A comparative structural and functional analysis of cytochrome cM, cytochrome c6 and plastocyanin from the cyanobacterium Synechocystis sp. PCC 6803

Molina-Heredia, Fernando P.; Balme, Alexis; Hervás, Manuel; Navarro, José A.; Rosa, Miguel Á. De la

doi:10.1016/s0014-5793(02)02576-0

Cited by 28 publications

(37 citation statements)

References 26 publications

(40 reference statements)

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“…The δ peak disappears, whereas a peak at 360 nm is observed instead. These spectral features are identical to those reported for native cytochrome c 6 purified from Synechocystis [12]. The extinction coefficient at pH 7.0 was determined to be 23 300 M −1 cm −1 at 553 nm for reduced Cyt c 6 .…”

Section: Resultssupporting

confidence: 78%

Kinetics of interprotein electron transfer between cytochrome c₆ and the soluble Cu_A domain of cyanobacterial cytochrome c oxidase

et al. 2004

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Cytochrome c 6 is a soluble metalloprotein located in the periplasmic space and the thylakoid lumen of many cyanobacteria and is known to carry electrons from cytochrome b 6 f to photosystem I. The Cu A domain of cytochrome c oxidase, the terminal enzyme which catalyzes the four-electron reduction of molecular oxygen in the respiratory chains of mitochondria and many bacteria, also has a periplasmic location. In order to test whether cytochrome c 6 could also function as a donor for cytochrome c oxidase, we investigated the kinetics of the electron transfer between recombinant cytochrome c 6 (produced in high yield in Escherichia coli by coexpressing the maturation proteins encoded by the ccmA-H gene cluster) and the recombinant soluble Cu A domain (i.e., the donor binding and electron entry site) of subunit II of cytochrome c oxidase from Synechocystis PCC 6803. The forward and the reverse electron transfer reactions were studied by the stopped-flow technique and yielded apparent bimolecular rate constants of (3.3 % 0.3) Â 10 5 M À1 s À1 and (3.9 % 0.1) Â 10 6 M À1 s À1 , respectively, in 5 mM potassium phosphate buffer, pH 7, containing 20 mM potassium chloride and 25°C. This corresponds to an equilibrium constant K eq of 0.085 in the physiological direction (D r G 00 ¼ 6:1 kJ/mol). The reduction of the Cu A fragment by cytochrome c 6 is almost independent on ionic strength, which is in contrast to the reaction of the Cu A domain with horse heart cytochrome c, which decreases with increasing ionic strength. The findings are discussed with respect to the potential role of cytochrome c 6 as mobile electron carrier in both cyanobacterial electron transport pathways.

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Section: Resultssupporting

confidence: 78%

Kinetics of interprotein electron transfer between cytochrome c₆ and the soluble Cu_A domain of cyanobacterial cytochrome c oxidase

et al. 2004

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“…10 kDa, and their midpoint redox potential values are around 350 mVat pH 7, which is in accordance with their role as electron shuttle between cytochrome b 6 f and PSI [59]. Moreover, their isoelectric Fig.…”

Section: Nc_005072 Syn6301supporting

confidence: 69%

Heme‐Copper Oxidases and Their Electron Donors in Cyanobacterial Respiratory Electron Transport

