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Title: Biosynthesis and Regulation of 2-Alkyl-4-Quinolones in Pseudomonas aeruginosa
Author: Fletcher, Matthew Paul
ISNI:       0000 0001 3470 2527
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2007
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Pseudomonas aentginosa is an opportunistic pathogen that produces an extensive arsenal of virulence determinants which are regulated in a cell-density dependent manner via quorum-sensing (QS). P. aeruginosa contains two sets of hierarchicallyarranged QS systems, known as las and rhl, which utilise acyl-homoserine lactone (AHL)-based signalling molecules. Recently, a novel class ofQS signal molecule has been discovered in P. aeruginosa, known as 2-alkyl-4-quinolones (AQs), arguably the most important of which are 2-heptyl-3-hydroxy-4-qunolone (PQS) and its immediate precursor 2-heptyl-4-quinolone (HHQ). The genes responsible for the synthesis and effect of AQs include pqsABCDE, pqsH and pqsR. The pqsABCDE genes are arranged in a five-gene operon, the expression of which is under the control of the transcriptional regulator, PqsR. PqsABCD direct the synthesis ofHHQ and PqsH converts this molecule into PQS. To explore AQ synthesis and action, two new bioluminescent biosensor strains were developed for the simple, rapid and inexpensive detection of AQs in bacterial cultures using thin layer chromatography (TLC) and microplate assays. On TLC, both bioreporters were capable of sensitive detection of PQS, HHQ, 2-nonyl-3hydroxy- 4-quinolone (C9-PQS), 2-nonyl-4-quinolone (NHQ) and 2-heptyl-4quinolone N-oxide (HHQNO). Using microplate assays, the bioreporters responded primarily to HHQ then PQS, but were also activated by other AQs in a dosedependent manner, most notably NHQ and C9-PQS. The biosensors were also used successfully to evaluate AQ production after 8 h in a series of P. aeruginosa mutant
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available