Yeast expression data from conditions that inhibit sirtuins

Sir2 is an NAD+-dependent histone deacetylase, and is the founding member of a large, phylogentically conserved, family of such deacetylases called the Sirtuins. The budding yeast, Saccharomyces cerevisiae, harbors 4 paralogs of Sir2, known as Hst1, Hst2, Hst3, and Hst4. Reducing the intracellular NAD+ concentration is inhibitory for the Sirtuins, and raising the intracellular nicotinamide (NAM) concentration is inhibitory. Microarray gene expression analysis was used to identify novel classes of yeast genes whose expression is altered when either NAD+ concentration is reduced or NAM is elevated. A subset of genes involved in thiamine biosynthesis was identified as being upregulated when Sir2 or Hst1 was inactivated. Several mutants in the NAD+ biosynthesis and salvage pathways were tested, along with WT and WT grown in the presence of 5 mM nicotinamide, which inhibits the Sirtuins. Duplicate cultures in rich YPD media were grown into log phase and then harvested. The deletion mutants npt1∆, bna1∆, tna1∆, and pnc1∆ were compared to a wild-type (WT) strain. Additionally, a WT strain grown in the presence of 5 mM NAM was compared to WT without NAM. Total RNA was isolated and used for microarray hybridizations onto Affymetrix Yeast 2.0 Gene arrrays.