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ABSTRACT: Background
The Gram-negative phytopathogenic bacterium Xanthomonas campestris pv. campestris recruits the hrp/T3SS system to inject pathogenicity effector proteins into host cells and uses the rpf/DSF cell-cell signaling system to regulate the expression of virulence factors such as extracellular enzymes and polysaccharide. Whether these two systems have any connection is unknown.Methods
Positive regulator candidates affecting hrpX expression were identified by sacB strategy. The transcriptional expression was determined by qRT-PCR and GUS activity analysis. Transcriptome analysis was performed by RNA deep-sequencing. The hypersensitive response (HR) was determined in the nonhost plant pepper ECW-10R and electrolyte leakage assay.Results
Mutation of the gene encoding the sensor RpfC of the rpf/DSF system significantly reduced the expression of hrpX, the key regulator of the hrp/T3SS system, all of the genes in the hrp cluster and most reported type III effector genes. Mutation of rpfG did not affect the expression of hrpX. The rpfC mutant showed a delayed and weakened HR induction.Conclusions
RpfC positively regulates the expression of hrpX independent of RpfG, showing a complex regulatory network linking the rpf/DSF and hrp/T3SS systems.
SUBMITTER: Jiang BL
PROVIDER: S-EPMC6122198 | biostudies-literature | 2018 Sep
REPOSITORIES: biostudies-literature
Jiang Bo-Le BL Jiang Guo-Feng GF Liu Wei W Yang Li-Chao LC Yang Li-Yan LY Wang Lin L Hang Xiao-Hong XH Tang Ji-Liang JL
BMC microbiology 20180903 1
<h4>Background</h4>The Gram-negative phytopathogenic bacterium Xanthomonas campestris pv. campestris recruits the hrp/T3SS system to inject pathogenicity effector proteins into host cells and uses the rpf/DSF cell-cell signaling system to regulate the expression of virulence factors such as extracellular enzymes and polysaccharide. Whether these two systems have any connection is unknown.<h4>Methods</h4>Positive regulator candidates affecting hrpX expression were identified by sacB strategy. The ...[more]