Identification of Non-histone Acetylation Targets in Saccharomyces cerevisiae

Lysine acetylation is a conserved post-translational modification (PTM) which was traditionally believed to be limited to histones and the regulation of gene expression. However, recent proteomic studies have identified lysine acetylation on proteins implicated in virtually all cellular processes indicating that this PTM plays a global regulatory role. Indeed, in humans, aberrance of lysine acetyltransferase (KAT) activity is associated with various pathogenesis. To date, over 2500 human proteins are known to be acetylated in vivo, but very few acetylations have been linked to specific KATs. Hence, to understand the biological relevance of KATs and acetylation in human pathology, it is important to learn about the mechanism regulating KAT activity and the identity of their in vivo targets. This is a complex task and will require the use of model organisms and system biology approaches. The work presented here explores the significance of self-acetylation in regulating KAT function by focusing on the highly NuA4 lysine acetyltransferase in the model organism Saccharomyces cerevisiae or budding yeast. Using genetics and biochemical assays I have identified NuA4 subunit Epl1 as a novel in vivo NuA4 substrate. I have also shown that Epl1 acetylation regulates NuA4 function at elevated temperatures. In an attempt to identify new biological processes regulated by yeast KATs and putative novel substrates, I have also performed a genome-wide synthetic dosage lethality screen with six non-essential yeast KATs; Hat1, Rtt109, Hpa2, Sas3, Sas2, and Elp3. My screen identified largely distinct sets of genetic interactions for each KAT suggesting that each KAT has specific cellular functions. Together, this study demonstrates the importance of auto-acetylation in regulating KAT function and the diversity of cellular processes impacted by KAT activity in vivo