ID   RIBBA_BACSU             Reviewed;         398 AA.
AC   P17620;
DT   01-AUG-1990, integrated into UniProtKB/Swiss-Prot.
DT   01-AUG-1990, sequence version 1.
DT   02-SEP-2026, entry version 173.
DE   RecName: Full=Riboflavin biosynthesis protein RibBA {ECO:0000255|HAMAP-Rule:MF_01283};
DE   Includes:
DE     RecName: Full=3,4-dihydroxy-2-butanone 4-phosphate synthase {ECO:0000255|HAMAP-Rule:MF_01283};
DE              Short=DHBP synthase {ECO:0000255|HAMAP-Rule:MF_01283};
DE              EC=4.1.99.12 {ECO:0000255|HAMAP-Rule:MF_01283};
DE   Includes:
DE     RecName: Full=GTP cyclohydrolase-2 {ECO:0000255|HAMAP-Rule:MF_01283};
DE              EC=3.5.4.25 {ECO:0000255|HAMAP-Rule:MF_01283};
DE     AltName: Full=GTP cyclohydrolase II {ECO:0000255|HAMAP-Rule:MF_01283};
GN   Name=ribBA {ECO:0000255|HAMAP-Rule:MF_01283}; Synonyms=ribA;
GN   OrderedLocusNames=BSU23260;
OS   Bacillus subtilis (strain 168).
OC   Bacteria; Bacillati; Bacillota; Bacilli; Caryophanales; Bacillaceae;
OC   Bacillus.
OX   NCBI_TaxID=224308;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=168 / Marburg / ATCC 6051 / DSM 10 / JCM 1465 / NBRC 13719 /
RC   NCIMB 3610 / NRRL NRS-744 / VKM B-501;
RX   PubMed=7934829; DOI=10.1111/j.1365-2958.1993.tb02670.x;
RA   Sorokin A.V., Zumstein E., Azevedo V., Ehrlich S.D., Serror P.;
RT   "The organization of the Bacillus subtilis 168 chromosome region between
RT   the spoVA and serA genetic loci, based on sequence data.";
RL   Mol. Microbiol. 10:385-395(1993).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=168 / SHGW;
RA   Mironov V.N.;
RL   Thesis (1989), USSR Academy of Sciences, Russia.
RN   [3]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=168;
RX   PubMed=9384377; DOI=10.1038/36786;
RA   Kunst F., Ogasawara N., Moszer I., Albertini A.M., Alloni G., Azevedo V.,
RA   Bertero M.G., Bessieres P., Bolotin A., Borchert S., Borriss R.,
RA   Boursier L., Brans A., Braun M., Brignell S.C., Bron S., Brouillet S.,
RA   Bruschi C.V., Caldwell B., Capuano V., Carter N.M., Choi S.-K.,
RA   Codani J.-J., Connerton I.F., Cummings N.J., Daniel R.A., Denizot F.,
RA   Devine K.M., Duesterhoeft A., Ehrlich S.D., Emmerson P.T., Entian K.-D.,
RA   Errington J., Fabret C., Ferrari E., Foulger D., Fritz C., Fujita M.,
RA   Fujita Y., Fuma S., Galizzi A., Galleron N., Ghim S.-Y., Glaser P.,
RA   Goffeau A., Golightly E.J., Grandi G., Guiseppi G., Guy B.J., Haga K.,
RA   Haiech J., Harwood C.R., Henaut A., Hilbert H., Holsappel S., Hosono S.,
RA   Hullo M.-F., Itaya M., Jones L.-M., Joris B., Karamata D., Kasahara Y.,
RA   Klaerr-Blanchard M., Klein C., Kobayashi Y., Koetter P., Koningstein G.,
RA   Krogh S., Kumano M., Kurita K., Lapidus A., Lardinois S., Lauber J.,
RA   Lazarevic V., Lee S.-M., Levine A., Liu H., Masuda S., Mauel C.,
RA   Medigue C., Medina N., Mellado R.P., Mizuno M., Moestl D., Nakai S.,
RA   Noback M., Noone D., O'Reilly M., Ogawa K., Ogiwara A., Oudega B.,
