荧光假单胞杆菌2P24中gacA、dsbA和phoP/phoQ基因对小RNA因子RsmZ的转录调控

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

摘要:

Pseudomonas fluorescens 2P24是分离自麦田的植物病害生物防治菌株，产生抗生素2, 4-二乙酰基间苯三酚（2,4-diacetylphloroglucinol；2,4-DAPG）是其主要防病机制。菌株2P24中小RNA基因rsmZ正调控抗生素2,4-DAPG的产量。【目的】本文研究上游调控因子对RsmZ转录表达的影响，以进一步理解抗生素产生机制。【方法】构建了rsmZ: : lacZ的转录融合结构，将含有该结构的报告载体转入2P24的多个调控基因缺失突变体中，检测相应的缺失基因对rsmZ转录水平的调控作用。【结果】结果表明，反应调控因子GacA对rsmZ基因的转录具有正调控作用，二硫键合成蛋白DsbA对其负调控；双因子调控系统PhoP/PhoQ突变后，rsmZ基因的转录明显滞后。【结论】小RNA基因rsmZ在菌株2P24中受到多个基因的调控，并在信号传递网络中起到重要作用。

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.