Fig 2.

DNA and amino acid sequences of the original CSP and selected mutant variants. The corresponding ampicillin tolerance levels were obtained from spotting E. coli DH5α-strains harboring pCSP1bla and its derivatives with the 5 best silent CSP mutants and the 12 best random CSP mutants onto LA containing either ampicillin and m-toluic acid (20 μM, induced) or ampicillin only (uninduced). Ampicillin tolerance of DH5α (pNSP1bla) is included as a control (no signal sequence [NoSP]). Periods (.) indicate that the base or amino acid is the same as in the unmodified CSP sequence, while “–” indicates gaps in the sequence (in pNSP1bla). “+” behind the ampicillin concentration given indicates that poor growth was observed at even higher concentrations, while a “–” shows that the growth was reduced at the concentration indicated.