RA   Park S.-H., Parro V., Pohl T.M., Portetelle D., Porwollik S.,
RA   Prescott A.M., Presecan E., Pujic P., Purnelle B., Rapoport G., Rey M.,
RA   Reynolds S., Rieger M., Rivolta C., Rocha E., Roche B., Rose M., Sadaie Y.,
RA   Sato T., Scanlan E., Schleich S., Schroeter R., Scoffone F., Sekiguchi J.,
RA   Sekowska A., Seror S.J., Serror P., Shin B.-S., Soldo B., Sorokin A.,
RA   Tacconi E., Takagi T., Takahashi H., Takemaru K., Takeuchi M.,
RA   Tamakoshi A., Tanaka T., Terpstra P., Tognoni A., Tosato V., Uchiyama S.,
RA   Vandenbol M., Vannier F., Vassarotti A., Viari A., Wambutt R., Wedler E.,
RA   Wedler H., Weitzenegger T., Winters P., Wipat A., Yamamoto H., Yamane K.,
RA   Yasumoto K., Yata K., Yoshida K., Yoshikawa H.-F., Zumstein E.,
RA   Yoshikawa H., Danchin A.;
RT   "The complete genome sequence of the Gram-positive bacterium Bacillus
RT   subtilis.";
RL   Nature 390:249-256(1997).
CC   -!- FUNCTION: Catalyzes the conversion of D-ribulose 5-phosphate to formate
CC       and 3,4-dihydroxy-2-butanone 4-phosphate. {ECO:0000255|HAMAP-
CC       Rule:MF_01283}.
CC   -!- FUNCTION: Catalyzes the conversion of GTP to 2,5-diamino-6-
CC       ribosylamino-4(3H)-pyrimidinone 5'-phosphate (DARP), formate and
CC       pyrophosphate. {ECO:0000255|HAMAP-Rule:MF_01283}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=D-ribulose 5-phosphate = (2S)-2-hydroxy-3-oxobutyl phosphate +
CC         formate + H(+); Xref=Rhea:RHEA:18457, ChEBI:CHEBI:15378,
CC         ChEBI:CHEBI:15740, ChEBI:CHEBI:58121, ChEBI:CHEBI:58830;
CC         EC=4.1.99.12; Evidence={ECO:0000255|HAMAP-Rule:MF_01283};
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=GTP + 4 H2O = 2,5-diamino-6-hydroxy-4-(5-phosphoribosylamino)-
CC         pyrimidine + formate + 2 phosphate + 3 H(+); Xref=Rhea:RHEA:23704,
CC         ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:15740,
CC         ChEBI:CHEBI:37565, ChEBI:CHEBI:43474, ChEBI:CHEBI:58614; EC=3.5.4.25;
CC         Evidence={ECO:0000255|HAMAP-Rule:MF_01283};
CC   -!- COFACTOR:
CC       Name=Mg(2+); Xref=ChEBI:CHEBI:18420; Evidence={ECO:0000255|HAMAP-
CC         Rule:MF_01283};
CC       Name=Mn(2+); Xref=ChEBI:CHEBI:29035; Evidence={ECO:0000255|HAMAP-
CC         Rule:MF_01283};
CC       Note=Binds 2 divalent metal cations per subunit. Magnesium or
CC       manganese. {ECO:0000255|HAMAP-Rule:MF_01283};
CC   -!- COFACTOR:
CC       Name=Zn(2+); Xref=ChEBI:CHEBI:29105; Evidence={ECO:0000255|HAMAP-
CC         Rule:MF_01283};
CC       Note=Binds 1 zinc ion per subunit. {ECO:0000255|HAMAP-Rule:MF_01283};
CC   -!- PATHWAY: Cofactor biosynthesis; riboflavin biosynthesis; 2-hydroxy-3-
CC       oxobutyl phosphate from D-ribulose 5-phosphate: step 1/1.
CC       {ECO:0000255|HAMAP-Rule:MF_01283}.
CC   -!- PATHWAY: Cofactor biosynthesis; riboflavin biosynthesis; 5-amino-6-(D-
CC       ribitylamino)uracil from GTP: step 1/4. {ECO:0000255|HAMAP-
CC       Rule:MF_01283}.
