FIG. 1.
Regulatory network controlling the D. dadantii T3SS. The D. dadantii T3SS is regulated by the HrpX/HrpY-HrpS-HrpL and the GacS/GacA-rsmB-HrpL regulatory pathways. The TCS HrpX/HrpY activates hrpS, which encodes a σ54 enhancer. HrpS is required for expression of the alternative sigma factor gene hrpL. HrpL activates expression of genes encoding the T3SS apparatus and its secreted substrates. RsmA is a small RNA-binding protein that acts by lowering the half-life of hrpL mRNA. GacS/GacA upregulates the expression of rsmB, which increases the mRNA level of hrpL by sequestering RsmA. +, positive regulation; −, negative regulation.