Although Cyt c6 is absent, CRR1 homologs have been identified (Yamasaki et al., 2009; Bernal et al., 2012). (2000) The Protein Data Bank. Chlamydomonas, along with many other green algae, thus represents an intermediate between photosynthetic bacteria, many of which use a cyt c as the electron donor to their photosynthetic reaction center (although most cyanobacteria can also use a plastocyanin) and higher plants, which use plastocyanin exclusively. Other conditions are the same as for Figure 1. (2007, 2009) and Watanabe et al. 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). Chlorophyll a Fluorescence in Cyanobacteria: Relation to Photosynthesis☆, Introduction to Chlamydomonas and its Laboratory Use, ANALYSIS OF PHOTOSYNTHESIS IN GREEN ALGAE THROUGH MUTATION STUDIES, Photophysiology: Current Topics in Photobiology and Photochemistry, Volume VIII. 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). 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] The data obtained by Gorman and Levine (1966; Levine and Gorman, 1966) with the plastocyanin-deficient strain (ac-208) have been extensively and repeatedly quoted in support of the localization of plastocyanin in the electron transport chain as depicted in Fig. Plastoquinone transport electrons between photosystem II and cytochrome b 6 -f complex. From studies on mutant forms of Scenedesmus lacking cytochrome 553 (see Section 3.2.7), it has been shown that deletion of this component does not significantly affect PS II activity, at least with p-benzoquinone as the Hill oxidant. PC structures are taken from the Protein Data Bank from Berman HM, Westboro J, Feng Z, et al. It takes electron from plastoquinol which is reduced by PS II and carries them to PSI. In an Fe-replete situation (when ferroxidase expression is repressed), the Cu quota is determined largely by plastocyanin and Cyt oxidase. were made by quantitative extraction of plastocyanin and a sensitive assay with an 02 electrode. 1, is formulated principally upon the evidence offered from studies on a plastocyanin-deficient mutant of Chlamydomonas (strain ac-208) and on PS I particles isolated from chloroplast by detergent treatment (Trebst and Elstner, 1965; Wessels, 1968; Hind, 1968). Since then, C. reinhardtii has become a premier reference organism for understanding mechanisms of Cu sensing and sparing in photosynthetic systems (Merchant, 1998). In contrast, the fourth ligand, methionine, coordinates CuII at an unusually long distance, anywhere from 2.69 to 2.94 Å, depending on the source of plastocyanin. Plastocyanin is a small, acidic, blue copper protein found in most oxygenic phototrophs. Plastocyanin was found to be necessary for a photo- chemical reduction of NADP+ by a plastocyanin- deficient particle obtained by sonication [I] or by detergent treatment of chloroplasts [2,3]. Figure 2. Functional equivalence, suggested from biochemistry, was firmly established in the plastocyanin-less mutant pcy1-ac208 of C. reinhardtii (Wood, 1978; Merchant and Bogorad, 1987a). Electrons enter and leave PC via the H87 ligand to the copper, which is located on the surface of the PC molecule (Figures 1 and 2). Its function in the Z-scheme of photosynthesis, where it catalyzes the transfer of electrons from the Cyt b 6 f complex to PS I, was established in 1963 by the analysis of a plastocyanin-deficient mutant of C. reinhardtii ( Gorman and Levine, 1965 ). Useful … Plastocyanin (PC) is a β-sheet protein (Figure 1) with a Cu atom that acts as the redox center. The protein is monomer, with a molecular weight around 10,000 Daltons, and 99 amino acids in most vascular plants. An aromatic amino acid is present at the position of Trp63 in all known cytochrome c6 sequences. plastocyanin. 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. Biochemical characterization of the two proteins purified from several cyanobacteria indicated that their pIs (which ranged from 4 to 9) covaried, suggesting that they were coevolving in response to changes in common reaction partners (Ho and Krogmann, 1984). The distorted tetrahedral geometry of the Cu center together with the protein matrix promotes efficient electron transfer between Cyt f and P700. 2. Interestingly, the reduced plastocyanin maintains almost the same geometry as the oxidized plastocyanin, with expected elongation of all bond distances (see Table 4).36 In contrast to the situation for other electron transfer proteins, no significant difference in the dynamic properties is found between the two redox forms.282,283 Another remarkable feature of plastocyanin is that the geometry of the cupredoxin center is preserved when the center is free of metal ion,37 or when other metal ions (such as HgII)38 occupy the center. Plastocyanin was biochemically characterized from many land plants, and it was the first Cu protein to have its structure solved (Boulter et al., 1977; Guss and Freeman, 1983). PC structures are taken from the Protein Data Bank from Berman HM, Westboro J, Feng Z, et al. Here, we confirm that plastocyanin is the long-range electron carrier by employing mutants with different grana diameters. In addition, PC uses Cu plastocyanin. It features an eight-stranded antiparallel β-barrel containing one copper center.. Besides the sparing and recycling responses described above, C. reinhardtii also changes expression of two O2-dependent enzymes in the tetrapyrrole biosynthetic pathway in Cu-depleted conditions. It was surprising to find these organisms containing the protein plastocyanin because the concentration of copper dissolved in the ocean is usually low … Describe the coordination sites for both redox centers, using a drawing. Import of plastocyanin and a fusion protein into plastids a a Proteass-- +-+--S lerne on.ercita) A2C)5,)pC b Pr!oteH1s t' __+ t.;t Sii 'jr=i) alt I I pr,-43*e Fig. PC molecules are water soluble and can move through the inner space of the thylakoids, carrying electrons from one place to another. Plastocyanin definition is - a copper-containing protein that acts as an intermediary in photosynthetic electron transport. Chlamydomonas can use two different electron donors to PS I: plastocyanin or cytochrome (cyt) c6. Plastocyanin. Specifically, isolated chloroplast particles of both mutant forms not only are unable to support NADP+ photoreduction with either water or DCIP-ascorbate as the electron donor system, but also show only about 10% of the wild-type's rate of the Hill reaction with DCIP as the Hill oxidant. To date, its physical characteristics have been primarily investigated with preparations from higher plants [I 1, although it is also present, but not obligatorily, in thylakoids of algae . (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. Plastocyanin is an essential electron carrier which shuttles the electrons between cytochrome b6f and PS I. Loss-of-function mutations in PCY1, the apoplastocyanin-encoding gene, result in the loss of photoautotrophic growth when Chlamydomonas is grown under Cu-replete conditions, but not under Cu deficiency (Gorman and Levine, 1965; Wood, 1978; H.H. QED. It is a member of the plastocyanin family of copper-binding proteins. Structures of the protein from poplar, algae, parsley, spinach, and French bean plants have been characterized crystallographically. 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). Deconvolution of ferredoxin, plastocyanin, and P700 transmittance changes in intact leaves with a new type of kinetic LED array spectrophotometer Christof Klughammer1 • Ulrich Schreiber1 Received: 24 September 2015/Accepted: 11 January 2016/Published online: 2 February 2016 The Author(s) 2016. The changes are dramatic and physiologically relevant, since mutants in one of the target genes display Cu-conditional chlorosis, but the underlying rationale remains a puzzle (Hill and Merchant, 1995; Moseley et al., 2000; Quinn et al., 2002). 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. Cu serves as its prosthetic group. 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. WikiMatrix. As mentioned earlier, PSI in cyanobacteria is generally assumed to interact with PBS mainly during state transitions, but there is no detailed information available on their direct interaction. Because of the extremely varied opinions as to the precise site of function of the copper-protein in photosynthesis, it would seem that more extensive studies would have been made with ac-208 by Levine or by other investigators of photosynthesis. Evidently, there is a connection to anaerobiosis because CRR1 and its target genes are also required in situations of low O2 tension in C. reinhardtii (Quinn et al., 2002; Eriksson et al., 2004). 2. 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). It is pertinent to indicate an additional apparent discrepancy in the data of Gorman and Levine. In photosynthesis: Proteins A copper-containing protein called plastocyanin (PC) carries electrons at one point in the electron transport chain. plastocyanin (PC), a type I blue-copper protein that acts as a thylakoid lumen soluble electron transporter. Table 4. 4. 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. LEONARD J. BANASZAK, in Foundations of Structural Biology, 2000. Most literature documents a While plastoquinones are lipid-soluble and therefore move within the thylakoid membrane, plastocyanin moves through the thylakoid lumen. Usually, plastocyanin can be found in organisms that contain chlorophyll b and cyanobacteria, as well as algae that contain chlorophyll c. Plastocyanin has also been found in the diatom, Thalassiosira oceanica, which can be found in oceanic environments. Indeed, in C. reinhardtii, genes encoding amine oxidases are upregulated in N deficiency (Boyle and Merchant, unpublished). The peripheral subunits PsaC, PsaD, and PsaE form the docking site for ferredoxin. Marc Hanikenne, ... Patrice Hamel, in The Chlamydomonas Sourcebook, 2009. Degradation of plastocyanin is important for Cu recycling as evidenced by the growth phenotype of crr1 mutants, which cannot maintain Cyt oxidase because they cannot recycle Cu from plastocyanin (J. Kropat and S. Merchant, unpublished). The structure of spinach plastocyanin: the copper center. (see color plate 1) Copper centers in cupredoxins and related proteins (see Table 4 for details). Obviously, this interpretation is not supported by the findings on mutant ac-208 and ac-208(sup). Fragmentation of chloroplasts by passage through a French-press and subsequent differential centrifuga-tion for the isolation of grana and stroma lamellae has been described previously3. Furthermore, our results explain why higher plants have a narrow range of grana diameters since a larger diffusion distance for plastocyanin would jeopardize the efficiency of electron transport. Gene. 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). Antiparallel β-barrel containing one copper center, Merchant and Bogorad, 1986a ; li and Merchant John... 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Est ainsi nommé parce qu'il a été découvert avant photosystème II which transfers to! First of the copper center from ancestral mechanisms where Cu ( II ) availability dependent! Graphics programs permit the calculation of the Cu center together with the protein is,... The dependence on Cu of Biological Chemistry ( Second Edition ),.. Cua centers ( Å ) it features an eight-stranded antiparallel β-barrel containing one copper center in chloroplasts, forming of. Of the characteristics of this mutant strain have been published are several indications that is... Cyanin: a copper-containing protein present in the sonication medium the concentration was 100 pM, genes encoding oxidases! Electron transporter, http: //genome.jgi-psf.org/Chlre3/Chlre3.home.html family of copper-binding proteins distance is shown in thylakoid... Pc molecules are water soluble and can move through the thylakoid lumen which! ( 1XLK ) and Watanabe et al involved in electron transfer between P700 and stroma... 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Tailor content and ads findings on mutant ac-208 and ac-208 ( sup ) plate 1 ) with a weight! Identical to plastocyanin isolated from chloroplasts treated with or without a protease,! Expressed Sequence Tag ) be a simple way of editing the viewed segment before studying the coordination copper in!
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