Structural Insight into Multivalent Galactoside Binding to Pseudomonas aeruginosa Lectin LecA

Abstract

Multivalent galactosides inhibiting Pseudomonas aeruginosa biofilms may help control this problematic pathogen. To understand the binding mode of tetravalent glycopeptide dendrimer GalAG2 [(Gal-β-OC6H4CO-Lys-Pro-Leu)4(Lys-Phe-Lys-Ile)2Lys-His-Ile-NH2] to its target lectin LecA, crystal structures of LecA complexes with divalent analog GalAG1 [(Gal-β-OC6H4CO-Lys-Pro-Leu)2Lys-Phe-Lys-Ile-NH2] and related glucose-triazole linked bis-galactosides 3u3 [Gal-β-O(CH2)n-(C2HN3)-4-Glc-β-(C2HN3)-[β-Glc-4-(N3HC2)]2-(CH2)n-O-β-Gal (n = 1)] and 5u3 (n = 3) were obtained, revealing a chelate bound 3u3, cross-linked 5u3, and monovalently bound GalAG1. Nevertheless, a chelate bound model better explaining their strong LecA binding and the absence of lectin aggregation was obtained by modeling for all three ligands. A model of the chelate bound GalAG2·LecA complex was also obtained rationalizing its unusually tight LecA binding (KD = 2.5 nM) and aggregation by lectin cross-linking. The very weak biofilm inhibition with divalent LecA inhibitors suggests that lectin aggregation is necessary for biofilm inhibition by GalAG2, pointing to multivalent glycoclusters as a unique opportunity to control P. aeruginosa biofilms.

Multivalency effects on Pseudomonas aeruginosa biofilm inhibition and dispersal by glycopeptide dendrimers targeting lectin LecA

“….6 ± 0.5 4.04 6.53 16 000 ± 500 -IPTG Isopropyl-β-thiogalactoside 1 10 400 16 5.9 ± 2 785 a Sequence notation for peptide dendrimers using single letter amino acid codes for L-amino acids and indicating the branching lysine in italics. See Fig.…”

“…14 These dendrimers bound tightly to their respective lectin, and inhibited the formation and induced partial dispersion of P. aeruginosa biofilms, representing an interesting example of bioactive synthetic dendrimers. 16 In the case of the GalAG2 lectin binding was enhanced by a specific CH-π interaction between the (ε)-CH of His50 on LecA and the aromatic ring of the GalA aglycone leading to further binding interactions between the terminal tripeptide arm of the dendrimer and LecA, however optimization of the amino acid sequence of this tripeptide only resulted in modest activity improvements. 16 In the case of the GalAG2 lectin binding was enhanced by a specific CH-π interaction between the (ε)-CH of His50 on LecA and the aromatic ring of the GalA aglycone leading to further binding interactions between the terminal tripeptide arm of the dendrimer and LecA, however optimization of the amino acid sequence of this tripeptide only resulted in modest activity improvements.…”

Multivalent Fucosides with Nanomolar Affinity for the Aspergillus fumigatus Lectin FleA Prevent Spore Adhesion to Pneumocytes

“…In the chelate binding mode, multivalent ligands occupy at least two binding sites of the multivalent receptor (the lectin) simultaneously.A fter the first interaction, subsequent binding events are favoredo ver dissociation of the ligand-receptor complex, due to the high ligand concentration in close proximity to additional receptor binding sites and to the lower entropic cost of subsequent binding events. Chelate interactions have been shown to improve the affinity of clustered sugars compared with their monovalent references by severalo rders of magnitude on several multimeric lectin targets, [7][8][9] such as wheat germ agglutinin (WGA), [10] Shiga-like toxins from Escherichiac oli, [11][12][13] LecA and LecB lectinsf rom Pseudomonas aeruginosa, [14][15][16][17][18][19][20][21] dendritic-cell-specific ICAM-3 grabbing non-integrin( DC-SIGN), [22][23][24][25] and PHL from Gram-negative Photorhabdus asymbiotica. [26] In comparison, multivalent fucosides of FleA have been little studied,w ith the exception of au nique, recent report of ap otent hexavalent aryl-fucose mimetic.…”

Purification, partial characterization and antimicrobial activity of Lectin from Chenopodium Quinoa seeds

“…They are a large and diverse group of proteins that have the ability to bind reversibly to monosaccharides and oligosaccharides, which can be defined as a class of structurally diverse proteins or glycoproteins (Sharon, 2008). These proteins are widely distributed in nature, being found in microorganisms (Visini et al, 2015), animals (Lundbo et al, 2015) and plants (Silva et al, 2007).…”