Overexpression of YAP2, coding for a new yAP protein, and YAP1 in Saccharomyces cerevisiae alleviates growth inhibition caused by 1,10-phenanthroline.

A new member of the yeast yAP family, designated YAP2, has been isolated and characterized. The protein displays a high homology with the DNA-binding domain of yAP-1, which contains a basic DNA-binding domain and leucine zipper motif and binds in vitro to the same cis-element. Growth arrest of yeast caused by low concentrations of 1,10-phenanthroline, resulting in zinc and/or iron deprivation, is overcome by over-expression of YAP1 or YAP2. In fact, yeast cells over-expressing YAP1 or YAP2 display pleiotropic drug resistance. On the other hand, a yap2 null mutant has an increased thermotolerance under starvation conditions caused by 1,10-phenanthroline. The latter mutant might become an excellent tool in the study of pathways leading toward thermotolerance acquisition.