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HAMAP rule MF_00482

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General rule information [?]

Accession MF_00482
Dates 1-JUN-2001 (Created)
1-JUN-2023 (Last updated, Version 70)
Name PSI_PsaB
Scope
Bacteria; Cyanobacteriota
Plastid
Templates P09144 (PSAB_CHLRE); P06512 (PSAB_SPIOL); P0A407 (PSAB_THEVB); P0A408 (PSAB_SYNEL); P29255 (PSAB_SYNY3): [Recover all]
Triggered by

Propagated annotation [?]


Identifier, protein and gene names [?]

Identifier
PSAB
case not <OG:Chloroplast>
Protein name
RecName: Full=Photosystem I P700 chlorophyll a apoprotein A2;
EC 1.97.1.12;
AltName: Full=PsaB;
else case <OG:Chloroplast>
Protein name
RecName: Full=Photosystem I P700 chlorophyll a apoprotein A2;
EC 1.97.1.12;
AltName: Full=PSI-B;
AltName: Full=PsaB;
end case
Gene name
psaB

Comments [?]

case <OC:Cyanobacteriota> or <OG:Chloroplast> and not <OC:Streptophyta>
Function PsaA and PsaB bind P700, the primary electron donor of photosystem I (PSI), as well as the electron acceptors A0, A1 and FX. PSI is a plastocyanin/cytochrome c6-ferredoxin oxidoreductase, converting photonic excitation into a charge separation, which transfers an electron from the donor P700 chlorophyll pair to the spectroscopically characterized acceptors A0, A1, FX, FA and FB in turn. Oxidized P700 is reduced on the lumenal side of the thylakoid membrane by plastocyanin or cytochrome c6.
else case <OG:Chloroplast> and <OC:Streptophyta>
Function PsaA and PsaB bind P700, the primary electron donor of photosystem I (PSI), as well as the electron acceptors A0, A1 and FX. PSI is a plastocyanin-ferredoxin oxidoreductase, converting photonic excitation into a charge separation, which transfers an electron from the donor P700 chlorophyll pair to the spectroscopically characterized acceptors A0, A1, FX, FA and FB in turn. Oxidized P700 is reduced on the lumenal side of the thylakoid membrane by plastocyanin.
end case
Catalytic activity RHEA:30407: hnu + oxidized [2Fe-2S]-[ferredoxin] + reduced [plastocyanin] = oxidized [plastocyanin] + reduced [2Fe-2S]-[ferredoxin]
EC 1.97.1.12
case <OC:Cyanobacteriota> and not <OC:Prochlorococcus>
Cofactor Note: PSI electron transfer chain: 5 chlorophyll a, 1 chlorophyll a', 2 phylloquinones and 3 4Fe-4S clusters. PSI core antenna: 90 chlorophyll a, 22 carotenoids, 3 phospholipids and 1 galactolipid. P700 is a chlorophyll a/chlorophyll a' dimer, A0 is one or more chlorophyll a, A1 is one or both phylloquinones and FX is a shared 4Fe-4S iron-sulfur center.
Subunit The PsaA/B heterodimer binds the P700 chlorophyll special pair and subsequent electron acceptors. PSI consists of a core antenna complex that captures photons, and an electron transfer chain that converts photonic excitation into a charge separation. The cyanobacterial PSI reaction center is composed of one copy each of PsaA,B,C,D,E,F,I,J,K,L,M and X, and forms trimeric complexes.
else case <OC:Prochlorococcus>
Cofactor Note: PSI electron transfer chain: 5 divinyl chlorophyll a, 1 divinyl chlorophyll a', 2 phylloquinones and 3 4Fe-4S clusters. PSI core antenna: 90 divinyl chlorophyll a, 22 carotenoids, 3 phospholipids and 1 galactolipid. P700 is a divinyl chlorophyll a/divinyl chlorophyll a' dimer, A0 is one or more divinyl chlorophyll a, A1 is one or both phylloquinones and FX is a shared 4Fe-4S iron-sulfur center.
Subunit The PsaA/B heterodimer binds the P700 divinyl chlorophyll special pair and subsequent electron acceptors. PSI consists of a core antenna complex that captures photons, and an electron transfer chain that converts photonic excitation into a charge separation. The cyanobacterial PSI reaction center is composed of one copy each of PsaA,B,C,D,E,F,I,J,K,L,M and X, and forms trimeric complexes.
else case <OG:Chloroplast>
Cofactor Note: P700 is a chlorophyll a/chlorophyll a' dimer, A0 is one or more chlorophyll a, A1 is one or both phylloquinones and FX is a shared 4Fe-4S iron-sulfur center.
Subunit The PsaA/B heterodimer binds the P700 chlorophyll special pair and subsequent electron acceptors. PSI consists of a core antenna complex that captures photons, and an electron transfer chain that converts photonic excitation into a charge separation. The eukaryotic PSI reaction center is composed of at least 11 subunits.
end case
case <OG:Chloroplast>
Subcellular location Plastid, chloroplast thylakoid membrane; Multi-pass membrane protein.
else case <OC:Gloeobacter>
Subcellular location Cell inner membrane; Multi-pass membrane protein.
else
Subcellular location Cellular thylakoid membrane; Multi-pass membrane protein.
end case
Similarity Belongs to the PsaA/PsaB family.

