An antipathogenic compound that targets the OxyR peroxide sensor in Pseudomonas aeruginosa

Abstract

Introduction. Antipathogenic or antivirulence strategy is to target a virulence pathway that is dispensable for growth, in the hope to mitigate the selection for drug resistance. Hypothesis/Gap Statment. Peroxide stress responses are one of the conserved virulence pathways in bacterial pathogens and thus good targets for antipathogenic strategy. Aim. This study aims to identify a new chemical compound that targets OxyR, the peroxide sensor required for the full virulence of the opportunistic human pathogen, Pseudomonas aeruginosa . Methodology. Computer-based virtual screening under consideration of the ‘eNTRy’ rules and molecular docking were conducted on the reduced form of the OxyR regulatory domain (RD). Selected hits were validated by their ability to phenocopy the oxyR null mutant and modulate the redox cycle of OxyR. Results. We first isolated three robust chemical hits that inhibit OxyR without affecting prototrophic growth or viability. One (compound 1) of those affected the redox cycle of OxyR in response to H2O2 treatment, in a way to impair its function. Compound 1 displayed selective antibacterial efficacy against P. aeruginosa in Drosophila infection model, without antibacterial activity against Staphylococcus aureus . Conclusion. These results suggest that compound 1 could be an antipathogenic hit inhibiting the P. aeruginosa OxyR. More importantly, our study provides an insight into the computer-based discovery of new-paradigm selective antibacterials to treat Gram-negative bacterial infections presumably with few concerns of drug resistance.

Discrete Dynamics of Warhead Modulation on Covalent Inhibition of Oxyr: A QM/MM Study

“…The experimental inhibitor of OxyR that was reported in 2021 by Oh et al presented the first OxyR inhibition study that revealed selective antibacterial efficacy against P. aeruginosa. 51 We modified this inhibitor (Figure 1) with the addition of methyl oxo-enoate and HMK. As shown in Scheme 3, the Exp-1 inhibitor reacts in a concerted fashion comprising a single TS, leading to the product formation E-I.…”

“…presented the first OxyR inhibition study that revealed selective antibacterial efficacy against P. aeruginosa . We modified this inhibitor (Figure ) with the addition of methyl oxo-enoate and HMK.…”

“…aeruginosa and E. coli, was modified . Addition of Michael acceptor warheads, namely, methyl oxo-enoate and HMK inspired from the dimethyl fumarate structure, was carried out, resulting in two inhibitors, namely, Exp-1 and Exp-2.…”

“…These inhibitors with reported biological activity encompass warheads like α-ketoamides, pyrazoles, aldehydes, and hydroxymethyl ketone (HMK). These warheads are famous in forming covalent adducts with extracellular signal-regulated kinases (ERK), akin to the peroxide stress response sensor OxyR. − Furthermore, Hyo-Young et al have recently reported the first experimental study on OxyR inhibition, which compelled us to incorporate that chemical structure in this study. We thus modified the experimental inhibitor with the addition of Michael acceptor warheads methyl oxo-enoate and HMK inspired from the dimethyl fumarate structure. , The chemical structures of all the four inhibitors are exhibited in Figure .…”

An iron-chelating sulfonamide identified from Drosophila-based screening for antipathogenic discovery

“…Among those virulence factors, the quorum-sensing systems are noteworthy, in that they are responsible for regulation of multiple virulence factors, involving the secreted chemicals called quormones, which could be targeted even without entry into the target pathogens [ 7 , 8 ]. Recently, we have identified a chemical hit to compromise the peroxide-sensor, OxyR through structure-based virtual screening [ 9 ] and developed an antipathogenic peptide that is derived from a phage protein targeting the bacterial motility and acute virulence [ 10 , 11 ].…”