Discovery of Two Classes of Potent Glycomimetic Inhibitors of Pseudomonas aeruginosa LecB with Distinct Binding Modes

Abstract

The treatment of infections due to the opportunistic pathogen Pseudomonas aeruginosa is often difficult, as a consequence of bacterial biofilm formation. Such a protective environment shields the bacterium from host defense and antibiotic treatment and secures its survival. One crucial factor for maintenance of the biofilm architecture is the carbohydrate-binding lectin LecB. Here, we report the identification of potent mannose-based LecB inhibitors from a screening of four series of mannosides in a novel competitive binding assay for LecB. Cinnamide and sulfonamide derivatives are inhibitors of bacterial adhesion with up to a 20-fold increase in affinity to LecB compared to the natural ligand methyl mannoside. Because many lectins of the host require terminal saccharides (e.g., fucosides), such capped structures as reported here may offer a beneficial selectivity profile for the pathogenic lectin. Both classes of compounds show distinct binding modes at the protein, offering the advantage of a simultaneous development of two new lead structures as anti-pseudomonadal drugs with an anti-virulence mode of action.

Development of a competitive binding assay for the Burkholderia cenocepacia lectin BC2L-A and structure activity relationship of natural and synthetic inhibitors

“…sulfonamide substituents in position 6 were previously reported as potent inhibitors of LecB. 22,31 However, since these compounds lack a free hydroxy group in position 6, the observed lack of inhibition of BC2L-A (data not shown) was consistent with the observations for the relative behavior of e.g., compound 9 and 10. We were further interested in the importance of the ring hydroxy groups for binding, which are directly coordinating to the two Ca 2+ ions in BC2L-A or in the related P. aeruginosa LecB.…”

“…26 The fluorescent tracer 3 was then obtained in 79% yield after coupling with fluorescein isothiocyanate (FITC). Then, mannose-based 3 and fucose-based 4 22 were titrated with BC2L-A and fluorescence polarization was determined ( Figure 1A). Mannose derivative 3…”

Innovative Solutions to Sticky Situations: Antiadhesive Strategies for Treating Bacterial Infections

“…For LecB, optimization of the disaccharide substructure L-Fucβ1-GlcNAc from Lewis-a identified a relatively high-affinity molecule with a K d = 290 nM (195). However, cross-reactivity of this compound with the lectin DC-SIGN, which is found on the surface of macrophages and dendritic cells, was identified as a potentially harmful side effect (195). To circumvent this problem, additional compounds utilizing mannose in place of fucose have been generated.…”

New Approaches to Control Infections: Anti-biofilm Strategies against Gram-negative Bacteria

“…29, K d = 3.3 µM) and LecB-mediated bacterial adhesion could be obtained. [69] Due to this terminal capping of mannose, a beneficial selectivity profile of these drug-like molecules for the pathogenic lectin over host lectins recognizing terminal mannosides was anticipated. Both classes of compounds differ in their binding mode to LecB, paving the way for two classes of novel lead structures for the treatment of chronic P. aeruginosa infections.…”