Keywords [?]

Transport
Electron transport
Photosynthesis
case <OC:Gloeobacter>
Cell membrane
Cell inner membrane
else
Thylakoid
end case
Photosystem I
Chromophore
Chlorophyll
Metal-binding
Iron
Oxidoreductase
Magnesium
Iron-sulfur
4Fe-4S
Membrane
Transmembrane
Transmembrane helix

Gene Ontology [?]

GO:0009055; Molecular function: electron transfer activity.
GO:0000287; Molecular function: magnesium ion binding.
GO:0015979; Biological process: photosynthesis.
case <OG:Chloroplast>
GO:0009535; Cellular component: chloroplast thylakoid membrane.
else case <OC:Gloeobacter>
GO:0005886; Cellular component: plasma membrane.
else
GO:0042651; Cellular component: thylakoid membrane.
end case

Cross-references [?]

Pfam PF00223; PsaA_PsaB; 1;
PIRSF PIRSF002905; PSI_A; 1;
PRINTS PR00257; PHOTSYSPSAAB; 1;
NCBIfam TIGR01336; psaB; 1;
PROSITE PS00419; PHOTOSYSTEM_I_PSAAB; 1;

Features [?]

From: PSAB_THEVB (P0A407)
Key     From     To       Description   Tag   Condition   FTGroup
TRANSMEM     39     70       Helical; Name=I        
TRANSMEM     132     156       Helical; Name=II        
TRANSMEM     173     195       Helical; Name=III        
TRANSMEM     270     287       Helical; Name=IV        
TRANSMEM     335     358       Helical; Name=V        
TRANSMEM     369     400       Helical; Name=VI        
TRANSMEM     420     449       Helical; Name=VII        
TRANSMEM     521     545       Helical; Name=VIII        
TRANSMEM     579     610       Helical; Name=IX        
TRANSMEM     651     672       Helical; Name=X        
TRANSMEM     709     737       Helical; Name=XI        
BINDING     566     566       /ligand="[4Fe-4S] cluster" /ligand_id="ChEBI:CHEBI:49883" /ligand_note="ligand shared between dimeric partners     C  
BINDING     575     575       /ligand="[4Fe-4S] cluster" /ligand_id="ChEBI:CHEBI:49883" /ligand_note="ligand shared between dimeric partners     C  
case not <OC:Prochlorococcus>
BINDING     661     661       /ligand="chlorophyll a" /ligand_id="ChEBI:CHEBI:58416" /ligand_label="B1" /ligand_part="Mg" /ligand_part_id="ChEBI:CHEBI:25107" /note="axial binding residue     H  
BINDING     669     669       /ligand="chlorophyll a" /ligand_id="ChEBI:CHEBI:58416" /ligand_label="B3" /ligand_part="Mg" /ligand_part_id="ChEBI:CHEBI:25107" /note="axial binding residue     M  
BINDING     677     677       /ligand="chlorophyll a" /ligand_id="ChEBI:CHEBI:58416" /ligand_label="B3     Y  
else case <OC:Prochlorococcus>
BINDING     661     661       /ligand="divinyl chlorophyll a" /ligand_id="ChEBI:CHEBI:73095" /ligand_label="B1" /ligand_part="Mg" /ligand_part_id="ChEBI:CHEBI:25107" /note="axial binding residue     H  
BINDING     669     669       /ligand="divinyl chlorophyll a" /ligand_id="ChEBI:CHEBI:73095" /ligand_label="B3" /ligand_part="Mg" /ligand_part_id="ChEBI:CHEBI:25107" /note="axial binding residue     M  
BINDING     677     677       /ligand="divinyl chlorophyll a" /ligand_id="ChEBI:CHEBI:73095" /ligand_label="B3     Y  
end case
BINDING     678     678       /ligand="phylloquinone" /ligand_id="ChEBI:CHEBI:18067" /ligand_label="B     W  

Additional information [?]

Size range 644-776 amino acids
Related rules None
Fusion Nter: None; Cter: <OmpA-like domain>
Comments G.violaceus is fused to an OmpA-like domain. AMPCA is atypical.


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