title: 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.
authors.affiliation: CERMAV-CNRS (affiliated to Grenoble Université and ICMG), BP53, 38041 Grenoble, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Arnaud
authors.forename: Julie
authors.initials: J
authors.lastname: Claudinon
authors.forename: Kevin
authors.initials: K
authors.lastname: Tröndle
authors.forename: Marie
authors.initials: M
authors.lastname: Trovaslet
authors.forename: Göran
authors.initials: G
authors.lastname: Larson
authors.forename: Aline
authors.initials: A
authors.lastname: Thomas
authors.forename: Annabelle
authors.initials: A
authors.lastname: Varrot
authors.forename: Winfried
authors.initials: W
authors.lastname: Römer
authors.forename: Anne
authors.initials: A
authors.lastname: Imberty
authors.forename: Aymeric
authors.initials: A
authors.lastname: Audfray
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D002460:Cell Line; D018360:Crystallography, X-Ray; D006017:Glycolipids / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D037102:Lectins / Q000737:chemistry* / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D043368:Ralstonia solanacearum / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D006017:Glycolipids; D037102:Lectins