ID   PSAB_PROM5              Reviewed;         742 AA.
AC   A2BYP8;
DT   11-SEP-2007, integrated into UniProtKB/Swiss-Prot.
DT   20-FEB-2007, sequence version 1.
DT   27-MAR-2024, entry version 98.
DE   RecName: Full=Photosystem I P700 chlorophyll a apoprotein A2 {ECO:0000255|HAMAP-Rule:MF_00482};
DE            EC=1.97.1.12 {ECO:0000255|HAMAP-Rule:MF_00482};
DE   AltName: Full=PsaB {ECO:0000255|HAMAP-Rule:MF_00482};
GN   Name=psaB {ECO:0000255|HAMAP-Rule:MF_00482};
GN   OrderedLocusNames=P9515_17021;
OS   Prochlorococcus marinus (strain MIT 9515).
OC   Bacteria; Cyanobacteriota; Cyanophyceae; Synechococcales;
OC   Prochlorococcaceae; Prochlorococcus.
OX   NCBI_TaxID=167542;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=MIT 9515;
RX   PubMed=18159947; DOI=10.1371/journal.pgen.0030231;
RA   Kettler G.C., Martiny A.C., Huang K., Zucker J., Coleman M.L., Rodrigue S.,
RA   Chen F., Lapidus A., Ferriera S., Johnson J., Steglich C., Church G.M.,
RA   Richardson P., Chisholm S.W.;
RT   "Patterns and implications of gene gain and loss in the evolution of
RT   Prochlorococcus.";
RL   PLoS Genet. 3:2515-2528(2007).
CC   -!- FUNCTION: PsaA and PsaB bind P700, the primary electron donor of
CC       photosystem I (PSI), as well as the electron acceptors A0, A1 and FX.
CC       PSI is a plastocyanin/cytochrome c6-ferredoxin oxidoreductase,
CC       converting photonic excitation into a charge separation, which
CC       transfers an electron from the donor P700 chlorophyll pair to the
CC       spectroscopically characterized acceptors A0, A1, FX, FA and FB in
CC       turn. Oxidized P700 is reduced on the lumenal side of the thylakoid
CC       membrane by plastocyanin or cytochrome c6. {ECO:0000255|HAMAP-
CC       Rule:MF_00482}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=hnu + oxidized [2Fe-2S]-[ferredoxin] + reduced [plastocyanin]
CC         = oxidized [plastocyanin] + reduced [2Fe-2S]-[ferredoxin];
CC         Xref=Rhea:RHEA:30407, Rhea:RHEA-COMP:10000, Rhea:RHEA-COMP:10001,
CC         Rhea:RHEA-COMP:10039, Rhea:RHEA-COMP:10040, ChEBI:CHEBI:29036,
CC         ChEBI:CHEBI:30212, ChEBI:CHEBI:33737, ChEBI:CHEBI:33738,
CC         ChEBI:CHEBI:49552; EC=1.97.1.12; Evidence={ECO:0000255|HAMAP-
CC         Rule:MF_00482};
CC   -!- COFACTOR:
CC       Note=PSI electron transfer chain: 5 divinyl chlorophyll a, 1 divinyl
CC       chlorophyll a', 2 phylloquinones and 3 4Fe-4S clusters. PSI core
CC       antenna: 90 divinyl chlorophyll a, 22 carotenoids, 3 phospholipids and
CC       1 galactolipid. P700 is a divinyl chlorophyll a/divinyl chlorophyll a'
CC       dimer, A0 is one or more divinyl chlorophyll a, A1 is one or both
CC       phylloquinones and FX is a shared 4Fe-4S iron-sulfur center.
