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Dubern JF, Diggle SP.. Quorum sensing by 2-alkyl-4-quinolones in Pseudomonas aeruginosa and other bacterial species. Mol Biosyst 4: 882-888

Institute of Infection, Immunity & Inflammation, Centre of Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom.
Molecular BioSystems (Impact Factor: 3.18). 10/2008; 4(9):882-8. DOI: 10.1039/b803796p
Source: PubMed

ABSTRACT Pseudomonas aeruginosa produces the cell-to-cell signal molecule 2-heptyl-3-hydroxy-4-quinolone (The Pseudomonas quinolone signal; PQS), which is integrated within a complicated quorum sensing signaling system. PQS belongs to the family of 2-alkyl-4-quinolones (AQs), which have been previously described for their antimicrobial activities. PQS is synthesized via the pqsABCDE operon which is responsible for generating multiple AQs including 2-heptyl-4-quinolone (HHQ), the immediate PQS precursor. In addition, PQS signaling plays an important role in P. aeruginosa pathogenesis because it regulates the production of diverse virulence factors including elastase, pyocyanin and LecA lectin in addition to affecting biofilm formation. Here, we summarize the most recent findings on the biosynthesis and regulation of PQS and other AQs including the discovery of AQs in other bacterial species.

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    • "The ability to cause such a wide array of infections is dependent on the expression of virulence factors (Strateva and Mitov 2011). Virulence factor regulation in P. aeruginosa is achieved through a density-dependent cell-to-cell communication network, involving three main quorum-sensing systems; the las, rhl (Schuster et al. 2013; Smith and Iglewski 2003) and Pseudomonas quinolone signal system (Dubern and Diggle 2008; Pesci et al. 1999). The las and rhl systems are LuxRI homologues, where lasI and rhlI direct synthesis of N-3- oxododecanoylhomoserine lactone (3-oxo-C12-HSL) and Nbutanoylhomoserine lactone (C4-HSL), respectively; these are diffusible signalling molecules which activate their respective DNA binding response regulators, LasR and RhlR, which, in turn, induces the expression of a wide range of genes, approximately 6 % of the genome (Schuster and Greenberg 2006; Schuster et al. 2013; Wagner et al. 2004; Williams et al. 2007). "
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    • "2- Heptyl-3-hydroxy-4-quinolone (pseudomonas quinolone signal; PQS), belonging to the family of 2-alkyl-4-quinolones (AQs), was previously described for their antimicrobial activities. Later on, it was found that PQS is integrated within an intricate QS circuit and plays an important role in Pseudomonas aeruginosa pathogenesis by regulating the production of diverse virulence factors including elastase, pyocyanin, and LecA lectin in addition to affecting biofilm formation (Dubern and Diggle, 2008; Heeb et al., 2011). Several other autoinducers like N -(3-oxododecanoyl) homoserine lactone and its tetrameric acid degradation product in Pseudomonas aeruginosa have antibacterial properties against Gram-positive bacteria (Kaufmann et al., 2005). "
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    • "Expression of the seven-gene phenazine biosynthesis (phz) operon is controlled in pseudomonads by homoserine lactone (HSL)-mediated quorum sensing (QS) (Brint and Ohman, 1995; Latifi et al., 1995; Wood and Pierson, 1996; Wood et al., 1997; Chancey et al., 1999; Khan et al., 2005; 2007) and is modulated by numerous transcriptional and translational regulators and small ncRNAs (Haas and Keel, 2003; Haas and Defago, 2005). QS regulation is the most complex in P. aeruginosa , where it consists of two hierarchical HSL-based circuits, Las and Rhl, whose activity is modulated by a third QS system based on 2-heptyl-3-hydroxy-4- quinolone, also known as the Pseudomonas quinolone signal (PQS) (Dubern and Diggle, 2008). In P. fluorescens and P. chlororaphis, QS regulatory genes are situated immediately upstream of the phenazine biosynthesis genes, as opposed to in P. aeruginosa, where las and rhl genes are not directly linked to the two copies of the phz gene cluster. "
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