Biosynthesis and Regulation of Phenazine Compounds in<i>Pseudomonas</i>spp.

Mavrodi, Dmitri V.; Thomashow, Linda S.; Blankenfeldt, Wulf

doi:10.1002/9783527622009.ch12

Cited by 8 publications

(11 citation statements)

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“…Quantitative analysis revealed that PHZ levels were down five-and sevenfold in PA23phzR and PA23-6863, respectively. This was not unexpected, as the phz biosynthetic operon is immediately downstream of phzI and phzR, and PHZs are QS-regulated in other bacterial strains (Mavrodi et al, 2006). QS control of PRN production (Table 2), on the other hand, has not been reported for other Pseudomonas spp.…”

Section: Generation and Phenotypic Characterization Of Pa23 Qs-deficimentioning

confidence: 91%

The PhzI/PhzR quorum-sensing system is required for pyrrolnitrin and phenazine production, and exhibits cross-regulation with RpoS in Pseudomonas chlororaphis PA23

2012

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The aim of the current study was to determine how quorum sensing (QS) affects the production of secondary metabolites in Pseudomonas chlororaphis strain PA23. A phzR mutant (PA23phzR) and an N-acylhomoserine lactone (AHL)-deficient strain (PA23-6863) were generated that no longer inhibited the fungal pathogen Sclerotinia sclerotiorum in vitro. Both strains exhibited reduced pyrrolnitrin (PRN), phenazine (PHZ) and protease production. Moreover, phzA-lacZ and prnA-lacZ transcription was significantly reduced in PA23phzR and PA23-6863. As the majority of secondary metabolites are produced at the onset of stationary phase, we investigated whether cross-regulation occurs between QS and RpoS. Analysis of transcriptional fusions revealed that RpoS has a positive and negative effect on phzI and phzR, respectively. In a reciprocal manner, RpoS is positively regulated by QS. Characterization of a phzRrpoS double mutant showed reduced antifungal activity as well as PRN and PHZ production, similar to the QS-deficient strains. Furthermore, phzR but not rpoS was able to complement the phzRrpoS double mutant for the aforementioned traits, indicating that the Phz QS system is a central regulator of PA23-mediated antagonism. Finally, we discovered that QS and RpoS have opposing effects on PA23 biofilm formation. While both QS-deficient strains produced little biofilm, the rpoS mutant showed enhanced biofilm production compared with PA23. Collectively, our findings indicate that QS controls diverse aspects of PA23 physiology, including secondary metabolism, RpoS and biofilm formation. As such, QS is expected to play a crucial role in PA23 biocontrol and persistence in the environment.

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Section: Generation and Phenotypic Characterization Of Pa23 Qs-deficimentioning

confidence: 91%

The PhzI/PhzR quorum-sensing system is required for pyrrolnitrin and phenazine production, and exhibits cross-regulation with RpoS in Pseudomonas chlororaphis PA23

2012

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“…The P. chlororaphis (aureofaciens) 30-84 genome sequence has been recently deposited in GenBank. The P. chlororaphis 30-84 biosynthetic operon contains seven conserved biosynthetic genes phzXYFABCD (according to the original nomenclature, Pierson et al, 1995;Mavrodi et al, 2006), which correspond to phzABCDEFG (according to the P. fluorescens nomenclature). Here, we use the P. chlororaphis nomenclature to conform to the original literature.…”

Section: Methodsmentioning

confidence: 99%

“…Phenazines, which constitute a group of nitrogen-containing, heterocyclic-ring compounds are produced by a number of different plant-beneficial pseudomonads and control a variety of plant diseases caused by plant-pathogenic fungi (Mavrodi et al, 2006). Distinct Pseudomonas strains often produce different phenazines, and most produce more than one derivative (Pierson & Pierson, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies demonstrated that Pseudomonas species utilize combinations of conserved regulatory systems including two-component signal transduction (TCST), quorum sensing (QS), post-transcriptional control by small non-coding RNAs and other regulators that are integrated into sensory networks to control phenazine production in response to diverse environmental inputs (Mavrodi et al, 2006;Mentel et al, 2009;Gross & Loper, 2009). In P. chlororaphis, as in most other phenazineproducing bacteria, synthesis of the core phenazine PCA is encoded by a conserved set of biosynthetic genes (Pierson et al, 1995;Mavrodi et al, 2006;Mentel et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…In P. chlororaphis, as in most other phenazineproducing bacteria, synthesis of the core phenazine PCA is encoded by a conserved set of biosynthetic genes (Pierson et al, 1995;Mavrodi et al, 2006;Mentel et al, 2009). Additionally, one or more accessory genes encode terminal modifying enzymes responsible for the conversion of the core phenazine PCA into other derivatives (Mavrodi et al, 2006). In several P. chlororaphis strains, phenazine biosynthesis is regulated by the PhzR/PhzI QS system, first described for 30-84 (Wood & Pierson, 1996;Pierson et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

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