Plastocyanin is electron carrier copper containing soluble metalloprotein that serves to carry electron between two photosystems of photosynthesis. (1968) and Tsujimoto et al. A gene encoding a flavin-utilizing amine oxidase is a CRR1 target and is upregulated in Cu deficiency. three-dimensional structure of oxidized poplar ( Populus nigra) plastocyanin has been determined by X-ray crystallography at 2.7 A resolution [1] and refined to 1.33 A [2]. Plastoquinone transport electrons between photosystem II and cytochrome b 6 -f complex. While plastoquinones are lipid-soluble and therefore move within the thylakoid membrane, plastocyanin moves through the thylakoid lumen. Furthermore, subunits PsaX and PsaM are only present in cyanobacteria, whereas, plants contain subunits PsaG and PsaH. Use of antibodies to block photosynthetic reactions generally dependent on plastocyanin; b. epr spectral assessment; c. treatment of chloroplasts with KCN and amphotericin B ; d. light-induced changes at 553 nm (= cytochrome f photooxidation). Interestingly, the green algae that express Cyt c6 as a plastocyanin replacement have also lost the otherwise ubiquitous gene(s) encoding CuZnSOD (Asada et al., 1977). It features an eight-stranded antiparallel β-barrel containing one copper center.. The copper atom in PC (dark blue) is coordinated to two histidines (H87: light green; H37: dark green), C84 (yellow) and M92 (cyan). 2. QED. Plastocyanin cytochrome c les deux branches sont actives donneur d’éléctrons pour P + est un cytochrome c plus rapide que l’autre donneur d’éléctrons pour P + est une out plastocyanine les électrons sont transférés sur une ferrédoxine et finalement sur le NAD(P), pas de transfert de protons au niveau du PSI/RCI mais production d’un substrat réducteur . Wildner and Hauska, 1974; Kunert and Böger, 1975, Merchant and Bogorad, 1986a; Li and Merchant, 1995, Marschner's Mineral Nutrition of Higher Plants (Third Edition). Wikipedia. (2018b) have suggested that the red-shifted chromophores (i.e., those with maxima at 672 nm) may be involved in direct EET to PSI in the PBS-PSI supercomplexes, as reported by Kondo et al. A recent transcriptome study identified an additional example of Cu sparing in C. reinhardtii (Castruita et al., 2011). The crystal structure of the trimeric PSI complex of the thermophilic cyanobacterium T. elongatus was solved at a resolution of 2.5 Å (Fromme et al., 2001; Jordan et al., 2001); a PSI monomer was shown to contain 12 protein subunits (PsaA-F, PsaI-M, and PsaX) and 127 cofactors: 96 Chls and 22 Cars; 2 phylloquinones (A1A and A1B); 3 [4Fe-4S] clusters; 1 putative Ca2 + ion; and 4 lipid molecules. The electron transfer reactions in which they participate rely on complex diffusion steps in a spatially restricted intracellular compartment (the thylakoid lumen), and this may require membrane reorganization (Hervás et al., 1998). (2014). In all cases the binding site is generally conserved. Associated with photosystem I. Plastocyanin, ein Kupferprotein, das bei den Lichtreaktionen der ⇒ Photosynthese als Redoxsystem in der Elektronentransportkette dem Photosystem I (P700) Elektronen vom Cytochrom bf Komplex zuleitet Although this PBS, known as CpcG2-PBS, interacts with PSI through rods (Kondo et al., 2007), it is not involved in state transitions (Kondo et al., 2009). Consequently, the techniques normally employed for the extraction and purification of plastocyanin would have resulted in its complete denaturation and, as a result, the mutant form would falsely appear to be lacking plastocyanin. 2001 Also, plastocyanin is dependent on copper, while plastoquinone is not dependent on copper. Although plastocyanin is thought of as the preferred intermediary between cyt b6f and the reaction center (see Chapter 17), cyt c6 replaces it under conditions of copper limitation (Merchant et al., 2006; see Chapter 10). PSI complexes in cyanobacteria form trimers that are in equilibrium with PSI monomers, which vary as a function of concentration of cations (Kruip et al., 1994) or protons (Schwabe et al., 2001); this aspect of cyanobacteria is quite different from that in plants and green algae, where PSIs exist only as monomers. Obviously, this interpretation is not supported by the findings on mutant ac-208 and ac-208(sup). Plastocyanin requires one electron for reduction. Select a category... Plastocyanin Cytochromes f Cytochromes c6 Photosystem I Protein Complex Cytochromes Spinacia oleracea Nostoc Prochlorothrix Electron Transport Copper Plants Photosynthetic Reaction Center Complex Proteins Plant Proteins Chlorophyta Cytochrome b6f Complex Azurin Chloroplasts Cyanobacteria Chlorophyll Oxidation … (1971), which demonstrated an absolute requirement of PS I reactions for plastocyanin, are all in direct contradiction to those of Arnon and colleagues. The lower Cu requirements of pcy1 mutants give an indication of the large contribution of plastocyanin to the cellular Cu quota (Hill and Merchant, 1992). Organism. (2000) The Protein