Role of Tat in type III secretion systems. Loss of TatC or the exported substrates AmiA AmiC and SufI decreases expression of a hilA-lac fusion (A) and an ssaG-lac fusion (B). β-galactosidase activity units are defined as (μmol of ONP formed/min) × 106/ (OD600 × ml of cell suspension) and are reported as mean ± standard deviation where n=4. Loss of TatC affects translocation of the SPI2 effector SspH2 (C). Strains were grown in SPI2 inducing conditions and then assayed as described in Materials and Methods. The LacZ-CyaA fusion is not competent for type III secretion. Type III secretion is also non-functional in a dsbA mutant background (Ellermeier and Slauch, 2004; Lin et al., 2008). Strains uses were JS749, JS2023, JS2024, JS2025, JS2026, JS2027, 14028 pCE39, 14028 pSG161, JS1194 pSG161, and JS362.