FIG. 3.

Analysis of translocation of CNF1 into HBMEC. HBMEC were preloaded with the BlaM substrate CCF4/AM and then infected with E. coli strains bearing different plasmids as indicated on the left. Plasmid pCX311 expresses a maltose-binding protein-Bla fusion and was used as the negative control, and pCXN expresses a CNF1-Bla fusion. RS218 is the wild-type strain, Δfdx is a fdx deletion mutant, and CΔfdx is a complemented strain of the fdx deletion mutant with fdx. For strain CΔfdx, 0.1% arabinose was added to promote the transcription of the complemented fdx gene. The software ImageJ was used to merge the green and blue channels (24).