Fig. 5

Proposed model for the regulation of phenazine biosynthesis by the TCST system in GP72. Solid straight arrows point to genes that are positively regulated. Blunt lines point to genes that are negatively affected. A dashed arrow indicates an unknown or as-yet uncharacterized regulatory pathway. In GP72, the sensors GacS and RpeB are activated by a putative environmental factor. Lon protease negatively affects GacA by controlling its protein stability. GacA positively controls the expression of rsmX, rsmY, and rsmZ, which in turn activates phenazine production by titrating the translation suppressor RsmE. In the absence of RpeA, RpeB is possibly over-phosphorylated by small phospho-donors (PD), resulting in the increased expression of the pip, phzR/phzI and the phenazine biosynthetic genes