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Glycolipid Binding Preferences of Shiga Toxin Variants

The major virulence factor of Shiga toxin producing E. coli, is Shiga toxin (Stx), an AB(5) toxin that consists of a ribosomal RNA-cleaving A-subunit surrounded by a pentamer of receptor-binding B subunits. The two major isoforms, Stx1 and Stx2, and Stx2 variants (Stx2a-h) significantly differ in to...

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Autores principales: Karve, Sayali S., Weiss, Alison A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4077739/
https://www.ncbi.nlm.nih.gov/pubmed/24983355
http://dx.doi.org/10.1371/journal.pone.0101173
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author Karve, Sayali S.
Weiss, Alison A.
author_facet Karve, Sayali S.
Weiss, Alison A.
author_sort Karve, Sayali S.
collection PubMed
description The major virulence factor of Shiga toxin producing E. coli, is Shiga toxin (Stx), an AB(5) toxin that consists of a ribosomal RNA-cleaving A-subunit surrounded by a pentamer of receptor-binding B subunits. The two major isoforms, Stx1 and Stx2, and Stx2 variants (Stx2a-h) significantly differ in toxicity. The exact reason for this toxicity difference is unknown, however different receptor binding preferences are speculated to play a role. Previous studies used enzyme linked immunosorbent assay (ELISA) to study binding of Stx1 and Stx2a toxoids to glycolipid receptors. Here, we studied binding of holotoxin and B-subunits of Stx1, Stx2a, Stx2b, Stx2c and Stx2d to glycolipid receptors globotriaosylceramide (Gb3) and globotetraosylceramide (Gb4) in the presence of cell membrane components such as phosphatidylcholine (PC), cholesterol (Ch) and other neutral glycolipids. In the absence of PC and Ch, holotoxins of Stx2 variants bound to mixtures of Gb3 with other glycolipids but not to Gb3 or Gb4 alone. Binding of all Stx holotoxins significantly increased in the presence of PC and Ch. Previously, Stx2a has been shown to form a less stable B-pentamer compared to Stx1. However, its effect on glycolipid receptor binding is unknown. In this study, we showed that even in the absence of the A-subunit, the B-subunits of both Stx1 and Stx2a were able to bind to the glycolipids and the more stable B-pentamer formed by Stx1 bound better than the less stable pentamer of Stx2a. B-subunit mutant of Stx1 L41Q, which shows similar stability as Stx2a B-subunits, lacked glycolipid binding, suggesting that pentamerization is more critical for binding of Stx1 than Stx2a.
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spelling pubmed-40777392014-07-03 Glycolipid Binding Preferences of Shiga Toxin Variants Karve, Sayali S. Weiss, Alison A. PLoS One Research Article The major virulence factor of Shiga toxin producing E. coli, is Shiga toxin (Stx), an AB(5) toxin that consists of a ribosomal RNA-cleaving A-subunit surrounded by a pentamer of receptor-binding B subunits. The two major isoforms, Stx1 and Stx2, and Stx2 variants (Stx2a-h) significantly differ in toxicity. The exact reason for this toxicity difference is unknown, however different receptor binding preferences are speculated to play a role. Previous studies used enzyme linked immunosorbent assay (ELISA) to study binding of Stx1 and Stx2a toxoids to glycolipid receptors. Here, we studied binding of holotoxin and B-subunits of Stx1, Stx2a, Stx2b, Stx2c and Stx2d to glycolipid receptors globotriaosylceramide (Gb3) and globotetraosylceramide (Gb4) in the presence of cell membrane components such as phosphatidylcholine (PC), cholesterol (Ch) and other neutral glycolipids. In the absence of PC and Ch, holotoxins of Stx2 variants bound to mixtures of Gb3 with other glycolipids but not to Gb3 or Gb4 alone. Binding of all Stx holotoxins significantly increased in the presence of PC and Ch. Previously, Stx2a has been shown to form a less stable B-pentamer compared to Stx1. However, its effect on glycolipid receptor binding is unknown. In this study, we showed that even in the absence of the A-subunit, the B-subunits of both Stx1 and Stx2a were able to bind to the glycolipids and the more stable B-pentamer formed by Stx1 bound better than the less stable pentamer of Stx2a. B-subunit mutant of Stx1 L41Q, which shows similar stability as Stx2a B-subunits, lacked glycolipid binding, suggesting that pentamerization is more critical for binding of Stx1 than Stx2a. Public Library of Science 2014-07-01 /pmc/articles/PMC4077739/ /pubmed/24983355 http://dx.doi.org/10.1371/journal.pone.0101173 Text en © 2014 Karve, Weiss http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Karve, Sayali S.
Weiss, Alison A.
Glycolipid Binding Preferences of Shiga Toxin Variants
title Glycolipid Binding Preferences of Shiga Toxin Variants
title_full Glycolipid Binding Preferences of Shiga Toxin Variants
title_fullStr Glycolipid Binding Preferences of Shiga Toxin Variants
title_full_unstemmed Glycolipid Binding Preferences of Shiga Toxin Variants
title_short Glycolipid Binding Preferences of Shiga Toxin Variants
title_sort glycolipid binding preferences of shiga toxin variants
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4077739/
https://www.ncbi.nlm.nih.gov/pubmed/24983355
http://dx.doi.org/10.1371/journal.pone.0101173
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