title: Carbohydrate conformation and lipid condensation in monolayers containing glycosphingolipid Gb3: influence of acyl chain structure.
abstract: Globotriaosylceramide (Gb3), a glycosphingolipid found in the plasma membrane of animal cells, is the endocytic receptor of the bacterial Shiga toxin. Using x-ray reflectivity (XR) and grazing incidence x-ray diffraction (GIXD), lipid monolayers containing Gb3 were investigated at the air-water interface. XR probed Gb3 carbohydrate conformation normal to the interface, whereas GIXD precisely characterized Gb3's influence on acyl chain in-plane packing and area per molecule (APM). Two phospholipids, 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), were used to study Gb3 packing in different lipid environments. Furthermore, the impact on monolayer structure of a naturally extracted Gb3 mixture was compared to synthetic Gb3 species with uniquely defined acyl chain structures. XR results showed that lipid environment and Gb3 acyl chain structure impact carbohydrate conformation with greater solvent accessibility observed for smaller phospholipid headgroups and long Gb3 acyl chains. In general, GIXD showed that Gb3 condensed phospholipid packing resulting in smaller APM than predicted by ideal mixing. Gb3's capacity to condense APM was larger for DSPC monolayers and exhibited different dependencies on acyl chain structure depending on the lipid environment. The interplay between Gb3-induced changes in lipid packing and the lipid environment's impact on carbohydrate conformation has broad implications for glycosphingolipid macromolecule recognition and ligand binding.
authors.affiliation: Institut Laue-Langevin, 38042 Grenoble Cedex 9, France. Electronic address: erik.b.watkins@gmail.com.
authors.forename: Erik B
authors.initials: EB
authors.lastname: Watkins
authors.affiliation: Institut Curie, Centre de Recherche, 75248 Paris Cedex 5, France; CNRS UMR3666, 75005 Paris, France; INSERM U1143, 75005 Paris, France.
authors.forename: Haifei
authors.initials: H
authors.lastname: Gao
authors.affiliation: Institut Laue-Langevin, 38042 Grenoble Cedex 9, France; Department of Physics and Astronomy, Box 516. SE-751 20, Uppsala University, Uppsala, Sweden.
authors.forename: Andrew J C
authors.initials: AJC
authors.lastname: Dennison
authors.affiliation: Institut Curie, Centre de Recherche, 75248 Paris Cedex 5, France; CNRS UMR3666, 75005 Paris, France; INSERM U1143, 75005 Paris, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Chopin
authors.affiliation: HASYLAB at DESY, Notkestrasse 85 D-22603, Hamburg, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Struth
authors.affiliation: Diamond Light Source, Harwell Science and Innovation Campus, Chilton, United Kingdom.
authors.forename: Thomas
authors.initials: T
authors.lastname: Arnold
authors.affiliation: Institut Curie, Centre de Recherche, 75248 Paris Cedex 5, France; CNRS UMR3666, 75005 Paris, France; INSERM U1143, 75005 Paris, France.
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Florent
authors.affiliation: Institut Curie, Centre de Recherche, 75248 Paris Cedex 5, France; CNRS UMR3666, 75005 Paris, France; INSERM U1143, 75005 Paris, France.
authors.forename: Ludger
authors.initials: L
authors.lastname: Johannes
mesh_terms: D000388:Air; D000818:Animals; D002236:Carbohydrate Conformation; D004912:Erythrocytes / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry; D011312:Pressure; D012997:Solvents / Q000737:chemistry; D013499:Surface Properties; D013552:Swine; D014281:Trihexosylceramides / Q000737:chemistry*; D014867:Water; D014961:X-Ray Diffraction
chemical_list: D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D012997:Solvents; D014281:Trihexosylceramides; D014867:Water; C007510:1,2-dipalmitoyl-3-phosphatidylethanolamine; C018549:globotriaosylceramide; C010942:1,2-distearoyllecithin