Analyses of Proteins Homologous to SpeG and hSSAT Provide Insight Toward the Evolutionarily Relationships Among Polyamine Acetyltransferases
By: Huy Do
Department: Chemistry & Biochemistry
Faculty Advisor: Dr. Misty Kuhn
Spermidine/spermine N-acetyltransferases (SSATs) are enzymes that use AcCoA to acetylate polyamine substrates. In bacteria, SSAT enzymatic activities contributes to the formation of biofilms which lead to increase in survival on surfaces such as teeth and surgical equipment. In humans, the hSSAT enzyme has also been characterized as drug target due to its involvement in intracellular polyamine degradation, which is known to be altered in Alzheimer’s disease, cystic fibrosis, and various types of cancers including lung, pancreatic, and ovarian. Therefore, understanding the structural characteristics that could directly influence the enzymatic activities of these proteins is critical for developing selective inhibitors toward the bacterial enzyme. Currently, SpeG and hSSAT are the two most well-characterized SSATs from prokaryotes and eukaryotes, respectively. Based on previous structural characterization, SpeG and hSSAT are known to be evolutionary related. Thus, in this study, a set of proteins predicted to be functionally homologous to SpeG and hSSAT were identified computationally and selected for further analysis. Our results demonstrate the relationship between these proteins in the context of both SpeG and hSSAT structures. Furthermore, we identified regions of alphafold models of these proteins that separate these homologs into subfamilies. Lastly, we purified nearly half of these proteins for further kinetic characterization toward spermidine and spermine.