Data Bank. Reviewed-Annotation score: -Experimental evidence at protein level i. The Cu atom is coordinated to four amino acid residues (H87, H37, S84, and M92) in a distorted tetrahedral geometry. Plastocyanin definition is - a copper-containing protein that acts as an intermediary in photosynthetic electron transport. These two electron carriers are present in millimolar concentrations inside the thylakoid lumen (11), where Cytc 6 is replaced by PC, and this substantially reduces the requirement for Fe. When soluble photosynthetic electron transfer catalysts were isolated from a cyanobacterial bloom in the Potomac, Cyt c6 was abundant, but when the organisms were cultured in the laboratory (in a medium amended with Cu), plastocyanin could be isolated (D. Krogmann, personal communication). The absorbancy changes attributed to the reduction of cytochrome 559 and cytochrome 553, which are considered to be an index of PS II activity, are still extant in ac-208 and indicate that PS II activity is unaffected in spite of the findings on the Hill reaction. The electron transport protein plastocyanin is present in the lumen and shuttles electrons from the cytochrome b6f protein complex to photosystem I. Plastocyanin is a soluble copper-containing protein present in the thylakoid lumen, which transfers electrons to photosystem I. The copper-containing acidic protein plastocyanin is seemingly ubiquitously distributed in the chloroplast of all higher plants and apparently also in most algae. In the chloroplast of the flowering plant Arabidopsis thaliana, a cytochrome c6-like protein is present, which was recently suggested to function as an alternative electron carrier to plastocyanin. The signal transduction pathway responsible for the switch between plastocyanin and Cyt c6 was shown in C. reinhardtii to respond directly to Cu rather than to feedback from the redox state of the chloroplast electron transfer chain (Merchant and Bogorad, 1987b). Table 4. Also Arntzen et al. Kevin E. Redding, in The Chlamydomonas Sourcebook, 2009. The cold sensitivity and reduced photosynthetic electron transport of a cyanobacterial plastocyanin mutant that compensates by increased expression of petJ encoding Cyt c6 are not inconsistent with this view (Clarke and Campbell, 1996). It is a member of plastocyanin family of copper binding… As in Photosystem II, light is harvested by antenna complexes, and the primary light reaction is a charge separation beginning stabilized by transfer of an electron to a quinone, but in Photosystem I the terminal electron acceptor is an FeS cluster, which permits reduction of ferredoxin. The regulatory pathways (i.e., Cu sensor, cis-acting sequences and DNA-binding proteins) are not yet elucidated, but the petJ gene (encoding the Cyt) responds transcriptionally to Cu nutrition status while the petE gene (encoding plastocyanin) responds transcriptionally in some cases and posttranscriptionally in others (Briggs et al., 1990; Bovy et al., 1992). Like plastocyanin from other species, it is an antiparallel β-barrel possessing a single copper atom, which is coordinated by two imidazole nitrogens (His37 and His87), a thioether … (2000) The Protein Data Bank. Moreover, plastoquinone is present in inner thylakoid membrane, while plastocyanin is present in the thylakoid lumen. The synthesis of plastocyanin (Cu) and Cyt c6 (Fe) was found to be reciprocally dependent on Cu nutrition in both cyanobacteria (Prochlorothrix hollandica, Anabaena, and Synechocystis spp.) Plastoquinone-plastocyanin reductase ( b6f complex ), present in cyanobacteria and the chloroplasts of plants, catalyses the oxidoreduction of plastoquinol and cytochrome f.:plastoquinol + 2 oxidized plastocyanin + 2 H + [ side 1 ] \ rightleftharpoons plastoquinone + 2 reduced plastocyanin + 2 H + [ side 2] (2018b) measured spectral dynamics of PC rods (also without any core) isolated from the ΔAB mutant of Synechocystis; this mutant has PBS with rods, but without core (Ajlani et al., 1995). Table 5. The presence of plastocyanin in plants is correlated with green, chloroplast-containing cells as is to be expected from its subcellular location in the chloroplast thylakoid lumen. Plastocyanin (PC) from poplar leaves is present in two isoforms, PCa and PCb, which differ in sequence by amino acid replacements at locations remote from the copper center and simultaneously act in the photosynthetic electron-transport chain. Metal–ligand bond distances of purple CuA centers (Å). It features an eight-stranded antiparallel β-barrel containing one copper center.. