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Annotation rule MF_00179
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General rule information [?]

Accession MF_00179
Dates 1-JUN-2001 (Created)
18-NOV-2019 (Last updated, Version 26)
Name RibA
Templates P0A7I7 (RIBA_ECOLI); O08315 (RIBA_HELPY): [Recover all]

Propagated annotation [?]

Identifier, protein and gene names [?]

Protein name
RecName: Full=GTP cyclohydrolase-2;
AltName: Full=GTP cyclohydrolase II;
Gene name

Comments [?]

Function Catalyzes the conversion of GTP to 2,5-diamino-6-ribosylamino-4(3H)-pyrimidinone 5'-phosphate (DARP), formate and pyrophosphate.
Catalytic activity RHEA:23704: GTP + 3 H2O = 2,5-diamino-6-hydroxy-4-(5-phosphoribosylamino)-pyrimidine + diphosphate + formate + 2 H(+)
Cofactor Zn(2+)
Note: Binds 1 zinc ion per subunit.
Pathway Cofactor biosynthesis; riboflavin biosynthesis; 5-amino-6-(D-ribitylamino)uracil from GTP: step 1/4.
case <OC:Enterobacterales>
Subunit Homodimer.
end case
Similarity Belongs to the GTP cyclohydrolase II family.

Keywords [?]

Gene Ontology [?]

GO:0003935; Molecular function: GTP cyclohydrolase II activity.
GO:0008270; Molecular function: zinc ion binding.
GO:0009231; Biological process: riboflavin biosynthetic process.

Cross-references [?]

Pfam PF00925; GTP_cyclohydro2; 1;
TIGRFAMs TIGR00505; RibA; 1;

Features [?]

Key     From     To       Description   Tag   Condition   FTGroup
NP_BIND     49     53       GTP        
NP_BIND     92     94       GTP     E-G-R  
ACT_SITE     126     126       Proton acceptor     D  
ACT_SITE     128     128       Nucleophile     R  
METAL     54     54       Zinc; catalytic     C  
METAL     65     65       Zinc; catalytic     C  
METAL     67     67       Zinc; catalytic     C  
BINDING (Optional)     70     70       GTP     Q  
BINDING     114     114       GTP     T  
BINDING     149     149       GTP     [TS]  
BINDING     154     154       GTP     K  

Additional information [?]

Size range 192-222 amino acids
Related rules MF_01283 (RIBBA supersedes the current rule)
Fusion Nter: <ribB-like>, <Unknown>; Cter: None
Comments RibA and RibB are fused in some organisms (see MF_01283 for bifunctional RibBA). Some RibA are preceded by a ribB-like domain, which does not seem to code for DHBP synthase activity because it lacks all the residues important for activity. Fused with an unknown N-terminal domain in XYLFA and XYLFT. Possible wrong start in STRCO.