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The Journal of Cell Biology Apr 1989The lateral distribution of plastocyanin in the thylakoid lumen of spinach and pea chloroplasts was studied by combining immunocytochemical localization and kinetic...
The lateral distribution of plastocyanin in the thylakoid lumen of spinach and pea chloroplasts was studied by combining immunocytochemical localization and kinetic measurements of P700+ reduction at high time resolution. In dark-adapted chloroplasts, the concentration of plastocyanin in the photosystem I containing stroma membranes exceeds that in photosystem II containing grana membranes by a factor of about two. Under these conditions, the reduction of P700+ with a halftime of 12 microseconds after a laser flash of saturating intensity indicates that to greater than 95% of total photosystem I a plastocyanin molecule is bound. An analysis of the labeling densities, the length of the different lumenal regions, and the total amounts of plastocyanin and P700 shows that most of the remaining presumable mobile plastocyanin is found in the granal lumen. This distribution of plastocyanin is consistent with a more negative surface charge density in the stromal than in the granal lumen. During illumination the concentration of plastocyanin in grana increases at the expense of that in stroma lamellae, indicating a light-driven diffusion from stroma to grana regions. Our observations provide evidence that a high concentration of plastocyanin in grana in the light favors the lateral electron transport from cytochrome b6/f complexes in appressed grana across the long distance to photosystem I in nonappressed stroma membranes.
Topics: Chlorophyll; Chloroplasts; Fabaceae; Kinetics; Light; Light-Harvesting Protein Complexes; Microscopy, Electron; Photosynthetic Reaction Center Complex Proteins; Photosystem I Protein Complex; Photosystem II Protein Complex; Plant Proteins; Plants; Plants, Medicinal; Plastocyanin
PubMed: 2647767
DOI: 10.1083/jcb.108.4.1397 -
European Journal of Biochemistry Nov 1996To compare cadmium-substituted plastocyanin with copper plastocyanin, the 1H-NMR spectra of CuI-, CuII- and Cd-plastocyanin from pea have been analyzed. Full assignments...
Analysis of the 1H-NMR chemical shifts of Cu(I)-, Cu(II)- and Cd-substituted pea plastocyanin. Metal-dependent differences in the hydrogen-bond network around the copper site.
To compare cadmium-substituted plastocyanin with copper plastocyanin, the 1H-NMR spectra of CuI-, CuII- and Cd-plastocyanin from pea have been analyzed. Full assignments of the spectra of CuI- and Cd-plastocyanin indicate chemical shift differences up to 1 ppm. The affected protons are located in the four loops that surround the Cu site. The largest differences were found for protons in the hydrogen bond network which stabilizes this part of the protein. This suggests that the chemical shift differences are caused by very small but extensive structural changes in the network upon replacement of CuI by Cd. For CuII-plastocyanin the resonances of 72% of the protons observed in the CuI form have been identified. Protons within approximately 0.9 nm of the CuII were not observed due to fast paramagnetic relaxation. The protons between 0.9-1.7 nm from the CuII showed chemical shift differences up to 0.4 ppm compared to both CuI- and Cd-plastocyanin. These differences can be predicted assuming that they represent pseudocontact shifts. When corrected for the pseudocontact shift contribution, the CuII-plastocyanin chemical shifts were nearly all identical within error to those of the Cd form, but not of the CuI-plastocyanin, indicating that the CuII-plastocyanin structure, in as far as it can be observed, resembles Cd-rather than CuI-plastocyanin. In a single stretch of residues (64-69) chemical shift differences remained between all three forms after correction. The fact that pseudocontact shifts were observed for protons which were not broadened may be attributable to the weaker distance dependence of the pseudocontact shift effect compared to paramagnetic relaxation. This results in two shells around the Cu atom, an inner paramagnetic shell (0-0.9 nm), in which protons are not observed due to broadening, and an outer paramagnetic shell (0.9-1.7 nm), in which protons can be observed and show pseudocontact shifts. It is concluded that Cd-plastocyanin is a suitable redox-inactive substitute for Cu-plastocyanin.
Topics: Amino Acid Sequence; Cadmium; Copper; Electron Spin Resonance Spectroscopy; Hydrogen Bonding; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Sequence Data; Pisum sativum; Plastocyanin
PubMed: 8954163
DOI: 10.1111/j.1432-1033.1996.0132r.x -
Biochimica Et Biophysica Acta Feb 2000The effect of electrostatic interactions on the conformation and thermal stability of plastocyanin (Pc) was studied by infrared spectroscopy. Association of any of the...
