ID   BCHB_CHLAA              Reviewed;         541 AA.
AC   Q9F6X5; A9WIN5;
DT   27-APR-2001, integrated into UniProtKB/Swiss-Prot.
DT   01-MAR-2001, sequence version 1.
DT   03-AUG-2022, entry version 101.
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=bchB {ECO:0000255|HAMAP-Rule:MF_00353}; OrderedLocusNames=Caur_2556;
OS   Chloroflexus aurantiacus (strain ATCC 29366 / DSM 635 / J-10-fl).
OC   Bacteria; Chloroflexi; Chloroflexia; Chloroflexales; Chloroflexineae;
OC   Chloroflexaceae; Chloroflexus.
OX   NCBI_TaxID=324602;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=10976061; DOI=10.1126/science.289.5485.1724;
RA   Xiong J., Fischer W.M., Inoue K., Nakahara M., Bauer C.E.;
RT   "Molecular evidence for the early evolution of photosynthesis.";
RL   Science 289:1724-1730(2000).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=ATCC 29366 / DSM 635 / J-10-fl;
RX   PubMed=21714912; DOI=10.1186/1471-2164-12-334;
RA   Tang K.H., Barry K., Chertkov O., Dalin E., Han C.S., Hauser L.J.,
RA   Honchak B.M., Karbach L.E., Land M.L., Lapidus A., Larimer F.W.,
RA   Mikhailova N., Pitluck S., Pierson B.K., Blankenship R.E.;
RT   "Complete genome sequence of the filamentous anoxygenic phototrophic
RT   bacterium Chloroflexus aurantiacus.";
RL   BMC Genomics 12:334-334(2011).
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 (BchN-BchB) 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; bacteriochlorophyll
CC       biosynthesis (light-independent). {ECO:0000255|HAMAP-Rule:MF_00353}.
CC   -!- SUBUNIT: Protochlorophyllide reductase is composed of three subunits;
CC       BchL, BchN and BchB. Forms a heterotetramer of two BchB and two BchN
CC       subunits. {ECO:0000255|HAMAP-Rule:MF_00353}.
CC   -!- SIMILARITY: Belongs to the ChlB/BchB/BchZ family. {ECO:0000255|HAMAP-
CC       Rule:MF_00353}.
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DR   EMBL; AF288460; AAG15210.1; -; Genomic_DNA.
DR   EMBL; CP000909; ABY35762.1; -; Genomic_DNA.
DR   RefSeq; WP_012258415.1; NC_010175.1.
DR   RefSeq; YP_001636151.1; NC_010175.1.
DR   AlphaFoldDB; Q9F6X5; -.
DR   SMR; Q9F6X5; -.
DR   STRING; 324602.Caur_2556; -.
DR   EnsemblBacteria; ABY35762; ABY35762; Caur_2556.
DR   KEGG; cau:Caur_2556; -.
DR   PATRIC; fig|324602.8.peg.2881; -.
DR   eggNOG; COG2710; Bacteria.
DR   HOGENOM; CLU_025470_0_0_0; -.
DR   InParanoid; Q9F6X5; -.
DR   OMA; TTFQARD; -.
DR   UniPathway; UPA00671; -.
DR   Proteomes; UP000002008; Chromosome.
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:0036070; P:light-independent bacteriochlorophyll 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; Bacteriochlorophyll biosynthesis;
KW   Chlorophyll biosynthesis; Iron; Iron-sulfur; Metal-binding;
KW   Nucleotide-binding; Oxidoreductase; Photosynthesis; Reference proteome.
FT   CHAIN           1..541
FT                   /note="Light-independent protochlorophyllide reductase
FT                   subunit B"
FT                   /id="PRO_0000219797"
FT   ACT_SITE        286
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         421..422
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_00353"
SQ   SEQUENCE   541 AA;  59182 MW;  0F3060E48358A5F7 CRC64;
     MRLAYWMYEG TAHHGVGRIA NSMRNVHAVF HAPQGDDYVN AIFAMLDRTP NFPAMTTSVV
     SGTDLARGTI RLPDTLRQVE ERVHPDLIVV VASCSTILLQ ENLEIAAQHA GLQCEVMVYD
     ANPYRMQEIV AAESLFTDLV KRFAKPQPRT ERPTVNILGP ASLGFHARHD LISLRRMLKT
     LGLEVNVVAP WGASIADLRR LPAAWLTIAP YRELGLRAAI YLEEQFGVPA LLDAPIGVQP
     TLRWIERLRE LLAQAGADVP MPPLTAFSLD GMSAPSAVPW FARTADMDSF SGKPAFVFGD
     ATHVVGVTRF LRDELGMPIA GAGTYVKHQA DWVREQLTGY VDEVLVTDEF QVVADRIAAL
     RPELVCGTQM ERHTSRRYDL NCMVISPPTH IENHLLAYRP FLGFDGADVI ADEVYTTCTL
     GMEKHLIDLF GDAGLDLPEK TERTPVAEPA PVAATVESPQ PQNEPAIAVA SAPSLTSAPA
     TPTPAAVVDP VWAADAEAML KKVPFFVRGR VRGNVEKYAR QRGHAVITAE VLLAAKEELG
     A