ID   RIBA_AZOBR              Reviewed;         385 AA.
AC   P43525;
DT   01-NOV-1995, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1995, sequence version 1.
DT   03-AUG-2022, entry version 104.
DE   RecName: Full=GTP cyclohydrolase-2;
DE            EC=3.5.4.25;
DE   AltName: Full=GTP cyclohydrolase II;
GN   Name=ribA;
OS   Azospirillum brasilense.
OC   Bacteria; Proteobacteria; Alphaproteobacteria; Rhodospirillales;
OC   Azospirillaceae; Azospirillum.
OX   NCBI_TaxID=192;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=ATCC 29145 / DSM 1690 / IMET 11303 / Sp7;
RX   PubMed=7883178; DOI=10.1016/0378-1119(94)00826-e;
RA   van Bastelaere E., Keijers V., Vanderleyden J.;
RT   "Cloning and sequencing of the putative Azospirillum brasilense gene
RT   encoding GTP cyclohydrolase II.";
RL   Gene 153:141-142(1995).
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:0000250}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=GTP + 4 H2O = 2,5-diamino-6-hydroxy-4-(5-phosphoribosylamino)-
CC         pyrimidine + formate + 3 H(+) + 2 phosphate; 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   -!- COFACTOR:
CC       Name=Zn(2+); Xref=ChEBI:CHEBI:29105; Evidence={ECO:0000250};
CC       Note=Binds 1 zinc ion per subunit. {ECO:0000250};
CC   -!- PATHWAY: Cofactor biosynthesis; riboflavin biosynthesis; 5-amino-6-(D-
CC       ribitylamino)uracil from GTP: step 1/4.
CC   -!- SIMILARITY: In the N-terminal section; belongs to the DHBP synthase
CC       family. {ECO:0000305}.
CC   -!- SIMILARITY: In the C-terminal section; belongs to the GTP
CC       cyclohydrolase II family. {ECO:0000305}.
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DR   EMBL; U09869; AAA82170.1; -; Genomic_DNA.
DR   PIR; I39498; I39498.
DR   AlphaFoldDB; P43525; -.
DR   SMR; P43525; -.
DR   UniPathway; UPA00275; UER00400.
DR   GO; GO:0005525; F:GTP binding; IEA:UniProtKB-KW.
DR   GO; GO:0003935; F:GTP cyclohydrolase II activity; 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   Gene3D; 3.40.50.10990; -; 1.
DR   HAMAP; MF_00179; RibA; 1.
DR   InterPro; IPR017945; DHBP_synth_RibB-like_a/b_dom.
DR   InterPro; IPR032677; GTP_cyclohydro_II.
DR   InterPro; IPR000926; RibA.
DR   InterPro; IPR036144; RibA-like_sf.
DR   Pfam; PF00925; GTP_cyclohydro2; 1.
DR   SUPFAM; SSF142695; SSF142695; 1.
DR   SUPFAM; SSF55821; SSF55821; 1.
DR   TIGRFAMs; TIGR00505; ribA; 1.
PE   3: Inferred from homology;
KW   GTP-binding; Hydrolase; Metal-binding; Nucleotide-binding;
KW   Riboflavin biosynthesis; Zinc.
FT   CHAIN           1..385
FT                   /note="GTP cyclohydrolase-2"
FT                   /id="PRO_0000151784"
FT   REGION          1..189
FT                   /note="DHBP synthase-like"
FT   REGION          190..385
FT                   /note="GTP cyclohydrolase II"
FT   ACT_SITE        317
FT                   /note="Proton acceptor"
FT                   /evidence="ECO:0000255"
FT   ACT_SITE        319
FT                   /note="Nucleophile"
FT                   /evidence="ECO:0000250"
FT   BINDING         240..244
FT                   /ligand="GTP"
FT                   /ligand_id="ChEBI:CHEBI:37565"
FT                   /evidence="ECO:0000250"
FT   BINDING         245
FT                   /ligand="Zn(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29105"
FT                   /ligand_note="catalytic"
FT                   /evidence="ECO:0000250"
FT   BINDING         256
FT                   /ligand="Zn(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29105"
FT                   /ligand_note="catalytic"
FT                   /evidence="ECO:0000250"
FT   BINDING         258
FT                   /ligand="Zn(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29105"
FT                   /ligand_note="catalytic"
FT                   /evidence="ECO:0000250"
FT   BINDING         261
FT                   /ligand="GTP"
FT                   /ligand_id="ChEBI:CHEBI:37565"
FT                   /evidence="ECO:0000250"
FT   BINDING         283..285
FT                   /ligand="GTP"
FT                   /ligand_id="ChEBI:CHEBI:37565"
FT                   /evidence="ECO:0000250"
FT   BINDING         305
FT                   /ligand="GTP"
FT                   /ligand_id="ChEBI:CHEBI:37565"
FT                   /evidence="ECO:0000250"
FT   BINDING         340
FT                   /ligand="GTP"
FT                   /ligand_id="ChEBI:CHEBI:37565"
FT                   /evidence="ECO:0000250"
FT   BINDING         345
FT                   /ligand="GTP"
FT                   /ligand_id="ChEBI:CHEBI:37565"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   385 AA;  40972 MW;  A98C225E2B068536 CRC64;
     MYADAPSDSA PPEAVLPMDE AAMRAVDRAT AALRRGEAVA IETADGSVGA AVSVESVAID
     AVQRLVQLTG AAPVLAVTRR RATVLKLMGE GTGVVALSLP RCLTADEAHA LADPEHRPDG
     DMPDGLTATA MDPGSRETAA VDLARLARLL PAAIVAPATD HTGSAAEWAA EHDLLLVRAR
     DIADYRVHVV RTLRRVAEAR VPLSGAENTS IAAFRPIDGG PEHLAIIVGN PVAGEPVLAR
     LHSECFTGDL LAGLRCDCGQ QLRGAIAEIA RHGSGVLLYL AQEGRGIGLV NKLRAYRIQD
     RGFDTVDANE ILGFEADERV YLPAAEMLRQ LGFTAVRLMT NNPEKLRQLA RCGIEVVERV
     PHIFPANGHN EGYLRTKAER SGHMF