On 2017 May 04, Ralf Koebnik commented:

This publication states that “HprX is the AraC/XylS regulator of the Xanthomonas citri T3SS and is activated by HrpG, a sensor kinase that phosphorylates HrpX [43].“ This is a wrong interpretation of Ref. 43. To be correct, it is HrpX, not HprX, and second, HrpX is not activated via phosphorylation by HrpG. Instead, HrpG (probably in a phorphorylated state, but this is still speculation) activates the transcription of the hrpX gene. HrpX in turn binds to the promoter region of hrp genes that encode the structural components of the T3SS.

On 2017 May 04, Ralf Koebnik commented:

This publication states that “HprX is the AraC/XylS regulator of the Xanthomonas citri T3SS and is activated by HrpG, a sensor kinase that phosphorylates HrpX [43].“ This is a wrong interpretation of Ref. 43. To be correct, it is HrpX, not HprX, and second, HrpX is not activated via phosphorylation by HrpG. Instead, HrpG (probably in a phorphorylated state, but this is still speculation) activates the transcription of the hrpX gene. HrpX in turn binds to the promoter region of hrp genes that encode the structural components of the T3SS.