The effect of electrostatic interactions on the conformation and thermal stability of plastocyanin (Pc) was studied by infrared spectroscopy. Association of any of the two redox states of the protein with positively charged membranes at neutral pH does not significantly change the secondary structure of Pc. However, upon membrane binding, the denaturation temperature decreases, regardless of the protein redox state. The extent of destabilization depends on the proportion of positively charged lipid headgroups in the membrane, becoming greater as the surface density of basic phospholipids increases. In contrast, at pH 4.8 the membrane binding-dependent conformational change becomes redox-sensitive. While the secondary structures and thermal stabilities of free and membrane-bound oxidized Pc are similar under acidic conditions, the conformation of the reduced form of the protein drastically rearranges upon membrane association. This rearrangement does not depend on electrostatic interactions to occur, since it is also observed in the presence of uncharged lipid bilayers. The conformational transition, only observed for reduced Pc, involves the exposure of hydrophobic regions that leads to intermolecular interactions at the membrane surface. Membrane-mediated partial unfolding of reduced Pc can be reversed by readjusting the pH to neutrality, in the absence of electrostatic interactions. This redox-dependent behavior might reflect specific structural requirements for the interaction of Pc with its redox partners.
Topics: Drug Stability; Fatty Acids, Monounsaturated; Fluorescent Dyes; Hot Temperature; Hydrogen-Ion Concentration; Lipid Bilayers; Oxidation-Reduction; Phosphatidylcholines; Plant Leaves; Plastocyanin; Protein Conformation; Quaternary Ammonium Compounds; Spectrophotometry, Infrared; Static Electricity; Thermodynamics; Trees
PubMed: 10675519
DOI: 10.1016/s0005-2736(99)00230-8 -
The Journal of Biological Chemistry Apr 1999Spectroscopic properties, amino acid sequence, electron transfer kinetics, and crystal structures of the oxidized (at 1.7 A resolution) and reduced form (at 1.8 A...
The structure and unusual pH dependence of plastocyanin from the fern Dryopteris crassirhizoma. The protonation of an active site histidine is hindered by pi-pi interactions.
Spectroscopic properties, amino acid sequence, electron transfer kinetics, and crystal structures of the oxidized (at 1.7 A resolution) and reduced form (at 1.8 A resolution) of a novel plastocyanin from the fern Dryopteris crassirhizoma are presented. Kinetic studies show that the reduced form of Dryopteris plastocyanin remains redox-active at low pH, under conditions where the oxidation of the reduced form of other plastocyanins is inhibited by the protonation of a solvent-exposed active site residue, His87 (equivalent to His90 in Dryopteris plastocyanin). The x-ray crystal structure analysis of Dryopteris plastocyanin reveals pi-pi stacking between Phe12 and His90, suggesting that the active site is uniquely protected against inactivation. Like higher plant plastocyanins, Dryopteris plastocyanin has an acidic patch, but this patch is located closer to the solvent-exposed active site His residue, and the total number of acidic residues is smaller. In the reactions of Dryopteris plastocyanin with inorganic redox reagents, the acidic patch (the "remote" site) and the hydrophobic patch surrounding His90 (the "adjacent" site) are equally efficient for electron transfer. These results indicate the significance of the lack of protonation at the active site of Dryopteris plastocyanin, the equivalence of the two electron transfer sites in this protein, and a possibility of obtaining a novel insight into the photosynthetic electron transfer system of the first vascular plant fern, including its molecular evolutionary aspects. This is the first report on the characterization of plastocyanin and the first three-dimensional protein structure from fern plant.
Topics: Amino Acid Sequence; Binding Sites; Histidine; Hydrogen-Ion Concentration; Models, Molecular; Molecular Sequence Data; Plants; Plastocyanin; Protein Conformation; Sequence Homology, Amino Acid
PubMed: 10206999
DOI: 10.1074/jbc.274.17.11817 -
Nature Chemical Biology Dec 2014We identified a Cu-accumulating structure with a dynamic role in intracellular Cu homeostasis. During Zn limitation, Chlamydomonas reinhardtii hyperaccumulates Cu, a...
We identified a Cu-accumulating structure with a dynamic role in intracellular Cu homeostasis. During Zn limitation, Chlamydomonas reinhardtii hyperaccumulates Cu, a process dependent on the nutritional Cu sensor CRR1, but it is functionally Cu deficient. Visualization of intracellular Cu revealed major Cu accumulation sites coincident with electron-dense structures that stained positive for low pH and polyphosphate, suggesting that they are lysosome-related organelles. Nano-secondary ion MS showed colocalization of Ca and Cu, and X-ray absorption spectroscopy was consistent with Cu(+) accumulation in an ordered structure. Zn resupply restored Cu homeostasis concomitant with reduced abundance of these structures. Cu isotope labeling demonstrated that sequestered Cu(+) became bioavailable for the synthesis of plastocyanin, and transcriptome profiling indicated that mobilized Cu became visible to CRR1. Cu trafficking to intracellular accumulation sites may be a strategy for preventing protein mismetallation during Zn deficiency and enabling efficient cuproprotein metallation or remetallation upon Zn resupply.
