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Differential regulation of the phenazine biosynthetic operons by quorum sensing in Pseudomonas aeruginosa PAO1-N


Steven Higgins

Giordano Rampioni

Mathew P. Fletcher

Professor of Molecular Microbiology

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Professor of Molecular Microbiology


The Pseudomonas aeruginosa quorum sensing (QS) network plays a key role in the adaptation to environmental changes and the control of virulence factor production in this opportunistic human pathogen. Three interlinked QS systems, namely las, rhl, and pqs, are central to the production of pyocyanin, a phenazine virulence factor which is typically used as phenotypic marker for analysing QS. Pyocyanin production in P. aeruginosa is a complex process involving two almost identical operons termed phzA1B1C1D1E1F1G1 (phz1) and phzA2B2C2D2E2F2G2 (phz2), which drive the production of phenazine-1-carboxylic acid (PCA) which is further converted to pyocyanin by two modifying enzymes PhzM and PhzS. Due to the high sequence conservation between the phz1 and phz2 operons (nucleotide identity > 98%), analysis of their individual expression by RNA hybridization, qRT-PCR or transcriptomics is challenging. To overcome this difficulty, we utilized luminescence based promoter fusions of each phenazine operon to measure in planktonic cultures their transcriptional activity in P. aeruginosa PAO1-N genetic backgrounds impaired in different components of the las, rhl, and pqs QS systems, in the presence or absence of different QS signal molecules. Using this approach, we found that all three QS systems play a role in differentially regulating the phz1 and phz2 phenazine operons, thus uncovering a higher level of complexity to the QS regulation of PCA biosynthesis in P. aeruginosa than previously appreciated.


Higgins, S., Heeb, S., Rampioni, G., Fletcher, M. P., Williams, P., & Cámara, M. (2018). Differential regulation of the phenazine biosynthetic operons by quorum sensing in Pseudomonas aeruginosa PAO1-N. Frontiers in Cellular and Infection Microbiology, 8, Article 252.

Journal Article Type Article
Acceptance Date Jul 3, 2018
Publication Date Jul 23, 2018
Deposit Date Jul 23, 2018
Publicly Available Date Jul 23, 2018
Journal Frontiers in Cellular and Infection Microbiology
Electronic ISSN 2235-2988
Publisher Frontiers Media
Peer Reviewed Peer Reviewed
Volume 8
Article Number 252
Public URL
Publisher URL


Operons fcimb-08-00252.pdf (1.4 Mb)

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