Information on EC 1.97.1.12 - photosystem I

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The expected taxonomic range for this enzyme is: Eukaryota, Bacteria

EC NUMBER
COMMENTARY
1.97.1.12
-
RECOMMENDED NAME
GeneOntology No.
photosystem I
-
REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
reduced plastocyanin + oxidized ferredoxin + hnu = oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
-
-
-
PATHWAY
KEGG Link
MetaCyc Link
hydrogen production VIII
-
photosynthesis light reactions
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SYSTEMATIC NAME
IUBMB Comments
plastocyanin:ferredoxin oxidoreductase (light-dependent)
Contains chlorophyll, phylloquinones, carotenoids and [4Fe-4S] clusters. Cytochrome c6 can act as an alternative electron donor, and flavodoxin as an alternative acceptor in some species.
SYNONYMS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
PS-I complex
-
-
PSI core complex
P42048
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ORGANISM
COMMENTARY
LITERATURE
SEQUENCE CODE
SEQUENCE DB
SOURCE
photosystem I reaction center subunit III, plastocyanin-docking protein
SwissProt
Manually annotated by BRENDA team
var. Alaska
-
-
Manually annotated by BRENDA team
Synechococcus sp. OD24
-
-
-
Manually annotated by BRENDA team
SUBSTRATE
PRODUCT                      
REACTION DIAGRAM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
(Substrate)
LITERATURE
(Substrate)
COMMENTARY
(Product)
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
-
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
-
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
-
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
-
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
-
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
-
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
P42048
-
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
characterization of the electron donor (plastocyanin) binding site. Plastocyanin binds in a small cavity on the lumenal surface of photosystem I, close to the center and with a slight bias toward the PsaL subunit of the complex
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
photosystem I (PS I) mediates electron-transfer from plastocyanin to ferredoxin via a photochemically active chlorophyll dimer (P700), a monomeric chlorophyll electron acceptor (A0), a phylloquinone (A1), and three [4Fe-4S] clusters (FX/A/B)
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
recombinant plastocyanin is the superior electron donor to photosystem I. Detailed analysis of PSI-mediated linear electron transfer from reduced plastocyanin to NADP+, in thylakoid membranes of wild type and a psaE mutant of Synechocystis PCC 6803
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
subunit PsaE (a peripheral subunit of the PSI complex) is involved in the docking of ferredoxin/flavodoxin to the PSI complex and also participates in the cyclic electron transfer around phosposystem I
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
the light-harvesting complexes and internal antenna of photosystem I absorb photons and transfer the excitation energy to P700, the primary electron donor. The subsequent charge separation and electron transport leads to the reduction of ferredoxin
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
the photosystem 1 subunit PsaF is involved in the docking of the electron-donor proteins plastocyanin and cytochrome c6, the recombinant protein binds to plastocyanin by a specific, native-like, electrostatic interaction
-
-
?
NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
(Substrate)
LITERATURE
(Substrate)
COMMENTARY
(Product)
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
-
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
-
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
-
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
-
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
-
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
-
-
-
-
?
reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
show the reaction diagram
P42048
-
-
-
?
