Publication in: Spring 2023 Issue

Covalent Probing of Quorum Sensing LuxS Towards the Inhibition of Biofilms
Evan Glass
Faculty Mentor(s):
Caitlin McMahon
Abstract / Summary:
Antibiotic resistance is an urgent problem as many species of bacteria have developed resistance to novel treatment methods through conserved expressions. One such mechanism is biofilm formation. Biofilms are protected clusters of bacteria that form due to a detected change in gene expression resulting in increased resistance. In the formation of biofilms, bacteria communicate via a process of quorum sensing through the transmittance and acceptance of signaling molecules. Our research aims to inhibit biofilm formation by targeting the quorum-sensing pathway specific to autoinducer-2. Our laboratory will use covalent modification of the signal-forming enzyme LuxS targeting a nucleophilic cysteine in the active site. Occupying the active site in LuxS will inhibit the formation of the autoinducer-2 signaling molecule. An experimental gel electrophoresis assay has been developed using covalent probes and click-chemistry to visualize modification with fluorescence. A series of electrophilic probes have been developed towards the observation of fluorescence in assays. Procedurally synthesizing new probes and performing assays will enable the characterization of the active site in LuxS, allowing the development of potent inhibitors. Inhibitors will incorporate electrophilic groups proven to modify the enzyme through active probes while appearing as structural mimics of the natural substrate. A vinyl sulfonamide probe has been made in the laboratory and assay conditions have been optimized. In the future, inhibitors will be tested for competitive behavior through the same fluorescent assays, blocking fluorescent labeling by the probe. By developing inhibitors of quorum sensing, biofilm formation will be disrupted leaving bacteria vulnerable to antibiotics and immune response.
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