Differential control of the PcoI/PcoR quorum-sensing system in Pseudomonas fluorescens 2P24 by sigma factor RpoS and the GacS/GacA two-component regulatory system.
A quorum-sensing (QS) locus PcoI/PcoR had been identified previously in the biological control bacterium Pseudomonas fluorescens 2P24. In this paper, we investigated the upstream regulators that influence the transcription of the N-acyl homoserine lactone (AHL) biosynthase gene pcoI using a chromosomal pcoIColon, two colonslacZ fusion reporter strain. Stationary sigma factor RpoS was identified as a negative regulator of QS system using a random mini-Tn5 mutant procedure. Furthermore, deletion mutagenesis and complementation experiments demonstrated that the two-component system GacS/GacA positively regulated the QS system by upregulating pcoI transcription. However, compared with the gacA or gacS mutant, introduction of a second mutation of rpoS in the gacA(-) or gacS(-) background did not lead to further change in the transcriptional expression of the pcoI gene or the synthesis of AHL. Our results suggest that in strain 2P24, RpoS could only play its negative regulatory role on the pcoI gene under a functional GacS/GacA system background.
Yan
Qing
Q
Department of Plant Pathology, China Agricultural University, Beijing 100094, China.
Wu
Xiao-Gang
XG
Wei
Hai-Lei
HL
Wang
Hui-Min
HM
Zhang
Li-Qun
LQ
D054742:Acyl-Butyrolactones / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011551:Pseudomonas fluorescens / Q000235:genetics / Q000378:metabolism*; D053038:Quorum Sensing; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*
D054742:Acyl-Butyrolactones; D001426:Bacterial Proteins; C091100:GacA protein, Bacteria; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D011494:Protein Kinases