COFACTOR
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
beta-carotene
-
cyanobacterial PSI complexes contain 22 molecules of beta-carotene, 17 of which are in all-trans configuration
Chlorophyll
-
photosystem I (PS I) mediates electron-transfer from plastocyanin to ferredoxin via a photochemically active chlorophyll dimer (P700), a monomeric chlorophyll electron acceptor (A0), a phylloquinone (A1), and three [4Fe-4S] clusters (FX/A/B)
Chlorophyll
-
173 chlorophyll molecules in the structure of the entire PSI super-complex. Chl1303 is located in the gap region between the core complex and the light-harvesting complex (LHCI). The Chl1303 position is sufficient for excitation energy transfer from the Lhca14 dimer to the core through chlorophylls 1302 and 1305
chlorophyll a
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most abundant cofactor in PSI, role of these molecules in light absorption, charge separation, electron transfer, and biogenesis
chlorophyll a'
-
one member of the P700 special pair is a chlorophyll a' molecule
Ferredoxin
-
-
-
Ferredoxin
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location of the ferredoxin-binding site in photosystem I, ferredoxin is bound on top of the stromal ridge principally interacting with the extrinsic subunits PsaC and PsaE
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iron-sulfur centre
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a PSI complex contains 12 iron atoms that constitute 3 [4Fe-4S] clusters
iron-sulfur centre
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electron transfer from the primary electron donor P700 to the FA/FB centers is demonstrated by flash-induced absorption change of the isolated reaction center complex, while electron paramagnetic resonance spectroscopy shows that the reaction center complex contains a full set of FeS clusters
Lipid
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four lipid molecules can be assigned in the high-resolution structure of PSI. Three of these molecules are phosphatidylglycerol and one is monogalactosyldiacylglycerol. These molecules are embedded in the PSI complex, with the acyl chains anchored among transmembrane helices. The phosphodiester group of one of the phospholipids coordinates an antenna chlorophyll molecule
phylloquinone
-
the PSI complex of cyanobacteria and chloroplasts contains two phylloquinone molecules, which function in the electron transfer as the redox center A1
phylloquinone
-
photosystem I (PS I) mediates electron-transfer from plastocyanin to ferredoxin via a photochemically active chlorophyll dimer (P700), a monomeric chlorophyll electron acceptor (A0), a phylloquinone (A1), and three [4Fe-4S] clusters (FX/A/B)
[4Fe-4S] center
-
photosystem I (PS I) mediates electron-transfer from plastocyanin to ferredoxin via a photochemically active chlorophyll dimer (P700), a monomeric chlorophyll electron acceptor (A0), a phylloquinone (A1), and three [4Fe-4S] clusters (FX/A/B). Iron-sulfur cluster FA is in closer proximity to P700 than the FB cluster
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[4Fe-4S] center
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the enzyme contains three [4Fe-4S] clusters: FA, FB and FX
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INHIBITORS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
Ag(I)-substituted plastocyanin
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competitive inhibitor of the reaction with normal Cu-containg plastocyanin
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Zn(II)-substituted plastocyanin
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competitive inhibitor of the reaction with normal Cu-containg plastocyanin
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KM VALUE [mM]
KM VALUE [mM] Maximum
SUBSTRATE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
0.007
-
reduced plastocyanin
-
pH and temperature not specified in the publication
Ki VALUE [mM]
Ki VALUE [mM] Maximum
INHIBITOR
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
IMAGE
0.03
-
Ag(I)-substituted plastocyanin
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pH and temperature not specified in the publication
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0.41
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Zn(II)-substituted plastocyanin
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pH and temperature not specified in the publication
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SOURCE TISSUE
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
SOURCE
PDB
SCOP
CATH
ORGANISM
Synechococcus sp. (strain ATCC 27264 / PCC 7002 / PR-6)
Synechocystis sp. (strain PCC 6803 / Kazusa)
Synechocystis sp. (strain PCC 6803 / Kazusa)
Thermosynechococcus elongatus (strain BP-1)
Thermosynechococcus elongatus (strain BP-1)
Thermosynechococcus elongatus (strain BP-1)
SUBUNITS
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
?
