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Gene Review:

ribA - GTP cyclohydrolase II

Escherichia coli str. K-12 substr. MG1655

Synonyms: ECK1272, JW1269

Ren, J. et al., Spoonamore, J.E. et al., Herz, S. et al., Worst, D.J. et al., Richter, G. et al., et al.

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Disease relevance of ribA

The acn gene is flanked by the cysB gene and a putative riboflavin biosynthesis gene resembling the ribA gene of Bacillus subtilis [1].
The gene was mapped to a position at 28.2 min on the E. coli chromosome and is identical with ribA [2].
Evolution of New Function in the GTP Cyclohydrolase II Proteins of Streptomyces coelicolor [3].

High impact information on ribA

Although GTP cyclohydrolase I and GTP cyclohydrolase II both use a zinc ion for the GTP ring opening and formate release, different residues are utilized in each case to catalyze this reaction step [4].
GTP cyclohydrolase II converts GTP to 2,5-diamino-6-beta-ribosyl-4(3H)-pyrimidinone 5'-phosphate, formate and pyrophosphate, the first step in riboflavin biosynthesis [4].
GTP cyclohydrolase II catalyzes a distinctive overall reaction from GTP cyclohydrolase I; the latter converts GTP to dihydroneopterin triphosphate, utilized in folate and tetrahydrobiopterin biosynthesis [4].
The physiological role(s) of the gene clusters that house GCH II homologues will be discussed [3].
The genome sequence of Streptomyces coelicolor contains three open reading frames (sco1441,sco2687, and sco6655) that encode proteins with significant (>40%) amino acid identity to GTP cyclohydrolase II (GCH II), which catalyzes the committed step in the biosynthesis of riboflavin [3].

Biological context of ribA

GTP cyclohydrolase II was overexpressed in a recombinant strain carrying a plasmid with the cloned gene [2].

Associations of ribA with chemical compounds

This gene encodes a bifunctional enzyme with the activities of both 3,4-dihydroxy-2-butanone 4-phosphate (DHBP) synthase and GTP cyclohydrolase II, which catalyze two essential steps in riboflavin biosynthesis [5].
Intron 4 is located in the region connecting the GTP cyclohydrolase II and 3,4-dihydroxy-2-butanone 4-phosphate synthase domain of the putative domains catalyzing the two reaction steps [6].

Other interactions of ribA

The recombinant fusion protein was purified and shown to have GTP cyclohydrolase II activity as well as 3,4-dihydroxy-2-butanone 4-phosphate synthase activity [6].

Analytical, diagnostic and therapeutic context of ribA

Sequence analysis revealed that the promoter derives from the ribA gene encoding GTP cyclohydrolase II, which is the first enzyme in the biosynthetic pathway of riboflavin [7].

References

The aconitase of Escherichia coli. Nucleotide sequence of the aconitase gene and amino acid sequence similarity with mitochondrial aconitases, the iron-responsive-element-binding protein and isopropylmalate isomerases. Prodromou, C., Artymiuk, P.J., Guest, J.R. Eur. J. Biochem. (1992) [Pubmed]
Biosynthesis of riboflavin: cloning, sequencing, mapping, and expression of the gene coding for GTP cyclohydrolase II in Escherichia coli. Richter, G., Ritz, H., Katzenmeier, G., Volk, R., Kohnle, A., Lottspeich, F., Allendorf, D., Bacher, A. J. Bacteriol. (1993) [Pubmed]
Evolution of New Function in the GTP Cyclohydrolase II Proteins of Streptomyces coelicolor. Spoonamore, J.E., Dahlgran, A.L., Jacobsen, N.E., Bandarian, V. Biochemistry (2006) [Pubmed]
GTP cyclohydrolase II structure and mechanism. Ren, J., Kotaka, M., Lockyer, M., Lamb, H.K., Hawkins, A.R., Stammers, D.K. J. Biol. Chem. (2005) [Pubmed]
Helicobacter pylori ribBA-mediated riboflavin production is involved in iron acquisition. Worst, D.J., Gerrits, M.M., Vandenbroucke-Grauls, C.M., Kusters, J.G. J. Bacteriol. (1998) [Pubmed]
Biosynthesis of riboflavin in plants. The ribA gene of Arabidopsis thaliana specifies a bifunctional GTP cyclohydrolase II/3,4-dihydroxy-2-butanone 4-phosphate synthase. Herz, S., Eberhardt, S., Bacher, A. Phytochemistry (2000) [Pubmed]
Regulation of the ribA gene encoding GTP cyclohydrolase II by the soxRS locus in Escherichia coli. Koh, Y.S., Choih, J., Lee, J.H., Roe, J.H. Mol. Gen. Genet. (1996) [Pubmed]

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