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Information on EC 1.97.1.12 - photosystem I
for references in articles please use BRENDA:EC1.97.1.12
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EC Tree 1 Oxidoreductases
1.97 Other oxidoreductases
1.97.1 Sole sub-subclass for oxidoreductases that do not belong in the other subclasses
1.97.1.12 photosystem I
IUBMB Comments
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.
The enzyme appears in viruses and cellular organisms
- 1.97.1.12
- photosystems
-
chlorophyl
- thylakoids
- chloroplast
-
light-harvesting
- cyanobacterium
- antenna
- spinach
- synechocystis
- synechococcus
- chlamydomonas
-
photochemical
-
photoinhibition
- plastoquinone
-
light-induced
- ferredoxins
- reinhardtii
-
photoautotrophic
-
non-photochemical
- methylviologen
-
pump-probe
- phycobilisomes
-
thermoluminescence
-
supercomplexes
-
pigment-protein
-
chlorophyll-proteins
- photooxidation
-
oxygen-evolving
- lhcii
-
photocurrent
-
3-3,4-dichlorophenyl-1,1-dimethylurea
-
grana
-
water-splitting
-
intersystem
-
photoprotection
- phylloquinone
-
excitonic
-
light-driven
-
photoreduced
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photoinhibitory
-
photoreduction
- thermosynechococcus
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far-red
-
picosecond
-
flash-induced
- violaxanthin
-
electrochromic
-
photophosphorylation
- elongatus
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photochemistry
Reaction Schemes
showSynonyms
photosystem i, psi core complex, ps-i complex, more
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SYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
PS I
PSI
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
reduced plastocyanin + oxidized ferredoxin + hnu = oxidized plastocyanin + reduced ferredoxin
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PATHWAY SOURCE
PATHWAYS
BRENDA
MetaCyc
cyclic electron flow, 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.
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
LITERATURE
COMMENTARY
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
reduced cytochrome b6 + oxidized ferredoxin + hv
oxidized cytochrome b6 + reduced ferredoxin
reduced cytochrome c6 + oxidized ferredoxin + hv
oxidized cytochrome c6 + reduced ferredoxin
reduced cytochrome c6 + oxidized flavodoxin + hv
oxidized cytochrome c6 + reduced flavodoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
reduced plastocyanin + oxidized flavodoxin + hv
oxidized plastocyanin + reduced flavodoxin
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reduced cytochrome b6 + oxidized ferredoxin + hv
oxidized cytochrome b6 + reduced ferredoxin
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reduced cytochrome b6 + oxidized ferredoxin + hv
oxidized cytochrome b6 + reduced ferredoxin
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reduced cytochrome c6 + oxidized ferredoxin + hv
oxidized cytochrome c6 + reduced ferredoxin
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reduced cytochrome c6 + oxidized ferredoxin + hv
oxidized cytochrome c6 + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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Substrates: 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
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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Substrates: 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
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
Chlamydomonas reinhardtii KRC91-1A
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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Substrates: 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 phosphosystem I
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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Substrates: plastocyanins from Nostoc sp. PCC 7119, Monoraphidium braunii, Arabidopsis thaliana, Spinacia oleracea, and wild-type and mutant (E85K, Q88R, E85K/Q88R, E85V, and V93K) plastocyanins from Chlamydomonas reinhardtii, docking simulations and modeling
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
Psychotria henryi
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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Substrates: 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
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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Substrates: 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
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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Substrates: variations in the luminal Mg(II) concentration may modulate the binding between plastocyanin and photosystem I subunit PsaF during the light-dark transitions, being stronger in the illuminated state
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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Substrates: 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)
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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Substrates: 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
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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Substrates: 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
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
Substrates: ferredoxin from Thermosynechococcus elongatus
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
Thermosynechococcus vestitus
