-
Proceedings of the National Academy of... Feb 1991Genes for the blue copper proteins Populus nigra var. italica plastocyanin and Pseudomonas aeruginosa azurin have been constructed by a stepwise procedure. The leader...
Genes for the blue copper proteins Populus nigra var. italica plastocyanin and Pseudomonas aeruginosa azurin have been constructed by a stepwise procedure. The leader sequence for azurin has been placed before the genes directing plastocyanin and azurin transport to the periplasmic space when the genes are expressed in Escherichia coli. Site-saturation mutagenesis has been used to alter two copper-binding residues of azurin (Met-121 and His-46) and Met-92 of plastocyanin. While the plastocyanin mutants do not appear to bind copper, the azurin variants all bind copper and show characteristic type I blue copper centers. In particular, the electronic spectra reflect the dominance of the charge transfer interaction between copper and the thiolate of Cys-112, being relatively insensitive to changes in Met-121 or His-46. In contrast, removal of Met-121 appreciably alters the EPR spectra of the mutants, although, to a first order, the spectra of all mutants are themselves similar, suggesting a more distorted geometry around copper in the mutants than in the wild type.
Topics: Amino Acid Sequence; Azurin; Base Sequence; Blotting, Western; Escherichia coli; Genes, Bacterial; Genes, Plant; Genes, Synthetic; Molecular Sequence Data; Mutagenesis, Insertional; Oligonucleotide Probes; Plants; Plastocyanin; Protein Conformation; Pseudomonas aeruginosa; Restriction Mapping
PubMed: 1899926
DOI: 10.1073/pnas.88.4.1325 -
Proceedings of the National Academy of... Jun 2020In photosynthetic electron transport, large multiprotein complexes are connected by small diffusible electron carriers, the mobility of which is challenged by...
In photosynthetic electron transport, large multiprotein complexes are connected by small diffusible electron carriers, the mobility of which is challenged by macromolecular crowding. For thylakoid membranes of higher plants, a long-standing question has been which of the two mobile electron carriers, plastoquinone or plastocyanin, mediates electron transport from stacked grana thylakoids where photosystem II (PSII) is localized to distant unstacked regions of the thylakoids that harbor PSI. Here, we confirm that plastocyanin is the long-range electron carrier by employing mutants with different grana diameters. 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. In the light of recent findings that the lumen of thylakoids, which forms the diffusion space of plastocyanin, undergoes dynamic swelling/shrinkage, this study demonstrates that plastocyanin diffusion is a crucial regulatory element of plant photosynthetic electron transport.
Topics: Computer Simulation; Electron Transport; Gene Expression Regulation, Plant; Magnoliopsida; Models, Biological; Photosystem I Protein Complex; Photosystem II Protein Complex; Plastocyanin
PubMed: 32541018
DOI: 10.1073/pnas.2005832117 -
Proceedings of the National Academy of... Feb 2021After the Great Oxidation Event (GOE), iron availability was greatly decreased, and photosynthetic organisms evolved several alternative proteins and mechanisms. One of...
After the Great Oxidation Event (GOE), iron availability was greatly decreased, and photosynthetic organisms evolved several alternative proteins and mechanisms. One of these proteins, plastocyanin, is a type I blue-copper protein that can replace cytochrome as a soluble electron carrier between cytochrome and photosystem I. In most cyanobacteria, expression of these two alternative proteins is regulated by copper availability, but the regulatory system remains unknown. Herein, we provide evidence that the regulatory system is composed of a BlaI/CopY-family transcription factor (PetR) and a BlaR-membrane protease (PetP). PetR represses (plastocyanin) expression and activates (cytochrome ), while PetP controls PetR levels in vivo. Using whole-cell extracts, we demonstrated that PetR degradation requires both PetP and copper. Transcriptomic analysis revealed that the PetRP system regulates only four genes (, , , and ), highlighting its specificity. Furthermore, the presence of and in early branching cyanobacteria indicates that acquisition of these genes could represent an early adaptation to decreased iron bioavailability following the GOE.
Topics: Bacterial Proteins; Base Sequence; Copper; Cytochromes c; Epistasis, Genetic; Models, Biological; Mutation; Peptide Hydrolases; Plastocyanin; Promoter Regions, Genetic; Protein Binding; Proteolysis; Regulon; Synechocystis
PubMed: 33495331
DOI: 10.1073/pnas.2017898118 -
Biophysical Journal Dec 2001The oxidation of cytochrome f by the soluble cupredoxin plastocyanin is a central reaction in the photosynthetic electron transfer chain of all oxygenic organisms. Here,...
