Fig. 3. Complementation of the B.thuringiensis 407 Cry^– A′Z ΔpapR mutant strain with synthetic peptides. (A) Amino acid sequence of the PapR protein and of the synthetic peptides used for the complementation experiment. The characters in bold correspond to the N-terminal signal peptide sequence. The potential cleavage site was predicted with the SignalP VI.I program (Nielsen et al., 1997). (B) β-galactosidase activity of the B.thuringiensis 407 Cry^– A′Z ΔpapR mutant strain. The cells were grown at 37°C in LB medium and each peptide (OS3, OS4, OS5, OS7 and OS9) was added to a final concentration of 5 µM at t1 (1 h after the onset of the stationary phase).