| EC |
4.1.2.50 |
| Accepted name: |
6-carboxytetrahydropterin synthase |
| Reaction: |
7,8-dihydroneopterin 3′-triphosphate + H2O = 6-carboxy-5,6,7,8-tetrahydropterin + acetaldehyde + triphosphate |
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For diagram of queuine biosynthesis, click here |
| Glossary: |
7,8-dihydroneopterin 3′-triphosphate = 2-amino-6-[(1S,2R)-1,2-dihydroxy-3-triphosphooxypropyl]-4-oxo-2,3,7,8-tetrahydropteridine
6-carboxy-5,6,7,8-tetrahydropterin = 2-amino-4-oxo-2,3,5,6,7,8-hexahydropteridine-6-carboxylate |
| Other name(s): |
CPH4 synthase; queD (gene name); ToyB; ykvK (gene name) |
| Systematic name: |
7,8-dihydroneopterin 3′-triphosphate acetaldehyde-lyase (6-carboxy-5,6,7,8-tetrahydropterin and triphosphate-forming) |
| Comments: |
Binds Zn2+. Isolated from the bacteria Bacillus subtilis and Escherichia coli. The reaction is part of the biosynthesis pathway of queuosine.The enzyme from Escherichia coli can also convert 6-pyruvoyl-5,6,7,8-tetrahydropterin and sepiapterin to 6-carboxy-5,6,7,8-tetrahydropterin [2]. |
| Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB |
| References: |
| 1. |
Cicmil, N. and Shi, L. Crystallization and preliminary X-ray characterization of queD from Bacillus subtilis, an enzyme involved in queuosine biosynthesis. Acta Crystallogr. Sect. F Struct. Biol. Cryst. Commun. 64 (2008) 119–122. [DOI] [PMID: 18259064] |
| 2. |
McCarty, R.M., Somogyi, A. and Bandarian, V. Escherichia coli QueD is a 6-carboxy-5,6,7,8-tetrahydropterin synthase. Biochemistry 48 (2009) 2301–2303. [DOI] [PMID: 19231875] |
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| [EC 4.1.2.50 created 2012] |
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| EC |
4.3.99.3 |
| Accepted name: |
7-carboxy-7-deazaguanine synthase |
| Reaction: |
6-carboxy-5,6,7,8-tetrahydropterin = 7-carboxy-7-carbaguanine + NH3 |
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For diagram of queuine biosynthesis, click here |
| Glossary: |
7-carboxy-7-carbaguanine = 7-carboxy-7-deazaguanine |
| Other name(s): |
7-carboxy-7-carbaguanine synthase; queE (gene name) |
| Systematic name: |
6-carboxy-5,6,7,8-tetrahydropterin ammonia-lyase |
| Comments: |
Requires Mg2+. The enzyme is a member of the superfamily of S-adenosyl-L-methionine-dependent radical (radical AdoMet) enzymes. Binds a [4Fe-4S] cluster that is coordinated by 3 cysteines and an exchangeable S-adenosyl-L-methionine molecule. The S-adenosyl-L-methionine is catalytic as it is regenerated at the end of the reaction. The reaction is part of the biosynthesis pathway of queuosine. |
| Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB |
| References: |
| 1. |
McCarty, R.M., Somogyi, A., Lin, G., Jacobsen, N.E. and Bandarian, V. The deazapurine biosynthetic pathway revealed: in vitro enzymatic synthesis of preQ0 from guanosine 5′-triphosphate in four steps. Biochemistry 48 (2009) 3847–3852. [DOI] [PMID: 19354300] |
| 2. |
McCarty, R.M., Krebs, C. and Bandarian, V. Spectroscopic, steady-state kinetic, and mechanistic characterization of the radical SAM enzyme QueE, which catalyzes a complex cyclization reaction in the biosynthesis of 7-deazapurines. Biochemistry 52 (2013) 188–198. [DOI] [PMID: 23194065] |
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| [EC 4.3.99.3 created 2012] |
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