Figure 4
BACTH analysis of CpxR-CpxR interactions. 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’. Full-length CpxR1-232 was translationally fused to the N-terminus of CyaA225-399 (T18 – magenta shade) giving rise to a CpxR1-232-T18 ‘prey’ hybrid. Based upon divisions of CpxR into N-terminal (pistachio green), internal linker (orange) and C-terminal (sky blue) domains, additional ‘prey’ T18 hybrids were constructed that consisted of only the N-terminus without linker (CpxR1-117-T18) or with linker (CpxR1-132-T18) and the C-terminus without linker (CpxR132-232-T18) or with linker (CpxR117-232-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 1521.9 ± 150.6 units of β-galactosidase activity/mg dry weight of bacteria. This has ~14.6 fold more enzymatic activity than bacteria co-expressing only T18 and T25 (104.6 ± 12.9 units of β-galactosidase activity). The fold change in enzymatic activity caused by CpxR-CpxR 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.