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. URL: https://www.sciencedirect.com/science/article/pii/B9780123786302001377, URL: https://www.sciencedirect.com/science/article/pii/B9780123982643000024, URL: https://www.sciencedirect.com/science/article/pii/B9780123849052000078, URL: https://www.sciencedirect.com/science/article/pii/B9780123708731000186, URL: https://www.sciencedirect.com/science/article/pii/B9780123742339000131, URL: https://www.sciencedirect.com/science/article/pii/B9780128143711000138, URL: https://www.sciencedirect.com/science/article/pii/B9780128146675000052, URL: https://www.sciencedirect.com/science/article/pii/B978012370873100006X, URL: https://www.sciencedirect.com/science/article/pii/B9780123748812000076, URL: https://www.sciencedirect.com/science/article/pii/B9780124199873000078, Encyclopedia of Biological Chemistry (Second Edition). Although the crystal structure of PSI core complex of T. elongatus is quite similar to those of plants (Ben-Shem et al., 2003), there are several differences, for example, the subunit PsaL is quite different in the two systems. Since then, C. reinhardtii has become a premier reference organism for understanding mechanisms of Cu sensing and sparing in photosynthetic systems (Merchant, 1998). It is shown that cyt. Figure 2. That this component plays an essential role in the electron transport system of photosynthesis seems unquestionable; the problem of localizing its precise site of action, however, still presents a dilemma for students of photosynthesis. Functional equivalence, suggested from biochemistry, was firmly established in the plastocyanin-less mutant pcy1-ac208 of C. reinhardtii (Wood, 1978; Merchant and Bogorad, 1987a). In cyanobacteria, PsaM and PsaL are responsible for PSI trimer formation (Jordan et al., 2001; Schluchter et al., 1996); in addition, a different PsaL structure and the absence of PsaM explain why PSIs are only monomeric in plants. We use cookies to help provide and enhance our service and tailor content and ads. Gene. In C. reinhardtii, CRR1 controls all known responses to Cu deficiency, including plastocyanin degradation (Eriksson et al., 2004). When researchers analyzed algae and cyanobacteria on the other hand, they were unable to isolate plastocyanin from some of them (Wildner and Hauska, 1974; Kunert and Böger, 1975), which led to the finding that a soluble c-type cytochrome could cover its function in many green algae and cyanobacteria (Bohner et al., 1980a,b; Sandmann and Böger, 1980; Sandmann et al., 1983; Briggs et al., 1990; Zhang et al., 1992). The plastocyanin content of etiolated bean leaves (Phaseolus vulgaris L.) was measured, and the development of the protein in response to light was followed. The polypeptide structure distorts the coordination environment around the Cu away from ideal tetrahedral geometry, stabilizing the Cu(I) form, which explains the high reduction potential of this protein (∼+370 mV). c 6), and Fd. Norman I. Bishop, in Photophysiology: Current Topics in Photobiology and Photochemistry, Volume VIII, 1973. The three strong ligands form a trigonal plane, with CuII positioned slightly (0.36 Å) above the plane (Table 4. Plastoquinone and plastocyanin are mobile electron carriers in the chloroplast electron transport chain. An aromatic amino acid is present at the position of Trp63 in all known cytochrome c6 sequences. WikiMatrix. The electron transport protein plastocyanin is present in the lumen and shuttles electrons from the cytochrome b6f protein complex to photosystem I. It is shown that cyt. No detectable amount of plastocyanin was present in the cytoplasmic or in the membrane fraction. Although Cyt c6 is absent, CRR1 homologs have been identified (Yamasaki et al., 2009; Bernal et al., 2012). Solanum tuberosum (Potato) Status. The Arabidopsis ortholog of C. reinhardtii CRR1, SPL7, functions to spare Cu for plastocyanin by replacing CuZnSOD with an FeSOD (Pilon et al., 2009). While plastoquinones are lipid-soluble and therefore move within the thylakoid membrane, plastocyanin moves through the thylakoid lumen. Plastocyanin. (see color plate 1) Copper centers in cupredoxins and related proteins (see Table 4 for details). The protein is monomeric, with a molecular weight around 10,500 Da, and 99 amino acids in most vascular plants. Mots en P à proximité: plaste, plasticité du sol, plasticité phénotypique, plastidome, plastifiant, plastocyanine, plastoglobule, plastoquinone, plastron, plateau continental, plateau de fruits de mer. 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Electron transfer c6 is absent, CRR1 homologs have been identified ( Yamasaki et,. -F complex the dark reaction between plastoquinol-1 and plastocyanin in the sonication medium the was. Isolated from spinach: the copper ion to the use of cookies score... + of photosystem I can use two different electron donors to PS I: plastocyanin or cytochrome Cyt! Have been characterized crystallographically measure the distance of the PsaA and PsaB proteins, which transfers to. Wildner and Hauska, 1974 ; Kunert and Böger, 1975, Merchant and,. And Watanabe et al., 2014 ) CRR1 and confirmed at the level of model... Ferroxidase expression is repressed ), a type I blue-copper protein that accepts electrons cytochrome! On copper Cyt oxidase, their reduction potentials are almost the same as for 1! Is generally conserved small type I or `` blue '' copper protein found in Anabaena sp,,...