Identification of BfmR, a Response Regulator Involved in Biofilm Development, as a Target for a 2-Aminoimidazole-Based Antibiofilm Agent

Abstract

2-aminoimidazoles (2AIs) have been documented to disrupt bacterial protection mechanisms, including biofilm formation and genetically-encoded antibiotic resistance traits. Using Acinetobacter baumannii, we provide initial insight into the mechanism of action of a 2AI-based antibiofilm agent. Confocal microscopy confirmed that the 2AI is cell permeable, while pull-down assays identified BfmR, a response regulator that is the master controller of biofilm formation, as a target for this compound. Binding assays demonstrated specificity of the 2AI for response regulators, while computational docking provided models for 2AI/BfmR interactions. The 2AI compound studied here represents a unique small molecule scaffold that targets bacterial response regulators.

Innovative Strategies for Combating Biofilm-Based Infections

“…The most active reverse amide 2-AI ( 85 ) is also an extremely effective dispersion agent, eradicating preformed P. aeruginosa biofi lms with mid-micromolar EC 50 values. Several of the reverse amide class of 2-AIs, including compound 86 , also inhibit biofi lm formation by A. baumannii and a biotinylated analogue of compound 86 was used to identify the molecular target of this class of molecules in A. baumannii as BfmR (Thompson et al 2012 ), the response regulator component of the BfmRS TCS. BfmR plays an important role in a biofi lm formation and bfmR mutants exhibit signifi cantly reduced biofi lm-forming ability and altered planktonic cellular morphology (Tomaras et al 2008 ), thus making BfmR an attractive anti-biofi lm target.…”

Evaluation of a 2-aminoimidazole variant as adjuvant treatment for dermal bacterial infections

“…These small-molecule inhibitors are cell permeable and bind a class of bacterial proteins called the response regulators (RRs) 36. More specifically, pull-down assays identified the master controller of biofilm formation, BfmR, as an RR-binding partner of a 2-AI in A. baumannii , another ESKAPE pathogen 36.…”

“…More specifically, pull-down assays identified the master controller of biofilm formation, BfmR, as an RR-binding partner of a 2-AI in A. baumannii , another ESKAPE pathogen 36. RRs play an integral role in a signal transduction pathway called the two-component system (TCS), and the majority of RRs are DNA-binding proteins 37–40.…”

Inhibition of Salmonella enterica Biofilm Formation Using Small-Molecule Adenosine Mimetics

“…Several genes and cellular processes involved in attachment and extracellular matrix production are shared among biofilm-forming bacterial pathogens (45); among these are the production of cellulose, type IV pili, and biofilmassociated protein (Bap) (35). Nonmicrobicidal approaches for A. baumannii have shown interference in biofilm formation with the addition of compounds with binding capacities in many domains of response regulators (46). Two-component systems have become a therapeutic target in recent years, due to their tight regulation of many virulence genes in A. baumannii and other pathogenic bacteria (47,48).…”