FIG 2.

A PA103 deaD mutant is noncytotoxic and defective for T3SS gene expression. (A) wt PA103 and a deaD mutant carrying either a vector control (pJN105) or a DeaD expression vector (pDeaD) were coincubated with CHO cells for 90 min and then assayed for LDH release. The reported values were normalized to wt PA103 carrying the pJN105 vector control (100% cytotoxicity). (B) A mini-CTX P_exsD-lacZ transcriptional reporter was introduced into wt PA103 and the exsD mutant. The resulting strains were cultured under low-Ca²⁺ conditions (TSB, 1 mM EGTA) in the presence of 25 mM arabinose and assayed for β-galactosidase activity and ExsA quantities by immunoblotting. The reported values were normalized to wt PA103 carrying the vector control (3,553 Miller units). *, P < 0.05; **, P < 0.005.