Figure 2. Yeast two-hybrid system for the interaction identification among Ndh subunits.

NdhB, NdhH and NdhO were constructed into bait vectors, whereas NdhA, NdhI, NdhK and GST were constructed into prey vectors, respectively. Subsequently, they were transformed into the yeast strain EGY48. Transformed yeast was dropped onto X-gal medium. Blue precipitate represents accumulated β-galactosidase activity resulting from the activation of the lacZ reporter gene by protein-protein interaction. The induction plate was incubated at 30 °C for 22 h and then photographed. The interactions of NdhO-NdhI, NdhB-GST and NdhH-GST were assayed as one positive and two negative controls, respectively. At least six independent experiments were performed, and the result of one representative is shown. See Supplementary Figure S1 for full views of yeast two-hybrid results.