Figure 3.

Influence of Crc on type III secretion system (T3SS) dependent on ExsA expression. (A) Immunoblotting detection of the expression level of ExsA and ExsD. Total proteins were prepared from strain PAO1pClacZ (pcZ) and its derivatives. The expression levels were assayed by immunoblotting using antibodies against ExsA, and ExsD as well as RNA polymerase, which serves as internal control. (B) In trans expression of exsA restored the T3SS gene expression in Δcrc mutant, but overexpression of crc in ΔexsA mutant failed to induce the expression of T3SS genes. In these in trans expression experiments, the empty vector pUCP19 was introduced into corresponding control strains for comparison analysis. Bacterial strains were grown under T3SS-inducing condition (Luria–Bertani + 5 mmol/L nitrilotiracetic acid).