ID   BLUB_RHOCA              Reviewed;         206 AA.
AC   P0CY55; O68092; Q52685;
DT   28-JUN-2011, integrated into UniProtKB/Swiss-Prot.
DT   28-JUN-2011, sequence version 1.
DT   03-AUG-2022, entry version 31.
DE   RecName: Full=5,6-dimethylbenzimidazole synthase;
DE            Short=DMB synthase;
DE            EC=1.13.11.79;
GN   Name=bluB;
OS   Rhodobacter capsulatus (Rhodopseudomonas capsulata).
OC   Bacteria; Proteobacteria; Alphaproteobacteria; Rhodobacterales;
OC   Rhodobacteraceae; Rhodobacter.
OX   NCBI_TaxID=1061;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=ATCC 33303 / B10;
RX   PubMed=7635831; DOI=10.1128/jb.177.15.4481-4487.1995;
RA   Pollich M., Klug G.;
RT   "Identification and sequence analysis of genes involved in late steps in
RT   cobalamin (vitamin B12) synthesis in Rhodobacter capsulatus.";
RL   J. Bacteriol. 177:4481-4487(1995).
CC   -!- FUNCTION: Involved in the biosynthesis of cobalamin (vitamin B12).
CC       Catalyzes the oxidative fragmentation and contraction of the
CC       isoalloxazine heterocycle and the cleavage of the ribityl tail of
CC       FMNH(2) to form 5,6-dimethylbenzimidazole (DMB) and D-erythrose 4-
CC       phosphate (E4P). NAD(P)H is only required initially to reduce FMN and
CC       oxygen drives the oxidative fragmentation (By similarity).
CC       {ECO:0000250}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=FMNH2 + O2 = 5,6-dimethylbenzimidazole + D-erythrose 4-
CC         phosphate + dialurate + H(+); Xref=Rhea:RHEA:27345,
CC         ChEBI:CHEBI:15378, ChEBI:CHEBI:15379, ChEBI:CHEBI:15890,
CC         ChEBI:CHEBI:16897, ChEBI:CHEBI:57618, ChEBI:CHEBI:140629;
CC         EC=1.13.11.79;
CC   -!- SUBUNIT: Homooctamer. {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the BluB family. {ECO:0000305}.
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DR   EMBL; Z46611; CAA86583.1; -; Genomic_DNA.
DR   PIR; S52225; S52225.
DR   AlphaFoldDB; P0CY55; -.
DR   SMR; P0CY55; -.
DR   GO; GO:0102919; F:5,6-dimethylbenzimidazole synthase activity; IEA:UniProtKB-EC.
DR   GO; GO:0000166; F:nucleotide binding; IEA:UniProtKB-KW.
DR   GO; GO:0016705; F:oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen; ISS:UniProtKB.
DR   GO; GO:0009236; P:cobalamin biosynthetic process; ISS:UniProtKB.
DR   CDD; cd02145; BluB; 1.
DR   Gene3D; 3.40.109.10; -; 1.
DR   InterPro; IPR012825; BluB.
DR   InterPro; IPR029479; Nitroreductase.
DR   InterPro; IPR000415; Nitroreductase-like.
DR   Pfam; PF00881; Nitroreductase; 1.
DR   SUPFAM; SSF55469; SSF55469; 1.
DR   TIGRFAMs; TIGR02476; BluB; 1.
PE   3: Inferred from homology;
KW   Cobalamin biosynthesis; Flavoprotein; FMN; NAD; NADP; Nucleotide-binding;
KW   Oxidoreductase.
FT   CHAIN           1..206
FT                   /note="5,6-dimethylbenzimidazole synthase"
FT                   /id="PRO_0000064946"
FT   BINDING         18..22
FT                   /ligand="FMN"
FT                   /ligand_id="ChEBI:CHEBI:58210"
FT                   /evidence="ECO:0000250"
FT   BINDING         46
FT                   /ligand="FMN"
FT                   /ligand_id="ChEBI:CHEBI:58210"
FT                   /evidence="ECO:0000250"
FT   BINDING         95
FT                   /ligand="FMN"
FT                   /ligand_id="ChEBI:CHEBI:58210"
FT                   /evidence="ECO:0000250"
FT   BINDING         153
FT                   /ligand="FMN"
FT                   /ligand_id="ChEBI:CHEBI:58210"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   206 AA;  22862 MW;  7A06059580967DEE CRC64;
     MNFEQTHRDA LTEVLRWRRD VRHFRPDPID EAVIDRLRAV MDMAPSVGNA RPWRVIRVDS
     PALRAEVLAN FNAARAAAGS AYAGEQAEAY ATLKLQGIDQ APLQLAVFTH RDPAAGHGLG
     RASMPVTLQQ STAMAFTRSG CRAGENLGLG MVSVLDPKAV ERLLNAPPDW DFVAWLCIGV
     PEFTDDTPLL HRAGWQENLP TEWERR