-
21000-22000 Da, photosystem 1 subunit PsaF that is involved in the docking of the electron-donor proteins plastocyanin and cytochrome c6, SDS-PAGE
additional information
-
plant and algal PSI complexes contain 14-15 protein subunits. Of these, only PsaA, PsaB, and PsaC bind the cofactors of the electron transfer system. PsaA and PsaB form the core complex around which other subunits are organized. The PsaC, PsaD, PsaH, and PsaE proteins form the stromal peripheral domain that contains the terminal electron donors and the ferredoxin-docking site. PsaN of plant and algal PSI is a lumenal peripheral protein. PsaN and the large lumenal domain of PsaF form the plastocyanin docking site of plant and algal PSI. The remaining proteins of PSI are integral membrane proteins with 13 transmembrane helices. The function of the PSI proteins
additional information
-
a cyanobacterial PSI monomer consists of 1112 protein subunits
additional information
-
PsaE (a peripheral subunit of the PSI complex) is involved in the docking of ferredoxin/flavodoxin to the PSI complex and also participates in the cyclic electron transfer around phosposystem I. The interactions formed between different subunits of the complex may be hydrophobic or electrostatic in nature
additional information
P42048
the PSI core complex prepared from cucumber cotyledons contains 80 chlorophylls per reaction center (P700) and eight polypeptides with apparent molecular masses of 65/63, 20,19.5,18.5,17.5,7.6, and 5.8 kDa. The amount of 18.5 kDa polypeptide in the PSI complex affects the activity. When this polypeptide is largely depleted, the complex is almost inactive. The inactivation is due to inhibition of electron transfer from plastocyanin to photooxidized P700. Chemical cross-linking and N-terminal amino acid sequencing experiments indicate that the 18.5-kDa polypeptide is the plastocyanin-docking protein and the psaF gene product
additional information
-
the photosystem I reaction center complex is composed of the 83 kDa subunits A and B, and at least six other subunits with molecular mass below 20 kDa
additional information
-
the photosystem I reaction center is obtained in two forms, monomeric and trimeric
Crystallization/COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
3.3 A crystal structure of the entire PSI super-complex, sitting drop variant of the vapor-diffusion technique at 4C
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sitting-drop variant of the vapour-diffusion technique at 4C, crystals diffract to 4 A resolution using synchrotron radiation and belong to the monoclinic crystal system, space group P21, with unit-cell parameters a = 181.90, b = 190.24, c = 219.66 A, beta = 90.484
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single crystals from a complex of photosystem I with ferredoxin are grown using PEG 400 and CaCl2 as precipitation agents. The crystals diffract X-rays to a resolution of 78 A. The space group iss determined to be orthorhombic with the unit cell dimensions a = 194 A, b = 208 A, and c = 354 A. The crystals contain photosystem I and ferredoxin in a 1:1 ratio. Electron paramagnetic resonance (EPR) measurements on these crystals are reported, where EPR signals of the three [4Fe-4S] clusters FA, FB, FX, and the [2Fe-2S] cluster of ferredoxin are detected
-
highly ordered two-dimensional crystals of photosystem I reaction center complex
-
isolation and reconstitution of the functional PSI complexes into 2D arrays. The solubilized and crystallized PSI has essentially the same protein composition, as shown by SDS/polyacrylamide gels
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TEMPERATURE STABILITY
TEMPERATURE STABILITY MAXIMUM
ORGANISM
UNIPROT ACCESSION NO.
COMMENTARY
LITERATURE
additional information
-
-
a group of short amphiphilic peptides improve the thermal stability of the multi-domain protein complex photosystem-I in aqueous solution. Ac-I5K2-CONH2 shows the best stabilizing effect by enhancing the melting temperature of PS-I from 48C to 53C at concentration of 0.65 mM and extending the half life of isolated PS-I significantly
GENERAL STABILITY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
a group of short amphiphilic peptides improve the thermal stability of the multi-domain protein complex photosystem-I in aqueous solution. Ac-I5K2-CONH2 shows the best stabilizing effect by enhancing the melting temperature of PS-I from 48C to 53C at concentration of 0.65 mM and extending the half life of isolated PS-I significantly
-
acetyl-VVVVVVD stabilizes the photosystem I complex to a lesser extent than acetyl-AAAAAAK
-
dodecyl-beta-D-maltoside partially stabilizes
-
in the presence of acetyl-AAAAAAK, the PS-I complex is stable in a dried form at room temperature for at least 3 weeks
-
octyl-beta-D-glucoside partially stabilizes
-
Purification/COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
rapid, high-yield purification of PS1
-
PsaE protein is purified to homogeneity by affinity chromatography. Subunit PsaE (a peripheral subunit of the PSI complex)is involved in the docking of ferredoxin/flavodoxin to the PSI complex and also participates in the cyclic electron transfer around phosposystem I
-
purification of the luminal domain of spinach photosystem 1 subunit PsaF
-
Cloned/COMMENTARY
ORGANISM
UNIPROT ACCESSION NO.
LITERATURE
the psaE gene is cloned and overexpressed in Escherichia coli. PsaE (a peripheral subunit of the PSI complex) is involved in the docking of ferredoxin/flavodoxin to the PSI complex and also participates in the cyclic electron transfer around phosposystem I
-
cloning of the luminal domain of spinach photosystem 1 subunit PsaF, expressed in Escherichia coli BL21 (DE3) using a pET32 Xa/LIC thioredoxin fusion system
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