Project Summary – Comparative structural and functional analysis of Pseudomonas aeruginosa inhibitor of vertebrate lysozyme paralogs. Thomas Leeper, PI, Kennesaw State University. The proposed integrative studies will investigate a significant regulator of peptidoglycan biochemistry in the cystic fibrosis pathogen Pseudomonas aeruginosa (PA), known to display multidrug resistance (MDR). Specifically, Inhibitor of Vertebrate Lysozyme protein 2 (IVYp2) will have its structure determined by NMR (Aim 1) and compared to its ability to inhibit hydrolase enzyme kinetics (Aim 2). While IVY proteins were originally suggested to inhibit lysozyme glycoside hydrolases, subsequent work suggested that the evolutionary origin of IVY’s may have been to inhibit lytic transglycosylases (LTs). For example, IVYp2 has no effect on lysozyme activity in enzyme inhibition assays but has been shown to inhibit LTs, at least in vitro. In order to determine which LTs are recognized in vivo enzyme inhibition assays with LTs (Aim 2) will be compared to novel applications of complementation and genetically encoded crosslinking studies in IVY knockout PA strains (Aim 3). The identified cognate IVY-LT pairs will be compared to the NMR structure of IVYp2 (Aim 1) and existing complex structures for other IVYs (i.e. IVYp1) bound to lysozyme to suggest regions important for LT molecular recognition. Graduate and undergraduate students, particularly those from underrepresented groups, will significantly participate in this research to facilitate data collection while providing them important training and advancement opportunities. These innovative studies will establish the background and workflow needed for future drug discovery efforts to develop new drug classes targeting novel biochemical pathways in MDR PA.