Figure 1.

Proteomics analysis of CsrA and identification of CsrA as a substrate of ClpP. (A) The abundance of CsrA in WT and ΔclpP at indicated growth phases. WT and ΔclpP were inoculated into fresh AYE medium at the same initial OD₆₀₀ values. Bacterial cells in the RP were harvested at an OD₆₀₀ of 0.7–1.0 and those in the TP were harvested approximately 6 h after the cessation of growth. Total proteins from indicated samples were extracted for proteomic analysis, and the representative peptides were identified by mass spectrometry. ICDH was measured as a loading control. Data represent mean ± SD derived from three independent experiments. ***p < 0.001 were identified by GraphPad Prism. (B) The abundance of CsrA in ΔclpP/pclpP^wt and ΔclpP/pclpP^trap in the TP. Bacterial cells were harvested approximately 6 h after the cessation of growth. Bacterial whole-cell lysates from ΔclpP/pclpP^wt and ΔclpP/pclpP^trap were prepared and His-tagged proteins were purified by Ni-NTA affinity. Substrates captured inside the proteolytic barrel were co-purified along with the His-tagged ClpP complex and identified by mass spectrometry. ClpP was measured as a loading control. Data represent mean ± SD derived from three independent experiments. ***p < 0.001 were identified by GraphPad Prism.