Structure Binding Relationship of Galactosylated Glycoclusters toward Pseudomonas aeruginosa Lectin LecA Using a DNA-Based Carbohydrate Microarray

Abstract

Pseudomonas aeruginosa (PA) is a major public health issue due to its impact on nosocomial infections as well as its impact on cystic fibrosis patient mortality. One of the main concerns is its ability to develop antibiotic resistance. Therefore, inhibition of PA virulence has been proposed as an alternative strategy to tackle PA based infections. LecA (or PA-IL), a galactose binding lectin from PA, is involved in its virulence. Herein, we aimed at designing high affinity synthetic ligands toward LecA for its inhibition and at understanding the key parameters governing the binding of multivalent galactosylated clusters. Twenty-five glycoclusters were synthesized and their bindings were studied on a carbohydrate microarray. Monosaccharide centered clusters and linear comb-like clusters were synthesized with different linkers separating the core and the galactosyl residues. Their length, flexibility, and aromaticity were varied. Our results showed that the binding profile of LecA to galactosylated clusters was dependent on both the core and the linker and also that the optimal linker was different for each core. Nevertheless, an aryl group in the linker structure drastically improved the binding to LecA. Our results also suggest that optimal distances are preferred between the core and the aromatic group and the core and the galactose.

Mannose-centered aromatic galactoclusters inhibit the biofilm formation of Pseudomonas aeruginosa

“…IC 50Lac values of the three DNA-tagged glycoclusters 1 DNA , 2 DNA and 3 DNA have been previously determined using the DDI glycoarray in comparison with 4 DNA used as a reference monovalent ligand (Table 3). 28 In this case, the IC 50Lac value corresponds to the concentration of lactose needed to inhibit 50% of LecA interactions with surface bound clusters. Thus, in this experiment, the higher the IC 50 value, the better is the binding.…”

“…16 Inhibition of LecA with synthetic ligands can be achieved with high affinity oligogalactosylated ligands. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] High binding can be obtained thanks to the so called glycoside cluster effect. 32,33 The design of multivalent ligands targeting LecA has been recently reviewed.…”

Effects of the Surface Densities of Glycoclusters on the Determination of Their IC50 and Kd Value Determination by Using a Microarray

“…[52] Glycoclusters G1 and G2 display aw eak and as trong affinity,r espectively,f or LecA. [23] The strong stabilization in the case of G2 is due to the presence of the phenyl aglycon, which is able to participate in a p-CH interaction with the His50 of LecA. [29,53] Although the phenyl group drastically enhances the binding of galactoclusters with LecA,t he presence of the galactose is still essential.…”

“…[23] IC 50 values are semiquantitative measurements obtained throughac ompetition assay in which immobilized glycoclustersa nd free lactose( ranking from 0.01 nm to 2.5 m)c ompetet ob ind Alexa 647-labeled LecA. They represent the concentration of lactose neededt od ecrease the fluorescences ignal at 635 nm, emitted by the complex formed between Alexa 647-labeled LecA and the glycocluster,b y5 0%.…”

“…Furthermore, the stabilization of such al ectin·glycocluster complex, thankst oa dditional interactions, should lead to the identification of the best candidates with which to target lectins of PA. [27][28][29] However, multivalent interactions are highly dependento nm atching between the glycocluster and the lectin topologies, and also to acertain extent on the number of carbohydrate residues and on the chemicaln ature of the linkers between the carbohydrate residues and the cores of the clusters. [23,25,27,29,30] Pseudomonas aeruginosa (PA) is an opportunistic bacterium involved in 10-30 %o fn osocomial diseases.I tc auses severe lung injury to cystic fibrosis patients, often leading to patient death. PA strains are multidrug resistant, thusm akingt he design of new therapeutics ac hallenge for public health.…”