Figure 3
Regions of CpxA interacting with CpxR as monitored by BACTH analysis. Full-length CpxR1-232 was translationally fused to the C-terminus of CyaA1-224 (T25 – dark green shade) creating a T25-CpxR1-232 hybrid used as the ‘bait’. As in Figure1, the same seven CpxA variants translationally fused to the N-terminus of CyaA225-399 (T18 – magenta shade) were used as ‘prey’ hybrids, that is CpxA1-458-T18, CpxA1-156-T18, CpxA1-240-T18, CpxA1-310-T18, CpxA157-310-T18, CpxA187-458-T18 and CpxA311-458-T18. BACTH interaction analysis of ‘bait’ and ‘prey’ hybrids was quantified via measurement of β-galactosidase activity and is represented as units/mg dry weight of host E. coli BTH101 bacteria (left column; black font). The internal positive control based upon the constructs expressing T18-Zip and T25-Zip yielded 1778.1 ± 120.3 units of β-galactosidase activity/mg dry weight of bacteria. This was ~32.8 fold more enzymatic activity produced compared to bacteria co-expressing only T18 and T25 (54.2 ± 9.0 units of β-galactosidase activity). The fold change in enzymatic activity caused by CpxR-CpxA interactions relative to this negative control is indicated in parentheses to the right. The asterisks (*) indicates a positive interaction. Data is presented as the mean (± standard error of the mean) of at least four independent experiments performed in triplicate.