Small-molecule activators of a bacterial signaling pathway inhibit virulence

Abstract

AbstractTheBurkholderiagenus encompasses multiple human pathogens, including potential bioterrorism agents, that are often extensively antibiotic resistant. The FixLJ pathway inBurkholderiais a two-component system that regulates virulence. Previous work showed thatfixLJmutations arising during chronic infection confer increased virulence while decreasing the activity of the FixLJ pathway. We hypothesized that small-molecule activators of the FixLJ pathway could serve as anti-virulence therapies. Here, we developed a high-throughput assay that screened over 28,000 compounds and identified 11 that could specifically active the FixLJ pathway. Eight of these compounds, denotedBurkholderiaFixActivator (BFA) 1-8, inhibited the intracellular survival ofBurkholderiain THP-1-dervived macrophages in afixLJ-dependent manner without significant toxicity. One of the compounds, BFA1, inhibited the intracellular survival in macrophages of multipleBurkholderiaspecies. Predictive modeling of the interaction of BFA1 withBurkholderiaFixL suggests that BFA1 binds to the putative ATP/ADP binding pocket in the kinase domain, indicating a potential mechanism for pathway activation. These results indicate that small-molecule FixLJ pathway activators are promising anti-virulence agents forBurkholderiaand define a new paradigm for antibacterial therapeutic discovery.