FIG. 3.

Two-hybrid assays. Bacterial two-hybrid assays were developed, and the mean values of the β-galactosidase activity corresponding to six samples in two independent experiments were represented. The whole coding regions of narI (I), narG (G), narH (H), and narJ(J) and deletion derivatives of narC coding for a signal peptide-defective protein (ΔPs) or for its cytoplasmic C-terminal (Cd) domain were cloned into plasmid pT18 and/or pT25 to generate the appropriate X-T18 and T25-X protein fusions, as indicated. Pairs of pT18 and pT25 derivatives were assayed for β-galactosidase expression in E. coli BTH101 cells. Controls for negative (Z) and positive (Gdh/Gdh) interactions were used.