Protocol to monitor activation of a two-component system in Dickeya dadantii during chicory leaf infection using Phos-tag gel.

Quantifying the phosphorylation levels of proteins involved in bacterial signaling pathways is essential for understanding their role in stress adaptation and infection processes. Here, we present a protocol for the semi-quantitative assessment of the phosphorylation level of the transcriptional regulator CpxR during the infection process using Phos-tag gel. We describe steps for Dickeya dadantii infection of chicory leaves, followed by bacterial extraction, rapid acidic cell lysis, and subsequent protein analysis using Phos-tag SDS-PAGE and western blot. For complete details on the use and execution of this protocol, please refer to Bontemps-Gallo et al. and Cochard et al..