CC       {ECO:0000255|HAMAP-Rule:MF_00482};
CC   -!- SUBUNIT: The PsaA/B heterodimer binds the P700 divinyl chlorophyll
CC       special pair and subsequent electron acceptors. PSI consists of a core
CC       antenna complex that captures photons, and an electron transfer chain
CC       that converts photonic excitation into a charge separation. The
CC       cyanobacterial PSI reaction center is composed of one copy each of
CC       PsaA,B,C,D,E,F,I,J,K,L,M and X, and forms trimeric complexes.
CC       {ECO:0000255|HAMAP-Rule:MF_00482}.
CC   -!- SUBCELLULAR LOCATION: Cellular thylakoid membrane {ECO:0000255|HAMAP-
CC       Rule:MF_00482}; Multi-pass membrane protein {ECO:0000255|HAMAP-
CC       Rule:MF_00482}.
CC   -!- SIMILARITY: Belongs to the PsaA/PsaB family. {ECO:0000255|HAMAP-
CC       Rule:MF_00482}.
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DR   EMBL; CP000552; ABM72909.1; -; Genomic_DNA.
DR   RefSeq; WP_011821001.1; NC_008817.1.
DR   AlphaFoldDB; A2BYP8; -.
DR   SMR; A2BYP8; -.
DR   STRING; 167542.P9515_17021; -.
DR   GeneID; 60201600; -.
DR   KEGG; pmc:P9515_17021; -.
DR   eggNOG; COG2885; Bacteria.
DR   HOGENOM; CLU_016126_1_0_3; -.
DR   OrthoDB; 499313at2; -.
DR   Proteomes; UP000001589; Chromosome.
DR   GO; GO:0009522; C:photosystem I; IEA:UniProtKB-KW.
DR   GO; GO:0031676; C:plasma membrane-derived thylakoid membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0051539; F:4 iron, 4 sulfur cluster binding; IEA:UniProtKB-KW.
DR   GO; GO:0016168; F:chlorophyll binding; IEA:UniProtKB-KW.
DR   GO; GO:0009055; F:electron transfer activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0000287; F:magnesium ion binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0015979; P:photosynthesis; IEA:UniProtKB-UniRule.
DR   Gene3D; 1.20.1130.10; Photosystem I PsaA/PsaB; 1.
DR   HAMAP; MF_00482; PSI_PsaB; 1.
DR   InterPro; IPR001280; PSI_PsaA/B.
DR   InterPro; IPR020586; PSI_PsaA/B_CS.
DR   InterPro; IPR036408; PSI_PsaA/B_sf.
DR   InterPro; IPR006244; PSI_PsaB.
DR   NCBIfam; TIGR01336; psaB; 1.
DR   PANTHER; PTHR30128; OUTER MEMBRANE PROTEIN, OMPA-RELATED; 1.
DR   PANTHER; PTHR30128:SF75; PHOTOSYSTEM I P700 CHLOROPHYLL A APOPROTEIN A2; 1.
DR   Pfam; PF00223; PsaA_PsaB; 1.
DR   PIRSF; PIRSF002905; PSI_A; 1.
DR   PRINTS; PR00257; PHOTSYSPSAAB.
DR   SUPFAM; SSF81558; Photosystem I subunits PsaA/PsaB; 1.
DR   PROSITE; PS00419; PHOTOSYSTEM_I_PSAAB; 1.
PE   3: Inferred from homology;
KW   4Fe-4S; Chlorophyll; Chromophore; Electron transport; Iron; Iron-sulfur;
KW   Magnesium; Membrane; Metal-binding; Oxidoreductase; Photosynthesis;
KW   Photosystem I; Thylakoid; Transmembrane; Transmembrane helix; Transport.
