Fig. 1

Frame-shifted cI and its function. a) Truth table and gene circuit design of the NOT gate. b) The partial sequence of wild type and single nucleotide deleted, frame-shifted cI. c) The fold changes in EGFP expression of the NOT gates between output logic level ‘1’ (high expression), when input is ‘0’ (absence of aTc) and output logic level 0 (low expression), when input is ‘1’ (200 ng/ml aTc, saturated concentration, see Fig. 2). The constructs Fs1–7 contain frame-shifted cI gene(Fs1: both frame-shifted cI and P_R-EGFP in pUC, Fs2: frame-shifted cI in pUC and P_R-EGFP in p15A, Fs3: frame-shifted cI in p15A and P_R-EGFP in pUC, Fs4: both frame-shifted cI and P_R-EGFP in ColE1, Fs5: frame-shifted cI in ColE1 and P_R-EGFP in p15A, Fs6: frame-shifted cI in p15A and P_R-EGFP in ColE1, Fs7: both frame-shifted cI and P_R-EGFP in p15A). d) Comparison of growth curves of E.coli DH5αZ1 expressing wild type cI (W1, induced with 200 ng/ml aTc), frame-shifted cI (Fs1, induced with 200 ng/ml aTc) and other non-expressing states (0 ng/ml) that are W1 uninduced, Fs1 uninduced and without plasmid .W1 contains both wild type cI and P_R-EGFP in pUC