Evaluation of expanded 2-aminobenzothiazole library as inhibitors of a model histidine kinase and virulence suppressors in Pseudomonas aeruginosa

Bacterial resistance to antibiotics is a rapidly increasing threat to human health. New strategies to combat resistant organisms are desperately needed. One potential avenue is targeting two-component systems, which are the main bacterial signal transduction pathways used to regulate development, metabolism, virulence, and antibiotic resistance. These systems consist of a homodimeric membrane-bound sensor histidine kinase, and a cognate effector, the response regulator. Histidine kinases play an essential role in the regulation of multiple virulence mechanisms including toxin production, immune evasion, and antibiotic resistance. Targeting virulence, as opposed to development of bactericidal compounds, could reduce evolutionary pressure for acquired resistance. Additionally, compounds targeting the highly conserved catalytic and adenosine triphosphate-binding (CA) domain have the potential to impair multiple two-component systems that regulate virulence in one or more pathogens. We conducted in vitro structure–activity relationship studies of 2-aminobenzothiazole-based inhibitors designed to target the CA domain. We found that these compounds, which inhibit the model histidine kinase, HK853 from Thermotoga maritima, have anti-virulence activities in Pseudomonas aeruginosa, reducing motility phenotypes and toxin production associated with the pathogenic functions of this bacterium.