CC   -!- SIMILARITY: In the N-terminal section; belongs to the DHBP synthase
CC       family. {ECO:0000255|HAMAP-Rule:MF_01283}.
CC   -!- SIMILARITY: In the C-terminal section; belongs to the GTP
CC       cyclohydrolase II family. {ECO:0000255|HAMAP-Rule:MF_01283}.
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DR   EMBL; L09228; AAA67483.1; -; Genomic_DNA.
DR   EMBL; X51510; CAA35880.1; -; Genomic_DNA.
DR   EMBL; AL009126; CAB14258.1; -; Genomic_DNA.
DR   PIR; S45545; S45545.
DR   RefSeq; NP_390207.1; NC_000964.3.
DR   RefSeq; WP_004398484.1; NC_000964.3.
DR   AlphaFoldDB; P17620; -.
DR   SMR; P17620; -.
DR   FunCoup; P17620; 467.
DR   IntAct; P17620; 1.
DR   MINT; P17620; -.
DR   STRING; 224308.BSU23260; -.
DR   PaxDb; 224308-BSU23260; -.
DR   DNASU; 938946; -.
DR   EnsemblBacteria; CAB14258; CAB14258; BSU_23260.
DR   GeneID; 938946; -.
DR   KEGG; bsu:BSU23260; -.
DR   PATRIC; fig|224308.179.peg.2533; -.
DR   eggNOG; COG0108; Bacteria.
DR   eggNOG; COG0807; Bacteria.
DR   InParanoid; P17620; -.
DR   OrthoDB; 9793111at2; -.
DR   PhylomeDB; P17620; -.
DR   BioCyc; BSUB:BSU23260-MONOMER; -.
DR   UniPathway; UPA00275; UER00399.
DR   UniPathway; UPA00275; UER00400.
DR   Proteomes; UP000001570; Chromosome.
DR   AbasyAtlas; P17620; -.
DR   GO; GO:0005829; C:cytosol; IBA:GO_Central.
DR   GO; GO:0008686; F:3,4-dihydroxy-2-butanone-4-phosphate synthase activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0003935; F:GTP cyclohydrolase II activity; IBA:GO_Central.
DR   GO; GO:0000287; F:magnesium ion binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0030145; F:manganese ion binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0008270; F:zinc ion binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0009231; P:riboflavin biosynthetic process; IEA:UniProtKB-UniRule.
DR   CDD; cd00641; GTP_cyclohydro2; 1.
DR   FunFam; 3.40.50.10990:FF:000001; Riboflavin biosynthesis protein RibBA; 1.
DR   FunFam; 3.90.870.10:FF:000001; Riboflavin biosynthesis protein RibBA; 1.
DR   Gene3D; 3.90.870.10; DHBP synthase; 1.
DR   Gene3D; 3.40.50.10990; GTP cyclohydrolase II; 1.
DR   HAMAP; MF_00179; RibA; 1.
DR   HAMAP; MF_00180; RibB; 1.
DR   HAMAP; MF_01283; RibBA; 1.
DR   InterPro; IPR017945; DHBP_synth_RibB-like_a/b_dom.
DR   InterPro; IPR000422; DHBP_synthase_RibB.
DR   InterPro; IPR032677; GTP_cyclohydro_II.
DR   InterPro; IPR000926; RibA.
DR   InterPro; IPR036144; RibA-like_sf.
DR   InterPro; IPR016299; Riboflavin_synth_RibBA.
DR   NCBIfam; NF001591; PRK00393.1; 1.
DR   NCBIfam; NF006803; PRK09311.1; 1.
DR   NCBIfam; TIGR00505; ribA; 1.
DR   NCBIfam; TIGR00506; ribB; 1.
DR   PANTHER; PTHR21327:SF18; 3,4-DIHYDROXY-2-BUTANONE 4-PHOSPHATE SYNTHASE; 1.
DR   PANTHER; PTHR21327; GTP CYCLOHYDROLASE II-RELATED; 1.
DR   Pfam; PF00926; DHBP_synthase; 1.
DR   Pfam; PF00925; GTP_cyclohydro2; 1.
