Amino acid divergence in the ligand‐binding pocket of Vibrio LuxR/HapR proteins determines the efficacy of thiophenesulfonamide inhibitors

Abstract

Vibrio bacteria are pathogens of fish, shellfish, coral, and humans due to contaminated seafood consumption. Vibrio virulence factors are controlled by the cell-to-cell communication called quorum sensing, thus this signaling system is a promising target for therapeutic design. We screened a compound library and identified nine compounds, including several 2thiophenesulfonamides, that inhibit the master quorum sensing transcription factor LuxR in Vibrio campbellii but do not affect cell growth. We synthesized a panel of 50 thiophenesulfonamide compounds to examine the structure-activity relationship effects on quorum sensing in vivo. The most potent molecule identified, PTSP (3-phenyl-1-(thiophen-2ylsulfonyl)-1H-pyrazole), specifically inhibits LuxR homologs in multiple strains of Vibrio vulnificus, Vibrio parahaemolyticus, and V. campbellii with sub-micromolar concentrations.PTSP efficacy is driven by amino acid conservation in the binding pocket, which is accurately predicted using in silico modeling of inhibitors. Our results underscore the potential for developing thiophenesulfonamides as specific quorum sensing-directed treatments for Vibrio infections.

Synthesis and Biological Assay of Small-Molecule Quorum Sensing Inhibitors: A Three-Week Course-Based Undergraduate Research Experience

“…38 Finally, while the thiophenesulfonyl chlorides A−C yield the most active compounds, benzenesulfonyl chloride (E) derivative 1E was reasonably active as well. 38 This is a much more inexpensive sulfonyl chloride, and a huge variety of arylsulfonyl chlorides are commercially available. A library based on benzenesulfonyl chloride derivatives would be a cost-effective way to scale this project up for a larger laboratory.…”

“…From a compound library screen, several sulfonamide molecules were identified that inhibit LuxR function. 38 Interestingly, an analogous screen identified a sulfonamide called Qstatin that inhibits the LuxR homologue SmcR in Vibrio vulnificus (Figure 1). Thus, the Qstatin structure was identified as a starting point and positive control for subsequent studies.…”

“…Thus, the Qstatin structure was identified as a starting point and positive control for subsequent studies. 38…”

“…Resynthesis of all three compounds showed that 10B was not only active but was is the most active LuxR inhibitor to come out of this library synthesis. 38 Second, this assay is very robust. The molecules do not have to be 100% pure to generate activity against LuxR.…”

“…The initial results gathered by students in this course over five semesters have led directly to one scientific publication, and as we have only begun to scratch the surface in terms of chemical space, there is ample opportunity for continued contributions in this area. 38…”