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
Thermosynechococcus vestitus
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Substrates: ferredoxin from Thermosynechococcus elongatus
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additional information
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Substrates: photo-oxidation of P700 causes a broad increase in absorption in the near-infrared region due to presence of a chlorophyll cation radical (P700+)
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additional information
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Substrates: in vitro plastoquinone reduction assay with the addition of ferredoxin
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additional information
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Substrates: in the Phaeodactylum tricornutum alga, as inmost diatoms, cytochrome c6 is the only electron donor to photosystem I, and thus they lack plastocyanin as an alternative electron carrier. Analysis of electron transfer to Phaeodactylum photosystem I from several plastocyanins from cyanobacteria, green algae and plants, as compared with its own cytochrome c6, overview. Diatom photosystem I is able to effectively react with eukaryotic acidic plastocyanins, although with less efficiency than with Phaeodactylum cytochrome c6. This efficiency increases in some green alga plastocyanin mutants mimicking the electrostatics of the interaction site on the diatom cytochrome. In addition, the structure of the transient electron transfer complex between cytochrome c6 and photosystem I from Phaeodactylum is analyzed by computational docking and compared to that of green lineage and mixed systems. The Phaeodactylum system shows a lower efficiency than the green systems, both in the formation of the properly arranged [cytochrome c6-photosystem I] complex and in the electron transfer itself. Structural modeling, overview
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Substrates: oxygen uptake in the light is analyzed in suspensions of isolated pea thylakoids upon inhibition of electron transport from photosystem II (PS II) by diuron and delivery of electrons to photosystem I (PS I) by means of artificial donors in the presence of ascorbate, O2 reduction in PS I. 2,6-dichlorophenolindophenol (DCPIP) cannot be used as the donor for photosystem I. N,N,N',N'-tetramethyl-p-phenylene diamine (TMPD), applied as a donor, does not affect immediately the reaction of the O2 reduction, since an increase in its concentration does not lead to an increase in the oxygen uptake rate in the light. In the experiments with TMPD, an increase in light intensity leads to an increase in the oxygen uptake rate, and this fact was interpreted as a consequence of the increase in the apparent rate constant of the reaction of the O2 reduction by the components of the acceptor side of photosystem I. TMPD redox transformation consists of only one step, while the DCPIP transformation includes two steps. Ascorbate is capable of donating electrons to the primary pair of PS I cofactors, P700+. Addition of either DCPIP or TMPD at concentration of 0.05 mM to the suspension containing both DCMU and ascorbate results in the twofold increase in the rate of the O2 consumption. O2 reduction by PS I uses ascorbate alone or in combination with lipophilic compounds as immediate donor of electrons
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Substrates: thylakoids freshly isolated from spinach are assayed for their ability to generate a light driven proton gradient. While high rates of cyclic electron flow are observed in vivo, isolated thylakoids show only very slow rates, suggesting that the activity of a key complex is lost or downregulated upon isolation. Isolation of thylakoids in the complete absence of DTTRED leads to loss of CEF activity that is only partially restored by subsequent addition of 2 mM DTTRED, redox titration of CEF activity, overview
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Substrates: interaction analysis of photosystem I (PS I) complexes from cyanobacteria Synechocystis sp. PCC 6803 containing various quinones in the A1-site (phylloquinone PhQ in the wild-type strain and plastoquinone (PQ) or 2,3-dichloronaphthoquinone (Cl2NQ) in the menB deletion strain) and different numbers of Fe4S4 clusters (intact wild-type and ferredoxin-core complexes depleted of FA/FB centers) with external acceptors, overview. The electron transfer chain of PS I consists of the primary donor-chlorophyll (Chl) dimer P700, primary acceptor A0 (four Chl molecules), A1 (two phylloquinone molecules), and iron-sulfur clusters FX, FA, and FB.The terminal FA/FB clusters are located on the small extrinsic PsaC subunit. Electron transport in PS I occurs through both branches of the redox cofactors A and B from P700 to FX. Reaction center of PS I contains two molecules of phylloquinone (PhQ) that are characterized by extremely low midpoint redox potential
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additional information
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Substrates: photo-oxidation of P700 causes a broad increase in absorption in the near-infrared region due to presence of a chlorophyll cation radical (P700+)
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additional information
