Affinities of Shiga toxins 1 and 2 for univalent and oligovalent Pk-trisaccharide analogs measured by electrospray ionization mass spectrometry.
The binding stoichiometry and affinities of the Shiga toxins, Stx1 and Stx2, for a series of uni- and oligovalent analogs of the Pk-trisaccharide were measured using the direct electrospray ionization mass spectrometry (ES-MS) assay. Importantly, it is shown that, for a given ligand, Stx1 and Stx2 exhibit similar affinities. The binding data suggest a high degree of similarity in the spatial arrangement and structural characteristics of the Pk binding sites in Stx1 and Stx2. The results confirm that both toxins recognize the alpha-D-Galp(1-->4)-beta-D-Galp(1-->4)-beta-D-Glcp carbohydrate motif of the cell surface glycolipid Gb3. This, taken together with the results of the chemical mapping study, suggests that the nature of the Pk binding interactions with Stx1 and Stx2 are similar. The affinities of Stx1-B(5) and Stx2 for the multivalent ligands reveals that site 2 of Stx2, which shares the same spatial arrangement as site 2 in Stx1, is the primary Pk binding site and that site 1 of Stx1 and of Stx2 can also participate in Pk binding.
Kitova
Elena N
EN
Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2 G2, Canada.
Kitov
Pavel I
PI
Paszkiewicz
Eugenia
E
Kim
Jonghwa
J
Mulvey
George L
GL
Armstrong
Glen D
GD
Bundle
David R
DR
Klassen
John S
JS
D001427:Bacterial Toxins / Q000378:metabolism; D001665:Binding Sites; D002240:Carbohydrate Sequence; D008969:Molecular Sequence Data; D036103:Nanotechnology; D022622:Shiga Toxin 1 / Q000737:chemistry / Q000378:metabolism*; D022641:Shiga Toxin 2 / Q000737:chemistry / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D014281:Trihexosylceramides / Q000378:metabolism; D014312:Trisaccharides / Q000737:chemistry / Q000378:metabolism*
D001427:Bacterial Toxins; D022622:Shiga Toxin 1; D022641:Shiga Toxin 2; D014281:Trihexosylceramides; D014312:Trisaccharides; C018549:globotriaosylceramide