Topics: Cations, Divalent; Chlamydomonas reinhardtii; Copper; Gene Expression Profiling; Homeostasis; Hydrogen-Ion Concentration; Isotope Labeling; Isotopes; Lysosomes; Molecular Imaging; Plastocyanin; Polyphosphates; Transcription Factors; Transcriptome; Zinc
PubMed: 25344811
DOI: 10.1038/nchembio.1662 -
European Journal of Biochemistry Jun 1978The interrelation of the copper protein plastocyanin, and a soluble c-type cytochrome, c-552, in photosynthetic electron transport has been studied in the genus...
The interrelation of the copper protein plastocyanin, and a soluble c-type cytochrome, c-552, in photosynthetic electron transport has been studied in the genus Chlamydomonas. With C. reinhardtii the plastocyanin: cytochrome c-552 ratio could be changed from 300:1 less than 1:16 simply by omitting copper from the medium, without any other detectable change. Plastocyanin was indetectable in a second species, C. mundana, for which the cytochrome c-552 level was always very high. The properties of Levine's C. reinhardtii mutant lacking plastocyanin, ac-208, were studies and it was found that the photosynthetic capabilities of a suppressed phenotype and suppressed genotype could be explained by reference to the cytochrome c-552 levels. Both proteins were successfully used in reconstitution experiments with chloroplast fragments. Both showed very fast kinetics for reduction by purified Chlamydomonas cytochrome f, but the rate of electron transfer from one to the other was much slower. It is concluded that they constitute an interchangeable pair, and the rationale for this and possible analogies are both discussed.
Topics: Biological Evolution; Chlamydomonas; Chlorophyll; Chloroplasts; Copper; Cytochrome c Group; Electron Transport; Photosynthesis; Plant Proteins; Plastocyanin
PubMed: 208838
DOI: 10.1111/j.1432-1033.1978.tb12346.x -
The Plant Cell Jan 2009Expression of miR398 is induced in response to copper deficiency and is involved in the degradation of mRNAs encoding copper/zinc superoxide dismutase in Arabidopsis...
Expression of miR398 is induced in response to copper deficiency and is involved in the degradation of mRNAs encoding copper/zinc superoxide dismutase in Arabidopsis thaliana. We found that SPL7 (for SQUAMOSA promoter binding protein-like7) is essential for this response of miR398. SPL7 is homologous to Copper response regulator1, the transcription factor that is required for switching between plastocyanin and cytochrome c(6) in response to copper deficiency in Chlamydomonas reinhardtii. SPL7 bound directly to GTAC motifs in the miR398 promoter in vitro, and these motifs were essential and sufficient for the response to copper deficiency in vivo. SPL7 is also required for the expression of multiple microRNAs, miR397, miR408, and miR857, involved in copper homeostasis and of genes encoding several copper transporters and a copper chaperone, indicating its central role in response to copper deficiency. Consistent with this idea, the growth of spl7 plants was severely impaired under low-copper conditions.
Topics: Arabidopsis; Arabidopsis Proteins; Copper; Gene Expression Regulation, Plant; MicroRNAs; Oligonucleotide Array Sequence Analysis; Plants, Genetically Modified; Promoter Regions, Genetic; Protein Binding; RNA, Messenger; RNA, Plant; Transcription Factors; Transcription, Genetic
PubMed: 19122104
DOI: 10.1105/tpc.108.060137 -
FEBS Letters Sep 2000A study by two-dimensional electrophoresis showed that the soluble, lumenal fraction of Arabidopsis thaliana thylakoids can be resolved into 300 protein spots. After...
A study by two-dimensional electrophoresis showed that the soluble, lumenal fraction of Arabidopsis thaliana thylakoids can be resolved into 300 protein spots. After subtraction of low-intensity spots and accounting for low-level stromal contamination, the number of more abundant, lumenal proteins was estimated to be between 30 and 60. Two of these proteins have been identified: a novel plastocyanin that also was the predominant component of the total plastocyanin pool, and a putative ascorbate peroxidase. Import studies showed that these proteins are routed to the thylakoid lumen by the Sec- and delta pH-dependent translocation pathways, respectively. In addition, novel isoforms of PsbO and PsbQ were identified.