DR   PIRSF; PIRSF001259; RibA; 1.
DR   SUPFAM; SSF142695; RibA-like; 1.
DR   SUPFAM; SSF55821; YrdC/RibB; 1.
PE   3: Inferred from homology;
KW   GTP-binding; Hydrolase; Lyase; Magnesium; Manganese; Metal-binding;
KW   Multifunctional enzyme; Nucleotide-binding; Reference proteome;
KW   Riboflavin biosynthesis; Zinc.
FT   CHAIN           1..398
FT                   /note="Riboflavin biosynthesis protein RibBA"
FT                   /id="PRO_0000151721"
FT   REGION          1..199
FT                   /note="DHBP synthase"
FT   REGION          200..398
FT                   /note="GTP cyclohydrolase II"
FT   ACT_SITE        328
FT                   /note="Proton acceptor; for GTP cyclohydrolase activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   ACT_SITE        330
FT                   /note="Nucleophile; for GTP cyclohydrolase activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         26..27
FT                   /ligand="D-ribulose 5-phosphate"
FT                   /ligand_id="ChEBI:CHEBI:58121"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         27
FT                   /ligand="Mg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:18420"
FT                   /ligand_label="1"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         27
FT                   /ligand="Mg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:18420"
FT                   /ligand_label="2"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         31
FT                   /ligand="D-ribulose 5-phosphate"
FT                   /ligand_id="ChEBI:CHEBI:58121"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         138..142
FT                   /ligand="D-ribulose 5-phosphate"
FT                   /ligand_id="ChEBI:CHEBI:58121"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         141
FT                   /ligand="Mg(2+)"
FT                   /ligand_id="ChEBI:CHEBI:18420"
FT                   /ligand_label="2"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         162
FT                   /ligand="D-ribulose 5-phosphate"
FT                   /ligand_id="ChEBI:CHEBI:58121"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         251..255
FT                   /ligand="GTP"
FT                   /ligand_id="ChEBI:CHEBI:37565"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         256
FT                   /ligand="Zn(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29105"
FT                   /ligand_note="catalytic"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         267
FT                   /ligand="Zn(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29105"
FT                   /ligand_note="catalytic"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         269
FT                   /ligand="Zn(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29105"
FT                   /ligand_note="catalytic"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         272
FT                   /ligand="GTP"
FT                   /ligand_id="ChEBI:CHEBI:37565"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         294..296
FT                   /ligand="GTP"
FT                   /ligand_id="ChEBI:CHEBI:37565"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         316
FT                   /ligand="GTP"
FT                   /ligand_id="ChEBI:CHEBI:37565"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         351
FT                   /ligand="GTP"
FT                   /ligand_id="ChEBI:CHEBI:37565"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   BINDING         356
FT                   /ligand="GTP"
FT                   /ligand_id="ChEBI:CHEBI:37565"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   SITE            124
FT                   /note="Essential for DHBP synthase activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
FT   SITE            162
FT                   /note="Essential for DHBP synthase activity"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01283"
SQ   SEQUENCE   398 AA;  44121 MW;  D9162EA7DAE611AA CRC64;
     MFHPIEEALD ALKKGEVIIV VDDEDRENEG DFVALAEHAT PEVINFMATH GRGLICTPLS
     EEIADRLDLH PMVEHNTDSH HTAFTVSIDH RETKTGISAQ ERSFTVQALL DSKSVPSDFQ
     RPGHIFPLIA KKGGVLKRAG HTEAAVDLAE ACGSPGAGVI CEIMNEDGTM ARVPELIEIA
     KKHQLKMITI KDLIQYRYNL TTLVEREVDI TLPTDFGTFK VYGYTNEVDG KEHVAFVMGD
     VPFGEEPVLV RVHSECLTGD VFGSHRCDCG PQLHAALNQI AAEGRGVLLY LRQEGRGIGL
     INKLKAYKLQ EQGYDTVEAN EALGFLPDLR NYGIGAQILR DLGVRNMKLL TNNPRKIAGL
     EGYGLSISER VPLQMEAKEH NKKYLQTKMN KLGHLLHF
//