Reaction: 6-carboxy-5,6,7,8-tetrahydropterin = 7-carboxy-7-carbaguanine + NH3
For diagram of reaction 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, CAS registry number:
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. [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. [PMID: 23194065]