Literature summary for 1.3.3.11 extracted from

Puehringer, S.; RoseFigura, J.; Metlitzky, M.; Toyama, H.; Klinman, J.P.; Schwarzenbacher, R.
Structural studies of mutant forms of the PQQ-forming enzyme PqqC in the presence of product and substrate (2010), Proteins, 78, 2554-2562.

Cloned(Commentary)

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 (Commentary)

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

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

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

Metals/Ions	Comment	Organism	Structure
additional information	PqqC is a metal free oxidase	Klebsiella pneumoniae

Molecular Weight [Da]

Molecular Weight [Da]	Molecular Weight Maximum [Da]	Comment	Organism
28910	-	x * 28910	Klebsiella pneumoniae

Natural Substrates/ Products (Substrates)

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

Organism	UniProt	Comment	Textmining
Klebsiella pneumoniae	A6T9H1	subsp. pneumoniae	-
Klebsiella pneumoniae MGH 78578	A6T9H1	subsp. pneumoniae	-

Purification (Commentary)

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

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	a

Substrates and Products (Substrate)

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

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

Synonyms	Comment	Organism
PqqC	-	Klebsiella pneumoniae
pyrroloquinoline quinone synthase C	-	Klebsiella pneumoniae

General Information

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