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Substrates: reduction of ferredoxin by photosystem I (PSI) involves the [4Fe-4S] clusters FA and FB harbored by subunit PsaC, with FB being the direct electron transfer partner of ferredoxin. Assay in presence of 5 mM MgCl2, 30 mM NaCl and 0.03% beta-dodecyl-maltoside, with 1-2.5 mM sodium ascorbate and 0.008-0.025 mM 2,6-dichlorophenolindophenol
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additional information
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Substrates: upon light excitation, the excited singlet state of the primary electron donor, P700 delivers an electron to the primary Chl acceptor A0A/ A0B forming the charge-separated state P700 +A0-. The electron is then transferred in sequence to A1A/ A1B, to the iron-sulfur cluster FX, and ultimately to FA/FB. The side production of superoxide radical in the A1-site by oxygen reduction via the Mehler reaction might comprise about 0.3% of the total electron flow in photosystem I, PS I. Interaction of PS I with external acceptors, methylviologen, 2,3-dichloro-naphthoquinone and oxygen, overview. Analysis of PS I complexes containing various quinones in the A1-binding site, i.e. phylloquinone PhQ, plastoquinone-9 PQ and 2,3-dichloro-naphthoquinone, as well as FX-core complexes, depleted of terminal iron-sulfur FA/FB clusters
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additional information
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Thermosynechococcus vestitus
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Substrates: reduction of ferredoxin by photosystem I (PSI) involves the [4Fe-4S] clusters FA and FB harbored by subunit PsaC, with FB being the direct electron transfer partner of ferredoxin. Assay in presence of 5 mM MgCl2, 30 mM NaCl and 0.03% beta-dodecyl-maltoside, with 1-2.5 mM sodium ascorbate and 0.008-0.025 mM 2,6-dichlorophenolindophenol
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NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
LITERATURE
COMMENTARY
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
reduced cytochrome b6 + oxidized ferredoxin + hv
oxidized cytochrome b6 + reduced ferredoxin
reduced cytochrome c6 + oxidized ferredoxin + hv
oxidized cytochrome c6 + reduced ferredoxin
reduced cytochrome c6 + oxidized flavodoxin + hv
oxidized cytochrome c6 + reduced flavodoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
reduced plastocyanin + oxidized flavodoxin + hv
oxidized plastocyanin + reduced flavodoxin
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reduced cytochrome b6 + oxidized ferredoxin + hv
oxidized cytochrome b6 + reduced ferredoxin
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reduced cytochrome b6 + oxidized ferredoxin + hv
oxidized cytochrome b6 + reduced ferredoxin
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reduced cytochrome c6 + oxidized ferredoxin + hv
oxidized cytochrome c6 + reduced ferredoxin
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reduced cytochrome c6 + oxidized ferredoxin + hv
oxidized cytochrome c6 + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
Chlamydomonas reinhardtii KRC91-1A
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
Psychotria henryi
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
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reduced plastocyanin + oxidized ferredoxin + hv
oxidized plastocyanin + reduced ferredoxin
Thermosynechococcus vestitus
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
2,3-dichloronaphthoquinone
in the mutant menB deletion strain
beta-carotene
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cyanobacterial PSI complexes contain 22 molecules of beta-carotene, 17 of which are in all-trans configuration
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
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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 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
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most abundant cofactor in PSI, role of these molecules in light absorption, charge separation, electron transfer, and biogenesis
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'
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one member of the P700 special pair is a chlorophyll a' molecule
chlorophyll a'
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one member of the P700 special pair is a chlorophyll a' molecule
chlorophyll a'
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one member of the P700 special pair is a chlorophyll a' molecule
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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a PSI complex contains 12 iron atoms that constitute 3 [4Fe-4S] clusters
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
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
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
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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)
phylloquinone
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the PSI complex of cyanobacteria and chloroplasts contains two phylloquinone molecules, which function in the electron transfer as the redox center A1
phylloquinone
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the PSI complex of cyanobacteria and chloroplasts contains two phylloquinone molecules, which function in the electron transfer as the redox center A1
phylloquinone
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the PSI complex of cyanobacteria and chloroplasts contains two phylloquinone molecules, which function in the electron transfer as the redox center A1
plastoquinone
