An Investigation of the Antibiotic Potential of ONO-RS-082 and its Unique Mechanism of Action

Abstract

The rising threat of antibiotic resistance is a pressing issue for the maintenance of modern health and medicine. Thus, the identification of novel antibiotic candidates that target multi-drug resistant bacteria with unique mechanisms of action (MoAs) is a crucial area for future research. Here, we investigate the antibiotic properties of a compound, ONO-RS-082 (ONO), which was identified by bacterial cytological profiling as operating via a novel MoA. We found that ONO successfully inhibits the growth of clinically relevant Gram-positive bacteria with potent bactericidal activity, low levels of resistance, and low levels of mammalian cell cytotoxicity. Furthermore, we investigated ONO’s unique MoA by combining proteomic and genetic assays and identified a ribosomal subunit protein (RpsP) along with three proteins involved with regulation of cell wall shape and elongation (MreC, MurAA, and FtsL) as potential targets of ONO. We additionally confirmed that ONO induces membrane permeabilization. Though we initially hypothesized that ONO might induce cell wall permeabilization as a secondary effect of targeting one of these proteins, treatment of bacteria with ONO did not produce phenotypic effects that we would expect from this MoA. Furthermore, ONO’s antibiotic permeabilization abilities acted with a faster time course than other antibiotics that affect cell wall biosynthesis and was more similar to that of membrane-targeting antibiotics. Based on these results, we hypothesize that ONO primarily works to target the membrane. Future experiments should look to understand the exact mechanism of this membrane permeabilization in order to determine the future in-vivo and clinical viability of this antibiotic candidate.