ID   CHLB_MESVI              Reviewed;         509 AA.
AC   Q9MUR9;
DT   11-JAN-2001, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-2000, sequence version 1.
DT   03-AUG-2022, entry version 75.
DE   RecName: Full=Light-independent protochlorophyllide reductase subunit B {ECO:0000255|HAMAP-Rule:MF_00353};
DE            Short=DPOR subunit B {ECO:0000255|HAMAP-Rule:MF_00353};
DE            Short=LI-POR subunit B {ECO:0000255|HAMAP-Rule:MF_00353};
DE            EC=1.3.7.7 {ECO:0000255|HAMAP-Rule:MF_00353};
GN   Name=chlB {ECO:0000255|HAMAP-Rule:MF_00353};
OS   Mesostigma viride (Green alga).
OG   Plastid; Chloroplast.
OC   Eukaryota; Viridiplantae; Streptophyta; Mesostigmatophyceae;
OC   Mesostigmatales; Mesostigmataceae; Mesostigma.
OX   NCBI_TaxID=41882;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=NIES-296 / KY-14 / CCMP 2046;
RX   PubMed=10688199; DOI=10.1038/35001059;
RA   Lemieux C., Otis C., Turmel M.;
RT   "Ancestral chloroplast genome in Mesostigma viride reveals an early branch
RT   of green plant evolution.";
RL   Nature 403:649-652(2000).
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. {ECO:0000255|HAMAP-Rule:MF_00353}.
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         Evidence={ECO:0000255|HAMAP-Rule:MF_00353};
CC   -!- COFACTOR:
CC       Name=[4Fe-4S] cluster; Xref=ChEBI:CHEBI:49883;
CC         Evidence={ECO:0000255|HAMAP-Rule:MF_00353};
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:0000255|HAMAP-Rule:MF_00353};
CC   -!- PATHWAY: Porphyrin-containing compound metabolism; chlorophyll
CC       biosynthesis (light-independent). {ECO:0000255|HAMAP-Rule:MF_00353}.
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. {ECO:0000255|HAMAP-Rule:MF_00353}.
CC   -!- SUBCELLULAR LOCATION: Plastid, chloroplast.
CC   -!- SIMILARITY: Belongs to the ChlB/BchB/BchZ family. {ECO:0000255|HAMAP-
CC       Rule:MF_00353}.
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DR   EMBL; AF166114; AAF43832.1; -; Genomic_DNA.
DR   RefSeq; NP_038391.1; NC_002186.1.
DR   AlphaFoldDB; Q9MUR9; -.
DR   SMR; Q9MUR9; -.
DR   PRIDE; Q9MUR9; -.
DR   GeneID; 800943; -.
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-UniRule.
DR   GO; GO:0005524; F:ATP binding; IEA:UniProtKB-UniRule.
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:0016636; F:oxidoreductase activity, acting on the CH-CH group of donors, iron-sulfur protein as acceptor; IEA:UniProtKB-UniRule.
DR   GO; GO:0036068; P:light-independent chlorophyll biosynthetic process; IEA:UniProtKB-UniPathway.
DR   GO; GO:0019685; P:photosynthesis, dark reaction; IEA:InterPro.
DR   Gene3D; 1.10.8.550; -; 1.
DR   HAMAP; MF_00353; ChlB_BchB; 1.
DR   InterPro; IPR013580; LI-POR_suB-like_C.
DR   InterPro; IPR000510; Nase/OxRdtase_comp1.
DR   InterPro; IPR042298; P-CP_red_C.
DR   InterPro; IPR005969; Protochl_reductB.
DR   InterPro; IPR016209; Protochlorophyllide_Rdtase.
DR   Pfam; PF00148; Oxidored_nitro; 1.
DR   Pfam; PF08369; PCP_red; 1.
DR   PIRSF; PIRSF000163; PCP_ChlB; 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..509
FT                   /note="Light-independent protochlorophyllide reductase
FT                   subunit B"
FT                   /id="PRO_0000219830"
FT   ACT_SITE        295
FT                   /note="Proton donor"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00353"
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:0000255|HAMAP-Rule:MF_00353"
FT   BINDING         430..431
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00353"
SQ   SEQUENCE   509 AA;  57570 MW;  C54A1F9372121980 CRC64;
     MKLAYWMYAG PAHIGTLRVA SSFKNVHAIM HAPLGDDYFN VMRSMLERER DFTPVTASIV
     DRHVLARGSQ NKVVDNITRK DKEERPDLIV LTPTCTSSIL QEDLQNFVNR ASMNSNSDVI
     LADVNHYRVN ELQAADRTLE QVVRFYIEKA KNNNDLDLIK TTKPSANIIG IFTLGFHNQH
     DCRELKRLLQ DLGIQINEVI PEGGSVSNLK KLPKAWFNLV PYREVGLMTA IYLEKEFKMP
     YVSTTPMGVV DTGSCIKEIE NIINSYTQDK ISYDEYIDKQ TRFVSQAAWF SRSIDCQNLT
     GKKAVVFGDA THAASMTRIL SKEMGIYVIC AGTYCTHDAD WFKEQVQGYC DEVLITDNHT
     EVGDLIARVE PAAIFGTQME RHIGKRLNIP CGVISAPVHI QNFPLGYRPF LGYEGTNQIA
     DLVYNSFTLG MEDHLLEIFG GHDTKEVITK GLSTDSELRW TSESENELRK IPGFVRGKIK
     RNTEKFARQN NVTEITVEIM YAAKEAMNA