The oxidation of cytochrome f by the soluble cupredoxin plastocyanin is a central reaction in the photosynthetic electron transfer chain of all oxygenic organisms. Here, two different computational approaches are used to gain new insights into the role of molecular recognition and protein-protein association processes in this redox reaction. First, a comparative analysis of the computed molecular electrostatic potentials of seven single and multiple point mutants of spinach plastocyanin (D42N, E43K, E43N, E43Q/D44N, E59K/E60Q, E59K/E60Q/E43N, Q88E) and the wt protein was carried out. The experimentally determined relative rates (k(2)) for the set of plastocyanin mutants are found to correlate well (r(2) = 0.90 - 0.97) with the computed measure of the similarity of the plastocyanin electrostatic potentials. Second, the effects on the plastocyanin/cytochrome f association rate of these mutations in the plastocyanin "eastern site" were evaluated by simulating the association of the wild type and mutant plastocyanins with cytochrome f by Brownian dynamics. Good agreement between the computed and experimental relative rates (k(2)) (r(2) = 0.89 - 0.92) was achieved for the plastocyanin mutants. The results obtained by applying both computational techniques provide support for the fundamental role of the acidic residues at the plastocyanin eastern site in the association with cytochrome f and in the overall electron-transfer process.
Topics: Computer Simulation; Cytochromes; Cytochromes f; Electron Transport; Hydrogen-Ion Concentration; Ligands; Models, Chemical; Models, Molecular; Mutation; Oxidation-Reduction; Oxygen; Plastocyanin; Point Mutation; Protein Binding; Protein Conformation; Spinacia oleracea; Static Electricity
PubMed: 11720977
DOI: 10.1016/S0006-3495(01)75947-4 -
Frontiers in Plant Science 2017miR408 is highly conserved among different plant species and targets transcripts encoding copper-binding proteins. The function of miR408 in reproductive development...
miR408 is highly conserved among different plant species and targets transcripts encoding copper-binding proteins. The function of miR408 in reproductive development remains largely unclear despite it being known to play important roles during vegetative development in Arabidopsis. Here, we show that transgenic Arabidopsis plants overexpressing have altered morphology including significantly increased leaf area, petiole length, plant height, flower size, and silique length, resulting in enhanced biomass and seed yield. The increase in plant size was primarily due to cell expansion rather than cell proliferation, and was consistent with higher levels of myosin gene expression and gibberellic acid (GA) measured in transgenic plants. In addition, photosynthetic rate was significantly increased in the MIR408-overexpressing plants, as manifested by higher levels of chloroplastic copper content and plastocyanin (PC) expression. In contrast, overexpression of miR408-regulated targets, and , resulted in reduced biomass production and seed yield. RNA-sequencing revealed that genes involved in primary metabolism and stress response were preferentially enriched in the genes upregulated in -overexpressing plants. These results indicate that miR408 plays an important role in regulating biomass and seed yield and that may be a potential candidate gene involved in the domestication of agricultural crops.
PubMed: 29422907
DOI: 10.3389/fpls.2017.02114 -
Journal of Computational Chemistry Jun 2017Plastocyanin is a copper containing protein that is involved in the electron transfer process in photosynthetic organisms. The active site of plastocyanin is described...
Plastocyanin is a copper containing protein that is involved in the electron transfer process in photosynthetic organisms. The active site of plastocyanin is described as an entatic state whereby its structure represents a compromise between the structures favored by the oxidized and reduced forms. In this study, the nature of the entatic state is investigated through density functional theory-based hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulations. The strain energy is computed to be 12.8 kcal/mol and 14.5 kcal/mol for the oxidized and reduced forms of the protein, indicating that the active site has an intermediate structure. It is shown that the energy gap between the oxidized and reduced forms varies significantly with the fluctuations in the structure of the active site at room temperature. An accurate determination of the reorganization energy requires averaging over conformation and a large region of the protein around the active site to be treated at the quantum mechanical level. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc.
Topics: Catalytic Domain; Electron Transport; Molecular Dynamics Simulation; Oxidation-Reduction; Plastocyanin; Protein Conformation; Quantum Theory; Thermodynamics
PubMed: 27859435
DOI: 10.1002/jcc.24666 -
The Journal of Biological Chemistry Jul 1994Plastocyanin and the 33-kDa subunit of the oxygen-evolving complex (OE33) are two of several thylakoid lumen-located proteins that are made in the cytosol, imported into...
