Synthesis of Gb₃ Glycosphingolipids with Labeled Head Groups: Distribution in Phase‐Separated Giant Unilamellar Vesicles

Abstract

The receptor lipid Gb 3 is responsible for the specific internalization of Shiga toxin (STx) into cells.The head group of Gb 3 defines the specificity of STx binding,and the backbone with different fatty acids is expected to influence its localization within membranes impacting membrane organization and protein internalization. To investigate this influence,aset of Gb 3 glycosphingolipids labeled with aB ODIPY fluorophore attached to the head group was synthesized. C 24 fatty acids, saturated, unsaturated, a-hydroxylated derivatives,and acombination thereof,w ere attached to the sphingosine backbone. The synthetic Gb 3 glycosphingolipids were reconstituted into coexisting liquid-ordered (l o )/liquid-disordered (l d )g iant unilamellar vesicles (GUVs), and STx binding was verified by fluorescence microscopy. Gb 3 with the C 24:0 fatty acid partitioned mostly in the l o phase,w hile the unsaturated C 24:1 fatty acid distributes more into the l d phase.T he a-hydroxylation does not influence its partitioning.

GlycoBODIPYs: Sugars Serving as a Natural Stock for Water‐soluble Fluorescent Probes of Complex Chiral Morphology

“…[15] Certain hydroxy functions or even complete sugar units can be redundant or derivatized, [16] as was also recently found in our group. [17] Although BODIPYs have already been transformed into water-soluble analogues by various approaches (Scheme 1) such as by sulfonation, [18] introduction of ammonium, [19] carboxylate, [20] multiple PEG residues, [21] or recently by a bistriflyl-substituted carbanion, [22] most of them suffer from a tedious synthetic route (sulfonated peptidyl linkers), [19] the incorporation of unnecessary structural ballast (PEG), or from the introduced charge, which can impair facile cell-uptake and further functionalizations in organic media. Furthermore, the native fluorescence of BODIPYs can often be substantially compromised after the derivatization process (PEG, peptidyl linkers, meso pyridinium [23] ).…”

The bacterial lectin LecA from P. aeruginosa alters membrane organization by dispersing ordered domains

“…Experiments with LecA binding exclusively to Lo domains would provide further insight. Unfortunately, most of Gb3 species yet available demonstrate in the best-case preferential incorporation in Lo domains 41,44-46 . Hereby, we conclude that LecA structure, valence as well as its specificity to membrane domains are decisive factors for the dispersion of Lo domains.…”

Carbohydrate-Based Macromolecular Biomaterials

“…115 Considering that the structure of the alkyl chain may largely affect the membrane organization and protein internalization, Sibold et al prepared various Gb 3 glycosphingolipids labeled with a BODIPY fluorophore. 118 Liquid-ordered (l 0 ) and liquid-disordered (l d ) giant unilamellar vesicles (GUVs) were afforded when the resulting glycosphingolipids were coassembled with other components. Gb 3 with a saturated C 24:0 fatty acid mostly distributes in the l 0 phase, while the unsaturated C 24:1 fatty acid mainly locates in the l d phase, and the Shiga toxin B subunits exclusively bind to Gb 3 in the l 0 phase of the GUVs.…”