Figure 8.

Regulation of T6SS and T4SS in A. tumefaciens. In acidic pH conditions such as those found around a plant wound site, the periplasmic regulator ExoR is degraded, this allows the activation of ChvG via autophosphorylation, ChvG can then activate its cognate response regulator ChvI, which then activates the T6SS. The activation of native DGCs by environmental stimuli leads to an increase in the local levels of cyclic di‐GMP. These increased levels of c‐di‐GMP are capable of repressing the transcription of the T6SS and the T4SS via an as yet uncharacterized regulator(s).