Promiscuous Shiga toxin 2e and its intimate relationship to Forssman

Abstract

Shiga toxin (Stx) 2e of Stx-producing Escherichia coli (STEC) represents the major virulence factor responsible for the pig edema disease which is characterized by hemorrhagic lesions, neurological disorders and often fatal outcomes. Stx2e-producing strains from the intestine of slaughtered pigs (n = 3), feces of piglets with postweaning diarrhea or edema disease (n = 12) and feces of humans with asymptomatic infections or mild diarrhea (n = 13) were comparatively analyzed for the binding specificities of Stx2e to glycosphingolipids (GSLs) of the globo-series. Besides equivalent binding towards globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer), we could demonstrate specific interaction of Stx2e preparations from human and porcine STEC isolates with Forssman GSL. Notably, Forssman GSL was recognized neither by structurally closely related Stx2 nor by Stx1 derived from human STEC isolates conferring Stx2e a unique recognition feature. Noteworthy, 7 (54%) of the 13 human and 8 (53%) of the 15 pig Stx2e samples exhibited cytotoxic action towards human brain microvascular endothelial cells. Our findings provide a basis for further exploring the functional role of the promiscuous receptor repertoire of Stx2e and the exact nature of the mechanisms that underlie different pathological outcomes of Stx2e-producing STEC in humans and pigs.

Shiga toxin glycosphingolipid receptors of Vero-B4 kidney epithelial cells and their membrane microdomain lipid environment

“…After retrograde routing of the holotoxin to the endoplasmic reticulum and cleavage of the A subunit, the A 1 fragment halts eukaryotic protein biosynthesis by inactivating ribosomes leading to cell death ( 36,37 ). The Stx subtypes, Stx1a, Stx2a, and Stx2e [for nomenclature of Stx subtypes refer to Scheutz et al ( 38 )], which have so far been investigated in more detail, can be distinguished with regard to their exact binding specifi city ( 39 ). Variants of the Stx1a subtype have been shown to exhibit preferential and moderate binding toward globotriaosylceramide (Gb3Cer, Gal ␣ 4Gal ␤ 4Glc ␤ 1Cer) and globotetraosylceramide (Gb4Cer, GalNAc ␤ 3Gal ␣ 4Gal ␤ 4Glc ␤ 1Cer), respectively.…”

“…Variants of the Stx1a subtype have been shown to exhibit preferential and moderate binding toward globotriaosylceramide (Gb3Cer, Gal ␣ 4Gal ␤ 4Glc ␤ 1Cer) and globotetraosylceramide (Gb4Cer, GalNAc ␤ 3Gal ␣ 4Gal ␤ 4Glc ␤ 1Cer), respectively. Stx2a variants prefer Gb3Cer and exhibit only marginal binding toward Gb4Cer, while Stx2e binds, in addition to Gb3Cer and a preference for Gb4Cer, also to the Forssman GSL, which represents a pentahexosylceramide with GalNAc ␣ 3GalNAc ␤ 3Gal ␣ 4Gal ␤ 4Glc ␤ 1Cer structure ( 39 ), indicating promiscuous binding of Stx2e to globo-series-related GSLs with elongated Gb3Cer/Gb4Cer core structures.…”

“…TLC immunostainings were done as described in several previous publications ( 62,63,70,72 ). In short, Stx1a-, Stx2a-, or Stx2e-containing supernatants (see Stx1a, Stx2a, Stx2e, anti-Stx, anti-GSL, and secondary antibodies above) were employed using the "microscale method" ( 39,77 ). The anti-Stx1 and anti-Stx2 antibodies were used in 1:1,000 dilutions, respectively, and primary anti-Gb3Cer and anti-Gb4Cer antibodies, as well as secondary alkaline phosphatase-conjugated antibodies, were applied in 1:2,000 dilutions each.…”

FORS, a new histo-blood group: A current review

“…but not in others (rabbits, pigs, humans, etc. ), referred to as FORS positive species and FORS negative species, respectively [4,7,8].…”

“…The expression of FORS Ag has been reported in cancer cells and tissues [8], and is a cancer epitope of interest. It is a normal constituent of fetal tissues and virtually absent in healthy adults, but it has been detected in elevated levels in various human lung, breast, and gastric cancer cell lines [19,20].…”