in the mutant menB deletion strain
[4Fe-4S] center
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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
[4Fe-4S] center
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the enzyme contains three [4Fe-4S] clusters: FA, FB and FX
[4Fe-4S]-center
Thermosynechococcus vestitus
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reduction of ferredoxin by photosystem I (PSI) involves the [4Fe-4S] clusters FA and FB harbored by subunit PsaC, with FB being the direct electron transfer partner of ferredoxin
[4Fe-4S]-center
reduction of ferredoxin by photosystem I (PSI) involves the [4Fe-4S] clusters FA and FB harbored by subunit PsaC, with FB being the direct electron transfer partner of ferredoxin
[4Fe-4S]-center
the enzyme contains [4Fe-4S] clusters
additional information
the electron transfer chain of PS I consists of the primary donor-chlorophyll (Chl) dimer P700, primary acceptor A0 (four Chl molecules), A1 (two phylloquinone molecules), and iron-sulfur clusters FX, FA, and FB. The terminal FA/FB clusters are located on the small extrinsic PsaC subunit. Electron transport in PS I occurs through both branches of the redox cofactors A and B from P700 to FX. 2,3-Dichlorophenolindophenol reduced by ascorbate serves as an external electron donor for the photooxidized P700, while methylviologen plays a role of external acceptor capturing electrons from the photoreduced terminal FA/FB cluster
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additional information
the electron-transfer cofactors are arranged in two nearly symmetric branches extending across the membrane from P700, which is a dimer of Chl a and a C-13 epimer of Chl a. Each branch contains an additional pair of Chl a molecules (ec2A/ec3A or ec2B/ec3B) and a phylloquinone (PhQA or PhQB), overview
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additional information
the electron-transfer cofactors are arranged in two nearly symmetric branches extending across the membrane from P700, which is a dimer of Chl a and a C-13 epimer of Chl a. Each branch contains an additional pair of Chl a molecules (ec2A/ec3A or ec2B/ec3B) and a phylloquinone (PhQA or PhQB), overview
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Mg2+
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variations in the luminal Mg(II) concentration may modulate the binding between plastocyanin and photosystem I subunit PsaF during the light-dark transitions, being stronger in the illuminated state. The Mg(II) ion probably is bound close to Glu43 in the lower acidic patch, and most likely in the form of a hexaquo complex embedded within the hydration shell of plastocanin, suggesting a specific binding site for Mg(II) that may regulate the binding of plastocyanin to photosystem 1 in vivo
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INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
Ag(I)-substituted plastocyanin
-
competitive inhibitor of the reaction with normal Cu-containg plastocyanin
-
superoxide
Psychotria henryi
-
superoxide generated in the chloroplast stroma causes photoinhibition of photosystem I, superoxide accelerates photoinhibition of PSI
Zn(II)-substituted plastocyanin
-
competitive inhibitor of the reaction with normal Cu-containg plastocyanin
-
additional information
Psychotria henryi
-
treatment of detached leaves with constant high light in the presence of methyl viologen (MV) or a soluble alpha-tocopherol analogue, 2,2,5,7,8-pentamethyl-6-chromanol (PMC). MV significantly depresses photochemical quantum yields in PSI and PSII when compared to PMC. Methyl viologen not only strongly downregulates electron flow from PSII to PSI (ETRII), but also intensely inhibits circular electron transport in the shade-establishing species. Activation of circular electron flow cannot prevent PSI photoinhibition in Psychotria henryi. Strong PSII photoinhibition by MV. Different mechanisms of PSI photoinhibition in higher plants, overview
-
gallium ferredoxin
binding of the redox-inactive gallium ferredoxin to PSI inhibits the electron transport reaction, binds to PSI competitively with ferredoxin suggesting a single ferredoxin?binding site in PSI, kinetics
-
gallium ferredoxin
Thermosynechococcus vestitus
-
binding of the redox-inactive gallium ferredoxin to PSI inhibits the electron transport reaction, binds to PSI competitively with ferredoxin suggesting a single ferredoxin?binding site in PSI, kinetics
-
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
reduced DTT
does not reduce the plastoquinone pool directly, but is dependent on ferredoxin, consistent with the involvement of a ferredoxin-dependent reaction, most likely the ferredoxin:quinone reductase (FQR)
additional information
isolation of thylakoids while in the continuous presence of reduced thiol reductant dithiothreitol (DTT), but not oxidized DTT, maintains high cyclic electron flow of photosystem I activity through an antimycin A-sensitive ferredoxin:quinone reductase (FQR). FQR mediated cyclic electron flow is highly sensitive to thylakoid isolation conditions, overview
-
additional information
positive correlation between non-photochemical quenching (NPQ) and stimulation of CEF-PS I
-
additional information
-
positive correlation between non-photochemical quenching (NPQ) and stimulation of CEF-PS I
-
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DISEASE
TITLE OF PUBLICATION
LINK TO PUBMED
Anemia, Hypochromic
Adaptation to Fe-deficiency requires remodeling of the photosynthetic apparatus.
