Cloned (Comment) | Organism |
---|---|
gene pqqC, expression of wild-type and mutant enzymes as His-tagged enzyme in Escherichia coli strain BL21(DE3) | Klebsiella pneumoniae |
Crystallization (Comment) | Organism |
---|---|
purified recombinant enzyme mutants H154S/PQQ Y175F/PQQ Y175S/R179S in complex with intermediate 3a-(2-amino-2-carboxyethyl)-4,5-dioxo-4,5,6,7,8,9-hexahydroquinoline-7,9-dicarboxylic acid, sitting drop-vapor diffusion method, optimized conditions for each mutant: 0.1 M HEPES, pH 7.0, 0.5% w/v PEG 8000 for mutant H154S/PQQ complex, 0.2 M ammonium sulfate, 0.1 M Bis-Tris, pH 6.5, 25% w/v PEGl 3350 for mutant Y175F/PQQ complex, and 0.2 M sodium chloride, 0.1 M Tris, pH 8.5, 25% w/v PEG 3350 for mutant R179S/Y175S/intermediate complex, all at 20°C, X-ray diffraction structure determination and analysis at 1.3-2.35 A resolution | Klebsiella pneumoniae |
Protein Variants | Comment | Organism |
---|---|---|
H154S | site-directed mutagenesis, active site mutant, even with substrate PQQ bound, the enzyme is still in the open conformation with helices alpha5b and alpha6 unfolded and the active site solvent accessible, no product formation | Klebsiella pneumoniae |
R179S/Y175S | site-directed mutagenesis, active site mutant, the mutant shows an open conformation with a reaction intermediate trapped in the active site, the intermediate is tricyclic but nonplanar, implying that it has not undergone oxidatio, R179S/Y175S shows acceptable substrate complex crystals | Klebsiella pneumoniae |
Y175F | site-directed mutagenesis, active site mutant, the mutant shows a closed conformation indicating that Y175 is not required for the conformational change, no product formation | Klebsiella pneumoniae |
Metals/Ions | Comment | Organism | Structure |
---|---|---|---|
additional information | PqqC is a metal free oxidase | Klebsiella pneumoniae |
Molecular Weight [Da] | Molecular Weight Maximum [Da] | Comment | Organism |
---|---|---|---|
28910 | - |
x * 28910 | Klebsiella pneumoniae |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
6-(2-amino-2-carboxyethyl)-7,8-dioxo-1,2,3,4,7,8-hexahydroquinoline-2,4-dicarboxylate + 3 O2 | Klebsiella pneumoniae | - |
4,5-dioxo-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylate + 2 H2O2 + 2 H2O | - |
? | |
6-(2-amino-2-carboxyethyl)-7,8-dioxo-1,2,3,4,7,8-hexahydroquinoline-2,4-dicarboxylate + 3 O2 | Klebsiella pneumoniae MGH 78578 | - |
4,5-dioxo-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylate + 2 H2O2 + 2 H2O | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Klebsiella pneumoniae | A6T9H1 | subsp. pneumoniae | - |
Klebsiella pneumoniae MGH 78578 | A6T9H1 | subsp. pneumoniae | - |
Purification (Comment) | Organism |
---|---|
recombinant His-tagged wild-type and mutant enzyme from Escherichia coli strain BL21(DE3) by nickel affinity chromatography and gel filtration | Klebsiella pneumoniae |
Reaction | Comment | Organism | Reaction ID |
---|---|---|---|
6-(2-amino-2-carboxyethyl)-7,8-dioxo-1,2,3,4,7,8-hexahydroquinoline-2,4-dicarboxylate + 3 O2 = 4,5-dioxo-4,5-dihydro-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylate + 2 H2O2 + 2 H2O | reaction mechanism consisting of a series of base catalyzed proton abstractions followed by quinoid/quinol tautomerizations and oxidations, overview | Klebsiella pneumoniae |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
6-(2-amino-2-carboxyethyl)-7,8-dioxo-1,2,3,4,7,8-hexahydroquinoline-2,4-dicarboxylate + 3 O2 | - |
Klebsiella pneumoniae | 4,5-dioxo-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylate + 2 H2O2 + 2 H2O | - |
? | |
6-(2-amino-2-carboxyethyl)-7,8-dioxo-1,2,3,4,7,8-hexahydroquinoline-2,4-dicarboxylate + 3 O2 | - |
Klebsiella pneumoniae MGH 78578 | 4,5-dioxo-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylate + 2 H2O2 + 2 H2O | - |
? |
Subunits | Comment | Organism |
---|---|---|
? | x * 28910 | Klebsiella pneumoniae |
More | the enzyme folds into a compact seven-helix bundle, which provide the scaffold for an active site cavity | Klebsiella pneumoniae |
Synonyms | Comment | Organism |
---|---|---|
PqqC | - |
Klebsiella pneumoniae |
pyrroloquinoline quinone synthase C | - |
Klebsiella pneumoniae |
General Information | Comment | Organism |
---|---|---|
metabolism | PqqC catalyzes the last step of pyrroloquinoline quinone biogenesis which involves a ring closure and an eight-electron oxidation of the substrate 3a-(2-amino-2-carboxyethyl)-4,5-dioxo-4,5,6,7,8,9-hexahydroquinoline-7,9-dicarboxylic acid | Klebsiella pneumoniae |
additional information | the enzyme has 14 conserved active site residues, which are in close contact with bound substrate pyrroloquinoline quinone. It exhibits a stepwise process in which substrate binding leads to the generation of the closed protein conformation, with the latter playing a critical role in O2 binding and catalysis | Klebsiella pneumoniae |
physiological function | pyrroloquinoline quinone, i.e. 4,5-dihydro-4,5-dioxo-1Hpyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid, PQQ, synthesized by the enzyme, is a bacterial cofactor in numerous alcohol dehydrogenases including methanol dehydrogenase and glucose dehydrogenase | Klebsiella pneumoniae |