ID   CHLB_CHLAP              Reviewed;         431 AA.
AC   P37823;
DT   01-OCT-1994, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-1994, sequence version 1.
DT   03-AUG-2022, entry version 77.
DE   RecName: Full=Light-independent protochlorophyllide reductase subunit B;
DE            Short=DPOR subunit B;
DE            Short=LI-POR subunit B;
DE            EC=1.3.7.7;
DE   Flags: Fragment;
GN   Name=chlB;
OS   Chlamydomonas applanata (Chlamydomonas humicola).
OG   Plastid; Chloroplast.
OC   Eukaryota; Viridiplantae; Chlorophyta; core chlorophytes; Chlorophyceae;
OC   CS clade; Chlamydomonadales; Chlamydomonadaceae; Chlamydomonas.
OX   NCBI_TaxID=35704;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=8219066; DOI=10.1007/bf00029006;
RA   Liu X.-Q., Xu H., Huang C.;
RT   "Chloroplast chlB gene is required for light-independent chlorophyll
RT   accumulation in Chlamydomonas reinhardtii.";
RL   Plant Mol. Biol. 23:297-308(1993).
CC   -!- FUNCTION: Component of the dark-operative protochlorophyllide reductase
CC       (DPOR) that uses Mg-ATP and reduced ferredoxin to reduce ring D of
CC       protochlorophyllide (Pchlide) to form chlorophyllide a (Chlide). This
CC       reaction is light-independent. The NB-protein (ChlN-ChlB) is the
CC       catalytic component of the complex (By similarity). {ECO:0000250}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=2 ADP + chlorophyllide a + oxidized 2[4Fe-4S]-[ferredoxin] + 2
CC         phosphate = 2 ATP + 2 H2O + protochlorophyllide a + reduced 2[4Fe-
CC         4S]-[ferredoxin]; Xref=Rhea:RHEA:28202, Rhea:RHEA-COMP:10002,
CC         Rhea:RHEA-COMP:10004, ChEBI:CHEBI:15377, ChEBI:CHEBI:30616,
CC         ChEBI:CHEBI:33722, ChEBI:CHEBI:33723, ChEBI:CHEBI:43474,
CC         ChEBI:CHEBI:83348, ChEBI:CHEBI:83350, ChEBI:CHEBI:456216; EC=1.3.7.7;
CC   -!- COFACTOR:
CC       Name=[4Fe-4S] cluster; Xref=ChEBI:CHEBI:49883; Evidence={ECO:0000250};
CC       Note=Binds 1 [4Fe-4S] cluster per heterodimer. The cluster is bound at
CC       the heterodimer interface by residues from both subunits.
CC       {ECO:0000250};
CC   -!- PATHWAY: Porphyrin-containing compound metabolism; chlorophyll
CC       biosynthesis (light-independent).
CC   -!- SUBUNIT: Protochlorophyllide reductase is composed of three subunits;
CC       ChlL, ChlN and ChlB. Forms a heterotetramer of two ChlB and two ChlN
CC       subunits (By similarity). {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Plastid, chloroplast.
CC   -!- SIMILARITY: Belongs to the ChlB/BchB/BchZ family. {ECO:0000305}.
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DR   AlphaFoldDB; P37823; -.
DR   SMR; P37823; -.
DR   PRIDE; P37823; -.
DR   UniPathway; UPA00670; -.
DR   GO; GO:0009507; C:chloroplast; IEA:UniProtKB-SubCell.
DR   GO; GO:0051539; F:4 iron, 4 sulfur cluster binding; IEA:UniProtKB-KW.
DR   GO; GO:0005524; F:ATP binding; IEA:UniProtKB-KW.
DR   GO; GO:0046872; F:metal ion binding; IEA:UniProtKB-KW.
DR   GO; GO:0016730; F:oxidoreductase activity, acting on iron-sulfur proteins as donors; IEA:InterPro.
DR   GO; GO:0036068; P:light-independent chlorophyll biosynthetic process; IEA:UniProtKB-UniPathway.
DR   GO; GO:0019685; P:photosynthesis, dark reaction; IEA:InterPro.
DR   InterPro; IPR000510; Nase/OxRdtase_comp1.
DR   InterPro; IPR005969; Protochl_reductB.
DR   Pfam; PF00148; Oxidored_nitro; 1.
DR   TIGRFAMs; TIGR01278; DPOR_BchB; 1.
PE   3: Inferred from homology;
KW   4Fe-4S; ATP-binding; Chlorophyll biosynthesis; Chloroplast; Iron;
KW   Iron-sulfur; Metal-binding; Nucleotide-binding; Oxidoreductase;
KW   Photosynthesis; Plastid.
FT   CHAIN           1..>431
FT                   /note="Light-independent protochlorophyllide reductase
FT                   subunit B"
FT                   /id="PRO_0000219813"
FT   REGION          150..187
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   COMPBIAS        164..178
FT                   /note="Polar residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   ACT_SITE        341
FT                   /note="Proton donor"
FT                   /evidence="ECO:0000250"
FT   BINDING         36
FT                   /ligand="[4Fe-4S] cluster"
FT                   /ligand_id="ChEBI:CHEBI:49883"
FT                   /ligand_note="ligand shared with heterodimeric partner"
FT                   /evidence="ECO:0000250"
FT   NON_TER         431
SQ   SEQUENCE   431 AA;  48004 MW;  6E46B44587B38ED5 CRC64;
     MKLAESMYAG PAHIGTLRVA SSFRNVHAIM HAPLGDDYFN VMRSMLERER DFTPVTASIV
     DRHVLARGSQ EKVVENIQRK DKEESPDLIL LTPTCTSSIL QEDLQNFVNR ASETSTSDVL
     LADVNHYRVN ELQAADRTLE QIVRFYIEKT RAKDPGSPDP GGAGRRQASS STESGTEENL
     KGACGGEKTK KPSANILGMF TLGFHNQHDC RELKRLLAEL DIEVNEVIPE GGLVSNLKNL
     PKAWFNIVPY REVGLMTAVY LEKEFGMPYT STTPMGIIQT SAFIREMALM CHEVYNNSST
     KCSQTDFESC LISNTKKVPK TYINKQTHFV SQAGWFARSI DCQNLTGQKT VVFGDATHAA
     SMTKILVREM GIHVVCAGTY CKHDADWFRE QVSGFCDQVL ITDDHSQIGD IISQIEPAAI
     FGTQMERHIG K