Table 2.

Effect of point mutations within Dr hemagglutinin on binding and apical F-actin disassembly in Caco-2/TC7 cellsa

PlasmidBindingb (mean % ± SEM)Apical F-actin disorganization (mean relative fluorescence intensity ± SEM)
pCC905.5 ± 0.495 ± 4
pCC90-D54stop0.7 ± 0.2* 0d
BN17 (draE)0.5 ± 0.2* 0d
pCC90-D54V5.1 ± 0.596 ± 4
pCC90-D54Y5.5 ± 0.295 ± 5
pCC90-T90M5.8 ± 0.493 ± 8
pCC90-I113T5.8 ± 0.593 ± 7
pCC90-D54G2.0 ± 0.3* 15 ± 10*
pCC90-D54C3.6 ± 0.5* 5 ± 4*
  • a Statistical analysis comparing pCC90 with the mutants was performed with a Student t test. ∗, Significant difference (P < 0.01).

  • b Percentage of 14C-radiolabeled bacteria bound ± SEM.

  • c Apical F-actin organization was revealed by direct immunofluorescence labeling using phalloidin-fluorescein. Results are presented as the mean (± SEM) percentage of cells presenting apical F-actin disorganization relative to the total number of cells (54). Relative immunofluorescence intensities: uninfected cells, 2.78 ± 0.25; pCC90-infected cells, 0.42 ± 0.15; pCC90-D54G, 2.03 ± 0.40*; pCC90-D54C, 2.68 ± 0.30* (arbitrary units).

  • d Although E. coli(pCC90-D54stop) and BN17 (draE) did not adhere to Caco-2/TC7 cells, isolated adhering E. coli could be observed in randomly distributed cells without alteration of the apical F-actin network.