FT   CHAIN           1..742
FT                   /note="Photosystem I P700 chlorophyll a apoprotein A2"
FT                   /id="PRO_0000300020"
FT   TRANSMEM        46..69
FT                   /note="Helical; Name=I"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   TRANSMEM        135..158
FT                   /note="Helical; Name=II"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   TRANSMEM        175..199
FT                   /note="Helical; Name=III"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   TRANSMEM        273..291
FT                   /note="Helical; Name=IV"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   TRANSMEM        336..359
FT                   /note="Helical; Name=V"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   TRANSMEM        375..401
FT                   /note="Helical; Name=VI"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   TRANSMEM        423..445
FT                   /note="Helical; Name=VII"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   TRANSMEM        525..543
FT                   /note="Helical; Name=VIII"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   TRANSMEM        583..604
FT                   /note="Helical; Name=IX"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   TRANSMEM        651..673
FT                   /note="Helical; Name=X"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   TRANSMEM        715..735
FT                   /note="Helical; Name=XI"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   BINDING         567
FT                   /ligand="[4Fe-4S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:49883"
FT                   /ligand_note="ligand shared between dimeric partners"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   BINDING         576
FT                   /ligand="[4Fe-4S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:49883"
FT                   /ligand_note="ligand shared between dimeric partners"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   BINDING         662
FT                   /ligand="divinyl chlorophyll a"
FT                   /ligand_id="ChEBI:CHEBI:73095"
FT                   /ligand_label="B1"
FT                   /ligand_part="Mg"
FT                   /ligand_part_id="ChEBI:CHEBI:25107"
FT                   /note="axial binding residue"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   BINDING         670
FT                   /ligand="divinyl chlorophyll a"
FT                   /ligand_id="ChEBI:CHEBI:73095"
FT                   /ligand_label="B3"
FT                   /ligand_part="Mg"
FT                   /ligand_part_id="ChEBI:CHEBI:25107"
FT                   /note="axial binding residue"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   BINDING         678
FT                   /ligand="divinyl chlorophyll a"
FT                   /ligand_id="ChEBI:CHEBI:73095"
FT                   /ligand_label="B3"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
FT   BINDING         679
FT                   /ligand="phylloquinone"
FT                   /ligand_id="ChEBI:CHEBI:18067"
FT                   /ligand_label="B"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00482"
SQ   SEQUENCE   742 AA;  82725 MW;  AE4A8A399874CA7C CRC64;
     MATKFPAFNQ GLAQDPTTRR IWYGIATAHD FESHDGMTEE KLYQKLFSTH FGHLAIIALW
     VAGNLFHIAW QGNFEQFVLD PTHVRPIAHA IWDPHFGSGI TEAMTQAGAD GPVNIAYSGL
     YHWWYTIGMR TNEQLFQASI FMSILACWTL FAGWLHLQPK FRPSLAWFKN NESRLNHHLA
     VLFGFSSIAW TGHLVHVAIP ESRGIHVGWD NWLTVLPHPA GLTPFFTLNW GAYAQNPDSL
     EQVFGTAEGA GTAIFTFLGG LHPQSEALWL TDIAHHHIAI GTVFIIAGHM YRNTFGIGHS
     LKEITEAHNT RHPLDPHKGS FGINHDGLYE TVTNSLHFQL GLALAALGVA TSLVAQHMGA
     LPSYAFIARD YTTQSALYTH HQYIAMFLMV GAFAHGAIFF VRDYDPELNK DNVLARVLGT
     KEALISHLSW VTMILGFHTL GIYVHNDVVV AFGNPEKQIL IEPVFAQFVQ AAQGKMMYGF
     NALLSDPTSA ASVAANSLPG NHYWMDLINR QDALSAFLPI GPADFLVHHA IALGLHTTAL
     ILIKGALDAR GTKLIPDKKD LGYAFPCDGP GRGGTCDSSS WDAMYLAMFW ALNLIAWVTF
     YWHWKHLAIW QGNVAQFNES GTYLMGWFRD YLWLNSAQLI NGYNPFGVNS LSVWAWMFLF
     GHLVWATGFM FLISWRGYWQ ELIETLVWAH QRTPIANLVG WRDKPVALSI VQARLVGLAH
     FTIGNILTFG AFVIASTSGK FG
//