FIG. 2.

BACTH analysis of interactions between Fts proteins. The efficiencies of functional complementation between the indicated hybrid proteins were quantified by measuring β-galactosidase (beta-Gal) activities in suspensions of toluene-treated E. coli DHM1 cells harboring the corresponding plasmids, as described in Materials and Methods. Each bar represents the mean value from results for at least three independent cultures. In all cases, standard deviations were within 20% of the mean except in the assays involving the T18-FtsQ hybrid, for which higher standard deviations (up to 40%) were observed due to the instability of the pUT18C-ftsQ plasmid. The two membrane proteins MalF and MalG of the E. coli maltose ABC transporter (20) were used as controls. Under the same assay conditions, functional complementation between T25-MalF and T18-MalG and between T25-MalG and T18-MalF yielded 10,000 ± 1,200 and 1,000 ± 150 U of β-galactosidase/mg (dry weight) of bacteria, respectively.