Control of the Ralstonia solanacearum Type III secretion system (Hrp) genes by the global virulence regulator PhcA.
Expression of several virulence factors in the plant pathogen bacterium Ralstonia solanacearum is controlled by a complex regulatory network, at the center of which is PhcA. We provide genetic evidence that PhcA also represses the expression of hrp genes that code for the Type III protein secretion system, a major pathogenicity determinant in this bacterium. The repression of hrp genes in complete medium is relieved in a phcA mutant and two distinct signals, a quorum-sensing signal and complex nitrogen sources, appear to trigger this PhcA-dependent repression. This control of hrp gene expression by PhcA is realized at the level of the HrpG regulatory protein.
Genin
Stéphane
S
Laboratoire Interactions Plantes-Microorganismes, CNRS-INRA, UMR2594, BP52627, 31326 Castanet-Tolosan, France. sgenin@toulouse.inra.fr
Brito
Belen
B
Denny
Timothy P
TP
Boucher
Christian
C
D001426:Bacterial Proteins / Q000502:physiology*; D001483:Base Sequence; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000502:physiology*; D005798:Genes, Bacterial; D012323:RNA Processing, Post-Transcriptional; D043368:Ralstonia solanacearum / Q000235:genetics* / Q000472:pathogenicity; D014157:Transcription Factors / Q000502:physiology*; D014774:Virulence
D001426:Bacterial Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; C082933:PhcA protein, Ralstonia solanacearum; D014157:Transcription Factors