Plastocyanin and the 33-kDa subunit of the oxygen-evolving complex (OE33) are two of several thylakoid lumen-located proteins that are made in the cytosol, imported into chloroplasts, and subsequently transported into thylakoids. Recently, competition studies showed that there are two pathways for protein transport into the thylakoid lumen and that plastocyanin and OE33 are on the same pathway (Cline, K., Henry, R., Li, C., and Yuan, J. (1993) EMBO J. 12, 4105-4114). Our expectation is that transport requirements reflect the steps of the process and that proteins on the same pathway share similar requirements. Unfortunately, the transport requirements for plastocyanin and OE33 are not well established. Here, we investigated transport in a reconstituted system with isolated thylakoids. Efficient transport of OE33 and plastocyanin was only obtained when stromal extract was included in the assay. Heat or protease treatment of stromal extract eliminated its ability to stimulate transport. Transport was abolished by treatments designed to deplete ATP or to prevent its formation and was greatly reduced in the presence of ionophores that dissipate the trans-thylakoidal proton gradient. These results show that transport of OE33 and plastocyanin requires ATP and is stimulated by stromal protein(s) and the trans-thylakoidal proton gradient. Taken together, these and previous results suggest that there are two mechanistically distinct pathways for protein transport into the thylakoid lumen.
Topics: Adenosine Triphosphate; Arabidopsis; Biological Transport; Chloroplasts; Hydrogen-Ion Concentration; Intracellular Membranes; Ionophores; Kinetics; Macromolecular Substances; Molecular Weight; Organelles; Photosynthetic Reaction Center Complex Proteins; Photosystem II Protein Complex; Plastocyanin; Proton-Translocating ATPases; Venturicidins
PubMed: 8034593
DOI: No ID Found -
Biochemistry. Biokhimiia Jun 2015The pigment-protein complex of photosystem I (PS I) catalyzes light-driven oxidation of plastocyanin or cytochrome c6 and reduction of ferredoxin or flavodoxin in... (Review)
Review
The pigment-protein complex of photosystem I (PS I) catalyzes light-driven oxidation of plastocyanin or cytochrome c6 and reduction of ferredoxin or flavodoxin in oxygenic photosynthetic organisms. In this review, we describe the current state of knowledge of the processes of excitation energy transfer and formation of the primary and secondary ion-radical pairs within PS I. The electron transfer reaction involving quinone cofactor in the A1 site and its role in providing asymmetry of electron transport as well as interaction with oxygen and ascorbate in PS I are discussed.
Topics: Electron Transport; Oxidation-Reduction; Photosystem I Protein Complex; Plastocyanin; Quinones
PubMed: 26531012
DOI: 10.1134/S0006297915060024 -
Physical Chemistry Chemical Physics :... Sep 2010The electronic absorption, electronic circular dichroism and X-ray absorption spectroscopy of the blue copper protein plastocyanin is studied with density functional...
The electronic absorption, electronic circular dichroism and X-ray absorption spectroscopy of the blue copper protein plastocyanin is studied with density functional theory, time-dependent density functional theory and multireference configuration interaction in conjunction with classical molecular dynamics simulations. A strong correlation is observed between the excitation energy of the intense ligand to metal charge transfer band and the copper-cysteine sulfur bond length. The results suggest that the copper-cysteine sulfur bond length in the crystal structure of plastocyanin is too short and should be closer to the corresponding bond lengths in related blue copper proteins. Averaging over many structural conformations is required to reproduce the major features of the experimental circular dichroism spectra. A correlation between the rotational strength of the ligand to metal charge transfer band and the distortion of the copper atom from the plane of the cysteine sulfur and histidine nitrogen atoms is found. X-ray absorption calculations show a smaller sulfur p orbital character in the singly occupied molecular orbital of cucumber basic protein compared to plastocyanin.
Topics: Catalytic Domain; Circular Dichroism; Copper; Crystallography, X-Ray; Molecular Dynamics Simulation; Plastocyanin; Sulfur; X-Ray Absorption Spectroscopy
PubMed: 20532328
DOI: 10.1039/c001805h -
FEBS Letters Oct 2016Plastocyanin (petE) plays an essential role in photosynthesis as an electron carrier between cytochrome b f and photosystem I, and in some cyanobacteria it can be...
Plastocyanin (petE) plays an essential role in photosynthesis as an electron carrier between cytochrome b f and photosystem I, and in some cyanobacteria it can be replaced by the haem-containing protein, cytochrome c (petJ). In Synechocystis sp. PCC 6803, transcription of petE and petJ is activated and repressed, respectively, by Cu. Here, we show that Ni can act similarly to Cu in inducing petE and repressing petJ, thus leading to a partial switch between cytochrome c and plastocyanin. Transcription of these genes is only altered by Ni in Cu-depleted medium, and none of the Ni-dependent transcription factors described in Synechocystis, NrsR and InrS seem to be involved in this regulation. Finally, we show that plastocyanin is essential for growth under conditions of excess Ni.
Topics: Bacterial Proteins; Cytochromes c6; Gene Expression Regulation, Bacterial; Nickel; Plastocyanin; Synechocystis; Transcription, Genetic
PubMed: 27685247
DOI: 10.1002/1873-3468.12438