Significance of the relationship between glutaredoxin and FAD/NAD(P) topologies and lysine acetylation
By: Tiffany Chambers and Saloni Chovatiya
Department: Biochemistry
Faculty Advisor: Dr. Misty L. Kuhn
Redox enzymes use a variety of cofactors to accomplish numerous cellular functions. Common cofactors for these reactions include FAD, NAD(P), and glutathione. FAD and NAD(P) cofactors receive electrons during catabolic processes in the breakdown of organic molecules such as carbohydrates and lipids; these substances are frequently referred to as electron carriers. Glutaredoxins are small (~100 amino acids) intracellular redox enzymes that use glutathione as a cofactor. These enzymes are involved in signal transduction, forming deoxyribonucleotides for DNA synthesis, generating reduced sulfur, and providing defense against oxidative stress. Previously reported data identified hundreds of proteins as acetylated in E. coli but there is currently no clear understanding of how these proteins are identified by lysine acetyltransferases to become acetylated. We sorted all these protein substrates by different predicted structural topologies into groups and analyzed the sites of acetylation. Two of these topologies include glutaredoxin and FAD/NAD(P). The goal of the experiment was to determine if the sites of lysine acetylation were located on these two domains or if they were located on other domains of the proteins with different topological characteristics. We found the glutaredoxin domains had more sites of lysine acetylation than FAD/NAD(P) domains. Additionally, we saw there were more sites of non-enzymatic acetylation than enzymatic acetylation on glutaredoxin domains compared to the FAD/NAD(P) domains. In the case of proteins with FAD/NAD(P) domains, we found more enzymatic acetylation occurred. Additionally, we observed variation in the location of lysine acetylation sites on different types of secondary structures for each of these topologies. These results provide new insight into how proteins with different topologies are recognized by non-enzymatic and enzymatic acetylation.