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PMID:18728009

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Citation

Zhang, YM, Frank, MW, Zhu, K, Mayasundari, A and Rock, CO (2008) PqsD is responsible for the synthesis of 2,4-dihydroxyquinoline, an extracellular metabolite produced by Pseudomonas aeruginosa. J. Biol. Chem. 283:28788-94

Abstract

2,4-Dihydroxyquinoline (DHQ) is an abundant extracellular metabolite of the opportunistic pathogen Pseudomonas aeruginosa that is secreted into growth medium in stationary phase to concentrations comparable with those of the Pseudomonas quinolone signal. Using a combination of biochemical and genetic approaches, we show that PqsD, a condensing enzyme in the pqs operon that is essential for Pseudomonas quinolone signal synthesis, accounts for DHQ formation in vivo. First, the anthraniloyl moiety is transferred to the active-site Cys of PqsD to form an anthraniloyl-PqsD intermediate, which then condenses with either malonyl-CoA or malonyl-acyl carrier protein to produce 3-(2-aminophenyl)-3-oxopropanoyl-CoA. This short-lived intermediate undergoes an intramolecular rearrangement to form DHQ. DHQ was produced by Escherichia coli coexpressing PqsA and PqsD, illustrating that these two proteins are the only factors necessary for DHQ synthesis. Thus, PqsD is responsible for the production of DHQ in P. aeruginosa.

Links

PubMed PMC2570881 Online version:10.1074/jbc.M804555200

Keywords

3-Oxoacyl-(Acyl-Carrier-Protein) Synthase/metabolism; 3-Oxoacyl-(Acyl-Carrier-Protein) Synthase/physiology; Amino Acid Sequence; Animals; Bacterial Proteins/chemistry; Catalysis; Catalytic Domain; Cysteine/chemistry; Cystic Fibrosis/microbiology; Kinetics; Mice; Models, Chemical; Molecular Sequence Data; Pseudomonas aeruginosa/metabolism; Quinolines/chemistry; Sequence Homology, Amino Acid; Time Factors

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

PSEAE:PQSD

enables

GO:0016746: acyltransferase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

PSEAE:PQSD

involved_in

GO:0044550: secondary metabolite biosynthetic process

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

PSEAE:PQSD

enables

GO:0016746: transferase activity, transferring acyl groups

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

PSEAE:PQSD

GO:0004315: 3-oxoacyl-[acyl-carrier-protein] synthase activity

ECO:0000314:

F

Figure 2 shows DHQ formation by PqsD in Vitro. Mutant strains showed PqsD was a part of DHQ synthesis in vivo and was further tested in vitro. Anthraniloyl-CoA was produced in situ by PqsA and reacted with malonyl-CoA (a product of PqsD) to form DHQ as supported by TLC and LC-MS. These tests confirm DHQ formation when compared against the DHQ standard. Figure 7 shows the proposed mechanism for DHQ synthesis with the products of the Pqs gene.

complete
CACAO 7692


See also

References

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