ID   BLUB_RHORT              Reviewed;         211 AA.
AC   Q2RNG5;
DT   16-OCT-2013, integrated into UniProtKB/Swiss-Prot.
DT   24-JAN-2006, sequence version 1.
DT   03-AUG-2022, entry version 82.
DE   RecName: Full=5,6-dimethylbenzimidazole synthase;
DE            Short=DMB synthase;
DE            EC=1.13.11.79;
GN   OrderedLocusNames=Rru_A3536;
OS   Rhodospirillum rubrum (strain ATCC 11170 / ATH 1.1.1 / DSM 467 / LMG 4362 /
OS   NCIMB 8255 / S1).
OC   Bacteria; Proteobacteria; Alphaproteobacteria; Rhodospirillales;
OC   Rhodospirillaceae; Rhodospirillum.
OX   NCBI_TaxID=269796;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=ATCC 11170 / ATH 1.1.1 / DSM 467 / LMG 4362 / NCIMB 8255 / S1;
RX   PubMed=21886856; DOI=10.4056/sigs.1804360;
RA   Munk A.C., Copeland A., Lucas S., Lapidus A., Del Rio T.G., Barry K.,
RA   Detter J.C., Hammon N., Israni S., Pitluck S., Brettin T., Bruce D.,
RA   Han C., Tapia R., Gilna P., Schmutz J., Larimer F., Land M., Kyrpides N.C.,
RA   Mavromatis K., Richardson P., Rohde M., Goeker M., Klenk H.P., Zhang Y.,
RA   Roberts G.P., Reslewic S., Schwartz D.C.;
RT   "Complete genome sequence of Rhodospirillum rubrum type strain (S1).";
RL   Stand. Genomic Sci. 4:293-302(2011).
RN   [2]
RP   FUNCTION, CATALYTIC ACTIVITY, MUTAGENESIS OF ARG-22, AND DISRUPTION
RP   PHENOTYPE.
RX   PubMed=17301238; DOI=10.1073/pnas.0609270104;
RA   Gray M.J., Escalante-Semerena J.C.;
RT   "Single-enzyme conversion of FMNH2 to 5,6-dimethylbenzimidazole, the lower
RT   ligand of B12.";
RL   Proc. Natl. Acad. Sci. U.S.A. 104:2921-2926(2007).
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.
CC       {ECO:0000269|PubMed:17301238}.
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; Evidence={ECO:0000269|PubMed:17301238};
CC   -!- SUBUNIT: Homooctamer. {ECO:0000250}.
CC   -!- DISRUPTION PHENOTYPE: Cells lacking this gene fail to synthesize
CC       cobalamin. {ECO:0000269|PubMed:17301238}.
CC   -!- SIMILARITY: Belongs to the BluB family. {ECO:0000305}.
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DR   EMBL; CP000230; ABC24330.1; -; Genomic_DNA.
DR   RefSeq; WP_011391283.1; NC_007643.1.
DR   RefSeq; YP_428617.1; NC_007643.1.
DR   AlphaFoldDB; Q2RNG5; -.
DR   SMR; Q2RNG5; -.
DR   STRING; 269796.Rru_A3536; -.
DR   EnsemblBacteria; ABC24330; ABC24330; Rru_A3536.
DR   KEGG; rru:Rru_A3536; -.
DR   PATRIC; fig|269796.9.peg.3653; -.
DR   eggNOG; COG0778; Bacteria.
DR   HOGENOM; CLU_070764_3_0_5; -.
DR   OMA; FMQPWDF; -.
DR   OrthoDB; 1847197at2; -.
DR   PhylomeDB; Q2RNG5; -.
DR   BRENDA; 1.13.11.79; 5420.
DR   Proteomes; UP000001929; Chromosome.
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; IDA:UniProtKB.
DR   GO; GO:0009236; P:cobalamin biosynthetic process; IDA: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   1: Evidence at protein level;
KW   Cobalamin biosynthesis; Flavoprotein; FMN; NAD; NADP; Nucleotide-binding;
KW   Oxidoreductase; Reference proteome.
FT   CHAIN           1..211
FT                   /note="5,6-dimethylbenzimidazole synthase"
FT                   /id="PRO_0000424084"
FT   BINDING         22..26
FT                   /ligand="FMN"
FT                   /ligand_id="ChEBI:CHEBI:58210"
FT                   /evidence="ECO:0000250"
FT   BINDING         50
FT                   /ligand="FMN"
FT                   /ligand_id="ChEBI:CHEBI:58210"
FT                   /evidence="ECO:0000250"
FT   BINDING         99
FT                   /ligand="FMN"
FT                   /ligand_id="ChEBI:CHEBI:58210"
FT                   /evidence="ECO:0000250"
FT   BINDING         158
FT                   /ligand="FMN"
FT                   /ligand_id="ChEBI:CHEBI:58210"
FT                   /evidence="ECO:0000250"
FT   MUTAGEN         22
FT                   /note="R->E: Completely abolishes DMB formation."
FT                   /evidence="ECO:0000269|PubMed:17301238"
SQ   SEQUENCE   211 AA;  23904 MW;  1687F48488019840 CRC64;
     MRTGPLFDPS FRDGLDALFQ WRRDVRHFRK DPIDEETVAR LLACADLAPS VGNSQPWRFV
     RVDDGARRGV IIDDFTRCNA AARALQPEER QDAYARLKLE GLREAPLQLA VFCDEATDQG
     HGLGQATMPE TRRYSVVMAI HTLWLAARAR GLGVGWVSVL DPQTVTAALD VPAEWAFVAY
     LCIGWPREEH PIPELERLGW QSRRPHPVVR R