Toward the Rational Design of Galactosylated Glycoclusters That Target Pseudomonas aeruginosa Lectin A (LecA): Influence of Linker Arms That Lead to Low‐Nanomolar Multivalent Ligands

Abstract

Anti-infectious strategies against pathogen infections can be achieved through antiadhesive strategies by using multivalent ligands of bacterial virulence factors. LecA and LecB are lectins of Pseudomonas aeruginosa implicated in biofilm formation. A series of 27 LecA-targeting glycoclusters have been synthesized. Nine aromatic galactose aglycons were investigated with three different linker arms that connect the central mannopyranoside core. A low-nanomolar (Kd =19 nm, microarray) ligand with a tyrosine-based linker arm could be identified in a structure-activity relationship study. Molecular modeling of the glycoclusters bound to the lectin tetramer was also used to rationalize the binding properties observed.

Development of Pseudomonas aeruginosa Lectin LecA Inhibitor by using Bivalent Galactosides Supported on Polyproline Peptide Scaffolds

“…[16] Another approach to enhancei nhibitor interaction to LecA is through multivalent binding. Because LecA is at etrameric lectin andt he two closest binding sites are separated by about 26 , [17] various artificial scaffolds including dendrimers, [11,[18][19][20][21][22][23][24] clusters, [12][13][14][25][26][27][28][29][30][31][32] and linear rigid spacers [33][34][35][36] have been exploited to present galactoside ligands to theb inding sites to enhancei nhibition activity. [37] In other cases, the artificial scaffoldsa re furtherf unctionalized to generate extra interactions with LecA for stronger binding.…”

Design and Synthesis of Galactosylated Bifurcated Ligands with Nanomolar Affinity for Lectin LecA from Pseudomonas aeruginosa

“…The bis‐galactosides were synthesized from eight galactosides incorporating different aglycons (Scheme ). Of these galactosides, two (compounds 7 a and 7 b ) were chosen to provide glycoclusters with low to medium affinities, on the basis of our previously reported results, four (compounds 7 c – f ) were expected to display high affinities, and two aglycons (compounds 7 g and 7 h ) were new, as analogues of aromatic aglycons 7 d and 7 e .…”

“…For both motifs, except in the case of the methylenepyridyl aglycon ( b ), all aromatic aglycons displayed an increased affinity in relation to the tri(ethylene glycol) (EG 3 ) linker ( a ). This stronger binding has been reported several times in the literature and is the result of face‐to‐edge or edge‐to‐edge π–π stacking between the aromatic ring and the His50 residue of the lectin. The fluorescence signals observed after binding of LecA to bis‐galactosides containing the EG 3 aglycon were weak ( 23 Aa 2569 a.u., 23 Ba 1672 a.u.…”

“…In the case of the B motif, the change in fluorescence intensity was mostly negligible except for the low‐affinity aglycons a and b , and also to a lower extent for the TyrNH 2 aglycon ( 24 Be ). As a result, glycodendrimers 24 Ad–h displayed stronger binding to LecA than the control (Ph‐Gal) 4 whereas all glycodendrimers containing a B motif displayed weaker fluorescence signals than the control, except for 24 Bf (TyrCO 2 H aglycon) . We recently showed that this TyrCO 2 H aglycon gave rise to a mannose‐centred tetragalactocluster of high affinity ( K d =19 n m ) .…”

“…As a result, glycodendrimers 24 Ad–h displayed stronger binding to LecA than the control (Ph‐Gal) 4 whereas all glycodendrimers containing a B motif displayed weaker fluorescence signals than the control, except for 24 Bf (TyrCO 2 H aglycon) . We recently showed that this TyrCO 2 H aglycon gave rise to a mannose‐centred tetragalactocluster of high affinity ( K d =19 n m ) . This difference in affinity could arise from the general structure and hence topology of these glycodendrimers.…”