Polypharmacology Approaches against the Pseudomonas aeruginosa MvfR Regulon and Their Application in Blocking Virulence and Antibiotic Tolerance

Abstract

Pseudomonas aeruginosa is an important nosocomial pathogen that is frequently recalcitrant to available antibiotics, underlining the urgent need for alternative therapeutic options against this pathogen. Targeting virulence functions is a promising alternative strategy as it is expected to generate less-selective resistance to treatment compared to antibiotics. Capitalizing on our nonligand-based benzamide-benzimidazole (BB) core structure compounds reported to efficiently block the activity of the P. aeruginosa multiple virulence factor regulator MvfR, here we report the first class of inhibitors shown to interfere with PqsBC enzyme activity, responsible for the synthesis of the MvfR activating ligands HHQ and PQS, and the first to target simultaneously MvfR and PqsBC activity. The use of these compounds reveals that inhibiting PqsBC is sufficient to block P. aeruginosa's acute virulence functions, as the synthesis of MvfR ligands is inhibited. Our results show that MvfR remains the best target of this QS pathway, as we show that antagonists of this target block both acute and persistence-related functions. The structural properties of the compounds reported in this study provide several insights that are instrumental for the design of improved MvfR regulon inhibitors against both acute and persistent P. aeruginosa infections. Moreover, the data presented offer the possibility of a polypharmacology approach of simultaneous silencing two targets in the same pathway. Such a combined antivirulence strategy holds promise in increasing therapeutic efficacy and providing alternatives in the event of a single target's resistance development.

The Alkylquinolone Repertoire of Pseudomonas aeruginosa is Linked to Structural Flexibility of the FabH‐like 2‐Heptyl‐3‐hydroxy‐4(1H)‐quinolone (PQS) Biosynthesis Enzyme PqsBC

“…As a result of its importance in controlling virulence and because of its unique occurrence in P. aeruginosa , the pqs system is currently under evaluation as a drug target in novel antivirulence strategies . The finding that PqsBC adopts distinct conformations that were resolved here to high resolution and could be addressed selectively could offer new opportunities for these drug‐discovery programs.…”

Identification of FDA-Approved Drugs as Antivirulence Agents Targeting the pqs Quorum-Sensing System of Pseudomonas aeruginosa

“…Potent PqsR antagonists with IC 50 s ranging from 0.4 to 38.5 M have been found among analogs of the natural agonists HHQ and PQS (59,(74)(75)(76). Whole-cell high-throughput screening and structure-activity relationship analyses led to the identification of benzamide-benzimidazole PqsR inhibitors with low IC 50 s (Ͻ1 M), some of which also inhibited the PqsBC complex (77)(78)(79). Also, 2-sulfonylpyrimidines were identified as hampering both AQ reception and biosynthesis (80).…”

Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers

“…In 2017, Maura et al synthesized inhibitors based on a benzimidazole scaffold ( Fig. 13 ) [ 68 ]. Starting from a PqsR inhibitor, changes of the electronic properties on the benzimidazole by introducing an electron-donating group led to a higher PqsBC inhibitory activity, while decreasing the affinity to PqsR (compound 28 ).…”

“…In an initial target assessment, Maura et al found that compound 52 showed an ambiguous profile. This raised the question if this compound class could target additional targets of the PQS-system besides PqsR [ 68 ]. Experiments with a PqsR isogenic mutant strain revealed that 52 inhibits HHQ and PQS production, while raising 2-AA levels, pointing at PqsBC as a second target, which was corroborated via SPR studies.…”