ID   ISIA_FISMU              Reviewed;         345 AA.
AC   Q9F488;
DT   07-FEB-2006, integrated into UniProtKB/Swiss-Prot.
DT   01-MAR-2001, sequence version 1.
DT   03-AUG-2022, entry version 63.
DE   RecName: Full=Iron stress-induced chlorophyll-binding protein;
DE   AltName: Full=CP43';
GN   Name=isiA;
OS   Fischerella muscicola.
OC   Bacteria; Cyanobacteria; Nostocales; Hapalosiphonaceae; Fischerella.
OX   NCBI_TaxID=92938;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA], AND INDUCTION.
RC   STRAIN=ATCC 29114 / PCC 73103 / SAG 1427-1;
RX   PubMed=11287157; DOI=10.1111/j.1574-6968.2001.tb10593.x;
RA   Geiss U., Vinnemeier J., Schoor A., Hagemann M.;
RT   "The iron-regulated isiA gene of Fischerella muscicola strain PCC 73103 is
RT   linked to a likewise regulated gene encoding a Pcb-like chlorophyll-binding
RT   protein.";
RL   FEMS Microbiol. Lett. 197:123-129(2001).
CC   -!- FUNCTION: Functions as an antenna for photosystem I (PSI) under iron-
CC       limiting conditions, when phycobilisomes disappear. In the
CC       (PSI)3(Isi3)18 complex most of the harvested energy is probably used by
CC       PSI; in other PSI-containing supercomplexes a large part of the energy
CC       will probably not be used for light harvesting, but rather is
CC       dissipated to protect the organism from light damage.
CC       {ECO:0000250|UniProtKB:Q55274}.
CC   -!- COFACTOR:
CC       Name=chlorophyll a; Xref=ChEBI:CHEBI:58416;
CC         Evidence={ECO:0000250|UniProtKB:Q55274};
CC       Note=Chlorophyll a. {ECO:0000250|UniProtKB:Q55274};
CC   -!- COFACTOR:
CC       Name=all-trans-beta-carotene; Xref=ChEBI:CHEBI:17579;
CC         Evidence={ECO:0000250|UniProtKB:Q55274};
CC   -!- SUBUNIT: Under iron-starvation forms a complex with PSI trimers, where
CC       the trimer is surrounded by a ring composed of 18 IsiA subunits.
CC       {ECO:0000250|UniProtKB:Q55274}.
CC   -!- SUBCELLULAR LOCATION: Cellular thylakoid membrane
CC       {ECO:0000250|UniProtKB:Q55274}; Multi-pass membrane protein
CC       {ECO:0000305}.
CC   -!- INDUCTION: By iron-starvation; however compared to Synechococcus PCC
CC       7942 and Synechocystis PCC 6803 induction is very slow.
CC       {ECO:0000269|PubMed:11287157}.
CC   -!- SIMILARITY: Belongs to the PsbB/PsbC family. IsiA/Pcb subfamily.
CC       {ECO:0000305}.
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DR   EMBL; AJ295840; CAC08491.1; -; Genomic_DNA.
DR   AlphaFoldDB; Q9F488; -.
DR   SMR; Q9F488; -.
DR   GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
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:0016168; F:chlorophyll binding; IEA:UniProtKB-KW.
DR   GO; GO:0009767; P:photosynthetic electron transport chain; IEA:InterPro.
DR   InterPro; IPR000932; PS_antenna-like.
DR   InterPro; IPR036001; PS_II_antenna-like_sf.
DR   PANTHER; PTHR33180; PTHR33180; 2.
DR   Pfam; PF00421; PSII; 1.
DR   SUPFAM; SSF161077; SSF161077; 1.
PE   2: Evidence at transcript level;
KW   Chlorophyll; Chromophore; Membrane; Photosynthesis; Photosystem I;
KW   Stress response; Thylakoid; Transmembrane; Transmembrane helix.
FT   CHAIN           1..345
FT                   /note="Iron stress-induced chlorophyll-binding protein"
FT                   /id="PRO_0000077557"
FT   TRANSMEM        25..45
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        64..84
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        89..109
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        203..223
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        240..260
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        309..329
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
SQ   SEQUENCE   345 AA;  38000 MW;  66BD0597B1CD5484 CRC64;
     MQTYDNPKVK YDWWAGNARF ANLSGLFIGA HVAQAALTTL WAGAFTWFEL SRYQSGVPMG
     EQGLILLPHL ATLGFGVGAG GQIVDTYPYF VIGALHIISS AVLGAGALLH TFKGPENLKD
     ATGPAREFHF EWDDANKLGL ILGHHLLFLG AGALLLVAKA MFWGGLYDTT IHDVRVVTEP
     TLNPFIIFGY QTHFASVDNL EDVVGGHIYV GLLLIFGGVW HILVKPLAWA KKLLIFSGEA
     ILSYSLGGIA LAGFVAAYFC AVNTLAYPVE FYGPPLEVKF WYLRPYFADT IQLPYGNYTS
     RAWLANTHFF LAFFFLQGHL WHALRAIGFD FKRVEKALSA VETSS