Structure-function analyses of a pertussis-like toxin from pathogenic Escherichia coli reveal a distinct mechanism of inhibition of trimeric G-proteins

Dene R. Littler, Sheng Y. Ang, Danilo G. Moriel, Martina Kocan, Oded Kleifeld, Matthew D. Johnson, Mai T. Tran, Adrienne Webster Paton, James C Paton, Roger J. Summers, Mark A. Schembri, Jamie Rossjohn, Travis Beddoe

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Pertussis-like toxins are secreted by several bacterial pathogens during infection. They belong to the AB5 virulence factors, which bind to glycans on host cell membranes for internalization. Host cell recognition and internalization are mediated by toxin B subunits sharing a unique pentameric ring-like assembly. Although the role of pertussis toxin in whooping cough is well-established, pertussis-like toxins produced by other bacteria are less studied, and their mechanisms of action are unclear. Here, we report that some extra-intestinal Escherichia coli pathogens (i.e. those that reside in the gut but can spread to other bodily locations) encode a pertussis-like toxin that inhibits mammalian cell growth in vitro. We found that this protein, EcPlt, is related to toxins produced by both nontyphoidal and typhoidal Salmonella serovars. Pertussis-like toxins are secreted as disulfide-bonded heterohexamers in which the catalytic ADP-ribosyltransferase subunit is activated when exposed to the reducing environment in mammalian cells. We found here that the reduced EcPlt exhibits large structural rearrangements associated with its activation. We noted that inhibitory residues tethered within the NAD+-binding site by an intramolecular disulfide in the oxidized state dissociate upon the reduction and enable loop restructuring to form the nucleotide-binding site. Surprisingly, although pertussis toxin targets a cysteine residue within the α subunit of inhibitory trimeric G-proteins, we observed that activated EcPlt toxin modifies a proximal lysine/asparagine residue instead. In conclusion, our results reveal the molecular mechanism underpinning activation of pertussis-like toxins, and we also identified differences in host target specificity.

Original languageEnglish
Pages (from-to)15143-15158
Number of pages16
JournalJournal of Biological Chemistry
Volume292
Issue number36
DOIs
Publication statusPublished - 8 Sep 2017

Keywords

  • ADP-ribosylation
  • Bacterial adhesion
  • Bordetella pertussis
  • cholera toxin
  • Escherichia coli (E.Coli)
  • host-pathogen interaction
  • toxin

Cite this

Littler, Dene R. ; Ang, Sheng Y. ; Moriel, Danilo G. ; Kocan, Martina ; Kleifeld, Oded ; Johnson, Matthew D. ; Tran, Mai T. ; Paton, Adrienne Webster ; Paton, James C ; Summers, Roger J. ; Schembri, Mark A. ; Rossjohn, Jamie ; Beddoe, Travis. / Structure-function analyses of a pertussis-like toxin from pathogenic Escherichia coli reveal a distinct mechanism of inhibition of trimeric G-proteins. In: Journal of Biological Chemistry. 2017 ; Vol. 292, No. 36. pp. 15143-15158.
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abstract = "Pertussis-like toxins are secreted by several bacterial pathogens during infection. They belong to the AB5 virulence factors, which bind to glycans on host cell membranes for internalization. Host cell recognition and internalization are mediated by toxin B subunits sharing a unique pentameric ring-like assembly. Although the role of pertussis toxin in whooping cough is well-established, pertussis-like toxins produced by other bacteria are less studied, and their mechanisms of action are unclear. Here, we report that some extra-intestinal Escherichia coli pathogens (i.e. those that reside in the gut but can spread to other bodily locations) encode a pertussis-like toxin that inhibits mammalian cell growth in vitro. We found that this protein, EcPlt, is related to toxins produced by both nontyphoidal and typhoidal Salmonella serovars. Pertussis-like toxins are secreted as disulfide-bonded heterohexamers in which the catalytic ADP-ribosyltransferase subunit is activated when exposed to the reducing environment in mammalian cells. We found here that the reduced EcPlt exhibits large structural rearrangements associated with its activation. We noted that inhibitory residues tethered within the NAD+-binding site by an intramolecular disulfide in the oxidized state dissociate upon the reduction and enable loop restructuring to form the nucleotide-binding site. Surprisingly, although pertussis toxin targets a cysteine residue within the α subunit of inhibitory trimeric G-proteins, we observed that activated EcPlt toxin modifies a proximal lysine/asparagine residue instead. In conclusion, our results reveal the molecular mechanism underpinning activation of pertussis-like toxins, and we also identified differences in host target specificity.",
keywords = "ADP-ribosylation, Bacterial adhesion, Bordetella pertussis, cholera toxin, Escherichia coli (E.Coli), host-pathogen interaction, toxin",
author = "Littler, {Dene R.} and Ang, {Sheng Y.} and Moriel, {Danilo G.} and Martina Kocan and Oded Kleifeld and Johnson, {Matthew D.} and Tran, {Mai T.} and Paton, {Adrienne Webster} and Paton, {James C} and Summers, {Roger J.} and Schembri, {Mark A.} and Jamie Rossjohn and Travis Beddoe",
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Structure-function analyses of a pertussis-like toxin from pathogenic Escherichia coli reveal a distinct mechanism of inhibition of trimeric G-proteins. / Littler, Dene R.; Ang, Sheng Y.; Moriel, Danilo G.; Kocan, Martina; Kleifeld, Oded; Johnson, Matthew D.; Tran, Mai T.; Paton, Adrienne Webster; Paton, James C; Summers, Roger J.; Schembri, Mark A.; Rossjohn, Jamie; Beddoe, Travis.

