MetaCyc Enzyme: 2-heptyl-3-hydroxy-4(1H)-quinolone synthase

Gene: pqsH Accession Number: G-12319 (MetaCyc)

Species: Pseudomonas aeruginosa PA14

The subunit structure of this enzyme has not been reported.

PqsH catalyzes the terminal step in biosynthesis of the Pseudomonas quinolone signal molecule (PQS, 2-heptyl-3-hydroxy-4(1H)-quinolone). Experiments showed that under anaerobic conditions PQS is not produced and that oxygen is the sole limiting substrate during anaerobic growth. Thus, oxygen levels modulate the PQS-controlled factors in this organism [Schertzer10].

Recombinant enzyme was overexprressed in Escherichia coli both with and without a N-terminal fusion with the maltose binding protein (MBP). The MBP fusion did not appear to decrease activity and it improved solubility [Schertzer10].

The enzyme was found to be a member of the flavin-dependent monooxygenase family that utilizes NAD(P)H and oxygen to hydroxylate aromatic substrates (in [Schertzer10]).

Unification Links: Protein Model Portal:Q9I0Q0

Relationship Links: Entrez-gene:Ortholog:879540 , InterPro:IN-FAMILY:IPR002938 , InterPro:IN-FAMILY:IPR003042 , Pfam:IN-FAMILY:PF01494 , Prints:IN-FAMILY:PR00420 , UniProt:Ortholog:Q9I0Q0

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Created 19-Nov-2010 by Fulcher CA , SRI International

Enzymatic reaction of: 2-heptyl-3-hydroxy-4(1H)-quinolone synthase

Synonyms: 2-heptyl-3-hydroxy-quinolone synthase

EC Number:

2-heptyl-4(1H)-quinolone + NADH + oxygen + H+ <=> 2-heptyl-3-hydroxy-4(1H)-quinolone + NAD+ + H2O

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is physiologically favored in the direction shown.

In Pathways: superpathway of quinolone and alkylquinolone biosynthesis , 2-heptyl-3-hydroxy-4(1H)-quinolone biosynthesis

This reaction was demonstrated in vitro. Highest activity was found with substrates containing alkyl chain lengths of 7 and 9 carbons. The product was identified by TLC, absorbance and fluorescence spectra, and positive electrospray ionization mass spectrometry [Schertzer10].

Kinetic characterization was done with the MBP fusion protein. The enzyme could also use NADPH although the catalytic efficiency was approximately 20-fold lower than for NADH [Schertzer10].

Kinetic Parameters:

Km (μM)


Schertzer10: Schertzer JW, Brown SA, Whiteley M (2010). "Oxygen levels rapidly modulate Pseudomonas aeruginosa social behaviours via substrate limitation of PqsH." Mol Microbiol 77(6);1527-38. PMID: 20662781

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 19.0 on Sat Oct 10, 2015, biocyc14.