Anemia, Hypochromic
Interaction of Chloroplasts with Inhibitors: Induction of Chlorosis by Diuron During Prolonged Illumination in Vitro.
Dehydration
Differences in the stimulation of cyclic electron flow in two tropical ferns under water stress are related to leaf anatomy.
Dehydration
Differential effects of severe water stress on linear and cyclic electron fluxes through Photosystem I in spinach leaf discs in CO(2)-enriched air.
Dehydration
Effects of dehydration on the electron transport of Chlorella. An in vivo fluorescence study.
Dehydration
Molecular reorganization induced by Ca2+ of plant photosystem I reconstituted into phosphatidylglycerol liposomes.
Dehydration
Reflectance and Cyclic Electron Flow as an Indicator of Drought Stress in Cotton (Gossypium hirsutum).
Dehydration
Trehalose matrix effects on charge-recombination kinetics in Photosystem I of oxygenic photosynthesis at different dehydration levels.
Hypersensitivity
Lack of the small plastid-encoded PsbJ polypeptide results in a defective water-splitting apparatus of photosystem II, reduced photosystem I levels, and hypersensitivity to light.
Infections
A myovirus encoding both photosystem I and II proteins enhances cyclic electron flow in infected Prochlorococcus cells.
Infections
AS-1 cyanophage infection inhibits the photosynthetic electron flow of photosystem II in Synechococcus sp. PCC 6301, a cyanobacterium.
Infections
Catharanthus roseus, an Experimental Host Plant for the Citrus Strain of Xylella fastidiosa.
Infections
Catharanthus roseus, an experimental host plant for the citrus strain of Xylella fastidiosa.
Infections
Cypress canker induced inhibition of photosynthesis in field grown cypress (Cupressus sempervirens L.) needles.
Infections
Light Suppresses Bacterial Population through the Accumulation of Hydrogen Peroxide in Tobacco Leaves Infected with Pseudomonas syringae pv. tabaci.
Infections
Photoinhibition and photoinhibition-like damage to the photosynthetic apparatus in tobacco leaves induced by pseudomonas syringae pv. Tabaci under light and dark conditions.
Iron Deficiencies
A chlorophyll a/b-binding protein homolog that is induced by iron deficiency is associated with enlarged photosystem I units in the eucaryotic alga Dunaliella salina.
Iron Deficiencies
A Nucleus-Encoded Chloroplast Phosphoprotein Governs Expression of the Photosystem I Subunit PsaC in Chlamydomonas reinhardtii.
Iron Deficiencies
Adaptation to iron deficiency: a comparison between the cyanobacterium Synechococcus elongatus PCC 7942 wild-type and a DpsA-free mutant.
Iron Deficiencies
Alteration of proteins and pigments influence the function of photosystem I under iron deficiency from Chlamydomonas reinhardtii.
Iron Deficiencies
An internal antisense RNA regulates expression of the photosynthesis gene isiA.
Iron Deficiencies
Changes in the LHCI aggregation state during iron repletion in the unicellular red alga Rhodella violacea.
Iron Deficiencies
Chlorophyll-Proteins and Electron Transport during Iron Nutrition-Mediated Chloroplast Development.
Iron Deficiencies
Differential degradation of photosystem I subunits under iron deficiency in rice.
Iron Deficiencies
Effects of iron limitation on the expression of metabolic genes in the marine cyanobacterium Trichodesmium erythraeum IMS101.
Iron Deficiencies
Fluorescence quenching of IsiA in early stage of iron deficiency and at cryogenic temperatures.
Iron Deficiencies
How does iron deficiency disrupt the electron flow in photosystem I of lettuce leaves?
Iron Deficiencies
Iron deficiency in cyanobacteria causes monomerization of photosystem I trimers and reduces the capacity for state transitions and the effective absorption cross section of photosystem I in vivo.
Iron Deficiencies
Iron deficiency induces a chlorophyll d-binding Pcb antenna system around Photosystem I in Acaryochloris marina.
Iron Deficiencies
Iron Deficiency Induces a Partial Inhibition of the Photosynthetic Electron Transport and a High Sensitivity to Light in the Diatom Phaeodactylum tricornutum.
