| Edwardsiella tarda is a leading pathogen threatening aquaculture industry.Its pathogenesis results from the repertoire of virulence factors expressed in temporal and spatial order.Type III secretion system(T3SS)and type VI secretion system(T6SS)are known as important virulence factors,and the EsrA-EsrB two-component system plays pivotal roles on T3SS and T6SS expression,while the regulation targets of EsrB is unclear.In this project,RNA-seq technique was used to analyze the transcription profiles of E.piscicida EIB202 under the condition of DMEM,and 618 genes were down-regulated at the transcriptional level,while the 388 genes were up-regulated in ?esrB.Besides the up-regulation of T3SS and T6SS,EsrB can also increase the expression of the iron uptake related genes,which are related to the virulence.Fur is a ferric uptake regulation factor,and the expression of Fur in WT is 4 times higher than that in AesrB,indicating that Fur is up-regulated by EsrB.Fur is a global regulator which controls a lot of genes' expression.In this study,ChIP-seq technique was used to investigate the role of Fur in the regulation of downstream genes in E.piscicida EIB202.Based on the statistical analysis of the results of the 98 DNA fragments enchriched by ChIP,the DNA binding sequence of Fur was combined and the binding logo was created,which enabled us to illuminate the global regulation network of Fur in the bacterium.In addition,intracellular cAMP level can be regulated by Fur through the direct binding to and regulation of icc gene.With the purpose of validating the RNA-seq data,the proteome of E.piscicida was analyzed by two-dimensional electrophoresis and 19 proteins regulated by EsrB were identified.Among the regulon of EsrB,we intrigulingly found that GlnA,a glutamine synthetase,is inhibited by EsrB.These data indicated that EsrB is closely related to the nitrogen metabolism of E.piscicida,which illuminate the relationship of virulence regulation and metabolism pathways of pathogenic bacteria. |
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