Bernroitner

Zámocký

Pairer

et al. 2008

Chemistry & Biodiversity

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Cyanobacteria are the paradigmatic organisms of oxygenic (plant-type) photosynthesis and aerobic respiration. Since there is still an amazing lack of knowledge on the role and mechanism of their respiratory electron transport, we have critically analyzed all fully or partially sequenced genomes for heme-copper oxidases and their (putative) electron donors cytochrome c(6), plastocyanin, and cytochrome c(M). Well-known structure-function relationships of the two branches of heme-copper oxidases, namely cytochrome c (aa(3)-type) oxidase (COX) and quinol (bo-type) oxidase (QOX), formed the base for a critical inspection of genes and ORFs found in cyanobacterial genomes. It is demonstrated that at least one operon encoding subunits I-III of COX is found in all cyanobacteria, whereas many non-N(2)-fixing species lack QOX. Sequence analysis suggests that both cyanobacterial terminal oxidases should be capable of both the four-electron reduction of dioxygen and proton pumping. All diazotrophic organisms have at least one operon that encodes QOX. In addition, the highly refined specialization in heterocyst forming Nostocales is reflected by the presence of two paralogs encoding COX. The majority of cyanobacterial genomes contain one gene or ORF for plastocyanin and cytochrome c(M), whereas 1-4 paralogs for cytochrome c(6) were found. These findings are discussed with respect to published data about the role of respiration in wild-type and mutated cyanobacterial strains in normal metabolism, stress adaptation, and nitrogen fixation. A model of the branched electron-transport pathways downstream of plastoquinol in cyanobacteria is presented.

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“…Several proposals have been made to explain the fact that these two deletion mutants can survive with neither Pc nor Cyt as the double knockout mutant has never been achieved. Some authors have suggested the existence of a third (but relatively inefficient) electron donor to PSI [44,45], and it has also been proposed the formation of a supercomplex between cytochrome b 6 f and PSI to allow direct electron transfer without any redox carrier [46]. Finally, the existence of an alternative electron transfer pathway has been discussed as well [47].…”

Section: Proteomics Of Knockout Mutants For Plastocyanin and Cytochromentioning

confidence: 99%

Proteomic analyses of the response of cyanobacteria to different stress conditions

Castielli¹,

Cerda²,

Navarro³

et al. 2009

FEBS Letters

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a b s t r a c tCyanobacteria are significant contributors to global photosynthetic productivity, thus making it relevant to study how the different environmental stresses can alter their physiological activities. Here, we review the current research work on the response of cyanobacteria to different kinds of stress, mainly focusing on their response to metal stress as studied by using the modern proteomic tools. We also report a proteomic analysis of plastocyanin and cytochrome c 6 deletion mutants of the cyanobacterium Synechocystis sp. PCC 6803 grown under copper or iron deprivation, as compared to wild-type cells, so as to get a further understanding of the metal homeostasis in cyanobacteria and their response to changing environmental conditions.

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A comparative structural and functional analysis of cytochrome c_M, cytochrome c₆ and plastocyanin from the cyanobacterium Synechocystis sp. PCC 6803

Cited by 28 publications

References 26 publications

Kinetics of interprotein electron transfer between cytochrome c₆ and the soluble Cu_A domain of cyanobacterial cytochrome c oxidase

Kinetics of interprotein electron transfer between cytochrome c₆ and the soluble Cu_A domain of cyanobacterial cytochrome c oxidase

Heme‐Copper Oxidases and Their Electron Donors in Cyanobacterial Respiratory Electron Transport

Proteomic analyses of the response of cyanobacteria to different stress conditions

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A comparative structural and functional analysis of cytochrome cM, cytochrome c6 and plastocyanin from the cyanobacterium Synechocystis sp. PCC 6803

Cited by 28 publications

References 26 publications

Kinetics of interprotein electron transfer between cytochrome c6 and the soluble CuA domain of cyanobacterial cytochrome c oxidase

Kinetics of interprotein electron transfer between cytochrome c6 and the soluble CuA domain of cyanobacterial cytochrome c oxidase

Heme‐Copper Oxidases and Their Electron Donors in Cyanobacterial Respiratory Electron Transport

Proteomic analyses of the response of cyanobacteria to different stress conditions

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A comparative structural and functional analysis of cytochrome c_M, cytochrome c₆ and plastocyanin from the cyanobacterium Synechocystis sp. PCC 6803

Kinetics of interprotein electron transfer between cytochrome c₆ and the soluble Cu_A domain of cyanobacterial cytochrome c oxidase

Kinetics of interprotein electron transfer between cytochrome c₆ and the soluble Cu_A domain of cyanobacterial cytochrome c oxidase