Identification and characterization ofpltZ, a gene involved in the repression of pyoluteorin biosynthesis inPseudomonassp. M18

Abstract

A new regulator gene named pltZ, which is located downstream of the plt gene cluster in the genome of Pseudomonas sp. M18, was identified, sequenced and characterized in this report. The deduced amino acid sequence of PltZ shares significant homology with other bacterial regulators in the TetR family. The chromosomal pltZ disruption mutant gave rise to 4.4-fold enhancement of pyoluteorin biosynthesis but did not exert significant influence on the accumulation of phenazine-1-carboxylic acid compared with the wild-type M18. The negative regulation of pltZ on pyoluteorin biosynthesis was further confirmed by multiplied pltZ gene dosage experiments and pltAPPlacZ translational fusion analyses.

The RNA Chaperone Hfq Regulates Antibiotic Biosynthesis in the Rhizobacterium Pseudomonas aeruginosa M18

“…Cells from fresh overnight cultures of P. aeruginosa M18 and its derivative strains were inoculated into 100 ml KMB in a 500-ml Erlenmeyer flask at a final concentration showing an optical density at 600 nm (OD 600 ) of 0.05 and then cultured at 28°C with shaking at 200 rpm. PCA and Plt were extracted with chloroform (pH 4.0) and ethyl acetate, respectively, and quantified with highperformance liquid chromatography (HPLC) as previously described (22). Quantification of PYO production was carried out at pH 7.0 in chloroform as previously described (10).…”

“…P. aeruginosa M18 and its derivative strains carrying the lacZ reporter plasmid (see Table S1 in the supplemental material) were inoculated from the overnight culture into 500-ml Erlenmeyer flasks containing 100 ml KMB to a final concentration with an OD 600 of 0.05 and then cultured at 28°C with shaking at 200 rpm. Cells were harvested at different time points for assaying the ␤-galactosidase specific activities, according to the method of Miller (34) and as described by Huang et al (22).…”

“…The other antibiotic produced by the strain M18 is Plt, which is biosynthesized via a hybrid polyketide synthase-nonribosomal peptide synthetase pathway. The plt gene cluster is composed of the structural operon pltLABCDEFG and the pltM gene, the ATPbinding cassette (ABC) transport operon pltHIJKNO, and two regulatory genes, pltR and pltZ, divergently transcribed from these two operons in both P. fluorescens [20][21][22]35). Our previous studies have shown that Plt biosynthesis is strongly downregulated by three typical quorum-sensing (QS) systems (Las, Rhl, and PQS) in strain M18 (8,30,54).…”

“…The P. aeruginosa strain M18 isolated from the rhizosphere was reported to simultaneously produce phenazine-1-carboxylic acid (PCA) and pyoluteorin (Plt), which can efficiently inhibit soilborne phytopathogenic fungi (22,53). Our previous comparative studies have shown that the predominant phenazine produced by M18 is PCA, while the clinically isolated P. aeruginosa strain PAO1 predominately accumulates pyocyanin (PYO), a derivative of PCA (19).…”

The Production, Separation and Stability of Pyoluteorin: A Biological Pesticide

“…Whereas the regulator gene pltZ, which is located downstream of the Plt gene cluster in the genome of Pseudomonas sp. M18, could repress Plt production (Huang et al, 2004). Plt biosynthesis could be enhanced by the amplification of the housekeeping sigma factor rpoD in Pseudomonas fluorescens CHA0 (Schnider et al, 1995).…”