HAL2 overexpression induces iron acquisition in bdf1Δ cells and enhances their salt resistance

The yeast Saccharomyces cerevisiae is capable of responding to various environmental stresses, such as salt stress. Such responses require a complex network and adjustment of the gene expression network. The goal of this study is to further understand the molecular mechanism of salt stress response in yeast, especially the molecular mechanism related to genes BDF1 and HAL2. The Bromodomain Factor 1 (Bdf1p) is a transcriptional regulator, which is part of the basal transcription factor TFIID. Cells lacking Bdf1p are salt sensitive with an abnormal mitochondrial function. We previously reported that the overexpression of HAL2 or deletion of HDA1 lowers the salt sensitivity of bdf1Δ. To better understand the mechanism behind the HAL2-related response to salt stress, we compared three global transcriptional profiles (bdf1Δ vs WT, bdf1Δ + HAL2 vs bdf1Δ, and bdf1Δhda1Δ vs bdf1Δ) in response to salt stress using DNA microarrays. Our results reveal that genes for iron acquisition and cellular and mitochondrial remodeling are induced by HAL2. Overexpression of HAL2 decreases the concentration of nitric oxide. Mitochondrial iron-sulfur cluster (ISC) assembly also decreases in bdf1Δ + HAL2. These changes are similar to the changes of transcriptional profiles induced by iron starvation. Taken together, our data suggest that mitochondrial functions and iron homeostasis play an important role in bdf1Δ-induced salt sensitivity and salt stress response in yeast.