Preprint Article Version 2 Preserved in Portico This version is not peer-reviewed

Specificity of Escherichia coli Heat-Labile Enterotoxin Investigated by Single-Site Mutagenesis and Crystallography

Version 1 : Received: 18 December 2018 / Approved: 19 December 2018 / Online: 19 December 2018 (16:20:44 CET)
Version 2 : Received: 28 January 2019 / Approved: 28 January 2019 / Online: 28 January 2019 (15:23:24 CET)

A peer-reviewed article of this Preprint also exists.

Heggelund, J.E.; Heim, J.B.; Bajc, G.; Hodnik, V.; Anderluh, G.; Krengel, U. Specificity of Escherichia coli Heat-Labile Enterotoxin Investigated by Single-Site Mutagenesis and Crystallography. Int. J. Mol. Sci. 2019, 20, 703. Heggelund, J.E.; Heim, J.B.; Bajc, G.; Hodnik, V.; Anderluh, G.; Krengel, U. Specificity of Escherichia coli Heat-Labile Enterotoxin Investigated by Single-Site Mutagenesis and Crystallography. Int. J. Mol. Sci. 2019, 20, 703.

Abstract

Diarrhoea caused by enterotoxigenic Escherichia coli is one of the leading causes of mortality in children under five years of age and is a great burden on developing countries. The major virulence factor of the bacterium is the heat-labile enterotoxin (LT), a close homologue of the cholera toxin. The toxins bind to carbohydrate receptors in the gastrointestinal tract, leading to toxin uptake and, ultimately, to severe diarrhoea. Previously, LT from human- and porcine-infecting ETEC (hLT and pLT, respectively) were shown to have different carbohydrate-binding specificities, in particular with respect to N-acetyllactosamine-terminating glycosphingolipids. Here, we probed eleven single-residue variants of the heat-labile enterotoxin with surface plasmon resonance spectroscopy and compared the data to the parent toxins. In addition we present a 1.45 Å crystal structure of pLTB in complex with branched Lacto-N-neohexaose (Galbeta4GlcNAcbeta6[Galbeta4GlcNAcbeta3]Galbeta4Glc). The largest difference in binding specificity is caused by mutation of residue 94, which links the primary and secondary binding sites of the toxins. Residue 95 (and to a smaller extent also residues 7 and 18) also contribute, whereas residue 4 shows no effect on monovalent binding of the ligand and may rather be important for multivalent binding and avidity.

Keywords

bacterial toxin; cholera toxin; Escherichia coli heat-labile enterotoxin; lectin; N-acetyllactosamine binding; neutral glycosphingolipids; protein-carbohydrate interactions; surface plasmon resonance spectroscopy; X-ray crystal structure

Subject

Biology and Life Sciences, Biochemistry and Molecular Biology

Comments (0)

We encourage comments and feedback from a broad range of readers. See criteria for comments and our Diversity statement.

Leave a public comment
Send a private comment to the author(s)
* All users must log in before leaving a comment
Views 0
Downloads 0
Comments 0


×
Alerts
Notify me about updates to this article or when a peer-reviewed version is published.
We use cookies on our website to ensure you get the best experience.
Read more about our cookies here.