Fig. 4

The DnaA protein weakly interacts with RepA protein in vivo. BTH101 cells were co-transformed with plasmid pairs encoding T18 and T25 respectively as negative control, then plated on the LB plates mentioned above with required antibiotics, incubated at 30 °C for 30 h. BTH101 cells were co-transformed with plasmid pairs encoding T18-TorR and T25-MreB respectively as positive control, proved previously. To exclude “false” blue colonies, 3 μl of the bacterial culture from each transformant after grown in LB for 2 h was mounted the same plate as described above, incubated at 30 °C for 30 h. All transformants illustrating different protein-protein interactions were simultaneously tested on one plate to have the same reaction condition. The blue bacterial halos indicate protein-protein interactions while the white halos show no interaction. Protein pairs under detection are as indicated