Serendipitous Discovery of a Competitive Inhibitor of FraB, a Salmonella Deglycase and Drug Target

Abstract

Although salmonellosis, an infectious disease, is a significant global healthcare burden, there are no Salmonella-specific vaccines or therapeutics for humans. Motivated by our finding that FraB, a Salmonella deglycase responsible for fructose-asparagine catabolism, is a viable drug target, we initiated experimental and computational efforts to identify inhibitors of FraB. To this end, our recent high-throughput screening initiative yielded almost exclusively uncompetitive inhibitors of FraB. In parallel with this advance, we report here how a separate structural and computational biology investigation of FrlB, a FraB paralog, led to the serendipitous discovery that 2-deoxy-6-phosphogluconate is a competitive inhibitor of FraB (KI ~ 3 μM). However, this compound was ineffective in inhibiting the growth of Salmonella in a liquid culture. In addition to poor uptake, cellular metabolic transformations by a Salmonella dehydrogenase and different phosphatases likely undermined the efficacy of 2-deoxy-6-phosphogluconate in live-cell assays. These insights inform our ongoing efforts to synthesize non-hydrolyzable/-metabolizable analogs of 2-deoxy-6-phosphogluconate. We showcase our findings largely to (re)emphasize the role of serendipity and the importance of multi-pronged approaches in drug discovery.

Discovery of Nanomolar Inhibitors for Human Dihydroorotate Dehydrogenase Using Structure-Based Drug Discovery Methods

“…The use of virtual screening methodologies to expedite the drug development timeline have gained momentum over recent years by substantially reducing the number of ligands that will need to be validated through experimental assays . Previously, our group and others have successfully implemented SBDD to identify small molecule binders for infectious and neurodegenerative diseases, cancer, heart failure, and various other acute conditions. ,,− …”

Insights into the catalytic mechanism of a bacterial deglycase essential for utilization of fructose‐lysine

“…Although FrlB is the focus of this study, FraB, a related deglycase, has recently been identified as a novel drug target since disrupting the FraB‐dependent metabolism of F‐Asn by Salmonella results in the accumulation of a toxic sugar‐phosphate metabolite (Sabag‐Daigle et al, 2016). To this end, we have invested much effort to design a narrow‐spectrum therapeutic to inhibit Salmonella FraB (Sabag‐Daigle et al, 2023; Thirugnanasambantham et al, 2022). Our interest in FraB inspired our studies of the catalytic mechanism of Salmonella FrlB.…”