FIGURE 7.

YchF is involved in the regulation of leaderless mRNA translation (A) Schematic view of the reporter constructs used in this study. P_lac refers to the lac promoter and P_ara to the arabinose promoter. SD, Shine-Dalgarno sequence; λ cI, repressor protein cI of phage λ; gfp, green fluorescent protein. (B) GFP fluorescence of wild-type and ΔychF cells harboring the indicated plasmids. Cells were grown in M63 medium and GFP expression was induced by either 1 mM IPTG (pMS_512 and pMS_53) or 0.2% arabinose (pMG991 and pMG999) for 2 h before GFP fluorescence was measured. GFP fluorescence before (basal, B) and after induction (signal, S) was measured, normalized to the optical density of the culture, and is displayed as S/B ratio. The values of at least 12 independent experiments are shown and the bars represent the mean values and the error bar the SEM. (C) Wild-type cells harboring the indicated plasmids were grown as in panel (B), but incubated with the indicated concentrations of kasugamycin (Ksg) for 1 h before induction. GFP fluorescence was measured as above. (D) As in panels (B,C), but strains were incubated for 1 h with 200 μg Ksg/ml when indicated before induction. GFP fluorescence was measured as above.