Interplay between BDF1 and BDF2 and their roles in regulating the yeast salt stress response

The homologous genes BDF1 and BDF2 in Saccharomyces cerevisiae encode bromodomain-containing transcription factors. Although double deletion of BDF1 and BDF2 is lethal, single deletion does not affect cell viability. The bdf2 cells showed normal growth upon salt stress. However, the absence of Bdf1p resulted in a salt-sensitive phenotype, and the salt sensitivity was suppressed by overexpression of BDF2. In this study, we further demonstrated that BDF2 shows dosage compensation in suppressing the salt sensitivity of bdf1. None of the tested domains replaced the function of intact Bdf1p. The 494626 region in Bdf1p was more important than the other domains for salt resistance. In addition, Bdf1p negatively regulated the expression of BDF2 by binding its promoter at loci 387 to 48. However, Bdf2p did not affect the expression of BDF1. In addition, Bdf1p and its defective functional domain mutants could combine with Bdf2p. This physical interaction increased the salt tolerance of bdf1. The mitochondrial dysfunctions caused by BDF1 deletion were restored by overexpression of BDF2 under salt stress conditions. Structured digital abstract BDF2 physically interacts with BDF1 by anti tag coimmunoprecipitation (View interaction) BDF2 physically interacts with BDF1 by pull down (View interaction)