The resistance-nodulation-division efflux pump EmhABC influences the production of 2,4-diacetylphloroglucinol in Pseudomonas fluorescens 2P24.
The resistance-nodulation-division efflux pump EmhABC influences the production of 2,4-diacetylphloroglucinol in Pseudomonas fluorescens 2P24.
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DOI：
10.1099/mic.0.031161-0
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发表时间：
2010
期刊：
影响因子：
1.5
通讯作者：
Tao Tian;Xiaogang Wu;Huiming Duan;Li-qun Zhang
中科院分区：
文献类型：
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作者：
Tao Tian;Xiaogang Wu;Huiming Duan;Li-qun Zhang
聚酮代谢产物2，4-二乙酰间苯三酚(2，4-DAPG)在荧光假单胞菌2P24生物防治土传植物病害中发挥重要作用。利用转座子诱变技术分离到2，4-DAPG胞外积累增加的两株突变株(PM810和PM820)。这两个突变体中的突变基因与荧光假单胞菌cLP6a的eMHR-EmhABC抗性-结瘤-分裂(RND)外排系统的基因有80%的同源性。菌株2P24中emhA(PM802)、emhB(PM803)和emhC(PM804)基因的缺失增加了2，4-DAPG的胞外积累，而eMHR(PM801)基因的缺失降低了2，4-DAPG的生物合成。启动子分析证实emhABC在eMHR干扰株(PM801)中的转录水平升高，并通过EmhABC外排泵间接负调控2，4-DAPG生物合成位点的转录。外源2，4-DAPG诱导PM901和PM811(emhA(-))染色体携带的Phla：：LacZ融合基因转录差异显著。此外，菌株2P24中的EmhABC系统参与了对氨苄西林、氯霉素、四环素、溴化乙锭和结晶紫等有毒化合物的抗性。综上所述，我们的结果表明EmhABC系统是影响荧光假单胞菌2P24产生抗生素2，4-DAPG并增强对有毒化合物抵抗力的重要因素。
The polyketide metabolite 2,4-diacetylphloroglucinol (2,4-DAPG) plays a major role in the biological control of soil-borne plant diseases by Pseudomonas fluorescens 2P24. Two mutants (PM810 and PM820) with increased extracellular accumulation of 2,4-DAPG were isolated using transposon mutagenesis. The disrupted genes in these two mutants shared >80 % identity with the genes of the EmhR-EmhABC resistance-nodulation-division (RND) efflux system of P. fluorescens cLP6a. The deletion of emhA (PM802), emhB (PM803) or emhC (PM804) genes in strain 2P24 increased the extracellular accumulation of 2,4-DAPG, whereas the deletion of the emhR (PM801) gene decreased the biosynthesis of 2,4-DAPG. The promoter assay confirmed the elevated transcription of emhABC in the EmhR disrupted strain (PM801) and an indirect negative regulation of 2,4-DAPG biosynthetic locus transcription by the EmhABC efflux pump. Induction by exogenous 2,4-DAPG led to remarkable differences in transcription of chromosome-borne phlA : : lacZ fusion in PM901 and PM811 (emhA(-)) strains. Additionally, the EmhABC system in strain 2P24 was involved in the resistance to a group of toxic compounds, including ampicillin, chloramphenicol, tetracycline, ethidium bromide and crystal violet. In conclusion, our results suggest that the EmhABC system is an important element that influences the production of antibiotic 2,4-DAPG and enhances resistance to toxic compounds in P. fluorescens 2P24.