Topics: Amino Acid Sequence; Arabidopsis; Ascorbate Peroxidases; Cell Fractionation; Chloroplasts; Molecular Sequence Data; Peroxidases; Plastocyanin; Proteome; Sequence Homology, Amino Acid; Thylakoids
PubMed: 11034343
DOI: 10.1016/s0014-5793(00)01890-1 -
Physiologia Plantarum Feb 2021We have investigated if the heterologous expression of a functional green alga plastocyanin in the diatom Phaeodactylum tricornutum can improve photosynthetic activity...
We have investigated if the heterologous expression of a functional green alga plastocyanin in the diatom Phaeodactylum tricornutum can improve photosynthetic activity and cell growth. Previous in vitro assays showed that a single-mutant of the plastocyanin from the green algae Chlamydomonas reinhardtii is effective in reducing P. tricornutum photosystem I. In this study, in vivo assays with P. tricornutum strains expressing this plastocyanin indicate that even the relatively low intracellular concentrations of holo-plastocyanin detected (≈4 μM) are enough to promote an increased growth (up to 60%) under iron-deficient conditions as compared with the WT strain, measured as higher cell densities, content in pigments and active photosystem I, global photosynthetic rates per cell, and even cell volume. In addition, the presence of plastocyanin as an additional photosynthetic electron carrier seems to decrease the over-reduction of the plastoquinone pool. Consequently, it promotes an improvement in the maximum quantum yield of both photosystem II and I, together with a decrease in the acceptor side photoinhibition of photosystem II-also associated to a reduced oxidative stress-a decrease in the peroxidation of membrane lipids in the choroplast, and a lower degree of limitation on the donor side of photosystem I. Thus the heterologous plastocyanin appears to act as a functional electron carrier, alternative to the native cytochrome c , under iron-limiting conditions.
Topics: Diatoms; Electron Transport; Iron; Photosynthesis; Photosystem I Protein Complex; Plastocyanin
PubMed: 33247466
DOI: 10.1111/ppl.13290 -
Protein Science : a Publication of the... May 2001Plastocyanin is a predominantly beta-sheet protein containing a type I copper center. The conformational ensemble of a denatured state of apo-plastocyanin formed in...
Plastocyanin is a predominantly beta-sheet protein containing a type I copper center. The conformational ensemble of a denatured state of apo-plastocyanin formed in solution under conditions of low salt and neutral pH has been investigated by multidimensional heteronuclear NMR spectroscopy. Chemical shift assignments were obtained by using three-dimensional triple-resonance NMR experiments to trace through-bond heteronuclear connectivities along the backbone and side chains. The (3)J(HN,Halpha) coupling constants, (15)N-edited proton-proton nuclear Overhauser effects (NOEs), and (15)N relaxation parameters were also measured for the purpose of structural and dynamic characterization. Most of the residues corresponding to beta-strands in the folded protein exhibit small upfield shifts of the (13)C(alpha) and (13)CO resonances relative to random coil values, suggesting a slight preference for backbone dihedral angles in the beta region of (phi,psi) space. This is further supported by the presence of strong sequential d(alphaN)(i, i + 1) NOEs throughout the sequence. The few d(NN)(i, i + 1) proton NOEs that are observed are mostly in regions that form loops in the native plastocyanin structure. No medium or long-range NOEs were observed. A short sequence, between residues 59 and 63, was found to populate a nonnative helical conformation in the unfolded state, as indicated by the shift of the (13)C(alpha), (13)CO, and (1)H(alpha) resonances relative to random coil values and by the decreased values of the (3)J(HN,Halpha) coupling constants. The (15)N relaxation parameters indicate restriction of motions on a nanosecond timescale in this region. Intriguingly, this helical conformation is present in a sequence that is close to but not in the same location as the single short helix in the native folded protein. The results are consistent with earlier NMR studies of peptide fragments of plastocyanin and confirm that the regions of the sequence that form beta-strands in the native protein spontaneously populate the beta-region of (phi,psi) space under folding conditions, even in the absence of stabilizing tertiary interactions. We conclude that the state of apo-plastocyanin present under nondenaturing conditions is a noncompact unfolded state with some evidence of nativelike and nonnative local structuring that may be initiation sites for folding of the protein.
Topics: Amino Acid Sequence; Apoproteins; Molecular Sequence Data; Nuclear Magnetic Resonance, Biomolecular; Plastocyanin; Protein Conformation; Protein Denaturation; Protein Folding; Structure-Activity Relationship; Thermodynamics; Trees
PubMed: 11316886
DOI: 10.1110/ps.00601