Regulation of gacA, dsbA and phoP/phoQ genes on the transcription of small RNA Gene RsmZ in Pseudomonas fluorescens 2P24

Abstract:

[Objective] Pseudomonas fluorescens 2P24 is a plant disease-suppressive bacterium isolated from wheat rhizosphere. Small RNA gene rsmZ in strain 2P24 plays an important role in the production of antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG), a key factor in disease suppression. [Objective] The aim of this study was to determine the influence of upstream regulators on the transcription of rsmZ. [Methods] A reporting vector was constructed by fusing the promoter region of rsmZ gene with a promoterless lacZ gene on plasmid pRK970Km. The resulting plasmid was introduced into several regulatory gene mutants and the corresponding effects on RsmZ transcription were investigated. [Results] The results indicated that a response regulator gene gacA from GacS/GacA two-component system positively regulated the transcription of RsmZ, whereas the oxidoreductase gene dsbA negatively regulated RsmZ expression. Furthermore, mutation on PhoP/PhoQ two-component system resulted in the delay of RsmZ transcription. [Conclusion] Our study suggests that the rsmZ gene in strain 2P24 transcripts under the pleiotropic regulation of a number of upstream genes, and may be involved in a more complex signal transduction cascade than that we have known.