Fig 2.

Induction of P_bceA (TMB1082) and P_liaI (TMB1080) by bacitracin (dark gray bars) and mersacidin (black bars) in rod-shaped wild-type cells and the corresponding L-forms. (A) Mid-log-phase cultures of TMB1080 and TMB1082 from both cell types were split and induced with bacitracin (50 μg ml⁻¹) and mersacidin (5 μg ml⁻¹). An uninduced sample served as a control (light gray bars). Cells were harvested after 30 min (wild type) and 4 h (L-forms), and samples were analyzed by β-galactosidase assay for P_liaI (TMB1080) and P_bceA (TMB1082) activity as described previously (44). Promoter activity is expressed in Miller units (MU). (B) Induction of bceA and liaI monitored by quantitative real-time RT-PCR. RNA was prepared from cells of strain PDC134 harvested at mid-logarithmic growth phase from cultures of rod-shaped cells or L forms that had been induced for 30 min with bacitracin (50 μg ml⁻¹). RT-PCR with gene-specific primers (Table 1) and calculation of induction ratios (x-fold changes; black bars) of liaI or bceA expression relative to an uninduced reference sample were performed as described in Materials and Methods.