[Transcriptional repression of pltZ on pyoluteorin ABC transporter of Pseudomonas sp. M18]

A pltZ gene involved in negatively regulating pyoluteorin (Plt) biosynthesis, and an ABC (ATP-binding cassette) transporter involved in pyoluteorin secretion and itself resistance, were identified downstream of Plt biosynthesis gene cluster in Pseudomonas sp. M18. The ABC transporter gene pltH'-lacZ translational and transcriptional fusion expression plasmids, pHZLF and pHZCF, were constructed using promoter probe vector pME6015 and pME6522 respectively, and then were introduced into the wild-type strain of Pseudomonas sp. M18 and the pltZ mutant strain M18Z. The chromosomal pltZ disruption mutant gave rise to 3.7-8.4-fold enhancement of translational pltH'-'lacZ fusion expression and 2.8-7.4-fold enhancement of transcriptional pltH'-'lacZ fusion expression compared with those in the wild-type strain M18. These results suggested that pltZ can repress transcription of Plt ABC transporter, and it can indirectly regulate Plt biosynthesis negatively through the Plt ABC transporter system.