UC Irvine

Nitric oxide synthase (NOS) is a heme-containing enzyme found in both mammals and select prokaryotes. Current evidence indicates NOS is only responsible for the generation of NO through the oxidation of L-Arg. Due to the critical signaling function of NO, NOS has emerged as an important therapeutic target as the over- or under-production of NO in mammals can lead to a variety of disease states. In sharp contrast, genetic and biochemical studies have demonstrated bacterial NO to protect gram-positive pathogens like Staphyloccocus aureus and Bacillis anthracis against oxidative and antibiotic stress. In order to first evaluate the protective functions afforded by bacterial NOS (bNOS), we identified several inhibitors that bind tightly to bNOS and demonstrated antimicrobial properties. These initial studies allowed for extensive crystallographic analyses in order to characterize inhibitor “hot-spots” and pharmacophores with improved bNOS inhibitor selectivity. Validation and characterization of these inhibitors also required development of new tools to assess bNOS inhibition. These tools include the utilization of bacterial redox partners we identified that support bNOS activity. More importantly, these tools allowed for the development of new assays to rapidly identify potent NOS inhibitors. Together, these studies represent the first exploitation of bNOS as a therapeutic target and make significant contributions towards the continued development and characterization of bNOS inhibitors.