ID   RISA_BUCAP              Reviewed;         208 AA.
AC   Q8KA22;
DT   08-NOV-2002, integrated into UniProtKB/Swiss-Prot.
DT   01-OCT-2002, sequence version 1.
DT   03-AUG-2022, entry version 106.
DE   RecName: Full=Riboflavin synthase;
DE            Short=RS;
DE            EC=2.5.1.9;
GN   Name=ribE; OrderedLocusNames=BUsg_104;
OS   Buchnera aphidicola subsp. Schizaphis graminum (strain Sg).
OC   Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales;
OC   Erwiniaceae; Buchnera.
OX   NCBI_TaxID=198804;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=Sg;
RX   PubMed=12089438; DOI=10.1126/science.1071278;
RA   Tamas I., Klasson L., Canbaeck B., Naeslund A.K., Eriksson A.-S.,
RA   Wernegreen J.J., Sandstroem J.P., Moran N.A., Andersson S.G.E.;
RT   "50 million years of genomic stasis in endosymbiotic bacteria.";
RL   Science 296:2376-2379(2002).
CC   -!- FUNCTION: Catalyzes the dismutation of two molecules of 6,7-dimethyl-8-
CC       ribityllumazine, resulting in the formation of riboflavin and 5-amino-
CC       6-(D-ribitylamino)uracil. {ECO:0000250}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=2 6,7-dimethyl-8-(1-D-ribityl)lumazine + H(+) = 5-amino-6-(D-
CC         ribitylamino)uracil + riboflavin; Xref=Rhea:RHEA:20772,
CC         ChEBI:CHEBI:15378, ChEBI:CHEBI:15934, ChEBI:CHEBI:57986,
CC         ChEBI:CHEBI:58201; EC=2.5.1.9;
CC   -!- PATHWAY: Cofactor biosynthesis; riboflavin biosynthesis; riboflavin
CC       from 2-hydroxy-3-oxobutyl phosphate and 5-amino-6-(D-
CC       ribitylamino)uracil: step 2/2.
CC   -!- SUBUNIT: Homotrimer. {ECO:0000250}.
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DR   EMBL; AE013218; AAM67674.1; -; Genomic_DNA.
DR   RefSeq; WP_011053640.1; NC_004061.1.
DR   AlphaFoldDB; Q8KA22; -.
DR   SMR; Q8KA22; -.
DR   STRING; 198804.BUsg_104; -.
DR   EnsemblBacteria; AAM67674; AAM67674; BUsg_104.
DR   KEGG; bas:BUsg_104; -.
DR   eggNOG; COG0307; Bacteria.
DR   HOGENOM; CLU_034388_0_1_6; -.
DR   OMA; HILSGHV; -.
DR   OrthoDB; 1276859at2; -.
DR   UniPathway; UPA00275; UER00405.
DR   Proteomes; UP000000416; Chromosome.
DR   GO; GO:0004746; F:riboflavin synthase activity; IEA:UniProtKB-EC.
DR   GO; GO:0009231; P:riboflavin biosynthetic process; IEA:UniProtKB-UniPathway.
DR   CDD; cd00402; Riboflavin_synthase_like; 1.
DR   Gene3D; 2.40.30.20; -; 2.
DR   InterPro; IPR023366; ATP_synth_asu-like_sf.
DR   InterPro; IPR001783; Lumazine-bd.
DR   InterPro; IPR026017; Lumazine-bd_dom.
DR   InterPro; IPR017938; Riboflavin_synthase-like_b-brl.
DR   PANTHER; PTHR21098; PTHR21098; 1.
DR   Pfam; PF00677; Lum_binding; 2.
DR   PIRSF; PIRSF000498; Riboflavin_syn_A; 1.
DR   SUPFAM; SSF63380; SSF63380; 2.
DR   TIGRFAMs; TIGR00187; ribE; 1.
DR   PROSITE; PS51177; LUMAZINE_BIND; 2.
PE   3: Inferred from homology;
KW   Repeat; Riboflavin biosynthesis; Transferase.
FT   CHAIN           1..208
FT                   /note="Riboflavin synthase"
FT                   /id="PRO_0000068161"
FT   REPEAT          1..97
FT                   /note="Lumazine-binding 1"
FT   REPEAT          98..195
FT                   /note="Lumazine-binding 2"
FT   BINDING         4..6
FT                   /ligand="2,4-dihydroxypteridine"
FT                   /ligand_id="ChEBI:CHEBI:16489"
FT                   /ligand_label="1"
FT                   /evidence="ECO:0000250|UniProtKB:Q2YN92"
FT   BINDING         48..50
FT                   /ligand="2,4-dihydroxypteridine"
FT                   /ligand_id="ChEBI:CHEBI:16489"
FT                   /ligand_label="2"
FT                   /ligand_note="ligand shared between two trimeric partners"
FT                   /evidence="ECO:0000250|UniProtKB:Q2YN92"
FT   BINDING         62..67
FT                   /ligand="2,4-dihydroxypteridine"
FT                   /ligand_id="ChEBI:CHEBI:16489"
FT                   /ligand_label="2"
FT                   /ligand_note="ligand shared between two trimeric partners"
FT                   /evidence="ECO:0000250|UniProtKB:P0AFU8"
FT   BINDING         101..103
FT                   /ligand="2,4-dihydroxypteridine"
FT                   /ligand_id="ChEBI:CHEBI:16489"
FT                   /ligand_label="2"
FT                   /ligand_note="ligand shared between two trimeric partners"
FT                   /evidence="ECO:0000250|UniProtKB:Q2YN92"
FT   BINDING         137
FT                   /ligand="2,4-dihydroxypteridine"
FT                   /ligand_id="ChEBI:CHEBI:16489"
FT                   /ligand_label="2"
FT                   /ligand_note="ligand shared between two trimeric partners"
FT                   /note="in other chain"
FT                   /evidence="ECO:0000250|UniProtKB:Q2YN92"
FT   BINDING         146..148
FT                   /ligand="2,4-dihydroxypteridine"
FT                   /ligand_id="ChEBI:CHEBI:16489"
FT                   /ligand_label="1"
FT                   /evidence="ECO:0000250|UniProtKB:Q2YN92"
FT   BINDING         160..165
FT                   /ligand="2,4-dihydroxypteridine"
FT                   /ligand_id="ChEBI:CHEBI:16489"
FT                   /ligand_label="1"
FT                   /evidence="ECO:0000250|UniProtKB:Q2YN92"
SQ   SEQUENCE   208 AA;  23365 MW;  CE00EE91A2C732AF CRC64;
     MFTGIVNGIA RVVSINKKKN FHTYTVNFSS ILLKNLKIGD SVAHNGCCLT VKYINCPHVV
     FDIMKITIAN TNLGVLNIGD YVNIERSLKY GDEMGGHIIS GHIMNTGEIS KISKLDKNYI
     LWCKVKDLSL MKYIFYKGFI AIDGISLTIN NIIKNEFCVS IIPETLSSTT IGFKKIGQLV
     NIEIDFYTQI IVDTTKRLIK KDISTLFK