Iron Deficiencies
Iron deficiency induces the formation of an antenna ring around trimeric photosystem I in cyanobacteria.
Iron Deficiencies
N-terminal processing of Lhca3 Is a key step in remodeling of the photosystem I-light-harvesting complex under iron deficiency in Chlamydomonas reinhardtii.
Iron Deficiencies
Structural analysis of the photosystem I supercomplex of cyanobacteria induced by iron deficiency.
Iron Deficiencies
Structural response of Photosystem 2 to iron deficiency: characterization of a new photosystem 2-IdiA complex from the cyanobacterium Thermosynechococcus elongatus BP-1.
Iron Deficiencies
[Structural and functional organization of chloroplasts in leaves of Pisum sativum L. under conditions of root hypoxia and iron deficiency]
Magnesium Deficiency
Magnesium deficiencyinduced impairment of photosynthesis in leaves of fruiting Citrus reticulata trees accompanied by up?regulation of antioxidant metabolism to avoid photo?oxidative damage
Magnesium Deficiency
Preferential damaging effects of limited magnesium bioavailability on photosystem I in Sulla carnosa plants.
Neoplasms
Cancer Cell Specific Delivery of Photosystem I Through Integrin Targeted Liposome Shows Significant Anticancer Activity.
Photophobia
Chloroplast site-directed mutagenesis of photosystem I in Chlamydomonas: electron transfer reactions and light sensitivity.
photosystem i deficiency
Biochemical and molecular characterization of photosystem I deficiency in the NCS6 mitochondrial mutant of maize.
Starvation
Aggregates of the chlorophyll-binding protein IsiA (CP43') dissipate energy in cyanobacteria.
Starvation
Ca(2+)-regulated cyclic electron flow supplies ATP for nitrogen starvation-induced lipid biosynthesis in green alga.
Starvation
Diatom proteomics reveals unique acclimation strategies to mitigate Fe limitation.
Starvation
Energy transfer and trapping in the Photosystem I complex of Synechococcus PCC 7942 and in its supercomplex with IsiA.
Starvation
Far-red light-regulated efficient energy transfer from phycobilisomes to photosystem I in the red microalga Galdieria sulphuraria and photosystems-related heterogeneity of phycobilisome population.
Starvation
Light-induced energy dissipation in iron-starved cyanobacteria: roles of OCP and IsiA proteins.
Starvation
Population-level coordination of pigment response in individual cyanobacterial cells under altered nitrogen levels.
Starvation
RESPONSE OF NANNOCHLOROPSIS GADITANA TO NITROGEN STARVATION INCLUDES A DE NOVO BIOSYNTHESIS OF TRIACYLGLYCEROLS, A DECREASE OF CHLOROPLAST GALACTOLIPIDS AND A REORGANIZATION OF THE PHOTOSYNTHETIC APPARATUS.
Starvation
Spectroscopic properties of PSI-IsiA supercomplexes from the cyanobacterium Synechococcus PCC 7942.
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.007
reduced plastocyanin
-
pH and temperature not specified in the publication
additional information
additional information
Thermosynechococcus vestitus
-
thermodynamics and kinetics
-
additional information
additional information
thermodynamics and kinetics
-
additional information
additional information
-
kinetic analysis of cytochrome c6 and different plastocyanins as electron donor cofactors, detailed overview
-
additional information
additional information
kinetics of electron transfer of wild-type and mutant enzymes, overview
-
additional information
additional information
Michaelis-Menten kinetics, three-state electron transport recombinantion kinetics, and kinetic modeling, interaction of PS I with external acceptors, methylviologen, and oxygen, detailed overview
-
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Ki VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.03
Ag(I)-substituted plastocyanin
-
pH and temperature not specified in the publication
-
0.41
Zn(II)-substituted plastocyanin
-
pH and temperature not specified in the publication
-
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
7.5
7.6
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pH RANGE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
additional information
additional information
cyclic electron flow around photosystem I is enhanced at low pH of 5.5. The light response curve of PS I is significantly affected by acidification of the thylakoid membranes
additional information
-
cyclic electron flow around photosystem I is enhanced at low pH of 5.5. The light response curve of PS I is significantly affected by acidification of the thylakoid membranes
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TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
22
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT