Reduction of Lectin Valency Drastically Changes Glycolipid Dynamics in Membranes but Not Surface Avidity

Abstract

Multivalency is proposed to play a role in the strong avidity of lectins for glycosylated cell surfaces and also in their ability to affect membrane dynamics by clustering glycosphingolipids. Lectins with modified valency were designed from the β-propeller fold of Ralstonia solanacearum lectin (RSL) that presents six fucose binding sites. After identification of key amino acids by molecular dynamics calculations, two mutants with reduced valency were produced. Isothermal titration calorimetry confirmed the loss of three high affinity binding sites for both mutants. Crystal structures indicated that residual low affinity binding occurred in W76A but not in R17A. The trivalent R17A mutant presented unchanged avidity toward fucosylated surfaces, when compared to hexavalent RSL. However, R17A is not able anymore to induce formation of membrane invaginations on giant unilamellar vesicules, indicating the crucial role of number of binding sites for clustering of glycolipids. In the human lung epithelial cell line H1299, wt-RSL is internalized within seconds whereas the kinetics of R17A uptake is largely delayed. Neolectins with tailored valency are promising tools to study membrane dynamics.

Dynamic Cooperative Glycan Assembly Blocks the Binding of Bacterial Lectins to Epithelial Cells

“…Zuschriften residence time at concentrations well below duplex formation with av ery slow dissociation phase that is characteristic of multivalent interactions.Asfurther controls,weprepared the equivalent of compound 7b with ag lucose instead of fucose (8)o ro mitting conjugation with ac arbohydrate (9). Neither of these controls had measurable affinities for the lectin (RSL).…”

“…oligosaccharides exposed on glycolipids is sufficient to induce membrane invaginations in giant liposomes. [7,8] Furthermore,o ligomeric interactions are important for this invagination, since mutated lectins bearing only three fucose binding sites (e.g.,t he R17A mutant) also interacted with liposomes but failed to yield invagination. Based on the interest in using nucleic acid hybridization of glycan-PNAc onjugates (PNA = peptide nucleic acid) [9][10][11][12][13][14][15][16] to tailor assemblies that can bridge multiple binding sites in target proteins,w e sought to evaluate the benefit of oligomeric assemblies for RSL and ultimately,t o outcompete the interaction of such lectins with epithelial cells.…”

Discovery of antitumor lectins from rainforest tree root transcriptomes

“…Most known β-protein lectins display 1-3 monosaccharide binding sites, and associate into homo-dimers, homo-tetramers, or homooctamers to increase their effective valency [26][27][28]. These arrangements enhance the capacity, potency, and specificity of lectins to bind their sugar targets, particularly complex N-linked glycans [29]. Uniquely, ML6 possesses six mannose-binding domains, all of which have divergent sequences relative to each other and are spaced in close proximity (22-25 amino acids separate domains; Fig 2A).…”

Plasma membrane reorganization: A glycolipid gateway for microbes

“…RSL consists of a tandem repeat of two β-sheets that trimerizes as a six-bladed β-propeller with six binding sites in total. Reducing the valency from six to three by engineering one of the two binding sites per monomer resulted in a trimeric trivalent lectin that lost the capacity to induce membrane invaginations in GUVs [94]. A further step forward to control the number and the position of each of the binding sites in order to decipher the role of multivalency on membrane dynamics of glycolipids was the design of neolectins [95,96].…”