In: Journal of Biological Chemistry, Vol. 292, No. 36, 08.09.2017, p. 15143-15158.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Structure-function analyses of a pertussis-like toxin from pathogenic Escherichia coli reveal a distinct mechanism of inhibition of trimeric G-proteins

AU - Littler, Dene R.

AU - Ang, Sheng Y.

AU - Moriel, Danilo G.

AU - Kocan, Martina

AU - Kleifeld, Oded

AU - Johnson, Matthew D.

AU - Tran, Mai T.

AU - Paton, Adrienne Webster

AU - Paton, James C

AU - Summers, Roger J.

AU - Schembri, Mark A.

AU - Rossjohn, Jamie

AU - Beddoe, Travis

PY - 2017/9/8

Y1 - 2017/9/8

N2 - Pertussis-like toxins are secreted by several bacterial pathogens during infection. They belong to the AB5 virulence factors, which bind to glycans on host cell membranes for internalization. Host cell recognition and internalization are mediated by toxin B subunits sharing a unique pentameric ring-like assembly. Although the role of pertussis toxin in whooping cough is well-established, pertussis-like toxins produced by other bacteria are less studied, and their mechanisms of action are unclear. Here, we report that some extra-intestinal Escherichia coli pathogens (i.e. those that reside in the gut but can spread to other bodily locations) encode a pertussis-like toxin that inhibits mammalian cell growth in vitro. We found that this protein, EcPlt, is related to toxins produced by both nontyphoidal and typhoidal Salmonella serovars. Pertussis-like toxins are secreted as disulfide-bonded heterohexamers in which the catalytic ADP-ribosyltransferase subunit is activated when exposed to the reducing environment in mammalian cells. We found here that the reduced EcPlt exhibits large structural rearrangements associated with its activation. We noted that inhibitory residues tethered within the NAD+-binding site by an intramolecular disulfide in the oxidized state dissociate upon the reduction and enable loop restructuring to form the nucleotide-binding site. Surprisingly, although pertussis toxin targets a cysteine residue within the α subunit of inhibitory trimeric G-proteins, we observed that activated EcPlt toxin modifies a proximal lysine/asparagine residue instead. In conclusion, our results reveal the molecular mechanism underpinning activation of pertussis-like toxins, and we also identified differences in host target specificity.

AB - Pertussis-like toxins are secreted by several bacterial pathogens during infection. They belong to the AB5 virulence factors, which bind to glycans on host cell membranes for internalization. Host cell recognition and internalization are mediated by toxin B subunits sharing a unique pentameric ring-like assembly. Although the role of pertussis toxin in whooping cough is well-established, pertussis-like toxins produced by other bacteria are less studied, and their mechanisms of action are unclear. Here, we report that some extra-intestinal Escherichia coli pathogens (i.e. those that reside in the gut but can spread to other bodily locations) encode a pertussis-like toxin that inhibits mammalian cell growth in vitro. We found that this protein, EcPlt, is related to toxins produced by both nontyphoidal and typhoidal Salmonella serovars. Pertussis-like toxins are secreted as disulfide-bonded heterohexamers in which the catalytic ADP-ribosyltransferase subunit is activated when exposed to the reducing environment in mammalian cells. We found here that the reduced EcPlt exhibits large structural rearrangements associated with its activation. We noted that inhibitory residues tethered within the NAD+-binding site by an intramolecular disulfide in the oxidized state dissociate upon the reduction and enable loop restructuring to form the nucleotide-binding site. Surprisingly, although pertussis toxin targets a cysteine residue within the α subunit of inhibitory trimeric G-proteins, we observed that activated EcPlt toxin modifies a proximal lysine/asparagine residue instead. In conclusion, our results reveal the molecular mechanism underpinning activation of pertussis-like toxins, and we also identified differences in host target specificity.

KW - ADP-ribosylation

KW - Bacterial adhesion

KW - Bordetella pertussis

KW - cholera toxin

KW - Escherichia coli (E.Coli)

KW - host-pathogen interaction

KW - toxin

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EP - 15158

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