll a (BChl) special pair for transduction into a transmembrane charge separation [Parson and Warshel, 2009]. A cycle of electron transfer reactions is thereby initiated between the primary iron-quinone acceptor (Q A ), the ubiquinol-cytochrome c 2 oxidoreductase ( bc 1 ) complex, cytochrome c 2 and the photooxidized special pair [Lavergne et al, 2009]. This results in the generation of an electrochemical proton gradient coupled to the synthesis of ATP.…”

Section: Introductionmentioning

confidence: 99%

Structural and Functional Proteomics of Intracytoplasmic Membrane Assembly in <b><i>Rhodobacter sphaeroides</i></b>

et al. 2013

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The results of a detailed structural and functional proteomic analysis of intracytoplasmic membrane (ICM) assembly in the model purple phototrophic bacterium Rhodobacter sphaeroides are reviewed in this report. Proteomics approaches have focused upon identification of membrane proteins temporally expressed during ICM development and spatially localized within the internal cell membranes, together with their structural and functional correlates. For the examination of temporal protein expression, procedures were established for the induction of ICM formation at low oxygen tension and for ICM remodeling in cells adapting to low intensity illumination, which permitted isolation by rate-zone sedimentation of ICM growth initiation sites (CM invaginations) in an upper-pigmented band (UPB), together with more mature ICM vesicles (chromatophores) as the main band. Nondenaturing clear native gel electrophoresis of the chromatophore fraction gave rise to four pigmented bands: the top and bottom bands contained the reaction center-light-harvesting 1 (RC-LH1) core complex and the LH2 peripheral antenna, respectively, while two bands of intermediate migration exhibited distinct associations of LH2 and core complexes. Proteomic analysis of the gel bands revealed developmental changes including increasing levels of LH2 polypeptides relative to those of core complexes as ICM development proceeded, as well as a large array of other associated proteins including high spectral counts for the F₁F_O-ATP synthase subunits, and the cytochrome bc₁ complex. High counts were also observed for RSP6124, a protein of unknown function, that were correlated with increasing LH2 levels. RC-LH1-containing clear native electrophoresis gel bands from the UPB were enriched in cytoplasmic membrane (CM) markers, including electron transfer and transport proteins, as well as general membrane assembly factors (viz., preprotein translocases YidC, YajC and SecY, bacterial type 1 signal peptidase and twin arg translocation subunit TatA), thereby confirming the origin of the UPB from both peripheral respiratory membrane and sites of active CM invagination in which preferential assembly of the RC-LH1 complex occurs. Functional aspects of the photosynthetic unit assembly process were monitored by fluorescence induction/relaxation measurements of the variable fluorescence arising from LH-bacteriochlorophyll a. Slowing of the rate of RC electron transfer turnover (τ_QA), as assessed from the relaxation phase, was correlated with the growth of the functional absorption cross section (σ) and LH2/LH1 molar ratios. This is thought to arise from the imposition of constraints upon free diffusion of ubiquinone (UQ) redox species between the RC and cytochrome bc₁ complex as the ICM bilayer becomes densely packed with LH2 rings. Such LH2 packing was confirmed in a comparison by high-resolution atomic force microscopy of ICM patches from cells grown at high and low light intensity [Adams and Hunter: Biochim Biophys Act...

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“…5b). The observation can be the consequence of changed stoichiometry of the species (there is enough prereduced cyt c2 to react with the scarcer P+) or can be related to the molecular organization of the photosynthetic apparatus like the RC-cyt c2 supercomplex (Lavergne et al 2008) or the heterogeneity (Crofts et al 1998). If the sample is exposed to mercury ions, the fraction of the fast component of P+ reduction will be smaller and independent on the flash intensity.…”

Section: Resultsmentioning

confidence: 99%

The reaction center is the sensitive target of the mercury(II) ion in intact cells of photosynthetic bacteria

et al. 2012

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The sensitivity of intact cells of purple photosynthetic bacterium Rhodobacter sphaeroides wild type to low level (~100 µM) of mercury (Hg 2+ ) contamination was evaluated by absorption and fluorescence spectroscopies of the bacteriochlorophyll-protein complexes. All assays related to the function of the reaction center (RC) protein (induction of the bacteriochlorophyll fluorescence, delayed fluorescence and light-induced oxidation and reduction of the bacteriochlorophyll dimer and energization of the photosynthetic membrane) showed prompt and later effects of the mercury ions. The damage expressed by decrease of the magnitude and changes of rates of the electron transfer kinetics followed complex (spatial and temporal) pattern according to the different Hg 2+ sensitivities of the electron transport (donor/acceptor) sites including the reduced bound and free cytochrome c2 and the primary reduced quinone. In contrast to the RC, the light harvesting system and the bc1 complex demonstrated much higher resistance against the mercury pollution. The 850 and 875 nm components of the peripheral and core complexes were particularly insensitive to the mercury(II) ions. The concentration of the photoactive RCs and the connectivity of the photosynthetic units decreased upon mercury treatment. The degree of inhibition of the photosynthetic apparatus was always higher when the cells were kept in the light than in the dark indicating the importance of metabolism in active transport of the mercury ions from outside to the intracytoplasmic membrane. Any of the tests applied in this study can be used for detection of changes in photosynthetic bacteria at the early stages of the action of toxicants.

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Functional Coupling Between Reaction Centers and Cytochrome bc 1 Complexes

Cited by 28 publications

References 173 publications

Nonredundant Roles for Cytochrome c ₂ and Two High-Potential Iron-Sulfur Proteins in the Photoferrotroph Rhodopseudomonas palustris TIE-1

Nonredundant Roles for Cytochrome c ₂ and Two High-Potential Iron-Sulfur Proteins in the Photoferrotroph Rhodopseudomonas palustris TIE-1

Structural and Functional Proteomics of Intracytoplasmic Membrane Assembly in <b><i>Rhodobacter sphaeroides</i></b>

The reaction center is the sensitive target of the mercury(II) ion in intact cells of photosynthetic bacteria

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Functional Coupling Between Reaction Centers and Cytochrome bc 1 Complexes

Cited by 28 publications

References 173 publications

Nonredundant Roles for Cytochrome c 2 and Two High-Potential Iron-Sulfur Proteins in the Photoferrotroph Rhodopseudomonas palustris TIE-1

Nonredundant Roles for Cytochrome c 2 and Two High-Potential Iron-Sulfur Proteins in the Photoferrotroph Rhodopseudomonas palustris TIE-1

Structural and Functional Proteomics of Intracytoplasmic Membrane Assembly in <b><i>Rhodobacter sphaeroides</i></b>

The reaction center is the sensitive target of the mercury(II) ion in intact cells of photosynthetic bacteria

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Nonredundant Roles for Cytochrome c ₂ and Two High-Potential Iron-Sulfur Proteins in the Photoferrotroph Rhodopseudomonas palustris TIE-1

Nonredundant Roles for Cytochrome c ₂ and Two High-Potential Iron-Sulfur Proteins in the Photoferrotroph Rhodopseudomonas palustris TIE-1